From 33cc3b9dd7bf3dae1c6cf86e46bb4923f96e7fff Mon Sep 17 00:00:00 2001
From: トトも <85485984+ElectronicsArchiver@users.noreply.github.com>
Date: Sat, 16 Apr 2022 20:18:56 +0200
Subject: Source / Include Folder (#88)

Moved Source Files Into `src` Folder
---
 src/parse.c | 3959 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 3959 insertions(+)
 create mode 100644 src/parse.c

(limited to 'src/parse.c')

diff --git a/src/parse.c b/src/parse.c
new file mode 100644
index 0000000..65087a0
--- /dev/null
+++ b/src/parse.c
@@ -0,0 +1,3959 @@
+/****************************************************************************
+ * bfs                                                                      *
+ * Copyright (C) 2015-2022 Tavian Barnes <tavianator@tavianator.com>        *
+ *                                                                          *
+ * Permission to use, copy, modify, and/or distribute this software for any *
+ * purpose with or without fee is hereby granted.                           *
+ *                                                                          *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES *
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF         *
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR  *
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES   *
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN    *
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF  *
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.           *
+ ****************************************************************************/
+
+/**
+ * The command line parser.  Expressions are parsed by recursive descent, with a
+ * grammar described in the comments of the parse_*() functions.  The parser
+ * also accepts flags and paths at any point in the expression, by treating
+ * flags like always-true options, and skipping over paths wherever they appear.
+ */
+
+#include "parse.h"
+#include "bfs.h"
+#include "bftw.h"
+#include "color.h"
+#include "ctx.h"
+#include "darray.h"
+#include "diag.h"
+#include "dir.h"
+#include "eval.h"
+#include "exec.h"
+#include "expr.h"
+#include "fsade.h"
+#include "opt.h"
+#include "printf.h"
+#include "pwcache.h"
+#include "stat.h"
+#include "typo.h"
+#include "util.h"
+#include "xregex.h"
+#include "xspawn.h"
+#include "xtime.h"
+#include <assert.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <fnmatch.h>
+#include <grp.h>
+#include <limits.h>
+#include <pwd.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/time.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+#include <time.h>
+#include <unistd.h>
+
+// Strings printed by -D tree for "fake" expressions
+static char *fake_and_arg = "-a";
+static char *fake_false_arg = "-false";
+static char *fake_hidden_arg = "-hidden";
+static char *fake_or_arg = "-o";
+static char *fake_print_arg = "-print";
+static char *fake_true_arg = "-true";
+
+// Cost estimation constants
+#define FAST_COST     40.0
+#define STAT_COST   1000.0
+#define PRINT_COST 20000.0
+
+struct bfs_expr bfs_true = {
+	.eval_fn = eval_true,
+	.argc = 1,
+	.argv = &fake_true_arg,
+	.pure = true,
+	.always_true = true,
+	.synthetic = true,
+	.cost = FAST_COST,
+	.probability = 1.0,
+};
+
+struct bfs_expr bfs_false = {
+	.eval_fn = eval_false,
+	.argc = 1,
+	.argv = &fake_false_arg,
+	.pure = true,
+	.always_false = true,
+	.synthetic = true,
+	.cost = FAST_COST,
+	.probability = 0.0,
+};
+
+void bfs_expr_free(struct bfs_expr *expr) {
+	if (!expr || expr == &bfs_true || expr == &bfs_false) {
+		return;
+	}
+
+	if (bfs_expr_has_children(expr)) {
+		bfs_expr_free(expr->rhs);
+		bfs_expr_free(expr->lhs);
+	} else if (expr->eval_fn == eval_exec) {
+		bfs_exec_free(expr->exec);
+	} else if (expr->eval_fn == eval_fprintf) {
+		bfs_printf_free(expr->printf);
+	} else if (expr->eval_fn == eval_regex) {
+		bfs_regfree(expr->regex);
+	}
+
+	free(expr);
+}
+
+struct bfs_expr *bfs_expr_new(bfs_eval_fn *eval_fn, size_t argc, char **argv) {
+	struct bfs_expr *expr = malloc(sizeof(*expr));
+	if (!expr) {
+		perror("malloc()");
+		return NULL;
+	}
+
+	expr->eval_fn = eval_fn;
+	expr->argc = argc;
+	expr->argv = argv;
+	expr->persistent_fds = 0;
+	expr->ephemeral_fds = 0;
+	expr->pure = false;
+	expr->always_true = false;
+	expr->always_false = false;
+	expr->synthetic = false;
+	expr->cost = FAST_COST;
+	expr->probability = 0.5;
+	expr->evaluations = 0;
+	expr->successes = 0;
+	expr->elapsed.tv_sec = 0;
+	expr->elapsed.tv_nsec = 0;
+	return expr;
+}
+
+/**
+ * Create a new unary expression.
+ */
+static struct bfs_expr *new_unary_expr(bfs_eval_fn *eval_fn, struct bfs_expr *rhs, char **argv) {
+	struct bfs_expr *expr = bfs_expr_new(eval_fn, 1, argv);
+	if (!expr) {
+		bfs_expr_free(rhs);
+		return NULL;
+	}
+
+	expr->lhs = NULL;
+	expr->rhs = rhs;
+	assert(bfs_expr_has_children(expr));
+
+	expr->persistent_fds = rhs->persistent_fds;
+	expr->ephemeral_fds = rhs->ephemeral_fds;
+	return expr;
+}
+
+/**
+ * Create a new binary expression.
+ */
+static struct bfs_expr *new_binary_expr(bfs_eval_fn *eval_fn, struct bfs_expr *lhs, struct bfs_expr *rhs, char **argv) {
+	struct bfs_expr *expr = bfs_expr_new(eval_fn, 1, argv);
+	if (!expr) {
+		bfs_expr_free(rhs);
+		bfs_expr_free(lhs);
+		return NULL;
+	}
+
+	expr->lhs = lhs;
+	expr->rhs = rhs;
+	assert(bfs_expr_has_children(expr));
+
+	if (argv == &fake_and_arg || argv == &fake_or_arg) {
+		expr->synthetic = true;
+	}
+
+	expr->persistent_fds = lhs->persistent_fds + rhs->persistent_fds;
+	if (lhs->ephemeral_fds > rhs->ephemeral_fds) {
+		expr->ephemeral_fds = lhs->ephemeral_fds;
+	} else {
+		expr->ephemeral_fds = rhs->ephemeral_fds;
+	}
+
+	return expr;
+}
+
+bool bfs_expr_has_children(const struct bfs_expr *expr) {
+	return expr->eval_fn == eval_and
+		|| expr->eval_fn == eval_or
+		|| expr->eval_fn == eval_not
+		|| expr->eval_fn == eval_comma;
+}
+
+bool bfs_expr_never_returns(const struct bfs_expr *expr) {
+	// Expressions that never return are vacuously both always true and always false
+	return expr->always_true && expr->always_false;
+}
+
+/**
+ * Set an expression to always return true.
+ */
+static void expr_set_always_true(struct bfs_expr *expr) {
+	expr->always_true = true;
+	expr->probability = 1.0;
+}
+
+/**
+ * Set an expression to never return.
+ */
+static void expr_set_never_returns(struct bfs_expr *expr) {
+	expr->always_true = expr->always_false = true;
+}
+
+/**
+ * Color use flags.
+ */
+enum use_color {
+	COLOR_NEVER,
+	COLOR_AUTO,
+	COLOR_ALWAYS,
+};
+
+/**
+ * Ephemeral state for parsing the command line.
+ */
+struct parser_state {
+	/** The command line being constructed. */
+	struct bfs_ctx *ctx;
+	/** The command line arguments being parsed. */
+	char **argv;
+	/** The name of this program. */
+	const char *command;
+
+	/** The current regex flags to use. */
+	enum bfs_regex_type regex_type;
+
+	/** Whether stdout is a terminal. */
+	bool stdout_tty;
+	/** Whether this session is interactive (stdin and stderr are each a terminal). */
+	bool interactive;
+	/** Whether -color or -nocolor has been passed. */
+	enum use_color use_color;
+	/** Whether a -print action is implied. */
+	bool implicit_print;
+	/** Whether the default root "." should be used. */
+	bool implicit_root;
+	/** Whether the expression has started. */
+	bool expr_started;
+	/** Whether an information option like -help or -version was passed. */
+	bool just_info;
+	/** Whether we are currently parsing an -exclude expression. */
+	bool excluding;
+
+	/** The last non-path argument. */
+	char **last_arg;
+	/** A "-depth"-type argument, if any. */
+	char **depth_arg;
+	/** A "-prune" argument, if any. */
+	char **prune_arg;
+	/** A "-mount" argument, if any. */
+	char **mount_arg;
+	/** An "-xdev" argument, if any. */
+	char **xdev_arg;
+	/** A "-files0-from" argument, if any. */
+	char **files0_arg;
+	/** A "-files0-from -" argument, if any. */
+	char **files0_stdin_arg;
+	/** An "-ok"-type expression, if any. */
+	const struct bfs_expr *ok_expr;
+
+	/** The current time. */
+	struct timespec now;
+};
+
+/**
+ * Possible token types.
+ */
+enum token_type {
+	/** A flag. */
+	T_FLAG,
+	/** A root path. */
+	T_PATH,
+	/** An option. */
+	T_OPTION,
+	/** A test. */
+	T_TEST,
+	/** An action. */
+	T_ACTION,
+	/** An operator. */
+	T_OPERATOR,
+};
+
+/**
+ * Print a low-level error message during parsing.
+ */
+static void parse_perror(const struct parser_state *state, const char *str) {
+	bfs_perror(state->ctx, str);
+}
+
+/** Initialize an empty highlighted range. */
+static void init_highlight(const struct bfs_ctx *ctx, bool *args) {
+	for (size_t i = 0; i < ctx->argc; ++i) {
+		args[i] = false;
+	}
+}
+
+/** Highlight a range of command line arguments. */
+static void highlight_args(const struct bfs_ctx *ctx, char **argv, size_t argc, bool *args) {
+	size_t i = argv - ctx->argv;
+	for (size_t j = 0; j < argc; ++j) {
+		assert(i + j < ctx->argc);
+		args[i + j] = true;
+	}
+}
+
+/**
+ * Print an error message during parsing.
+ */
+BFS_FORMATTER(2, 3)
+static void parse_error(const struct parser_state *state, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bool highlight[ctx->argc];
+	init_highlight(ctx, highlight);
+	highlight_args(ctx, state->argv, 1, highlight);
+	bfs_argv_error(ctx, highlight);
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bfs_verror(state->ctx, format, args);
+	va_end(args);
+}
+
+/**
+ * Print an error about some command line arguments.
+ */
+BFS_FORMATTER(4, 5)
+static void parse_argv_error(const struct parser_state *state, char **argv, size_t argc, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bool highlight[ctx->argc];
+	init_highlight(ctx, highlight);
+	highlight_args(ctx, argv, argc, highlight);
+	bfs_argv_error(ctx, highlight);
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bfs_verror(ctx, format, args);
+	va_end(args);
+}
+
+/**
+ * Print an error about conflicting command line arguments.
+ */
+BFS_FORMATTER(6, 7)
+static void parse_conflict_error(const struct parser_state *state, char **argv1, size_t argc1, char **argv2, size_t argc2, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bool highlight[ctx->argc];
+	init_highlight(ctx, highlight);
+	highlight_args(ctx, argv1, argc1, highlight);
+	highlight_args(ctx, argv2, argc2, highlight);
+	bfs_argv_error(ctx, highlight);
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bfs_verror(ctx, format, args);
+	va_end(args);
+}
+
+/**
+ * Print an error about an expression.
+ */
+BFS_FORMATTER(3, 4)
+static void parse_expr_error(const struct parser_state *state, const struct bfs_expr *expr, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bfs_expr_error(ctx, expr);
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bfs_verror(ctx, format, args);
+	va_end(args);
+}
+
+/**
+ * Print a warning message during parsing.
+ */
+BFS_FORMATTER(2, 3)
+static bool parse_warning(const struct parser_state *state, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bool highlight[ctx->argc];
+	init_highlight(ctx, highlight);
+	highlight_args(ctx, state->argv, 1, highlight);
+	if (!bfs_argv_warning(ctx, highlight)) {
+		return false;
+	}
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bool ret = bfs_vwarning(state->ctx, format, args);
+	va_end(args);
+	return ret;
+}
+
+/**
+ * Print a warning about conflicting command line arguments.
+ */
+BFS_FORMATTER(6, 7)
+static bool parse_conflict_warning(const struct parser_state *state, char **argv1, size_t argc1, char **argv2, size_t argc2, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bool highlight[ctx->argc];
+	init_highlight(ctx, highlight);
+	highlight_args(ctx, argv1, argc1, highlight);
+	highlight_args(ctx, argv2, argc2, highlight);
+	if (!bfs_argv_warning(ctx, highlight)) {
+		return false;
+	}
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bool ret = bfs_vwarning(ctx, format, args);
+	va_end(args);
+	return ret;
+}
+
+/**
+ * Print a warning about an expression.
+ */
+BFS_FORMATTER(3, 4)
+static bool parse_expr_warning(const struct parser_state *state, const struct bfs_expr *expr, const char *format, ...) {
+	int error = errno;
+	const struct bfs_ctx *ctx = state->ctx;
+
+	if (!bfs_expr_warning(ctx, expr)) {
+		return false;
+	}
+
+	va_list args;
+	va_start(args, format);
+	errno = error;
+	bool ret = bfs_vwarning(ctx, format, args);
+	va_end(args);
+	return ret;
+}
+
+/**
+ * Fill in a "-print"-type expression.
+ */
+static void init_print_expr(struct parser_state *state, struct bfs_expr *expr) {
+	expr_set_always_true(expr);
+	expr->cost = PRINT_COST;
+	expr->cfile = state->ctx->cout;
+}
+
+/**
+ * Open a file for an expression.
+ */
+static int expr_open(struct parser_state *state, struct bfs_expr *expr, const char *path) {
+	struct bfs_ctx *ctx = state->ctx;
+
+	FILE *file = NULL;
+	CFILE *cfile = NULL;
+
+	file = xfopen(path, O_WRONLY | O_CREAT | O_TRUNC | O_CLOEXEC);
+	if (!file) {
+		goto fail;
+	}
+
+	cfile = cfwrap(file, state->use_color ? ctx->colors : NULL, true);
+	if (!cfile) {
+		goto fail;
+	}
+
+	CFILE *dedup = bfs_ctx_dedup(ctx, cfile, path);
+	if (!dedup) {
+		goto fail;
+	}
+
+	if (dedup != cfile) {
+		cfclose(cfile);
+	}
+
+	expr->cfile = dedup;
+	return 0;
+
+fail:
+	parse_expr_error(state, expr, "%m.\n");
+	if (cfile) {
+		cfclose(cfile);
+	} else if (file) {
+		fclose(file);
+	}
+	return -1;
+}
+
+/**
+ * Invoke bfs_stat() on an argument.
+ */
+static int stat_arg(const struct parser_state *state, char **arg, struct bfs_stat *sb) {
+	const struct bfs_ctx *ctx = state->ctx;
+
+	bool follow = ctx->flags & (BFTW_FOLLOW_ROOTS | BFTW_FOLLOW_ALL);
+	enum bfs_stat_flags flags = follow ? BFS_STAT_TRYFOLLOW : BFS_STAT_NOFOLLOW;
+
+	int ret = bfs_stat(AT_FDCWD, *arg, flags, sb);
+	if (ret != 0) {
+		parse_argv_error(state, arg, 1, "%m.\n");
+	}
+	return ret;
+}
+
+/**
+ * Parse the expression specified on the command line.
+ */
+static struct bfs_expr *parse_expr(struct parser_state *state);
+
+/**
+ * Advance by a single token.
+ */
+static char **parser_advance(struct parser_state *state, enum token_type type, size_t argc) {
+	if (type != T_FLAG && type != T_PATH) {
+		state->expr_started = true;
+	}
+
+	if (type != T_PATH) {
+		state->last_arg = state->argv;
+	}
+
+	char **argv = state->argv;
+	state->argv += argc;
+	return argv;
+}
+
+/**
+ * Parse a root path.
+ */
+static int parse_root(struct parser_state *state, const char *path) {
+	char *copy = strdup(path);
+	if (!copy) {
+		parse_perror(state, "strdup()");
+		return -1;
+	}
+
+	struct bfs_ctx *ctx = state->ctx;
+	if (DARRAY_PUSH(&ctx->paths, &copy) != 0) {
+		parse_perror(state, "DARRAY_PUSH()");
+		free(copy);
+		return -1;
+	}
+
+	state->implicit_root = false;
+	return 0;
+}
+
+/**
+ * While parsing an expression, skip any paths and add them to ctx->paths.
+ */
+static int skip_paths(struct parser_state *state) {
+	while (true) {
+		const char *arg = state->argv[0];
+		if (!arg) {
+			return 0;
+		}
+
+		if (arg[0] == '-') {
+			if (strcmp(arg, "--") == 0) {
+				// find uses -- to separate flags from the rest
+				// of the command line.  We allow mixing flags
+				// and paths/predicates, so we just ignore --.
+				parser_advance(state, T_FLAG, 1);
+				continue;
+			}
+			if (strcmp(arg, "-") != 0) {
+				// - by itself is a file name.  Anything else
+				// starting with - is a flag/predicate.
+				return 0;
+			}
+		}
+
+		// By POSIX, these are always options
+		if (strcmp(arg, "(") == 0 || strcmp(arg, "!") == 0) {
+			return 0;
+		}
+
+		if (state->expr_started) {
+			// By POSIX, these can be paths.  We only treat them as
+			// such at the beginning of the command line.
+			if (strcmp(arg, ")") == 0 || strcmp(arg, ",") == 0) {
+				return 0;
+			}
+		}
+
+		if (parse_root(state, arg) != 0) {
+			return -1;
+		}
+
+		parser_advance(state, T_PATH, 1);
+	}
+}
+
+/** Integer parsing flags. */
+enum int_flags {
+	IF_BASE_MASK   = 0x03F,
+	IF_INT         = 0x040,
+	IF_LONG        = 0x080,
+	IF_LONG_LONG   = 0x0C0,
+	IF_SIZE_MASK   = 0x0C0,
+	IF_UNSIGNED    = 0x100,
+	IF_PARTIAL_OK  = 0x200,
+	IF_QUIET       = 0x400,
+};
+
+/**
+ * Parse an integer.
+ */
+static const char *parse_int(const struct parser_state *state, char **arg, const char *str, void *result, enum int_flags flags) {
+	char *endptr;
+
+	int base = flags & IF_BASE_MASK;
+	if (base == 0) {
+		base = 10;
+	}
+
+	errno = 0;
+	long long value = strtoll(str, &endptr, base);
+	if (errno != 0) {
+		if (errno == ERANGE) {
+			goto range;
+		} else {
+			goto bad;
+		}
+	}
+
+	if (endptr == str) {
+		goto bad;
+	}
+
+	if (!(flags & IF_PARTIAL_OK) && *endptr != '\0') {
+		goto bad;
+	}
+
+	if ((flags & IF_UNSIGNED) && value < 0) {
+		goto negative;
+	}
+
+	switch (flags & IF_SIZE_MASK) {
+	case IF_INT:
+		if (value < INT_MIN || value > INT_MAX) {
+			goto range;
+		}
+		*(int *)result = value;
+		break;
+
+	case IF_LONG:
+		if (value < LONG_MIN || value > LONG_MAX) {
+			goto range;
+		}
+		*(long *)result = value;
+		break;
+
+	case IF_LONG_LONG:
+		*(long long *)result = value;
+		break;
+
+	default:
+		assert(!"Invalid int size");
+		goto bad;
+	}
+
+	return endptr;
+
+bad:
+	if (!(flags & IF_QUIET)) {
+		parse_argv_error(state, arg, 1, "${bld}%s${rs} is not a valid integer.\n", str);
+	}
+	return NULL;
+
+negative:
+	if (!(flags & IF_QUIET)) {
+		parse_argv_error(state, arg, 1, "Negative integer ${bld}%s${rs} is not allowed here.\n", str);
+	}
+	return NULL;
+
+range:
+	if (!(flags & IF_QUIET)) {
+		parse_argv_error(state, arg, 1, "${bld}%s${rs} is too large an integer.\n", str);
+	}
+	return NULL;
+}
+
+/**
+ * Parse an integer and a comparison flag.
+ */
+static const char *parse_icmp(const struct parser_state *state, struct bfs_expr *expr, enum int_flags flags) {
+	char **arg = &expr->argv[1];
+	const char *str = *arg;
+	switch (str[0]) {
+	case '-':
+		expr->int_cmp = BFS_INT_LESS;
+		++str;
+		break;
+	case '+':
+		expr->int_cmp = BFS_INT_GREATER;
+		++str;
+		break;
+	default:
+		expr->int_cmp = BFS_INT_EQUAL;
+		break;
+	}
+
+	return parse_int(state, arg, str, &expr->num, flags | IF_LONG_LONG | IF_UNSIGNED);
+}
+
+/**
+ * Check if a string could be an integer comparison.
+ */
+static bool looks_like_icmp(const char *str) {
+	int i;
+
+	// One +/- for the comparison flag, one for the sign
+	for (i = 0; i < 2; ++i) {
+		if (str[i] != '-' && str[i] != '+') {
+			break;
+		}
+	}
+
+	return str[i] >= '0' && str[i] <= '9';
+}
+
+/**
+ * Parse a single flag.
+ */
+static struct bfs_expr *parse_flag(struct parser_state *state, size_t argc) {
+	parser_advance(state, T_FLAG, argc);
+	return &bfs_true;
+}
+
+/**
+ * Parse a flag that doesn't take a value.
+ */
+static struct bfs_expr *parse_nullary_flag(struct parser_state *state) {
+	return parse_flag(state, 1);
+}
+
+/**
+ * Parse a single option.
+ */
+static struct bfs_expr *parse_option(struct parser_state *state, size_t argc) {
+	parser_advance(state, T_OPTION, argc);
+	return &bfs_true;
+}
+
+/**
+ * Parse an option that doesn't take a value.
+ */
+static struct bfs_expr *parse_nullary_option(struct parser_state *state) {
+	return parse_option(state, 1);
+}
+
+/**
+ * Parse an option that takes a value.
+ */
+static struct bfs_expr *parse_unary_option(struct parser_state *state) {
+	return parse_option(state, 2);
+}
+
+/**
+ * Parse a single test.
+ */
+static struct bfs_expr *parse_test(struct parser_state *state, bfs_eval_fn *eval_fn, size_t argc) {
+	char **argv = parser_advance(state, T_TEST, argc);
+	struct bfs_expr *expr = bfs_expr_new(eval_fn, argc, argv);
+	if (expr) {
+		expr->pure = true;
+	}
+	return expr;
+}
+
+/**
+ * Parse a test that doesn't take a value.
+ */
+static struct bfs_expr *parse_nullary_test(struct parser_state *state, bfs_eval_fn *eval_fn) {
+	return parse_test(state, eval_fn, 1);
+}
+
+/**
+ * Parse a test that takes a value.
+ */
+static struct bfs_expr *parse_unary_test(struct parser_state *state, bfs_eval_fn *eval_fn) {
+	const char *arg = state->argv[0];
+	const char *value = state->argv[1];
+	if (!value) {
+		parse_error(state, "${blu}%s${rs} needs a value.\n", arg);
+		return NULL;
+	}
+
+	return parse_test(state, eval_fn, 2);
+}
+
+/**
+ * Parse a single action.
+ */
+static struct bfs_expr *parse_action(struct parser_state *state, bfs_eval_fn *eval_fn, size_t argc) {
+	char **argv = parser_advance(state, T_ACTION, argc);
+
+	if (state->excluding) {
+		parse_argv_error(state, argv, argc, "This action is not supported within ${red}-exclude${rs}.\n");
+		return NULL;
+	}
+
+	if (eval_fn != eval_prune && eval_fn != eval_quit) {
+		state->implicit_print = false;
+	}
+
+	return bfs_expr_new(eval_fn, argc, argv);
+}
+
+/**
+ * Parse an action that takes no arguments.
+ */
+static struct bfs_expr *parse_nullary_action(struct parser_state *state, bfs_eval_fn *eval_fn) {
+	return parse_action(state, eval_fn, 1);
+}
+
+/**
+ * Parse an action that takes one argument.
+ */
+static struct bfs_expr *parse_unary_action(struct parser_state *state, bfs_eval_fn *eval_fn) {
+	const char *arg = state->argv[0];
+	const char *value = state->argv[1];
+	if (!value) {
+		parse_error(state, "${blu}%s${rs} needs a value.\n", arg);
+		return NULL;
+	}
+
+	return parse_action(state, eval_fn, 2);
+}
+
+/**
+ * Add an expression to the exclusions.
+ */
+static int parse_exclude(struct parser_state *state, struct bfs_expr *expr) {
+	struct bfs_ctx *ctx = state->ctx;
+	ctx->exclude = new_binary_expr(eval_or, ctx->exclude, expr, &fake_or_arg);
+	if (ctx->exclude) {
+		return 0;
+	} else {
+		return -1;
+	}
+}
+
+/**
+ * Parse a test expression with integer data and a comparison flag.
+ */
+static struct bfs_expr *parse_test_icmp(struct parser_state *state, bfs_eval_fn *eval_fn) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_fn);
+	if (!expr) {
+		return NULL;
+	}
+
+	if (!parse_icmp(state, expr, 0)) {
+		bfs_expr_free(expr);
+		return NULL;
+	}
+
+	return expr;
+}
+
+/**
+ * Print usage information for -D.
+ */
+static void debug_help(CFILE *cfile) {
+	cfprintf(cfile, "Supported debug flags:\n\n");
+
+	cfprintf(cfile, "  ${bld}help${rs}:   This message.\n");
+	cfprintf(cfile, "  ${bld}cost${rs}:   Show cost estimates.\n");
+	cfprintf(cfile, "  ${bld}exec${rs}:   Print executed command details.\n");
+	cfprintf(cfile, "  ${bld}opt${rs}:    Print optimization details.\n");
+	cfprintf(cfile, "  ${bld}rates${rs}:  Print predicate success rates.\n");
+	cfprintf(cfile, "  ${bld}search${rs}: Trace the filesystem traversal.\n");
+	cfprintf(cfile, "  ${bld}stat${rs}:   Trace all stat() calls.\n");
+	cfprintf(cfile, "  ${bld}tree${rs}:   Print the parse tree.\n");
+	cfprintf(cfile, "  ${bld}all${rs}:    All debug flags at once.\n");
+}
+
+/** Check if a substring matches a debug flag. */
+static bool parse_debug_flag(const char *flag, size_t len, const char *expected) {
+	if (len == strlen(expected)) {
+		return strncmp(flag, expected, len) == 0;
+	} else {
+		return false;
+	}
+}
+
+/**
+ * Parse -D FLAG.
+ */
+static struct bfs_expr *parse_debug(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_ctx *ctx = state->ctx;
+
+	const char *arg = state->argv[0];
+	const char *flags = state->argv[1];
+	if (!flags) {
+		parse_error(state, "${cyn}%s${rs} needs a flag.\n\n", arg);
+		debug_help(ctx->cerr);
+		return NULL;
+	}
+
+	parser_advance(state, T_FLAG, 1);
+
+	bool unrecognized = false;
+
+	for (const char *flag = flags, *next; flag; flag = next) {
+		size_t len = strcspn(flag, ",");
+		if (flag[len]) {
+			next = flag + len + 1;
+		} else {
+			next = NULL;
+		}
+
+		if (parse_debug_flag(flag, len, "help")) {
+			debug_help(ctx->cout);
+			state->just_info = true;
+			return NULL;
+		} else if (parse_debug_flag(flag, len, "all")) {
+			ctx->debug = DEBUG_ALL;
+			continue;
+		}
+
+		enum debug_flags i;
+		for (i = 1; DEBUG_ALL & i; i <<= 1) {
+			const char *name = debug_flag_name(i);
+			if (parse_debug_flag(flag, len, name)) {
+				break;
+			}
+		}
+
+		if (DEBUG_ALL & i) {
+			ctx->debug |= i;
+		} else {
+			if (parse_warning(state, "Unrecognized debug flag ${bld}")) {
+				fwrite(flag, 1, len, stderr);
+				cfprintf(ctx->cerr, "${rs}.\n\n");
+				unrecognized = true;
+			}
+		}
+	}
+
+	if (unrecognized) {
+		debug_help(ctx->cerr);
+		cfprintf(ctx->cerr, "\n");
+	}
+
+	parser_advance(state, T_FLAG, 1);
+	return &bfs_true;
+}
+
+/**
+ * Parse -On.
+ */
+static struct bfs_expr *parse_optlevel(struct parser_state *state, int arg1, int arg2) {
+	int *optlevel = &state->ctx->optlevel;
+
+	if (strcmp(state->argv[0], "-Ofast") == 0) {
+		*optlevel = 4;
+	} else if (!parse_int(state, state->argv, state->argv[0] + 2, optlevel, IF_INT | IF_UNSIGNED)) {
+		return NULL;
+	}
+
+	if (*optlevel > 4) {
+		parse_warning(state, "${cyn}-O${bld}%s${rs} is the same as ${cyn}-O${bld}4${rs}.\n\n", state->argv[0] + 2);
+	}
+
+	return parse_nullary_flag(state);
+}
+
+/**
+ * Parse -[PHL], -follow.
+ */
+static struct bfs_expr *parse_follow(struct parser_state *state, int flags, int option) {
+	struct bfs_ctx *ctx = state->ctx;
+	ctx->flags &= ~(BFTW_FOLLOW_ROOTS | BFTW_FOLLOW_ALL);
+	ctx->flags |= flags;
+	if (option) {
+		return parse_nullary_option(state);
+	} else {
+		return parse_nullary_flag(state);
+	}
+}
+
+/**
+ * Parse -X.
+ */
+static struct bfs_expr *parse_xargs_safe(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->xargs_safe = true;
+	return parse_nullary_flag(state);
+}
+
+/**
+ * Parse -executable, -readable, -writable
+ */
+static struct bfs_expr *parse_access(struct parser_state *state, int flag, int arg2) {
+	struct bfs_expr *expr = parse_nullary_test(state, eval_access);
+	if (!expr) {
+		return NULL;
+	}
+
+	expr->num = flag;
+	expr->cost = STAT_COST;
+
+	switch (flag) {
+	case R_OK:
+		expr->probability = 0.99;
+		break;
+	case W_OK:
+		expr->probability = 0.8;
+		break;
+	case X_OK:
+		expr->probability = 0.2;
+		break;
+	}
+
+	return expr;
+}
+
+/**
+ * Parse -acl.
+ */
+static struct bfs_expr *parse_acl(struct parser_state *state, int flag, int arg2) {
+#if BFS_CAN_CHECK_ACL
+	struct bfs_expr *expr = parse_nullary_test(state, eval_acl);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = 0.00002;
+	}
+	return expr;
+#else
+	parse_error(state, "Missing platform support.\n");
+	return NULL;
+#endif
+}
+
+/**
+ * Parse -[aBcm]?newer.
+ */
+static struct bfs_expr *parse_newer(struct parser_state *state, int field, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_newer);
+	if (!expr) {
+		return NULL;
+	}
+
+	struct bfs_stat sb;
+	if (stat_arg(state, &expr->argv[1], &sb) != 0) {
+		goto fail;
+	}
+
+	expr->cost = STAT_COST;
+	expr->reftime = sb.mtime;
+	expr->stat_field = field;
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -[aBcm]min.
+ */
+static struct bfs_expr *parse_min(struct parser_state *state, int field, int arg2) {
+	struct bfs_expr *expr = parse_test_icmp(state, eval_time);
+	if (!expr) {
+		return NULL;
+	}
+
+	expr->cost = STAT_COST;
+	expr->reftime = state->now;
+	expr->stat_field = field;
+	expr->time_unit = BFS_MINUTES;
+	return expr;
+}
+
+/**
+ * Parse -[aBcm]time.
+ */
+static struct bfs_expr *parse_time(struct parser_state *state, int field, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_time);
+	if (!expr) {
+		return NULL;
+	}
+
+	expr->cost = STAT_COST;
+	expr->reftime = state->now;
+	expr->stat_field = field;
+
+	const char *tail = parse_icmp(state, expr, IF_PARTIAL_OK);
+	if (!tail) {
+		goto fail;
+	}
+
+	if (!*tail) {
+		expr->time_unit = BFS_DAYS;
+		return expr;
+	}
+
+	unsigned long long time = expr->num;
+	expr->num = 0;
+
+	while (true) {
+		switch (*tail) {
+		case 'w':
+			time *= 7;
+			BFS_FALLTHROUGH;
+		case 'd':
+			time *= 24;
+			BFS_FALLTHROUGH;
+		case 'h':
+			time *= 60;
+			BFS_FALLTHROUGH;
+		case 'm':
+			time *= 60;
+			BFS_FALLTHROUGH;
+		case 's':
+			break;
+		default:
+			parse_expr_error(state, expr, "Unknown time unit ${bld}%c${rs}.\n", *tail);
+			goto fail;
+		}
+
+		expr->num += time;
+
+		if (!*++tail) {
+			break;
+		}
+
+		tail = parse_int(state, &expr->argv[1], tail, &time, IF_PARTIAL_OK | IF_LONG_LONG | IF_UNSIGNED);
+		if (!tail) {
+			goto fail;
+		}
+		if (!*tail) {
+			parse_expr_error(state, expr, "Missing time unit.\n");
+			goto fail;
+		}
+	}
+
+	expr->time_unit = BFS_SECONDS;
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -capable.
+ */
+static struct bfs_expr *parse_capable(struct parser_state *state, int flag, int arg2) {
+#if BFS_CAN_CHECK_CAPABILITIES
+	struct bfs_expr *expr = parse_nullary_test(state, eval_capable);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = 0.000002;
+	}
+	return expr;
+#else
+	parse_error(state, "Missing platform support.\n");
+	return NULL;
+#endif
+}
+
+/**
+ * Parse -(no)?color.
+ */
+static struct bfs_expr *parse_color(struct parser_state *state, int color, int arg2) {
+	struct bfs_ctx *ctx = state->ctx;
+	struct colors *colors = ctx->colors;
+
+	if (color) {
+		if (!colors) {
+			parse_error(state, "%s.\n", strerror(ctx->colors_error));
+			return NULL;
+		}
+
+		state->use_color = COLOR_ALWAYS;
+		ctx->cout->colors = colors;
+		ctx->cerr->colors = colors;
+	} else {
+		state->use_color = COLOR_NEVER;
+		ctx->cout->colors = NULL;
+		ctx->cerr->colors = NULL;
+	}
+
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -{false,true}.
+ */
+static struct bfs_expr *parse_const(struct parser_state *state, int value, int arg2) {
+	parser_advance(state, T_TEST, 1);
+	return value ? &bfs_true : &bfs_false;
+}
+
+/**
+ * Parse -daystart.
+ */
+static struct bfs_expr *parse_daystart(struct parser_state *state, int arg1, int arg2) {
+	struct tm tm;
+	if (xlocaltime(&state->now.tv_sec, &tm) != 0) {
+		parse_perror(state, "xlocaltime()");
+		return NULL;
+	}
+
+	if (tm.tm_hour || tm.tm_min || tm.tm_sec || state->now.tv_nsec) {
+		++tm.tm_mday;
+	}
+	tm.tm_hour = 0;
+	tm.tm_min = 0;
+	tm.tm_sec = 0;
+
+	time_t time;
+	if (xmktime(&tm, &time) != 0) {
+		parse_perror(state, "xmktime()");
+		return NULL;
+	}
+
+	state->now.tv_sec = time;
+	state->now.tv_nsec = 0;
+
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -delete.
+ */
+static struct bfs_expr *parse_delete(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->flags |= BFTW_POST_ORDER;
+	state->depth_arg = state->argv;
+	return parse_nullary_action(state, eval_delete);
+}
+
+/**
+ * Parse -d.
+ */
+static struct bfs_expr *parse_depth(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->flags |= BFTW_POST_ORDER;
+	state->depth_arg = state->argv;
+	return parse_nullary_flag(state);
+}
+
+/**
+ * Parse -depth [N].
+ */
+static struct bfs_expr *parse_depth_n(struct parser_state *state, int arg1, int arg2) {
+	const char *arg = state->argv[1];
+	if (arg && looks_like_icmp(arg)) {
+		return parse_test_icmp(state, eval_depth);
+	} else {
+		return parse_depth(state, arg1, arg2);
+	}
+}
+
+/**
+ * Parse -{min,max}depth N.
+ */
+static struct bfs_expr *parse_depth_limit(struct parser_state *state, int is_min, int arg2) {
+	struct bfs_ctx *ctx = state->ctx;
+	const char *arg = state->argv[0];
+	const char *value = state->argv[1];
+	if (!value) {
+		parse_error(state, "${blu}%s${rs} needs a value.\n", arg);
+		return NULL;
+	}
+
+	int *depth = is_min ? &ctx->mindepth : &ctx->maxdepth;
+	if (!parse_int(state, &state->argv[1], value, depth, IF_INT | IF_UNSIGNED)) {
+		return NULL;
+	}
+
+	return parse_unary_option(state);
+}
+
+/**
+ * Parse -empty.
+ */
+static struct bfs_expr *parse_empty(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_test(state, eval_empty);
+	if (!expr) {
+		return NULL;
+	}
+
+	expr->cost = 2000.0;
+	expr->probability = 0.01;
+
+	if (state->ctx->optlevel < 4) {
+		// Since -empty attempts to open and read directories, it may
+		// have side effects such as reporting permission errors, and
+		// thus shouldn't be re-ordered without aggressive optimizations
+		expr->pure = false;
+	}
+
+	expr->ephemeral_fds = 1;
+
+	return expr;
+}
+
+/**
+ * Parse -exec(dir)?/-ok(dir)?.
+ */
+static struct bfs_expr *parse_exec(struct parser_state *state, int flags, int arg2) {
+	struct bfs_exec *execbuf = bfs_exec_parse(state->ctx, state->argv, flags);
+	if (!execbuf) {
+		return NULL;
+	}
+
+	struct bfs_expr *expr = parse_action(state, eval_exec, execbuf->tmpl_argc + 2);
+	if (!expr) {
+		bfs_exec_free(execbuf);
+		return NULL;
+	}
+
+	expr->exec = execbuf;
+
+	if (execbuf->flags & BFS_EXEC_MULTI) {
+		expr_set_always_true(expr);
+	} else {
+		expr->cost = 1000000.0;
+	}
+
+	expr->ephemeral_fds = 2;
+	if (execbuf->flags & BFS_EXEC_CHDIR) {
+		if (execbuf->flags & BFS_EXEC_MULTI) {
+			expr->persistent_fds = 1;
+		} else {
+			++expr->ephemeral_fds;
+		}
+	}
+
+	if (execbuf->flags & BFS_EXEC_CONFIRM) {
+		state->ok_expr = expr;
+	}
+
+	return expr;
+}
+
+/**
+ * Parse -exit [STATUS].
+ */
+static struct bfs_expr *parse_exit(struct parser_state *state, int arg1, int arg2) {
+	size_t argc = 1;
+	const char *value = state->argv[1];
+
+	int status = EXIT_SUCCESS;
+	if (value && parse_int(state, NULL, value, &status, IF_INT | IF_UNSIGNED | IF_QUIET)) {
+		argc = 2;
+	}
+
+	struct bfs_expr *expr = parse_action(state, eval_exit, argc);
+	if (expr) {
+		expr_set_never_returns(expr);
+		expr->num = status;
+	}
+	return expr;
+}
+
+/**
+ * Parse -f PATH.
+ */
+static struct bfs_expr *parse_f(struct parser_state *state, int arg1, int arg2) {
+	const char *path = state->argv[1];
+	if (!path) {
+		parse_error(state, "${cyn}-f${rs} requires a path.\n");
+		return NULL;
+	}
+
+	if (parse_root(state, path) != 0) {
+		return NULL;
+	}
+
+	parser_advance(state, T_FLAG, 1);
+	parser_advance(state, T_PATH, 1);
+	return &bfs_true;
+}
+
+/**
+ * Parse -files0-from PATH.
+ */
+static struct bfs_expr *parse_files0_from(struct parser_state *state, int arg1, int arg2) {
+	const char *arg = state->argv[0];
+	const char *from = state->argv[1];
+	if (!from) {
+		parse_error(state, "${blu}%s${rs} requires a path.\n", arg);
+		return NULL;
+	}
+
+	state->files0_arg = parser_advance(state, T_OPTION, 1);
+
+	FILE *file;
+	if (strcmp(from, "-") == 0) {
+		file = stdin;
+	} else {
+		file = xfopen(from, O_RDONLY | O_CLOEXEC);
+	}
+	if (!file) {
+		parse_error(state, "%m.\n");
+		return NULL;
+	}
+
+	struct bfs_expr *expr = &bfs_true;
+
+	while (true) {
+		char *path = xgetdelim(file, '\0');
+		if (!path) {
+			if (errno) {
+				parse_error(state, "%m.\n");
+				expr = NULL;
+			}
+			break;
+		}
+
+		int ret = parse_root(state, path);
+		free(path);
+		if (ret != 0) {
+			expr = NULL;
+			break;
+		}
+	}
+
+	if (file == stdin) {
+		state->files0_stdin_arg = state->files0_arg;
+	} else {
+		fclose(file);
+	}
+
+	state->implicit_root = false;
+	parser_advance(state, T_OPTION, 1);
+	return expr;
+}
+
+/**
+ * Parse -flags FLAGS.
+ */
+static struct bfs_expr *parse_flags(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_flags);
+	if (!expr) {
+		return NULL;
+	}
+
+	const char *flags = expr->argv[1];
+	switch (flags[0]) {
+	case '-':
+		expr->flags_cmp = BFS_MODE_ALL;
+		++flags;
+		break;
+	case '+':
+		expr->flags_cmp = BFS_MODE_ANY;
+		++flags;
+		break;
+	default:
+		expr->flags_cmp = BFS_MODE_EQUAL;
+		break;
+	}
+
+	if (xstrtofflags(&flags, &expr->set_flags, &expr->clear_flags) != 0) {
+		if (errno == ENOTSUP) {
+			parse_expr_error(state, expr, "Missing platform support.\n");
+		} else {
+			parse_expr_error(state, expr, "Invalid flags.\n");
+		}
+		bfs_expr_free(expr);
+		return NULL;
+	}
+
+	return expr;
+}
+
+/**
+ * Parse -fls FILE.
+ */
+static struct bfs_expr *parse_fls(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_action(state, eval_fls);
+	if (!expr) {
+		goto fail;
+	}
+
+	if (expr_open(state, expr, expr->argv[1]) != 0) {
+		goto fail;
+	}
+
+	expr_set_always_true(expr);
+	expr->cost = PRINT_COST;
+	expr->reftime = state->now;
+
+	// We'll need these for user/group names, so initialize them now to
+	// avoid EMFILE later
+	bfs_ctx_users(state->ctx);
+	bfs_ctx_groups(state->ctx);
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -fprint FILE.
+ */
+static struct bfs_expr *parse_fprint(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_action(state, eval_fprint);
+	if (expr) {
+		expr_set_always_true(expr);
+		expr->cost = PRINT_COST;
+		if (expr_open(state, expr, expr->argv[1]) != 0) {
+			goto fail;
+		}
+	}
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -fprint0 FILE.
+ */
+static struct bfs_expr *parse_fprint0(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_action(state, eval_fprint0);
+	if (expr) {
+		expr_set_always_true(expr);
+		expr->cost = PRINT_COST;
+		if (expr_open(state, expr, expr->argv[1]) != 0) {
+			goto fail;
+		}
+	}
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -fprintf FILE FORMAT.
+ */
+static struct bfs_expr *parse_fprintf(struct parser_state *state, int arg1, int arg2) {
+	const char *arg = state->argv[0];
+
+	const char *file = state->argv[1];
+	if (!file) {
+		parse_error(state, "${blu}%s${rs} needs a file.\n", arg);
+		return NULL;
+	}
+
+	const char *format = state->argv[2];
+	if (!format) {
+		parse_error(state, "${blu}%s${rs} needs a format string.\n", arg);
+		return NULL;
+	}
+
+	struct bfs_expr *expr = parse_action(state, eval_fprintf, 3);
+	if (!expr) {
+		return NULL;
+	}
+
+	expr_set_always_true(expr);
+
+	expr->cost = PRINT_COST;
+
+	if (expr_open(state, expr, file) != 0) {
+		goto fail;
+	}
+
+	if (bfs_printf_parse(state->ctx, expr, format) != 0) {
+		goto fail;
+	}
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -fstype TYPE.
+ */
+static struct bfs_expr *parse_fstype(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_fstype);
+	if (!expr) {
+		return NULL;
+	}
+
+	if (!bfs_ctx_mtab(state->ctx)) {
+		parse_expr_error(state, expr, "Couldn't parse the mount table: %m.\n");
+		bfs_expr_free(expr);
+		return NULL;
+	}
+
+	expr->cost = STAT_COST;
+	return expr;
+}
+
+/**
+ * Parse -gid/-group.
+ */
+static struct bfs_expr *parse_group(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_gid);
+	if (!expr) {
+		return NULL;
+	}
+
+	const struct bfs_groups *groups = bfs_ctx_groups(state->ctx);
+	if (!groups) {
+		parse_expr_error(state, expr, "Couldn't parse the group table: %m.\n");
+		goto fail;
+	}
+
+	const struct group *grp = bfs_getgrnam(groups, expr->argv[1]);
+	if (grp) {
+		expr->num = grp->gr_gid;
+		expr->int_cmp = BFS_INT_EQUAL;
+	} else if (looks_like_icmp(expr->argv[1])) {
+		if (!parse_icmp(state, expr, 0)) {
+			goto fail;
+		}
+	} else {
+		parse_expr_error(state, expr, "No such group.\n");
+		goto fail;
+	}
+
+	expr->cost = STAT_COST;
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -unique.
+ */
+static struct bfs_expr *parse_unique(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->unique = true;
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -used N.
+ */
+static struct bfs_expr *parse_used(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_test_icmp(state, eval_used);
+	if (expr) {
+		expr->cost = STAT_COST;
+	}
+	return expr;
+}
+
+/**
+ * Parse -uid/-user.
+ */
+static struct bfs_expr *parse_user(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_uid);
+	if (!expr) {
+		return NULL;
+	}
+
+	const struct bfs_users *users = bfs_ctx_users(state->ctx);
+	if (!users) {
+		parse_expr_error(state, expr, "Couldn't parse the user table: %m.\n");
+		goto fail;
+	}
+
+	const struct passwd *pwd = bfs_getpwnam(users, expr->argv[1]);
+	if (pwd) {
+		expr->num = pwd->pw_uid;
+		expr->int_cmp = BFS_INT_EQUAL;
+	} else if (looks_like_icmp(expr->argv[1])) {
+		if (!parse_icmp(state, expr, 0)) {
+			goto fail;
+		}
+	} else {
+		parse_expr_error(state, expr, "No such user.\n");
+		goto fail;
+	}
+
+	expr->cost = STAT_COST;
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -hidden.
+ */
+static struct bfs_expr *parse_hidden(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_test(state, eval_hidden);
+	if (expr) {
+		expr->probability = 0.01;
+	}
+	return expr;
+}
+
+/**
+ * Parse -(no)?ignore_readdir_race.
+ */
+static struct bfs_expr *parse_ignore_races(struct parser_state *state, int ignore, int arg2) {
+	state->ctx->ignore_races = ignore;
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -inum N.
+ */
+static struct bfs_expr *parse_inum(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_test_icmp(state, eval_inum);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = expr->int_cmp == BFS_INT_EQUAL ? 0.01 : 0.50;
+	}
+	return expr;
+}
+
+/**
+ * Parse -links N.
+ */
+static struct bfs_expr *parse_links(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_test_icmp(state, eval_links);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = bfs_expr_cmp(expr, 1) ? 0.99 : 0.01;
+	}
+	return expr;
+}
+
+/**
+ * Parse -ls.
+ */
+static struct bfs_expr *parse_ls(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_action(state, eval_fls);
+	if (!expr) {
+		return NULL;
+	}
+
+	init_print_expr(state, expr);
+	expr->reftime = state->now;
+
+	// We'll need these for user/group names, so initialize them now to
+	// avoid EMFILE later
+	bfs_ctx_users(state->ctx);
+	bfs_ctx_groups(state->ctx);
+
+	return expr;
+}
+
+/**
+ * Parse -mount.
+ */
+static struct bfs_expr *parse_mount(struct parser_state *state, int arg1, int arg2) {
+	parse_warning(state, "In the future, ${blu}%s${rs} will skip mount points entirely, unlike\n", state->argv[0]);
+	bfs_warning(state->ctx, "${blu}-xdev${rs}, due to http://austingroupbugs.net/view.php?id=1133.\n\n");
+
+	state->ctx->flags |= BFTW_PRUNE_MOUNTS;
+	state->mount_arg = state->argv;
+	return parse_nullary_option(state);
+}
+
+/**
+ * Common code for fnmatch() tests.
+ */
+static struct bfs_expr *parse_fnmatch(const struct parser_state *state, struct bfs_expr *expr, bool casefold) {
+	if (!expr) {
+		return NULL;
+	}
+
+	if (casefold) {
+#ifdef FNM_CASEFOLD
+		expr->num = FNM_CASEFOLD;
+#else
+		parse_expr_error(state, expr, "Missing platform support.\n");
+		bfs_expr_free(expr);
+		return NULL;
+#endif
+	} else {
+		expr->num = 0;
+	}
+
+	// POSIX says, about fnmatch():
+	//
+	//     If pattern ends with an unescaped <backslash>, fnmatch() shall
+	//     return a non-zero value (indicating either no match or an error).
+	//
+	// But not all implementations obey this, so check for it ourselves.
+	const char *pattern = expr->argv[1];
+	size_t i, len = strlen(pattern);
+	for (i = 0; i < len; ++i) {
+		if (pattern[len - i - 1] != '\\') {
+			break;
+		}
+	}
+	if (i % 2 != 0) {
+		parse_expr_warning(state, expr, "Unescaped trailing backslash.\n\n");
+		bfs_expr_free(expr);
+		return &bfs_false;
+	}
+
+	expr->cost = 400.0;
+
+	if (strchr(pattern, '*')) {
+		expr->probability = 0.5;
+	} else {
+		expr->probability = 0.1;
+	}
+
+	return expr;
+}
+
+/**
+ * Parse -i?name.
+ */
+static struct bfs_expr *parse_name(struct parser_state *state, int casefold, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_name);
+	return parse_fnmatch(state, expr, casefold);
+}
+
+/**
+ * Parse -i?path, -i?wholename.
+ */
+static struct bfs_expr *parse_path(struct parser_state *state, int casefold, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_path);
+	return parse_fnmatch(state, expr, casefold);
+}
+
+/**
+ * Parse -i?lname.
+ */
+static struct bfs_expr *parse_lname(struct parser_state *state, int casefold, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_lname);
+	return parse_fnmatch(state, expr, casefold);
+}
+
+/** Get the bfs_stat_field for X/Y in -newerXY. */
+static enum bfs_stat_field parse_newerxy_field(char c) {
+	switch (c) {
+	case 'a':
+		return BFS_STAT_ATIME;
+	case 'B':
+		return BFS_STAT_BTIME;
+	case 'c':
+		return BFS_STAT_CTIME;
+	case 'm':
+		return BFS_STAT_MTIME;
+	default:
+		return 0;
+	}
+}
+
+/** Parse an explicit reference timestamp for -newerXt and -*since. */
+static int parse_reftime(const struct parser_state *state, struct bfs_expr *expr) {
+	if (parse_timestamp(expr->argv[1], &expr->reftime) == 0) {
+		return 0;
+	} else if (errno != EINVAL) {
+		parse_expr_error(state, expr, "%m.\n");
+		return -1;
+	}
+
+	parse_expr_error(state, expr, "Invalid timestamp.\n\n");
+	fprintf(stderr, "Supported timestamp formats are ISO 8601-like, e.g.\n\n");
+
+	struct tm tm;
+	if (xlocaltime(&state->now.tv_sec, &tm) != 0) {
+		parse_perror(state, "xlocaltime()");
+		return -1;
+	}
+
+	int year = tm.tm_year + 1900;
+	int month = tm.tm_mon + 1;
+	fprintf(stderr, "  - %04d-%02d-%02d\n", year, month, tm.tm_mday);
+	fprintf(stderr, "  - %04d-%02d-%02dT%02d:%02d:%02d\n", year, month, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+#if __FreeBSD__
+	int gmtoff = tm.tm_gmtoff;
+#else
+	int gmtoff = -timezone;
+#endif
+	int tz_hour = gmtoff/3600;
+	int tz_min = (labs(gmtoff)/60)%60;
+	fprintf(stderr, "  - %04d-%02d-%02dT%02d:%02d:%02d%+03d:%02d\n",
+	        year, month, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, tz_hour, tz_min);
+
+	if (xgmtime(&state->now.tv_sec, &tm) != 0) {
+		parse_perror(state, "xgmtime()");
+		return -1;
+	}
+
+	year = tm.tm_year + 1900;
+	month = tm.tm_mon + 1;
+	fprintf(stderr, "  - %04d-%02d-%02dT%02d:%02d:%02dZ\n", year, month, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec);
+
+	return -1;
+}
+
+/**
+ * Parse -newerXY.
+ */
+static struct bfs_expr *parse_newerxy(struct parser_state *state, int arg1, int arg2) {
+	const char *arg = state->argv[0];
+	if (strlen(arg) != 8) {
+		parse_error(state, "Expected ${blu}-newer${bld}XY${rs}; found ${blu}-newer${bld}%s${rs}.\n", arg + 6);
+		return NULL;
+	}
+
+	struct bfs_expr *expr = parse_unary_test(state, eval_newer);
+	if (!expr) {
+		goto fail;
+	}
+
+	expr->stat_field = parse_newerxy_field(arg[6]);
+	if (!expr->stat_field) {
+		parse_expr_error(state, expr,
+		                 "For ${blu}-newer${bld}XY${rs}, ${bld}X${rs} should be ${bld}a${rs}, ${bld}c${rs}, ${bld}m${rs}, or ${bld}B${rs}, not ${err}%c${rs}.\n",
+		                 arg[6]);
+		goto fail;
+	}
+
+	if (arg[7] == 't') {
+		if (parse_reftime(state, expr) != 0) {
+			goto fail;
+		}
+	} else {
+		enum bfs_stat_field field = parse_newerxy_field(arg[7]);
+		if (!field) {
+			parse_expr_error(state, expr,
+			                 "For ${blu}-newer${bld}XY${rs}, ${bld}Y${rs} should be ${bld}a${rs}, ${bld}c${rs}, ${bld}m${rs}, ${bld}B${rs}, or ${bld}t${rs}, not ${err}%c${rs}.\n",
+			                 arg[7]);
+			goto fail;
+		}
+
+		struct bfs_stat sb;
+		if (stat_arg(state, &expr->argv[1], &sb) != 0) {
+			goto fail;
+		}
+
+
+		const struct timespec *reftime = bfs_stat_time(&sb, field);
+		if (!reftime) {
+			parse_expr_error(state, expr, "Couldn't get file %s.\n", bfs_stat_field_name(field));
+			goto fail;
+		}
+
+		expr->reftime = *reftime;
+	}
+
+	expr->cost = STAT_COST;
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -nogroup.
+ */
+static struct bfs_expr *parse_nogroup(struct parser_state *state, int arg1, int arg2) {
+	if (!bfs_ctx_groups(state->ctx)) {
+		parse_error(state, "Couldn't parse the group table: %m.\n");
+		return NULL;
+	}
+
+	struct bfs_expr *expr = parse_nullary_test(state, eval_nogroup);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = 0.01;
+	}
+	return expr;
+}
+
+/**
+ * Parse -nohidden.
+ */
+static struct bfs_expr *parse_nohidden(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *hidden = bfs_expr_new(eval_hidden, 1, &fake_hidden_arg);
+	if (!hidden) {
+		return NULL;
+	}
+
+	hidden->probability = 0.01;
+	hidden->pure = true;
+	hidden->synthetic = true;
+
+	if (parse_exclude(state, hidden) != 0) {
+		return NULL;
+	}
+
+	parser_advance(state, T_OPTION, 1);
+	return &bfs_true;
+}
+
+/**
+ * Parse -noleaf.
+ */
+static struct bfs_expr *parse_noleaf(struct parser_state *state, int arg1, int arg2) {
+	parse_warning(state, "${ex}bfs${rs} does not apply the optimization that ${blu}%s${rs} inhibits.\n\n", state->argv[0]);
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -nouser.
+ */
+static struct bfs_expr *parse_nouser(struct parser_state *state, int arg1, int arg2) {
+	if (!bfs_ctx_users(state->ctx)) {
+		parse_error(state, "Couldn't parse the user table: %m.\n");
+		return NULL;
+	}
+
+	struct bfs_expr *expr = parse_nullary_test(state, eval_nouser);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = 0.01;
+	}
+	return expr;
+}
+
+/**
+ * Parse a permission mode like chmod(1).
+ */
+static int parse_mode(const struct parser_state *state, const char *mode, struct bfs_expr *expr) {
+	if (mode[0] >= '0' && mode[0] <= '9') {
+		unsigned int parsed;
+		if (!parse_int(state, NULL, mode, &parsed, 8 | IF_INT | IF_UNSIGNED | IF_QUIET)) {
+			goto fail;
+		}
+		if (parsed > 07777) {
+			goto fail;
+		}
+
+		expr->file_mode = parsed;
+		expr->dir_mode = parsed;
+		return 0;
+	}
+
+	expr->file_mode = 0;
+	expr->dir_mode = 0;
+
+	// Parse the same grammar as chmod(1), which looks like this:
+	//
+	// MODE : CLAUSE ["," CLAUSE]*
+	//
+	// CLAUSE : WHO* ACTION+
+	//
+	// WHO : "u" | "g" | "o" | "a"
+	//
+	// ACTION : OP PERM*
+	//        | OP PERMCOPY
+	//
+	// OP : "+" | "-" | "="
+	//
+	// PERM : "r" | "w" | "x" | "X" | "s" | "t"
+	//
+	// PERMCOPY : "u" | "g" | "o"
+
+	// State machine state
+	enum {
+		MODE_CLAUSE,
+		MODE_WHO,
+		MODE_ACTION,
+		MODE_ACTION_APPLY,
+		MODE_OP,
+		MODE_PERM,
+	} mstate = MODE_CLAUSE;
+
+	enum {
+		MODE_PLUS,
+		MODE_MINUS,
+		MODE_EQUALS,
+	} op;
+
+	mode_t who;
+	mode_t file_change;
+	mode_t dir_change;
+
+	const char *i = mode;
+	while (true) {
+		switch (mstate) {
+		case MODE_CLAUSE:
+			who = 0;
+			mstate = MODE_WHO;
+			BFS_FALLTHROUGH;
+
+		case MODE_WHO:
+			switch (*i) {
+			case 'u':
+				who |= 0700;
+				break;
+			case 'g':
+				who |= 0070;
+				break;
+			case 'o':
+				who |= 0007;
+				break;
+			case 'a':
+				who |= 0777;
+				break;
+			default:
+				mstate = MODE_ACTION;
+				continue;
+			}
+			break;
+
+		case MODE_ACTION_APPLY:
+			switch (op) {
+			case MODE_EQUALS:
+				expr->file_mode &= ~who;
+				expr->dir_mode &= ~who;
+				BFS_FALLTHROUGH;
+			case MODE_PLUS:
+				expr->file_mode |= file_change;
+				expr->dir_mode |= dir_change;
+				break;
+			case MODE_MINUS:
+				expr->file_mode &= ~file_change;
+				expr->dir_mode &= ~dir_change;
+				break;
+			}
+			BFS_FALLTHROUGH;
+
+		case MODE_ACTION:
+			if (who == 0) {
+				who = 0777;
+			}
+
+			switch (*i) {
+			case '+':
+				op = MODE_PLUS;
+				mstate = MODE_OP;
+				break;
+			case '-':
+				op = MODE_MINUS;
+				mstate = MODE_OP;
+				break;
+			case '=':
+				op = MODE_EQUALS;
+				mstate = MODE_OP;
+				break;
+
+			case ',':
+				if (mstate == MODE_ACTION_APPLY) {
+					mstate = MODE_CLAUSE;
+				} else {
+					goto fail;
+				}
+				break;
+
+			case '\0':
+				if (mstate == MODE_ACTION_APPLY) {
+					goto done;
+				} else {
+					goto fail;
+				}
+
+			default:
+				goto fail;
+			}
+			break;
+
+		case MODE_OP:
+			switch (*i) {
+			case 'u':
+				file_change = (expr->file_mode >> 6) & 07;
+				dir_change = (expr->dir_mode >> 6) & 07;
+				break;
+			case 'g':
+				file_change = (expr->file_mode >> 3) & 07;
+				dir_change = (expr->dir_mode >> 3) & 07;
+				break;
+			case 'o':
+				file_change = expr->file_mode & 07;
+				dir_change = expr->dir_mode & 07;
+				break;
+
+			default:
+				file_change = 0;
+				dir_change = 0;
+				mstate = MODE_PERM;
+				continue;
+			}
+
+			file_change |= (file_change << 6) | (file_change << 3);
+			file_change &= who;
+			dir_change |= (dir_change << 6) | (dir_change << 3);
+			dir_change &= who;
+			mstate = MODE_ACTION_APPLY;
+			break;
+
+		case MODE_PERM:
+			switch (*i) {
+			case 'r':
+				file_change |= who & 0444;
+				dir_change |= who & 0444;
+				break;
+			case 'w':
+				file_change |= who & 0222;
+				dir_change |= who & 0222;
+				break;
+			case 'x':
+				file_change |= who & 0111;
+				BFS_FALLTHROUGH;
+			case 'X':
+				dir_change |= who & 0111;
+				break;
+			case 's':
+				if (who & 0700) {
+					file_change |= S_ISUID;
+					dir_change |= S_ISUID;
+				}
+				if (who & 0070) {
+					file_change |= S_ISGID;
+					dir_change |= S_ISGID;
+				}
+				break;
+			case 't':
+				if (who & 0007) {
+					file_change |= S_ISVTX;
+					dir_change |= S_ISVTX;
+				}
+				break;
+			default:
+				mstate = MODE_ACTION_APPLY;
+				continue;
+			}
+			break;
+		}
+
+		++i;
+	}
+
+done:
+	return 0;
+
+fail:
+	parse_expr_error(state, expr, "Invalid mode.\n");
+	return -1;
+}
+
+/**
+ * Parse -perm MODE.
+ */
+static struct bfs_expr *parse_perm(struct parser_state *state, int field, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_perm);
+	if (!expr) {
+		return NULL;
+	}
+
+	const char *mode = expr->argv[1];
+	switch (mode[0]) {
+	case '-':
+		expr->mode_cmp = BFS_MODE_ALL;
+		++mode;
+		break;
+	case '/':
+		expr->mode_cmp = BFS_MODE_ANY;
+		++mode;
+		break;
+	case '+':
+		if (mode[1] >= '0' && mode[1] <= '9') {
+			expr->mode_cmp = BFS_MODE_ANY;
+			++mode;
+			break;
+		}
+		BFS_FALLTHROUGH;
+	default:
+		expr->mode_cmp = BFS_MODE_EQUAL;
+		break;
+	}
+
+	if (parse_mode(state, mode, expr) != 0) {
+		goto fail;
+	}
+
+	expr->cost = STAT_COST;
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -print.
+ */
+static struct bfs_expr *parse_print(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_action(state, eval_fprint);
+	if (expr) {
+		init_print_expr(state, expr);
+	}
+	return expr;
+}
+
+/**
+ * Parse -print0.
+ */
+static struct bfs_expr *parse_print0(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_action(state, eval_fprint0);
+	if (expr) {
+		init_print_expr(state, expr);
+	}
+	return expr;
+}
+
+/**
+ * Parse -printf FORMAT.
+ */
+static struct bfs_expr *parse_printf(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_action(state, eval_fprintf);
+	if (!expr) {
+		return NULL;
+	}
+
+	init_print_expr(state, expr);
+
+	if (bfs_printf_parse(state->ctx, expr, expr->argv[1]) != 0) {
+		bfs_expr_free(expr);
+		return NULL;
+	}
+
+	return expr;
+}
+
+/**
+ * Parse -printx.
+ */
+static struct bfs_expr *parse_printx(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_action(state, eval_fprintx);
+	if (expr) {
+		init_print_expr(state, expr);
+	}
+	return expr;
+}
+
+/**
+ * Parse -prune.
+ */
+static struct bfs_expr *parse_prune(struct parser_state *state, int arg1, int arg2) {
+	state->prune_arg = state->argv;
+
+	struct bfs_expr *expr = parse_nullary_action(state, eval_prune);
+	if (expr) {
+		expr_set_always_true(expr);
+	}
+	return expr;
+}
+
+/**
+ * Parse -quit.
+ */
+static struct bfs_expr *parse_quit(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_action(state, eval_quit);
+	if (expr) {
+		expr_set_never_returns(expr);
+	}
+	return expr;
+}
+
+/**
+ * Parse -i?regex.
+ */
+static struct bfs_expr *parse_regex(struct parser_state *state, int flags, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_regex);
+	if (!expr) {
+		goto fail;
+	}
+
+	if (bfs_regcomp(&expr->regex, expr->argv[1], state->regex_type, flags) != 0) {
+		if (!expr->regex) {
+			parse_perror(state, "bfs_regcomp()");
+			goto fail;
+		}
+
+		char *str = bfs_regerror(expr->regex);
+		if (!str) {
+			parse_perror(state, "bfs_regerror()");
+			goto fail;
+		}
+
+		parse_expr_error(state, expr, "%s.\n", str);
+		free(str);
+		goto fail;
+	}
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -E.
+ */
+static struct bfs_expr *parse_regex_extended(struct parser_state *state, int arg1, int arg2) {
+	state->regex_type = BFS_REGEX_POSIX_EXTENDED;
+	return parse_nullary_flag(state);
+}
+
+/**
+ * Parse -regextype TYPE.
+ */
+static struct bfs_expr *parse_regextype(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_ctx *ctx = state->ctx;
+	CFILE *cfile = ctx->cerr;
+
+	const char *arg = state->argv[0];
+	const char *type = state->argv[1];
+	if (!type) {
+		parse_error(state, "${blu}%s${rs} needs a value.\n\n", arg);
+		goto list_types;
+	}
+
+	parser_advance(state, T_OPTION, 1);
+
+	// See https://www.gnu.org/software/gnulib/manual/html_node/Predefined-Syntaxes.html
+	if (strcmp(type, "posix-basic") == 0
+	    || strcmp(type, "ed") == 0
+	    || strcmp(type, "sed") == 0) {
+		state->regex_type = BFS_REGEX_POSIX_BASIC;
+	} else if (strcmp(type, "posix-extended") == 0) {
+		state->regex_type = BFS_REGEX_POSIX_EXTENDED;
+#if BFS_WITH_ONIGURUMA
+	} else if (strcmp(type, "emacs") == 0) {
+		state->regex_type = BFS_REGEX_EMACS;
+	} else if (strcmp(type, "grep") == 0) {
+		state->regex_type = BFS_REGEX_GREP;
+#endif
+	} else if (strcmp(type, "help") == 0) {
+		state->just_info = true;
+		cfile = ctx->cout;
+		goto list_types;
+	} else {
+		parse_error(state, "Unsupported regex type.\n\n");
+		goto list_types;
+	}
+
+	parser_advance(state, T_OPTION, 1);
+	return &bfs_true;
+
+list_types:
+	cfprintf(cfile, "Supported types are:\n\n");
+	cfprintf(cfile, "  ${bld}posix-basic${rs}:    POSIX basic regular expressions (BRE)\n");
+	cfprintf(cfile, "  ${bld}posix-extended${rs}: POSIX extended regular expressions (ERE)\n");
+	cfprintf(cfile, "  ${bld}ed${rs}:             Like ${grn}ed${rs} (same as ${bld}posix-basic${rs})\n");
+#if BFS_WITH_ONIGURUMA
+	cfprintf(cfile, "  ${bld}emacs${rs}:          Like ${grn}emacs${rs}\n");
+	cfprintf(cfile, "  ${bld}grep${rs}:           Like ${grn}grep${rs}\n");
+#endif
+	cfprintf(cfile, "  ${bld}sed${rs}:            Like ${grn}sed${rs} (same as ${bld}posix-basic${rs})\n");
+	return NULL;
+}
+
+/**
+ * Parse -s.
+ */
+static struct bfs_expr *parse_s(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->flags |= BFTW_SORT;
+	return parse_nullary_flag(state);
+}
+
+/**
+ * Parse -samefile FILE.
+ */
+static struct bfs_expr *parse_samefile(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_samefile);
+	if (!expr) {
+		return NULL;
+	}
+
+	struct bfs_stat sb;
+	if (stat_arg(state, &expr->argv[1], &sb) != 0) {
+		bfs_expr_free(expr);
+		return NULL;
+	}
+
+	expr->dev = sb.dev;
+	expr->ino = sb.ino;
+
+	expr->cost = STAT_COST;
+	expr->probability = 0.01;
+
+	return expr;
+}
+
+/**
+ * Parse -S STRATEGY.
+ */
+static struct bfs_expr *parse_search_strategy(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_ctx *ctx = state->ctx;
+	CFILE *cfile = ctx->cerr;
+
+	const char *flag = state->argv[0];
+	const char *arg = state->argv[1];
+	if (!arg) {
+		parse_error(state, "${cyn}%s${rs} needs an argument.\n\n", flag);
+		goto list_strategies;
+	}
+
+	parser_advance(state, T_FLAG, 1);
+
+	if (strcmp(arg, "bfs") == 0) {
+		ctx->strategy = BFTW_BFS;
+	} else if (strcmp(arg, "dfs") == 0) {
+		ctx->strategy = BFTW_DFS;
+	} else if (strcmp(arg, "ids") == 0) {
+		ctx->strategy = BFTW_IDS;
+	} else if (strcmp(arg, "eds") == 0) {
+		ctx->strategy = BFTW_EDS;
+	} else if (strcmp(arg, "help") == 0) {
+		state->just_info = true;
+		cfile = ctx->cout;
+		goto list_strategies;
+	} else {
+		parse_error(state, "Unrecognized search strategy.\n\n");
+		goto list_strategies;
+	}
+
+	parser_advance(state, T_FLAG, 1);
+	return &bfs_true;
+
+list_strategies:
+	cfprintf(cfile, "Supported search strategies:\n\n");
+	cfprintf(cfile, "  ${bld}bfs${rs}: breadth-first search\n");
+	cfprintf(cfile, "  ${bld}dfs${rs}: depth-first search\n");
+	cfprintf(cfile, "  ${bld}ids${rs}: iterative deepening search\n");
+	cfprintf(cfile, "  ${bld}eds${rs}: exponential deepening search\n");
+	return NULL;
+}
+
+/**
+ * Parse -[aBcm]?since.
+ */
+static struct bfs_expr *parse_since(struct parser_state *state, int field, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_newer);
+	if (!expr) {
+		return NULL;
+	}
+
+	if (parse_reftime(state, expr) != 0) {
+		goto fail;
+	}
+
+	expr->cost = STAT_COST;
+	expr->stat_field = field;
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -size N[cwbkMGTP]?.
+ */
+static struct bfs_expr *parse_size(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_unary_test(state, eval_size);
+	if (!expr) {
+		return NULL;
+	}
+
+	const char *unit = parse_icmp(state, expr, IF_PARTIAL_OK);
+	if (!unit) {
+		goto fail;
+	}
+
+	if (strlen(unit) > 1) {
+		goto bad_unit;
+	}
+
+	switch (*unit) {
+	case '\0':
+	case 'b':
+		expr->size_unit = BFS_BLOCKS;
+		break;
+	case 'c':
+		expr->size_unit = BFS_BYTES;
+		break;
+	case 'w':
+		expr->size_unit = BFS_WORDS;
+		break;
+	case 'k':
+		expr->size_unit = BFS_KB;
+		break;
+	case 'M':
+		expr->size_unit = BFS_MB;
+		break;
+	case 'G':
+		expr->size_unit = BFS_GB;
+		break;
+	case 'T':
+		expr->size_unit = BFS_TB;
+		break;
+	case 'P':
+		expr->size_unit = BFS_PB;
+		break;
+
+	default:
+		goto bad_unit;
+	}
+
+	expr->cost = STAT_COST;
+	expr->probability = expr->int_cmp == BFS_INT_EQUAL ? 0.01 : 0.50;
+
+	return expr;
+
+bad_unit:
+	parse_expr_error(state, expr, "Expected a size unit (one of ${bld}cwbkMGTP${rs}); found ${err}%s${rs}.\n", unit);
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -sparse.
+ */
+static struct bfs_expr *parse_sparse(struct parser_state *state, int arg1, int arg2) {
+	struct bfs_expr *expr = parse_nullary_test(state, eval_sparse);
+	if (expr) {
+		expr->cost = STAT_COST;
+	}
+	return expr;
+}
+
+/**
+ * Parse -status.
+ */
+static struct bfs_expr *parse_status(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->status = true;
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -x?type [bcdpflsD].
+ */
+static struct bfs_expr *parse_type(struct parser_state *state, int x, int arg2) {
+	bfs_eval_fn *eval = x ? eval_xtype : eval_type;
+	struct bfs_expr *expr = parse_unary_test(state, eval);
+	if (!expr) {
+		return NULL;
+	}
+
+	unsigned int types = 0;
+	float probability = 0.0;
+
+	const char *c = expr->argv[1];
+	while (true) {
+		enum bfs_type type;
+		float type_prob;
+
+		switch (*c) {
+		case 'b':
+			type = BFS_BLK;
+			type_prob = 0.00000721183;
+			break;
+		case 'c':
+			type = BFS_CHR;
+			type_prob = 0.0000499855;
+			break;
+		case 'd':
+			type = BFS_DIR;
+			type_prob = 0.114475;
+			break;
+		case 'D':
+			type = BFS_DOOR;
+			type_prob = 0.000001;
+			break;
+		case 'p':
+			type = BFS_FIFO;
+			type_prob = 0.00000248684;
+			break;
+		case 'f':
+			type = BFS_REG;
+			type_prob = 0.859772;
+			break;
+		case 'l':
+			type = BFS_LNK;
+			type_prob = 0.0256816;
+			break;
+		case 's':
+			type = BFS_SOCK;
+			type_prob = 0.0000116881;
+			break;
+		case 'w':
+			type = BFS_WHT;
+			type_prob = 0.000001;
+			break;
+
+		case '\0':
+			parse_expr_error(state, expr, "Expected a type flag.\n");
+			goto fail;
+
+		default:
+			parse_expr_error(state, expr, "Unknown type flag ${err}%c${rs}; expected one of [${bld}bcdpflsD${rs}].\n", *c);
+			goto fail;
+		}
+
+		unsigned int flag = 1 << type;
+		if (!(types & flag)) {
+			types |= flag;
+			probability += type_prob;
+		}
+
+		++c;
+		if (*c == '\0') {
+			break;
+		} else if (*c == ',') {
+			++c;
+			continue;
+		} else {
+			parse_expr_error(state, expr, "Types must be comma-separated.\n");
+			goto fail;
+		}
+	}
+
+	expr->num = types;
+	expr->probability = probability;
+
+	if (x && state->ctx->optlevel < 4) {
+		// Since -xtype dereferences symbolic links, it may have side
+		// effects such as reporting permission errors, and thus
+		// shouldn't be re-ordered without aggressive optimizations
+		expr->pure = false;
+	}
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+/**
+ * Parse -(no)?warn.
+ */
+static struct bfs_expr *parse_warn(struct parser_state *state, int warn, int arg2) {
+	state->ctx->warn = warn;
+	return parse_nullary_option(state);
+}
+
+/**
+ * Parse -xattr.
+ */
+static struct bfs_expr *parse_xattr(struct parser_state *state, int arg1, int arg2) {
+#if BFS_CAN_CHECK_XATTRS
+	struct bfs_expr *expr = parse_nullary_test(state, eval_xattr);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = 0.01;
+	}
+	return expr;
+#else
+	parse_error(state, "Missing platform support.\n");
+	return NULL;
+#endif
+}
+
+/**
+ * Parse -xattrname.
+ */
+static struct bfs_expr *parse_xattrname(struct parser_state *state, int arg1, int arg2) {
+#if BFS_CAN_CHECK_XATTRS
+	struct bfs_expr *expr = parse_unary_test(state, eval_xattrname);
+	if (expr) {
+		expr->cost = STAT_COST;
+		expr->probability = 0.01;
+	}
+	return expr;
+#else
+	parse_error(state, "Missing platform support.\n");
+	return NULL;
+#endif
+}
+
+/**
+ * Parse -xdev.
+ */
+static struct bfs_expr *parse_xdev(struct parser_state *state, int arg1, int arg2) {
+	state->ctx->flags |= BFTW_PRUNE_MOUNTS;
+	state->xdev_arg = state->argv;
+	return parse_nullary_option(state);
+}
+
+/**
+ * Launch a pager for the help output.
+ */
+static CFILE *launch_pager(pid_t *pid, CFILE *cout) {
+	char *pager = getenv("PAGER");
+
+	char *exe;
+	if (pager && pager[0]) {
+		exe = bfs_spawn_resolve(pager);
+	} else {
+		exe = bfs_spawn_resolve("less");
+		if (!exe) {
+			exe = bfs_spawn_resolve("more");
+		}
+	}
+	if (!exe) {
+		goto fail;
+	}
+
+	int pipefd[2];
+	if (pipe(pipefd) != 0) {
+		goto fail_exe;
+	}
+
+	FILE *file = fdopen(pipefd[1], "w");
+	if (!file) {
+		goto fail_pipe;
+	}
+	pipefd[1] = -1;
+
+	CFILE *ret = cfwrap(file, NULL, true);
+	if (!ret) {
+		goto fail_file;
+	}
+	file = NULL;
+
+	struct bfs_spawn ctx;
+	if (bfs_spawn_init(&ctx) != 0) {
+		goto fail_ret;
+	}
+
+	if (bfs_spawn_addclose(&ctx, fileno(ret->file)) != 0) {
+		goto fail_ctx;
+	}
+	if (bfs_spawn_adddup2(&ctx, pipefd[0], STDIN_FILENO) != 0) {
+		goto fail_ctx;
+	}
+	if (bfs_spawn_addclose(&ctx, pipefd[0]) != 0) {
+		goto fail_ctx;
+	}
+
+	char *argv[] = {
+		exe,
+		NULL,
+		NULL,
+	};
+
+	if (strcmp(xbasename(exe), "less") == 0) {
+		// We know less supports colors, other pagers may not
+		ret->colors = cout->colors;
+		argv[1] = "-FKRX";
+	}
+
+	*pid = bfs_spawn(exe, &ctx, argv, NULL);
+	if (*pid < 0) {
+		goto fail_ctx;
+	}
+
+	xclose(pipefd[0]);
+	bfs_spawn_destroy(&ctx);
+	free(exe);
+	return ret;
+
+fail_ctx:
+	bfs_spawn_destroy(&ctx);
+fail_ret:
+	cfclose(ret);
+fail_file:
+	if (file) {
+		fclose(file);
+	}
+fail_pipe:
+	if (pipefd[1] >= 0) {
+		xclose(pipefd[1]);
+	}
+	if (pipefd[0] >= 0) {
+		xclose(pipefd[0]);
+	}
+fail_exe:
+	free(exe);
+fail:
+	return cout;
+}
+
+/**
+ * "Parse" -help.
+ */
+static struct bfs_expr *parse_help(struct parser_state *state, int arg1, int arg2) {
+	CFILE *cout = state->ctx->cout;
+
+	pid_t pager = -1;
+	if (state->stdout_tty) {
+		cout = launch_pager(&pager, cout);
+	}
+
+	cfprintf(cout, "Usage: ${ex}%s${rs} [${cyn}flags${rs}...] [${mag}paths${rs}...] [${blu}expression${rs}...]\n\n",
+		 state->command);
+
+	cfprintf(cout, "${ex}bfs${rs} is compatible with ${ex}find${rs}, with some extensions. "
+		       "${cyn}Flags${rs} (${cyn}-H${rs}/${cyn}-L${rs}/${cyn}-P${rs} etc.), ${mag}paths${rs},\n"
+		       "and ${blu}expressions${rs} may be freely mixed in any order.\n\n");
+
+	cfprintf(cout, "${bld}Flags:${rs}\n\n");
+
+	cfprintf(cout, "  ${cyn}-H${rs}\n");
+	cfprintf(cout, "      Follow symbolic links on the command line, but not while searching\n");
+	cfprintf(cout, "  ${cyn}-L${rs}\n");
+	cfprintf(cout, "      Follow all symbolic links\n");
+	cfprintf(cout, "  ${cyn}-P${rs}\n");
+	cfprintf(cout, "      Never follow symbolic links (the default)\n");
+
+	cfprintf(cout, "  ${cyn}-E${rs}\n");
+	cfprintf(cout, "      Use extended regular expressions (same as ${blu}-regextype${rs} ${bld}posix-extended${rs})\n");
+	cfprintf(cout, "  ${cyn}-X${rs}\n");
+	cfprintf(cout, "      Filter out files with non-${ex}xargs${rs}-safe names\n");
+	cfprintf(cout, "  ${cyn}-d${rs}\n");
+	cfprintf(cout, "      Search in post-order (same as ${blu}-depth${rs})\n");
+	cfprintf(cout, "  ${cyn}-s${rs}\n");
+	cfprintf(cout, "      Visit directory entries in sorted order\n");
+	cfprintf(cout, "  ${cyn}-x${rs}\n");
+	cfprintf(cout, "      Don't descend into other mount points (same as ${blu}-xdev${rs})\n");
+
+	cfprintf(cout, "  ${cyn}-f${rs} ${mag}PATH${rs}\n");
+	cfprintf(cout, "      Treat ${mag}PATH${rs} as a path to search (useful if begins with a dash)\n");
+	cfprintf(cout, "  ${cyn}-D${rs} ${bld}FLAG${rs}\n");
+	cfprintf(cout, "      Turn on a debugging flag (see ${cyn}-D${rs} ${bld}help${rs})\n");
+	cfprintf(cout, "  ${cyn}-O${bld}N${rs}\n");
+	cfprintf(cout, "      Enable optimization level ${bld}N${rs} (default: ${bld}3${rs})\n");
+	cfprintf(cout, "  ${cyn}-S${rs} ${bld}bfs${rs}|${bld}dfs${rs}|${bld}ids${rs}|${bld}eds${rs}\n");
+	cfprintf(cout, "      Use ${bld}b${rs}readth-${bld}f${rs}irst/${bld}d${rs}epth-${bld}f${rs}irst/${bld}i${rs}terative/${bld}e${rs}xponential ${bld}d${rs}eepening ${bld}s${rs}earch\n");
+	cfprintf(cout, "      (default: ${cyn}-S${rs} ${bld}bfs${rs})\n\n");
+
+	cfprintf(cout, "${bld}Operators:${rs}\n\n");
+
+	cfprintf(cout, "  ${red}(${rs} ${blu}expression${rs} ${red})${rs}\n\n");
+
+	cfprintf(cout, "  ${red}!${rs} ${blu}expression${rs}\n");
+	cfprintf(cout, "  ${red}-not${rs} ${blu}expression${rs}\n\n");
+
+	cfprintf(cout, "  ${blu}expression${rs} ${blu}expression${rs}\n");
+	cfprintf(cout, "  ${blu}expression${rs} ${red}-a${rs} ${blu}expression${rs}\n");
+	cfprintf(cout, "  ${blu}expression${rs} ${red}-and${rs} ${blu}expression${rs}\n\n");
+
+	cfprintf(cout, "  ${blu}expression${rs} ${red}-o${rs} ${blu}expression${rs}\n");
+	cfprintf(cout, "  ${blu}expression${rs} ${red}-or${rs} ${blu}expression${rs}\n\n");
+
+	cfprintf(cout, "  ${blu}expression${rs} ${red},${rs} ${blu}expression${rs}\n\n");
+
+	cfprintf(cout, "${bld}Special forms:${rs}\n\n");
+
+	cfprintf(cout, "  ${red}-exclude${rs} ${blu}expression${rs}\n");
+	cfprintf(cout, "      Exclude all paths matching the ${blu}expression${rs} from the search.\n\n");
+
+	cfprintf(cout, "${bld}Options:${rs}\n\n");
+
+	cfprintf(cout, "  ${blu}-color${rs}\n");
+	cfprintf(cout, "  ${blu}-nocolor${rs}\n");
+	cfprintf(cout, "      Turn colors on or off (default: ${blu}-color${rs} if outputting to a terminal,\n");
+	cfprintf(cout, "      ${blu}-nocolor${rs} otherwise)\n");
+	cfprintf(cout, "  ${blu}-daystart${rs}\n");
+	cfprintf(cout, "      Measure times relative to the start of today\n");
+	cfprintf(cout, "  ${blu}-depth${rs}\n");
+	cfprintf(cout, "      Search in post-order (descendents first)\n");
+	cfprintf(cout, "  ${blu}-files0-from${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "      Search the NUL ('\\0')-separated paths from ${bld}FILE${rs} (${bld}-${rs} for standard input).\n");
+	cfprintf(cout, "  ${blu}-follow${rs}\n");
+	cfprintf(cout, "      Follow all symbolic links (same as ${cyn}-L${rs})\n");
+	cfprintf(cout, "  ${blu}-ignore_readdir_race${rs}\n");
+	cfprintf(cout, "  ${blu}-noignore_readdir_race${rs}\n");
+	cfprintf(cout, "      Whether to report an error if ${ex}bfs${rs} detects that the file tree is modified\n");
+	cfprintf(cout, "      during the search (default: ${blu}-noignore_readdir_race${rs})\n");
+	cfprintf(cout, "  ${blu}-maxdepth${rs} ${bld}N${rs}\n");
+	cfprintf(cout, "  ${blu}-mindepth${rs} ${bld}N${rs}\n");
+	cfprintf(cout, "      Ignore files deeper/shallower than ${bld}N${rs}\n");
+	cfprintf(cout, "  ${blu}-mount${rs}\n");
+	cfprintf(cout, "      Don't descend into other mount points (same as ${blu}-xdev${rs} for now, but will\n");
+	cfprintf(cout, "      skip mount points entirely in the future)\n");
+	cfprintf(cout, "  ${blu}-nohidden${rs}\n");
+	cfprintf(cout, "      Exclude hidden files\n");
+	cfprintf(cout, "  ${blu}-noleaf${rs}\n");
+	cfprintf(cout, "      Ignored; for compatibility with GNU find\n");
+	cfprintf(cout, "  ${blu}-regextype${rs} ${bld}TYPE${rs}\n");
+	cfprintf(cout, "      Use ${bld}TYPE${rs}-flavored regexes (default: ${bld}posix-basic${rs}; see ${blu}-regextype${rs} ${bld}help${rs})\n");
+	cfprintf(cout, "  ${blu}-status${rs}\n");
+	cfprintf(cout, "      Display a status bar while searching\n");
+	cfprintf(cout, "  ${blu}-unique${rs}\n");
+	cfprintf(cout, "      Skip any files that have already been seen\n");
+	cfprintf(cout, "  ${blu}-warn${rs}\n");
+	cfprintf(cout, "  ${blu}-nowarn${rs}\n");
+	cfprintf(cout, "      Turn on or off warnings about the command line\n");
+	cfprintf(cout, "  ${blu}-xdev${rs}\n");
+	cfprintf(cout, "      Don't descend into other mount points\n\n");
+
+	cfprintf(cout, "${bld}Tests:${rs}\n\n");
+
+#if BFS_CAN_CHECK_ACL
+	cfprintf(cout, "  ${blu}-acl${rs}\n");
+	cfprintf(cout, "      Find files with a non-trivial Access Control List\n");
+#endif
+	cfprintf(cout, "  ${blu}-${rs}[${blu}aBcm${rs}]${blu}min${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files ${blu}a${rs}ccessed/${blu}B${rs}irthed/${blu}c${rs}hanged/${blu}m${rs}odified ${bld}N${rs} minutes ago\n");
+	cfprintf(cout, "  ${blu}-${rs}[${blu}aBcm${rs}]${blu}newer${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "      Find files ${blu}a${rs}ccessed/${blu}B${rs}irthed/${blu}c${rs}hanged/${blu}m${rs}odified more recently than ${bld}FILE${rs} was\n"
+	               "      modified\n");
+	cfprintf(cout, "  ${blu}-${rs}[${blu}aBcm${rs}]${blu}since${rs} ${bld}TIME${rs}\n");
+	cfprintf(cout, "      Find files ${blu}a${rs}ccessed/${blu}B${rs}irthed/${blu}c${rs}hanged/${blu}m${rs}odified more recently than ${bld}TIME${rs}\n");
+	cfprintf(cout, "  ${blu}-${rs}[${blu}aBcm${rs}]${blu}time${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files ${blu}a${rs}ccessed/${blu}B${rs}irthed/${blu}c${rs}hanged/${blu}m${rs}odified ${bld}N${rs} days ago\n");
+#if BFS_CAN_CHECK_CAPABILITIES
+	cfprintf(cout, "  ${blu}-capable${rs}\n");
+	cfprintf(cout, "      Find files with POSIX.1e capabilities set\n");
+#endif
+	cfprintf(cout, "  ${blu}-depth${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files with depth ${bld}N${rs}\n");
+	cfprintf(cout, "  ${blu}-empty${rs}\n");
+	cfprintf(cout, "      Find empty files/directories\n");
+	cfprintf(cout, "  ${blu}-executable${rs}\n");
+	cfprintf(cout, "  ${blu}-readable${rs}\n");
+	cfprintf(cout, "  ${blu}-writable${rs}\n");
+	cfprintf(cout, "      Find files the current user can execute/read/write\n");
+	cfprintf(cout, "  ${blu}-false${rs}\n");
+	cfprintf(cout, "  ${blu}-true${rs}\n");
+	cfprintf(cout, "      Always false/true\n");
+	cfprintf(cout, "  ${blu}-fstype${rs} ${bld}TYPE${rs}\n");
+	cfprintf(cout, "      Find files on file systems with the given ${bld}TYPE${rs}\n");
+	cfprintf(cout, "  ${blu}-gid${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "  ${blu}-uid${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files owned by group/user ID ${bld}N${rs}\n");
+	cfprintf(cout, "  ${blu}-group${rs} ${bld}NAME${rs}\n");
+	cfprintf(cout, "  ${blu}-user${rs}  ${bld}NAME${rs}\n");
+	cfprintf(cout, "      Find files owned by the group/user ${bld}NAME${rs}\n");
+	cfprintf(cout, "  ${blu}-hidden${rs}\n");
+	cfprintf(cout, "      Find hidden files\n");
+#ifdef FNM_CASEFOLD
+	cfprintf(cout, "  ${blu}-ilname${rs} ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-iname${rs}  ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-ipath${rs}  ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-iregex${rs} ${bld}REGEX${rs}\n");
+	cfprintf(cout, "  ${blu}-iwholename${rs} ${bld}GLOB${rs}\n");
+	cfprintf(cout, "      Case-insensitive versions of ${blu}-lname${rs}/${blu}-name${rs}/${blu}-path${rs}"
+	               "/${blu}-regex${rs}/${blu}-wholename${rs}\n");
+#endif
+	cfprintf(cout, "  ${blu}-inum${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files with inode number ${bld}N${rs}\n");
+	cfprintf(cout, "  ${blu}-links${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files with ${bld}N${rs} hard links\n");
+	cfprintf(cout, "  ${blu}-lname${rs} ${bld}GLOB${rs}\n");
+	cfprintf(cout, "      Find symbolic links whose target matches the ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-name${rs} ${bld}GLOB${rs}\n");
+	cfprintf(cout, "      Find files whose name matches the ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-newer${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "      Find files newer than ${bld}FILE${rs}\n");
+	cfprintf(cout, "  ${blu}-newer${bld}XY${rs} ${bld}REFERENCE${rs}\n");
+	cfprintf(cout, "      Find files whose ${bld}X${rs} time is newer than the ${bld}Y${rs} time of"
+	               " ${bld}REFERENCE${rs}.  ${bld}X${rs} and ${bld}Y${rs}\n");
+	cfprintf(cout, "      can be any of [${bld}aBcm${rs}].  ${bld}Y${rs} may also be ${bld}t${rs} to parse ${bld}REFERENCE${rs} an explicit\n");
+	cfprintf(cout, "      timestamp.\n");
+	cfprintf(cout, "  ${blu}-nogroup${rs}\n");
+	cfprintf(cout, "  ${blu}-nouser${rs}\n");
+	cfprintf(cout, "      Find files owned by nonexistent groups/users\n");
+	cfprintf(cout, "  ${blu}-path${rs} ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-wholename${rs} ${bld}GLOB${rs}\n");
+	cfprintf(cout, "      Find files whose entire path matches the ${bld}GLOB${rs}\n");
+	cfprintf(cout, "  ${blu}-perm${rs} ${bld}[-]MODE${rs}\n");
+	cfprintf(cout, "      Find files with a matching mode\n");
+	cfprintf(cout, "  ${blu}-regex${rs} ${bld}REGEX${rs}\n");
+	cfprintf(cout, "      Find files whose entire path matches the regular expression ${bld}REGEX${rs}\n");
+	cfprintf(cout, "  ${blu}-samefile${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "      Find hard links to ${bld}FILE${rs}\n");
+	cfprintf(cout, "  ${blu}-since${rs} ${bld}TIME${rs}\n");
+	cfprintf(cout, "      Find files modified since ${bld}TIME${rs}\n");
+	cfprintf(cout, "  ${blu}-size${rs} ${bld}[-+]N[cwbkMGTP]${rs}\n");
+	cfprintf(cout, "      Find files with the given size, in 1-byte ${bld}c${rs}haracters, 2-byte ${bld}w${rs}ords,\n");
+	cfprintf(cout, "      512-byte ${bld}b${rs}locks (default), or ${bld}k${rs}iB/${bld}M${rs}iB/${bld}G${rs}iB/${bld}T${rs}iB/${bld}P${rs}iB\n");
+	cfprintf(cout, "  ${blu}-sparse${rs}\n");
+	cfprintf(cout, "      Find files that occupy fewer disk blocks than expected\n");
+	cfprintf(cout, "  ${blu}-type${rs} ${bld}[bcdlpfswD]${rs}\n");
+	cfprintf(cout, "      Find files of the given type\n");
+	cfprintf(cout, "  ${blu}-used${rs} ${bld}[-+]N${rs}\n");
+	cfprintf(cout, "      Find files last accessed ${bld}N${rs} days after they were changed\n");
+#if BFS_CAN_CHECK_XATTRS
+	cfprintf(cout, "  ${blu}-xattr${rs}\n");
+	cfprintf(cout, "      Find files with extended attributes\n");
+	cfprintf(cout, "  ${blu}-xattrname${rs} ${bld}NAME${rs}\n");
+	cfprintf(cout, "      Find files with the extended attribute ${bld}NAME${rs}\n");
+#endif
+	cfprintf(cout, "  ${blu}-xtype${rs} ${bld}[bcdlpfswD]${rs}\n");
+	cfprintf(cout, "      Find files of the given type, following links when ${blu}-type${rs} would not, and\n");
+	cfprintf(cout, "      vice versa\n\n");
+
+	cfprintf(cout, "${bld}Actions:${rs}\n\n");
+
+	cfprintf(cout, "  ${blu}-delete${rs}\n");
+	cfprintf(cout, "  ${blu}-rm${rs}\n");
+	cfprintf(cout, "      Delete any found files (implies ${blu}-depth${rs})\n");
+	cfprintf(cout, "  ${blu}-exec${rs} ${bld}command ... {} ;${rs}\n");
+	cfprintf(cout, "      Execute a command\n");
+	cfprintf(cout, "  ${blu}-exec${rs} ${bld}command ... {} +${rs}\n");
+	cfprintf(cout, "      Execute a command with multiple files at once\n");
+	cfprintf(cout, "  ${blu}-ok${rs} ${bld}command ... {} ;${rs}\n");
+	cfprintf(cout, "      Prompt the user whether to execute a command\n");
+	cfprintf(cout, "  ${blu}-execdir${rs} ${bld}command ... {} ;${rs}\n");
+	cfprintf(cout, "  ${blu}-execdir${rs} ${bld}command ... {} +${rs}\n");
+	cfprintf(cout, "  ${blu}-okdir${rs} ${bld}command ... {} ;${rs}\n");
+	cfprintf(cout, "      Like ${blu}-exec${rs}/${blu}-ok${rs}, but run the command in the same directory as the found\n");
+	cfprintf(cout, "      file(s)\n");
+	cfprintf(cout, "  ${blu}-exit${rs} [${bld}STATUS${rs}]\n");
+	cfprintf(cout, "      Exit immediately with the given status (%d if unspecified)\n", EXIT_SUCCESS);
+	cfprintf(cout, "  ${blu}-fls${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "  ${blu}-fprint${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "  ${blu}-fprint0${rs} ${bld}FILE${rs}\n");
+	cfprintf(cout, "  ${blu}-fprintf${rs} ${bld}FILE${rs} ${bld}FORMAT${rs}\n");
+	cfprintf(cout, "      Like ${blu}-ls${rs}/${blu}-print${rs}/${blu}-print0${rs}/${blu}-printf${rs}, but write to ${bld}FILE${rs} instead of standard\n"
+	               "      output\n");
+	cfprintf(cout, "  ${blu}-ls${rs}\n");
+	cfprintf(cout, "      List files like ${ex}ls${rs} ${bld}-dils${rs}\n");
+	cfprintf(cout, "  ${blu}-print${rs}\n");
+	cfprintf(cout, "      Print the path to the found file\n");
+	cfprintf(cout, "  ${blu}-print0${rs}\n");
+	cfprintf(cout, "      Like ${blu}-print${rs}, but use the null character ('\\0') as a separator rather than\n");
+	cfprintf(cout, "      newlines\n");
+	cfprintf(cout, "  ${blu}-printf${rs} ${bld}FORMAT${rs}\n");
+	cfprintf(cout, "      Print according to a format string (see ${ex}man${rs} ${bld}find${rs}).  The additional format\n");
+	cfprintf(cout, "      directives %%w and %%W${bld}k${rs} for printing file birth times are supported.\n");
+	cfprintf(cout, "  ${blu}-printx${rs}\n");
+	cfprintf(cout, "      Like ${blu}-print${rs}, but escape whitespace and quotation characters, to make the\n");
+	cfprintf(cout, "      output safe for ${ex}xargs${rs}.  Consider using ${blu}-print0${rs} and ${ex}xargs${rs} ${bld}-0${rs} instead.\n");
+	cfprintf(cout, "  ${blu}-prune${rs}\n");
+	cfprintf(cout, "      Don't descend into this directory\n");
+	cfprintf(cout, "  ${blu}-quit${rs}\n");
+	cfprintf(cout, "      Quit immediately\n");
+	cfprintf(cout, "  ${blu}-version${rs}\n");
+	cfprintf(cout, "      Print version information\n");
+	cfprintf(cout, "  ${blu}-help${rs}\n");
+	cfprintf(cout, "      Print this help message\n\n");
+
+	cfprintf(cout, "%s\n", BFS_HOMEPAGE);
+
+	if (pager > 0) {
+		cfclose(cout);
+		waitpid(pager, NULL, 0);
+	}
+
+	state->just_info = true;
+	return NULL;
+}
+
+/**
+ * "Parse" -version.
+ */
+static struct bfs_expr *parse_version(struct parser_state *state, int arg1, int arg2) {
+	cfprintf(state->ctx->cout, "${ex}bfs${rs} ${bld}%s${rs}\n\n", BFS_VERSION);
+
+	printf("%s\n", BFS_HOMEPAGE);
+
+	state->just_info = true;
+	return NULL;
+}
+
+typedef struct bfs_expr *parse_fn(struct parser_state *state, int arg1, int arg2);
+
+/**
+ * An entry in the parse table for literals.
+ */
+struct table_entry {
+	char *arg;
+	enum token_type type;
+	parse_fn *parse;
+	int arg1;
+	int arg2;
+	bool prefix;
+};
+
+/**
+ * The parse table for literals.
+ */
+static const struct table_entry parse_table[] = {
+	{"--", T_FLAG},
+	{"--help", T_ACTION, parse_help},
+	{"--version", T_ACTION, parse_version},
+	{"-Bmin", T_TEST, parse_min, BFS_STAT_BTIME},
+	{"-Bnewer", T_TEST, parse_newer, BFS_STAT_BTIME},
+	{"-Bsince", T_TEST, parse_since, BFS_STAT_BTIME},
+	{"-Btime", T_TEST, parse_time, BFS_STAT_BTIME},
+	{"-D", T_FLAG, parse_debug},
+	{"-E", T_FLAG, parse_regex_extended},
+	{"-H", T_FLAG, parse_follow, BFTW_FOLLOW_ROOTS, false},
+	{"-L", T_FLAG, parse_follow, BFTW_FOLLOW_ALL, false},
+	{"-O", T_FLAG, parse_optlevel, 0, 0, true},
+	{"-P", T_FLAG, parse_follow, 0, false},
+	{"-S", T_FLAG, parse_search_strategy},
+	{"-X", T_FLAG, parse_xargs_safe},
+	{"-a", T_OPERATOR},
+	{"-acl", T_TEST, parse_acl},
+	{"-amin", T_TEST, parse_min, BFS_STAT_ATIME},
+	{"-and", T_OPERATOR},
+	{"-anewer", T_TEST, parse_newer, BFS_STAT_ATIME},
+	{"-asince", T_TEST, parse_since, BFS_STAT_ATIME},
+	{"-atime", T_TEST, parse_time, BFS_STAT_ATIME},
+	{"-capable", T_TEST, parse_capable},
+	{"-cmin", T_TEST, parse_min, BFS_STAT_CTIME},
+	{"-cnewer", T_TEST, parse_newer, BFS_STAT_CTIME},
+	{"-color", T_OPTION, parse_color, true},
+	{"-csince", T_TEST, parse_since, BFS_STAT_CTIME},
+	{"-ctime", T_TEST, parse_time, BFS_STAT_CTIME},
+	{"-d", T_FLAG, parse_depth},
+	{"-daystart", T_OPTION, parse_daystart},
+	{"-delete", T_ACTION, parse_delete},
+	{"-depth", T_OPTION, parse_depth_n},
+	{"-empty", T_TEST, parse_empty},
+	{"-exclude", T_OPERATOR},
+	{"-exec", T_ACTION, parse_exec, 0},
+	{"-execdir", T_ACTION, parse_exec, BFS_EXEC_CHDIR},
+	{"-executable", T_TEST, parse_access, X_OK},
+	{"-exit", T_ACTION, parse_exit},
+	{"-f", T_FLAG, parse_f},
+	{"-false", T_TEST, parse_const, false},
+	{"-files0-from", T_OPTION, parse_files0_from},
+	{"-flags", T_TEST, parse_flags},
+	{"-fls", T_ACTION, parse_fls},
+	{"-follow", T_OPTION, parse_follow, BFTW_FOLLOW_ALL, true},
+	{"-fprint", T_ACTION, parse_fprint},
+	{"-fprint0", T_ACTION, parse_fprint0},
+	{"-fprintf", T_ACTION, parse_fprintf},
+	{"-fstype", T_TEST, parse_fstype},
+	{"-gid", T_TEST, parse_group},
+	{"-group", T_TEST, parse_group},
+	{"-help", T_ACTION, parse_help},
+	{"-hidden", T_TEST, parse_hidden},
+	{"-ignore_readdir_race", T_OPTION, parse_ignore_races, true},
+	{"-ilname", T_TEST, parse_lname, true},
+	{"-iname", T_TEST, parse_name, true},
+	{"-inum", T_TEST, parse_inum},
+	{"-ipath", T_TEST, parse_path, true},
+	{"-iregex", T_TEST, parse_regex, BFS_REGEX_ICASE},
+	{"-iwholename", T_TEST, parse_path, true},
+	{"-links", T_TEST, parse_links},
+	{"-lname", T_TEST, parse_lname, false},
+	{"-ls", T_ACTION, parse_ls},
+	{"-maxdepth", T_OPTION, parse_depth_limit, false},
+	{"-mindepth", T_OPTION, parse_depth_limit, true},
+	{"-mmin", T_TEST, parse_min, BFS_STAT_MTIME},
+	{"-mnewer", T_TEST, parse_newer, BFS_STAT_MTIME},
+	{"-mount", T_OPTION, parse_mount},
+	{"-msince", T_TEST, parse_since, BFS_STAT_MTIME},
+	{"-mtime", T_TEST, parse_time, BFS_STAT_MTIME},
+	{"-name", T_TEST, parse_name, false},
+	{"-newer", T_TEST, parse_newer, BFS_STAT_MTIME},
+	{"-newer", T_TEST, parse_newerxy, 0, 0, true},
+	{"-nocolor", T_OPTION, parse_color, false},
+	{"-nogroup", T_TEST, parse_nogroup},
+	{"-nohidden", T_TEST, parse_nohidden},
+	{"-noignore_readdir_race", T_OPTION, parse_ignore_races, false},
+	{"-noleaf", T_OPTION, parse_noleaf},
+	{"-not", T_OPERATOR},
+	{"-nouser", T_TEST, parse_nouser},
+	{"-nowarn", T_OPTION, parse_warn, false},
+	{"-o", T_OPERATOR},
+	{"-ok", T_ACTION, parse_exec, BFS_EXEC_CONFIRM},
+	{"-okdir", T_ACTION, parse_exec, BFS_EXEC_CONFIRM | BFS_EXEC_CHDIR},
+	{"-or", T_OPERATOR},
+	{"-path", T_TEST, parse_path, false},
+	{"-perm", T_TEST, parse_perm},
+	{"-print", T_ACTION, parse_print},
+	{"-print0", T_ACTION, parse_print0},
+	{"-printf", T_ACTION, parse_printf},
+	{"-printx", T_ACTION, parse_printx},
+	{"-prune", T_ACTION, parse_prune},
+	{"-quit", T_ACTION, parse_quit},
+	{"-readable", T_TEST, parse_access, R_OK},
+	{"-regex", T_TEST, parse_regex, 0},
+	{"-regextype", T_OPTION, parse_regextype},
+	{"-rm", T_ACTION, parse_delete},
+	{"-s", T_FLAG, parse_s},
+	{"-samefile", T_TEST, parse_samefile},
+	{"-since", T_TEST, parse_since, BFS_STAT_MTIME},
+	{"-size", T_TEST, parse_size},
+	{"-sparse", T_TEST, parse_sparse},
+	{"-status", T_OPTION, parse_status},
+	{"-true", T_TEST, parse_const, true},
+	{"-type", T_TEST, parse_type, false},
+	{"-uid", T_TEST, parse_user},
+	{"-unique", T_OPTION, parse_unique},
+	{"-used", T_TEST, parse_used},
+	{"-user", T_TEST, parse_user},
+	{"-version", T_ACTION, parse_version},
+	{"-warn", T_OPTION, parse_warn, true},
+	{"-wholename", T_TEST, parse_path, false},
+	{"-writable", T_TEST, parse_access, W_OK},
+	{"-x", T_FLAG, parse_xdev},
+	{"-xattr", T_TEST, parse_xattr},
+	{"-xattrname", T_TEST, parse_xattrname},
+	{"-xdev", T_OPTION, parse_xdev},
+	{"-xtype", T_TEST, parse_type, true},
+	{0},
+};
+
+/** Look up an argument in the parse table. */
+static const struct table_entry *table_lookup(const char *arg) {
+	for (const struct table_entry *entry = parse_table; entry->arg; ++entry) {
+		bool match;
+		if (entry->prefix) {
+			match = strncmp(arg, entry->arg, strlen(entry->arg)) == 0;
+		} else {
+			match = strcmp(arg, entry->arg) == 0;
+		}
+		if (match) {
+			return entry;
+		}
+	}
+
+	return NULL;
+}
+
+/** Search for a fuzzy match in the parse table. */
+static const struct table_entry *table_lookup_fuzzy(const char *arg) {
+	const struct table_entry *best = NULL;
+	int best_dist;
+
+	for (const struct table_entry *entry = parse_table; entry->arg; ++entry) {
+		int dist = typo_distance(arg, entry->arg);
+		if (!best || dist < best_dist) {
+			best = entry;
+			best_dist = dist;
+		}
+	}
+
+	return best;
+}
+
+/**
+ * LITERAL : OPTION
+ *         | TEST
+ *         | ACTION
+ */
+static struct bfs_expr *parse_literal(struct parser_state *state) {
+	// Paths are already skipped at this point
+	const char *arg = state->argv[0];
+
+	if (arg[0] != '-') {
+		goto unexpected;
+	}
+
+	const struct table_entry *match = table_lookup(arg);
+	if (match) {
+		if (match->parse) {
+			goto matched;
+		} else {
+			goto unexpected;
+		}
+	}
+
+	match = table_lookup_fuzzy(arg);
+
+	CFILE *cerr = state->ctx->cerr;
+	parse_error(state, "Unknown argument; did you mean ");
+	switch (match->type) {
+	case T_FLAG:
+		cfprintf(cerr, "${cyn}%s${rs}?", match->arg);
+		break;
+	case T_OPERATOR:
+		cfprintf(cerr, "${red}%s${rs}?", match->arg);
+		break;
+	default:
+		cfprintf(cerr, "${blu}%s${rs}?", match->arg);
+		break;
+	}
+
+	if (!state->interactive || !match->parse) {
+		fprintf(stderr, "\n");
+		goto unmatched;
+	}
+
+	fprintf(stderr, " ");
+	if (ynprompt() <= 0) {
+		goto unmatched;
+	}
+
+	fprintf(stderr, "\n");
+	state->argv[0] = match->arg;
+
+matched:
+	return match->parse(state, match->arg1, match->arg2);
+
+unmatched:
+	return NULL;
+
+unexpected:
+	parse_error(state, "Expected a predicate.\n");
+	return NULL;
+}
+
+/**
+ * FACTOR : "(" EXPR ")"
+ *        | "!" FACTOR | "-not" FACTOR
+ *        | "-exclude" FACTOR
+ *        | LITERAL
+ */
+static struct bfs_expr *parse_factor(struct parser_state *state) {
+	if (skip_paths(state) != 0) {
+		return NULL;
+	}
+
+	const char *arg = state->argv[0];
+	if (!arg) {
+		parse_argv_error(state, state->last_arg, 1, "Expression terminated prematurely here.\n");
+		return NULL;
+	}
+
+	if (strcmp(arg, "(") == 0) {
+		parser_advance(state, T_OPERATOR, 1);
+
+		struct bfs_expr *expr = parse_expr(state);
+		if (!expr) {
+			return NULL;
+		}
+
+		if (skip_paths(state) != 0) {
+			bfs_expr_free(expr);
+			return NULL;
+		}
+
+		arg = state->argv[0];
+		if (!arg || strcmp(arg, ")") != 0) {
+			parse_argv_error(state, state->last_arg, 1, "Expected a ${red})${rs}.\n");
+			bfs_expr_free(expr);
+			return NULL;
+		}
+
+		parser_advance(state, T_OPERATOR, 1);
+		return expr;
+	} else if (strcmp(arg, "-exclude") == 0) {
+		if (state->excluding) {
+			parse_error(state, "${err}%s${rs} is not supported within ${red}-exclude${rs}.\n", arg);
+			return NULL;
+		}
+
+		parser_advance(state, T_OPERATOR, 1);
+		state->excluding = true;
+
+		struct bfs_expr *factor = parse_factor(state);
+		if (!factor) {
+			return NULL;
+		}
+
+		state->excluding = false;
+
+		if (parse_exclude(state, factor) != 0) {
+			return NULL;
+		}
+
+		return &bfs_true;
+	} else if (strcmp(arg, "!") == 0 || strcmp(arg, "-not") == 0) {
+		char **argv = parser_advance(state, T_OPERATOR, 1);
+
+		struct bfs_expr *factor = parse_factor(state);
+		if (!factor) {
+			return NULL;
+		}
+
+		return new_unary_expr(eval_not, factor, argv);
+	} else {
+		return parse_literal(state);
+	}
+}
+
+/**
+ * TERM : FACTOR
+ *      | TERM FACTOR
+ *      | TERM "-a" FACTOR
+ *      | TERM "-and" FACTOR
+ */
+static struct bfs_expr *parse_term(struct parser_state *state) {
+	struct bfs_expr *term = parse_factor(state);
+
+	while (term) {
+		if (skip_paths(state) != 0) {
+			bfs_expr_free(term);
+			return NULL;
+		}
+
+		const char *arg = state->argv[0];
+		if (!arg) {
+			break;
+		}
+
+		if (strcmp(arg, "-o") == 0 || strcmp(arg, "-or") == 0
+		    || strcmp(arg, ",") == 0
+		    || strcmp(arg, ")") == 0) {
+			break;
+		}
+
+		char **argv = &fake_and_arg;
+		if (strcmp(arg, "-a") == 0 || strcmp(arg, "-and") == 0) {
+			argv = parser_advance(state, T_OPERATOR, 1);
+		}
+
+		struct bfs_expr *lhs = term;
+		struct bfs_expr *rhs = parse_factor(state);
+		if (!rhs) {
+			bfs_expr_free(lhs);
+			return NULL;
+		}
+
+		term = new_binary_expr(eval_and, lhs, rhs, argv);
+	}
+
+	return term;
+}
+
+/**
+ * CLAUSE : TERM
+ *        | CLAUSE "-o" TERM
+ *        | CLAUSE "-or" TERM
+ */
+static struct bfs_expr *parse_clause(struct parser_state *state) {
+	struct bfs_expr *clause = parse_term(state);
+
+	while (clause) {
+		if (skip_paths(state) != 0) {
+			bfs_expr_free(clause);
+			return NULL;
+		}
+
+		const char *arg = state->argv[0];
+		if (!arg) {
+			break;
+		}
+
+		if (strcmp(arg, "-o") != 0 && strcmp(arg, "-or") != 0) {
+			break;
+		}
+
+		char **argv = parser_advance(state, T_OPERATOR, 1);
+
+		struct bfs_expr *lhs = clause;
+		struct bfs_expr *rhs = parse_term(state);
+		if (!rhs) {
+			bfs_expr_free(lhs);
+			return NULL;
+		}
+
+		clause = new_binary_expr(eval_or, lhs, rhs, argv);
+	}
+
+	return clause;
+}
+
+/**
+ * EXPR : CLAUSE
+ *      | EXPR "," CLAUSE
+ */
+static struct bfs_expr *parse_expr(struct parser_state *state) {
+	struct bfs_expr *expr = parse_clause(state);
+
+	while (expr) {
+		if (skip_paths(state) != 0) {
+			bfs_expr_free(expr);
+			return NULL;
+		}
+
+		const char *arg = state->argv[0];
+		if (!arg) {
+			break;
+		}
+
+		if (strcmp(arg, ",") != 0) {
+			break;
+		}
+
+		char **argv = parser_advance(state, T_OPERATOR, 1);
+
+		struct bfs_expr *lhs = expr;
+		struct bfs_expr *rhs = parse_clause(state);
+		if (!rhs) {
+			bfs_expr_free(lhs);
+			return NULL;
+		}
+
+		expr = new_binary_expr(eval_comma, lhs, rhs, argv);
+	}
+
+	return expr;
+}
+
+/**
+ * Parse the top-level expression.
+ */
+static struct bfs_expr *parse_whole_expr(struct parser_state *state) {
+	if (skip_paths(state) != 0) {
+		return NULL;
+	}
+
+	struct bfs_expr *expr = &bfs_true;
+	if (state->argv[0]) {
+		expr = parse_expr(state);
+		if (!expr) {
+			return NULL;
+		}
+	}
+
+	if (state->argv[0]) {
+		parse_error(state, "Unexpected argument.\n");
+		goto fail;
+	}
+
+	if (state->implicit_print) {
+		struct bfs_expr *print = bfs_expr_new(eval_fprint, 1, &fake_print_arg);
+		if (!print) {
+			goto fail;
+		}
+		init_print_expr(state, print);
+		print->synthetic = true;
+
+		expr = new_binary_expr(eval_and, expr, print, &fake_and_arg);
+		if (!expr) {
+			goto fail;
+		}
+	}
+
+	if (state->mount_arg && state->xdev_arg) {
+		parse_conflict_warning(state, state->mount_arg, 1, state->xdev_arg, 1,
+		                       "${blu}%s${rs} is redundant in the presence of ${blu}%s${rs}.\n\n",
+		                       state->xdev_arg[0], state->mount_arg[0]);
+	}
+
+	if (state->ctx->warn && state->depth_arg && state->prune_arg) {
+		parse_conflict_warning(state, state->depth_arg, 1, state->prune_arg, 1,
+		                       "${blu}%s${rs} does not work in the presence of ${blu}%s${rs}.\n",
+		                       state->prune_arg[0], state->depth_arg[0]);
+
+		if (state->interactive) {
+			bfs_warning(state->ctx, "Do you want to continue? ");
+			if (ynprompt() == 0) {
+				goto fail;
+			}
+		}
+
+		fprintf(stderr, "\n");
+	}
+
+	if (state->ok_expr && state->files0_stdin_arg) {
+		parse_conflict_error(state, state->ok_expr->argv, state->ok_expr->argc, state->files0_stdin_arg, 2,
+		                     "${blu}%s${rs} conflicts with ${blu}%s${rs} ${bld}%s${rs}.\n",
+		                     state->ok_expr->argv[0], state->files0_stdin_arg[0], state->files0_stdin_arg[1]);
+		goto fail;
+	}
+
+	return expr;
+
+fail:
+	bfs_expr_free(expr);
+	return NULL;
+}
+
+void bfs_ctx_dump(const struct bfs_ctx *ctx, enum debug_flags flag) {
+	if (!bfs_debug_prefix(ctx, flag)) {
+		return;
+	}
+
+	CFILE *cerr = ctx->cerr;
+
+	cfprintf(cerr, "${ex}%s${rs} ", ctx->argv[0]);
+
+	if (ctx->flags & BFTW_FOLLOW_ALL) {
+		cfprintf(cerr, "${cyn}-L${rs} ");
+	} else if (ctx->flags & BFTW_FOLLOW_ROOTS) {
+		cfprintf(cerr, "${cyn}-H${rs} ");
+	} else {
+		cfprintf(cerr, "${cyn}-P${rs} ");
+	}
+
+	if (ctx->xargs_safe) {
+		cfprintf(cerr, "${cyn}-X${rs} ");
+	}
+
+	if (ctx->flags & BFTW_SORT) {
+		cfprintf(cerr, "${cyn}-s${rs} ");
+	}
+
+	if (ctx->optlevel != 3) {
+		cfprintf(cerr, "${cyn}-O${bld}%d${rs} ", ctx->optlevel);
+	}
+
+	const char *strategy = NULL;
+	switch (ctx->strategy) {
+	case BFTW_BFS:
+		strategy = "bfs";
+		break;
+	case BFTW_DFS:
+		strategy = "dfs";
+		break;
+	case BFTW_IDS:
+		strategy = "ids";
+		break;
+	case BFTW_EDS:
+		strategy = "eds";
+		break;
+	}
+	assert(strategy);
+	cfprintf(cerr, "${cyn}-S${rs} ${bld}%s${rs} ", strategy);
+
+	enum debug_flags debug = ctx->debug;
+	if (debug == DEBUG_ALL) {
+		cfprintf(cerr, "${cyn}-D${rs} ${bld}all${rs} ");
+	} else if (debug) {
+		cfprintf(cerr, "${cyn}-D${rs} ");
+		for (enum debug_flags i = 1; DEBUG_ALL & i; i <<= 1) {
+			if (debug & i) {
+				cfprintf(cerr, "${bld}%s${rs}", debug_flag_name(i));
+				debug ^= i;
+				if (debug) {
+					cfprintf(cerr, ",");
+				}
+			}
+		}
+		cfprintf(cerr, " ");
+	}
+
+	for (size_t i = 0; i < darray_length(ctx->paths); ++i) {
+		const char *path = ctx->paths[i];
+		char c = path[0];
+		if (c == '-' || c == '(' || c == ')' || c == '!' || c == ',') {
+			cfprintf(cerr, "${cyn}-f${rs} ");
+		}
+		cfprintf(cerr, "${mag}%s${rs} ", path);
+	}
+
+	if (ctx->cout->colors) {
+		cfprintf(cerr, "${blu}-color${rs} ");
+	} else {
+		cfprintf(cerr, "${blu}-nocolor${rs} ");
+	}
+	if (ctx->flags & BFTW_POST_ORDER) {
+		cfprintf(cerr, "${blu}-depth${rs} ");
+	}
+	if (ctx->ignore_races) {
+		cfprintf(cerr, "${blu}-ignore_readdir_race${rs} ");
+	}
+	if (ctx->mindepth != 0) {
+		cfprintf(cerr, "${blu}-mindepth${rs} ${bld}%d${rs} ", ctx->mindepth);
+	}
+	if (ctx->maxdepth != INT_MAX) {
+		cfprintf(cerr, "${blu}-maxdepth${rs} ${bld}%d${rs} ", ctx->maxdepth);
+	}
+	if (ctx->flags & BFTW_SKIP_MOUNTS) {
+		cfprintf(cerr, "${blu}-mount${rs} ");
+	}
+	if (ctx->status) {
+		cfprintf(cerr, "${blu}-status${rs} ");
+	}
+	if (ctx->unique) {
+		cfprintf(cerr, "${blu}-unique${rs} ");
+	}
+	if ((ctx->flags & (BFTW_SKIP_MOUNTS | BFTW_PRUNE_MOUNTS)) == BFTW_PRUNE_MOUNTS) {
+		cfprintf(cerr, "${blu}-xdev${rs} ");
+	}
+
+	if (flag == DEBUG_RATES) {
+		if (ctx->exclude != &bfs_false) {
+			cfprintf(cerr, "(${red}-exclude${rs} %pE) ", ctx->exclude);
+		}
+		cfprintf(cerr, "%pE", ctx->expr);
+	} else {
+		if (ctx->exclude != &bfs_false) {
+			cfprintf(cerr, "(${red}-exclude${rs} %pe) ", ctx->exclude);
+		}
+		cfprintf(cerr, "%pe", ctx->expr);
+	}
+
+	fputs("\n", stderr);
+}
+
+/**
+ * Dump the estimated costs.
+ */
+static void dump_costs(const struct bfs_ctx *ctx) {
+	const struct bfs_expr *expr = ctx->expr;
+	bfs_debug(ctx, DEBUG_COST, "       Cost: ~${ylw}%g${rs}\n", expr->cost);
+	bfs_debug(ctx, DEBUG_COST, "Probability: ~${ylw}%g%%${rs}\n", 100.0*expr->probability);
+}
+
+/**
+ * Get the current time.
+ */
+static int parse_gettime(const struct bfs_ctx *ctx, struct timespec *ts) {
+#if _POSIX_TIMERS > 0
+	int ret = clock_gettime(CLOCK_REALTIME, ts);
+	if (ret != 0) {
+		bfs_perror(ctx, "clock_gettime()");
+	}
+	return ret;
+#else
+	struct timeval tv;
+	int ret = gettimeofday(&tv, NULL);
+	if (ret == 0) {
+		ts->tv_sec = tv.tv_sec;
+		ts->tv_nsec = tv.tv_usec * 1000L;
+	} else {
+		bfs_perror(ctx, "gettimeofday()");
+	}
+	return ret;
+#endif
+}
+
+struct bfs_ctx *bfs_parse_cmdline(int argc, char *argv[]) {
+	struct bfs_ctx *ctx = bfs_ctx_new();
+	if (!ctx) {
+		perror("bfs_new_ctx()");
+		goto fail;
+	}
+
+	static char* default_argv[] = {"bfs", NULL};
+	if (argc < 1) {
+		argc = 1;
+		argv = default_argv;
+	}
+
+	ctx->argc = argc;
+	ctx->argv = malloc((argc + 1)*sizeof(*ctx->argv));
+	if (!ctx->argv) {
+		perror("malloc()");
+		goto fail;
+	}
+	for (int i = 0; i <= argc; ++i) {
+		ctx->argv[i] = argv[i];
+	}
+
+	enum use_color use_color = COLOR_AUTO;
+	if (getenv("NO_COLOR")) {
+		// https://no-color.org/
+		use_color = COLOR_NEVER;
+	}
+
+	ctx->colors = parse_colors();
+	if (!ctx->colors) {
+		ctx->colors_error = errno;
+	}
+
+	ctx->cerr = cfwrap(stderr, use_color ? ctx->colors : NULL, false);
+	if (!ctx->cerr) {
+		perror("cfwrap()");
+		goto fail;
+	}
+
+	ctx->cout = cfwrap(stdout, use_color ? ctx->colors : NULL, false);
+	if (!ctx->cout) {
+		bfs_perror(ctx, "cfwrap()");
+		goto fail;
+	}
+
+	if (!bfs_ctx_dedup(ctx, ctx->cout, NULL) || !bfs_ctx_dedup(ctx, ctx->cerr, NULL)) {
+		bfs_perror(ctx, "bfs_ctx_dedup()");
+		goto fail;
+	}
+
+	bool stdin_tty = isatty(STDIN_FILENO);
+	bool stdout_tty = isatty(STDOUT_FILENO);
+	bool stderr_tty = isatty(STDERR_FILENO);
+
+	if (getenv("POSIXLY_CORRECT")) {
+		ctx->posixly_correct = true;
+	} else {
+		ctx->warn = stdin_tty;
+	}
+
+	struct parser_state state = {
+		.ctx = ctx,
+		.argv = ctx->argv + 1,
+		.command = ctx->argv[0],
+		.regex_type = BFS_REGEX_POSIX_BASIC,
+		.stdout_tty = stdout_tty,
+		.interactive = stdin_tty && stderr_tty,
+		.use_color = use_color,
+		.implicit_print = true,
+		.implicit_root = true,
+		.just_info = false,
+		.excluding = false,
+		.last_arg = NULL,
+		.depth_arg = NULL,
+		.prune_arg = NULL,
+		.mount_arg = NULL,
+		.xdev_arg = NULL,
+		.files0_arg = NULL,
+		.files0_stdin_arg = NULL,
+		.ok_expr = NULL,
+	};
+
+	if (strcmp(xbasename(state.command), "find") == 0) {
+		// Operate depth-first when invoked as "find"
+		ctx->strategy = BFTW_DFS;
+	}
+
+	if (parse_gettime(ctx, &state.now) != 0) {
+		goto fail;
+	}
+
+	ctx->exclude = &bfs_false;
+	ctx->expr = parse_whole_expr(&state);
+	if (!ctx->expr) {
+		if (state.just_info) {
+			goto done;
+		} else {
+			goto fail;
+		}
+	}
+
+	if (bfs_optimize(ctx) != 0) {
+		goto fail;
+	}
+
+	if (darray_length(ctx->paths) == 0) {
+		if (!state.implicit_root) {
+			parse_argv_error(&state, state.files0_arg, 2, "No root paths specified.\n");
+			goto fail;
+		} else if (parse_root(&state, ".") != 0) {
+			goto fail;
+		}
+	}
+
+	if ((ctx->flags & BFTW_FOLLOW_ALL) && !ctx->unique) {
+		// We need bftw() to detect cycles unless -unique does it for us
+		ctx->flags |= BFTW_DETECT_CYCLES;
+	}
+
+	bfs_ctx_dump(ctx, DEBUG_TREE);
+	dump_costs(ctx);
+
+done:
+	return ctx;
+
+fail:
+	bfs_ctx_free(ctx);
+	return NULL;
+}
-- 
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