Merge branch 'main' into find2fdfind2fd

1 files changed, 370 insertions, 0 deletions

diff --git a/src/prelude.h b/src/prelude.h
new file mode 100644
index 0000000..72f88b0
--- /dev/null
+++ b/src/prelude.h
@@ -0,0 +1,370 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+/**
+ * Configuration and feature/platform detection.
+ */
+
+#ifndef BFS_PRELUDE_H
+#define BFS_PRELUDE_H
+
+// Possible __STDC_VERSION__ values
+
+#define C95 199409L
+#define C99 199901L
+#define C11 201112L
+#define C17 201710L
+#define C23 202311L
+
+#include <stddef.h>
+
+#if __STDC_VERSION__ < C23
+#  include <stdalign.h>
+#  include <stdbool.h>
+#  include <stdnoreturn.h>
+#endif
+
+// bfs packaging configuration
+
+#include "config.h"
+
+#ifndef BFS_COMMAND
+#  define BFS_COMMAND "bfs"
+#endif
+#ifndef BFS_HOMEPAGE
+#  define BFS_HOMEPAGE "https://tavianator.com/projects/bfs.html"
+#endif
+
+// This is a symbol instead of a literal so we don't have to rebuild everything
+// when the version number changes
+extern const char bfs_version[];
+
+// Check for system headers
+
+#ifdef __has_include
+
+#if __has_include(<mntent.h>)
+#  define BFS_HAS_MNTENT_H true
+#endif
+#if __has_include(<paths.h>)
+#  define BFS_HAS_PATHS_H true
+#endif
+#if __has_include(<sys/extattr.h>)
+#  define BFS_HAS_SYS_EXTATTR_H true
+#endif
+#if __has_include(<sys/mkdev.h>)
+#  define BFS_HAS_SYS_MKDEV_H true
+#endif
+#if __has_include(<sys/param.h>)
+#  define BFS_HAS_SYS_PARAM_H true
+#endif
+#if __has_include(<sys/sysmacros.h>)
+#  define BFS_HAS_SYS_SYSMACROS_H true
+#endif
+#if __has_include(<sys/xattr.h>)
+#  define BFS_HAS_SYS_XATTR_H true
+#endif
+#if __has_include(<threads.h>)
+#  define BFS_HAS_THREADS_H true
+#endif
+#if __has_include(<util.h>)
+#  define BFS_HAS_UTIL_H true
+#endif
+
+#else // !__has_include
+
+#define BFS_HAS_MNTENT_H __GLIBC__
+#define BFS_HAS_PATHS_H true
+#define BFS_HAS_SYS_EXTATTR_H __FreeBSD__
+#define BFS_HAS_SYS_MKDEV_H false
+#define BFS_HAS_SYS_PARAM_H true
+#define BFS_HAS_SYS_SYSMACROS_H __GLIBC__
+#define BFS_HAS_SYS_XATTR_H __linux__
+#define BFS_HAS_THREADS_H (!__STDC_NO_THREADS__)
+#define BFS_HAS_UTIL_H __NetBSD__
+
+#endif // !__has_include
+
+#ifndef BFS_USE_MNTENT_H
+#  define BFS_USE_MNTENT_H BFS_HAS_MNTENT_H
+#endif
+#ifndef BFS_USE_PATHS_H
+#  define BFS_USE_PATHS_H BFS_HAS_PATHS_H
+#endif
+#ifndef BFS_USE_SYS_EXTATTR_H
+#  define BFS_USE_SYS_EXTATTR_H BFS_HAS_SYS_EXTATTR_H
+#endif
+#ifndef BFS_USE_SYS_MKDEV_H
+#  define BFS_USE_SYS_MKDEV_H BFS_HAS_SYS_MKDEV_H
+#endif
+#ifndef BFS_USE_SYS_PARAM_H
+#  define BFS_USE_SYS_PARAM_H BFS_HAS_SYS_PARAM_H
+#endif
+#ifndef BFS_USE_SYS_SYSMACROS_H
+#  define BFS_USE_SYS_SYSMACROS_H BFS_HAS_SYS_SYSMACROS_H
+#endif
+#ifndef BFS_USE_SYS_XATTR_H
+#  define BFS_USE_SYS_XATTR_H BFS_HAS_SYS_XATTR_H
+#endif
+#ifndef BFS_USE_THREADS_H
+#  define BFS_USE_THREADS_H BFS_HAS_THREADS_H
+#endif
+#ifndef BFS_USE_UTIL_H
+#  define BFS_USE_UTIL_H BFS_HAS_UTIL_H
+#endif
+
+// Stub out feature detection on old/incompatible compilers
+
+#ifndef __has_feature
+#  define __has_feature(feat) false
+#endif
+
+#ifndef __has_c_attribute
+#  define __has_c_attribute(attr) false
+#endif
+
+#ifndef __has_attribute
+#  define __has_attribute(attr) false
+#endif
+
+// Fundamental utilities
+
+/**
+ * Get the length of an array.
+ */
+#define countof(array) (sizeof(array) / sizeof(0[array]))
+
+/**
+ * False sharing/destructive interference/largest cache line size.
+ */
+#ifdef __GCC_DESTRUCTIVE_SIZE
+#  define FALSE_SHARING_SIZE __GCC_DESTRUCTIVE_SIZE
+#else
+#  define FALSE_SHARING_SIZE 64
+#endif
+
+/**
+ * True sharing/constructive interference/smallest cache line size.
+ */
+#ifdef __GCC_CONSTRUCTIVE_SIZE
+#  define TRUE_SHARING_SIZE __GCC_CONSTRUCTIVE_SIZE
+#else
+#  define TRUE_SHARING_SIZE 64
+#endif
+
+/**
+ * Polyfill max_align_t if we don't already have it.
+ */
+#if !BFS_HAS_MAX_ALIGN_T
+typedef union {
+#  ifdef __BIGGEST_ALIGNMENT__
+	alignas(__BIGGEST_ALIGNMENT__) char c;
+#  else
+	long double ld;
+	long long ll;
+	void *ptr;
+#  endif
+} max_align_t;
+#endif
+
+/**
+ * Alignment specifier that avoids false sharing.
+ */
+#define cache_align alignas(FALSE_SHARING_SIZE)
+
+// Wrappers for attributes
+
+/**
+ * Silence warnings about switch/case fall-throughs.
+ */
+#if __has_attribute(fallthrough)
+#  define fallthru __attribute__((fallthrough))
+#else
+#  define fallthru ((void)0)
+#endif
+
+/**
+ * Silence warnings about unused declarations.
+ */
+#if __has_attribute(unused)
+#  define attr_maybe_unused __attribute__((unused))
+#else
+#  define attr_maybe_unused
+#endif
+
+/**
+ * Warn if a value is unused.
+ */
+#if __has_attribute(warn_unused_result)
+#  define attr_nodiscard __attribute__((warn_unused_result))
+#else
+#  define attr_nodiscard
+#endif
+
+/**
+ * Hint to avoid inlining a function.
+ */
+#if __has_attribute(noinline)
+#  define attr_noinline __attribute__((noinline))
+#else
+#  define attr_noinline
+#endif
+
+/**
+ * Hint that a function is unlikely to be called.
+ */
+#if __has_attribute(cold)
+#  define attr_cold attr_noinline __attribute__((cold))
+#else
+#  define attr_cold attr_noinline
+#endif
+
+/**
+ * Adds compiler warnings for bad printf()-style function calls, if supported.
+ */
+#if __has_attribute(format)
+#  define attr_printf(fmt, args) __attribute__((format(printf, fmt, args)))
+#else
+#  define attr_printf(fmt, args)
+#endif
+
+/**
+ * Annotates functions that potentially modify and return format strings.
+ */
+#if __has_attribute(format_arg)
+#  define attr_format_arg(arg) __attribute__((format_arg(arg)))
+#else
+#  define attr_format_arg(args)
+#endif
+
+/**
+ * Annotates allocator-like functions.
+ */
+#if __has_attribute(malloc)
+#  if __GNUC__ >= 11 && !__OPTIMIZE__ // malloc(deallocator) disables inlining on GCC
+#    define attr_malloc(...) attr_nodiscard __attribute__((malloc(__VA_ARGS__)))
+#  else
+#    define attr_malloc(...) attr_nodiscard __attribute__((malloc))
+#  endif
+#else
+#  define attr_malloc(...) attr_nodiscard
+#endif
+
+/**
+ * Specifies that a function returns allocations with a given alignment.
+ */
+#if __has_attribute(alloc_align)
+#  define attr_alloc_align(param) __attribute__((alloc_align(param)))
+#else
+#  define attr_alloc_align(param)
+#endif
+
+/**
+ * Specifies that a function returns allocations with a given size.
+ */
+#if __has_attribute(alloc_size)
+#  define attr_alloc_size(...) __attribute__((alloc_size(__VA_ARGS__)))
+#else
+#  define attr_alloc_size(...)
+#endif
+
+/**
+ * Shorthand for attr_alloc_align() and attr_alloc_size().
+ */
+#define attr_aligned_alloc(align, ...) \
+	attr_alloc_align(align) \
+	attr_alloc_size(__VA_ARGS__)
+
+/**
+ * Check if function multiversioning via GNU indirect functions (ifunc) is supported.
+ */
+#ifndef BFS_USE_TARGET_CLONES
+#  if __has_attribute(target_clones) && (__GLIBC__ || __FreeBSD__)
+#    define BFS_USE_TARGET_CLONES true
+#  endif
+#endif
+
+/**
+ * Apply the target_clones attribute, if available.
+ */
+#if BFS_USE_TARGET_CLONES
+#  define attr_target_clones(...) __attribute__((target_clones(__VA_ARGS__)))
+#else
+#  define attr_target_clones(...)
+#endif
+
+/**
+ * Shorthand for multiple attributes at once. attr(a, b(c), d) is equivalent to
+ *
+ *     attr_a
+ *     attr_b(c)
+ *     attr_d
+ */
+#define attr(...) \
+	attr__(attr_##__VA_ARGS__, none, none, none, none, none, none, none, none, none, )
+
+/**
+ * attr() helper.  For exposition, pretend we support only 2 args, instead of 9.
+ * There are a few cases:
+ *
+ *     attr()
+ *         => attr__(attr_, none, none)
+ *         => attr_                =>
+ *            attr_none            =>
+ *            attr_too_many_none() =>
+ *
+ *     attr(a)
+ *         => attr__(attr_a, none, none)
+ *         => attr_a               => __attribute__((a))
+ *            attr_none            =>
+ *            attr_too_many_none() =>
+ *
+ *     attr(a, b(c))
+ *         => attr__(attr_a, b(c), none, none)
+ *         => attr_a                   => __attribute__((a))
+ *            attr_b(c)                => __attribute__((b(c)))
+ *            attr_too_many_none(none) =>
+ *
+ *     attr(a, b(c), d)
+ *         => attr__(attr_a, b(c), d, none, none)
+ *         => attr_a                      => __attribute__((a))
+ *            attr_b(c)                   => __attribute__((b(c)))
+ *            attr_too_many_d(none, none) => error
+ *
+ * Some attribute names are the same as standard library functions, e.g. printf.
+ * Standard libraries are permitted to define these functions as macros, like
+ *
+ *     #define printf(...) __builtin_printf(__VA_ARGS__)
+ *
+ * The token paste in
+ *
+ *     #define attr(...) attr__(attr_##__VA_ARGS__, none, none)
+ *
+ * is necessary to prevent macro expansion before evaluating attr__().
+ * Otherwise, we could get
+ *
+ *     attr(printf(1, 2))
+ *         => attr__(__builtin_printf(1, 2), none, none)
+ *         => attr____builtin_printf(1, 2)
+ *         => error
+ */
+#define attr__(a1, a2, a3, a4, a5, a6, a7, a8, a9, none, ...) \
+	a1 \
+	attr_##a2 \
+	attr_##a3 \
+	attr_##a4 \
+	attr_##a5 \
+	attr_##a6 \
+	attr_##a7 \
+	attr_##a8 \
+	attr_##a9 \
+	attr_too_many_##none(__VA_ARGS__)
+
+// Ignore `attr_none` from expanding 1-9 argument attr(a1, a2, ...)
+#define attr_none
+// Ignore `attr_` from expanding 0-argument attr()
+#define attr_
+// Only trigger an error on more than 9 arguments
+#define attr_too_many_none(...)
+
+#endif // BFS_PRELUDE_H