build: Replace `make config` with a `./configure` script

This lets us do more traditional out-of-tree builds like

    $ ../path/to/bfs/configure
    $ make

The .mk files are moved from ./config to ./build, mostly so that
./configure will auto-complete easily.

49 files changed, 988 insertions, 0 deletions

diff --git a/build/cc.sh b/build/cc.sh
new file mode 100755
index 0000000..45d51ca
--- /dev/null
+++ b/build/cc.sh
@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Run the compiler and check if it succeeded
+
+set -eu
+
+TMP=$(mktemp)
+trap 'rm -f "$TMP"' EXIT
+
+(
+    set -x
+    $XCC $XCPPFLAGS $XCFLAGS $XLDFLAGS "$@" $XLDLIBS -o "$TMP"
+)
diff --git a/build/config.mk b/build/config.mk
new file mode 100644
index 0000000..153838d
--- /dev/null
+++ b/build/config.mk
@@ -0,0 +1,62 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that implements `./configure`
+
+include build/prelude.mk
+include build/exports.mk
+
+# All configuration steps
+config: gen/config.mk gen/config.h
+.PHONY: config
+
+# Makefile fragments generated by `./configure`
+MKS := \
+    gen/vars.mk \
+    gen/flags.mk \
+    gen/deps.mk \
+    gen/pkgs.mk
+
+# The main configuration file, which includes the others
+gen/config.mk: ${MKS}
+	${MSG} "[ GEN] $@"
+	@printf '# %s\n' "$@" >$@
+	@printf 'include %s\n' ${.ALLSRC} >>$@
+	${VCAT} gen/config.mk
+.PHONY: gen/config.mk
+
+# Saves the configurable variables
+gen/vars.mk::
+	@${MKDIR} ${@D}
+	${MSG} "[ GEN] $@"
+	@printf '# %s\n' "$@" >$@
+	@printf 'PREFIX := %s\n' "$$XPREFIX" >>$@
+	@printf 'MANDIR := %s\n' "$$XMANDIR" >>$@
+	@printf 'OS := %s\n' "$${OS:-$$(uname)}" >>$@
+	@printf 'CC := %s\n' "$$XCC" >>$@
+	@printf 'INSTALL := %s\n' "$$XINSTALL" >>$@
+	@printf 'MKDIR := %s\n' "$$XMKDIR" >>$@
+	@printf 'PKG_CONFIG := %s\n' "$$XPKG_CONFIG" >>$@
+	@printf 'RM := %s\n' "$$XRM" >>$@
+	${VCAT} $@
+
+# Sets the build flags.  This depends on vars.mk and uses a recursive make so
+# that the default flags can depend on variables like ${OS}.
+gen/flags.mk: gen/vars.mk
+	@+${MAKE} -sf build/flags.mk $@
+.PHONY: gen/flags.mk
+
+# Check for dependency generation support
+gen/deps.mk: gen/flags.mk
+	@+${MAKE} -sf build/deps.mk $@
+.PHONY: gen/deps.mk
+
+# Auto-detect dependencies and their build flags
+gen/pkgs.mk: gen/flags.mk
+	@+${MAKE} -sf build/pkgs.mk $@
+.PHONY: gen/pkgs.mk
+
+# Compile-time feature detection
+gen/config.h: gen/config.mk
+	@+${MAKE} -sf build/header.mk $@
+.PHONY: gen/config.h
diff --git a/build/define-if.sh b/build/define-if.sh
new file mode 100755
index 0000000..295ead8
--- /dev/null
+++ b/build/define-if.sh
@@ -0,0 +1,20 @@
+#!/bin/sh
+
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Output a C preprocessor definition based on whether a command succeeds
+
+set -eu
+
+SLUG="${1#build/}"
+SLUG="${SLUG%.c}"
+MACRO="BFS_$(printf '%s' "$SLUG" | tr '/a-z-' '_A-Z_')"
+shift
+
+if "$@"; then
+    printf '#define %s true\n' "$MACRO"
+else
+    printf '#define %s false\n' "$MACRO"
+    exit 1
+fi
diff --git a/build/deps.mk b/build/deps.mk
new file mode 100644
index 0000000..e8dd9fb
--- /dev/null
+++ b/build/deps.mk
@@ -0,0 +1,18 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that generates gen/deps.mk
+
+include build/prelude.mk
+include gen/vars.mk
+include gen/flags.mk
+include build/exports.mk
+
+gen/deps.mk::
+	${MSG} "[ GEN] $@"
+	printf '# %s\n' "$@" >$@
+	if build/cc.sh -MD -MP -MF /dev/null build/empty.c; then \
+	    printf 'DEPFLAGS := -MD -MP\n'; \
+	fi >>$@ 2>$@.log
+	${VCAT} $@
+	printf -- '-include %s\n' ${OBJS:.o=.d} >>$@
diff --git a/build/empty.c b/build/empty.c
new file mode 100644
index 0000000..4fa9a5b
--- /dev/null
+++ b/build/empty.c
@@ -0,0 +1,6 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+int main(void) {
+	return 0;
+}
diff --git a/build/exports.mk b/build/exports.mk
new file mode 100644
index 0000000..ed19134
--- /dev/null
+++ b/build/exports.mk
@@ -0,0 +1,20 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile fragment that exports variables used by configuration scripts
+
+export XPREFIX=${PREFIX}
+export XMANDIR=${MANDIR}
+
+export XCC=${CC}
+export XINSTALL=${INSTALL}
+export XMKDIR=${MKDIR}
+export XPKG_CONFIG=${PKG_CONFIG}
+export XRM=${RM}
+
+export XCPPFLAGS=${CPPFLAGS}
+export XCFLAGS=${CFLAGS}
+export XLDFLAGS=${LDFLAGS}
+export XLDLIBS=${LDLIBS}
+
+export XNOLIBS=${NOLIBS}
diff --git a/build/flags.mk b/build/flags.mk
new file mode 100644
index 0000000..0a44e94
--- /dev/null
+++ b/build/flags.mk
@@ -0,0 +1,136 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that generates gen/flags.mk
+
+include build/prelude.mk
+include gen/vars.mk
+
+# Configurable flags
+CPPFLAGS ?=
+CFLAGS ?= \
+    -g \
+    -Wall \
+    -Wformat=2 \
+    -Werror=implicit \
+    -Wimplicit-fallthrough \
+    -Wmissing-declarations \
+    -Wshadow \
+    -Wsign-compare \
+    -Wstrict-prototypes
+LDFLAGS ?=
+LDLIBS ?=
+
+export XCPPFLAGS=${CPPFLAGS}
+export XCFLAGS=${CFLAGS}
+export XLDFLAGS=${LDFLAGS}
+export XLDLIBS=${LDLIBS}
+
+# Immutable flags
+export BFS_CPPFLAGS= \
+    -Isrc \
+    -Igen \
+    -D__EXTENSIONS__ \
+    -D_ATFILE_SOURCE \
+    -D_BSD_SOURCE \
+    -D_DARWIN_C_SOURCE \
+    -D_DEFAULT_SOURCE \
+    -D_GNU_SOURCE \
+    -D_POSIX_PTHREAD_SEMANTICS \
+    -D_FILE_OFFSET_BITS=64 \
+    -D_TIME_BITS=64
+export BFS_CFLAGS= -std=c17 -pthread
+
+# Platform-specific system libraries
+LDLIBS,DragonFly := -lposix1e
+LDLIBS,Linux := -lrt
+LDLIBS,NetBSD := -lutil
+LDLIBS,SunOS := -lsec -lsocket -lnsl
+export BFS_LDLIBS=${LDLIBS,${OS}}
+
+# Build profiles
+_ASAN := ${TRUTHY,${ASAN}}
+_LSAN := ${TRUTHY,${LSAN}}
+_MSAN := ${TRUTHY,${MSAN}}
+_TSAN := ${TRUTHY,${TSAN}}
+_UBSAN := ${TRUTHY,${UBSAN}}
+_GCOV := ${TRUTHY,${GCOV}}
+_LINT := ${TRUTHY,${LINT}}
+_RELEASE := ${TRUTHY,${RELEASE}}
+
+# https://github.com/google/sanitizers/issues/342
+TSAN_CPPFLAGS,y := -DBFS_USE_TARGET_CLONES=0
+export TSAN_CPPFLAGS=${TSAN_CPPFLAGS,${_TSAN}}
+
+ASAN_CFLAGS,y := -fsanitize=address
+LSAN_CFLAGS,y := -fsanitize=leak
+MSAN_CFLAGS,y := -fsanitize=memory -fsanitize-memory-track-origins
+TSAN_CFLAGS,y := -fsanitize=thread
+UBSAN_CFLAGS.y := -fsanitize=undefined
+
+export ASAN_CFLAGS=${ASAN_CFLAGS,${_ASAN}}
+export LSAN_CFLAGS=${LSAN_CFLAGS,${_LSAN}}
+export MSAN_CFLAGS=${MSAN_CFLAGS,${_MSAN}}
+export TSAN_CFLAGS=${TSAN_CFLAGS,${_TSAN}}
+export UBSAN_CFLAGS=${UBSAN_CFLAGS,${_UBSAN}}
+
+SAN_CFLAGS,y := -fno-sanitize-recover=all
+INSANE := ${NOT,${_ASAN}${_LSAN}${_MSAN}${_TSAN}${_UBSAN}}
+SAN := ${NOT,${INSANE}}
+export SAN_CFLAGS=${SAN_CFLAGS,${SAN}}
+
+# MSAN and TSAN both need all code to be instrumented
+YESLIBS := ${NOT,${_MSAN}${_TSAN}}
+NOLIBS ?= ${NOT,${YESLIBS}}
+export XNOLIBS=${NOLIBS}
+
+# gcov only intercepts fork()/exec() with -std=gnu*
+GCOV_CFLAGS,y := -std=gnu17 --coverage
+export GCOV_CFLAGS=${GCOV_CFLAGS,${_GCOV}}
+
+LINT_CPPFLAGS,y := -D_FORTIFY_SOURCE=3 -DBFS_LINT
+LINT_CFLAGS,y := -Werror -O2
+
+export LINT_CPPFLAGS=${LINT_CPPFLAGS,${_LINT}}
+export LINT_CFLAGS=${LINT_CFLAGS,${_LINT}}
+
+RELEASE_CPPFLAGS,y := -DNDEBUG
+RELEASE_CFLAGS,y := -O3 -flto=auto
+
+export RELEASE_CPPFLAGS=${RELEASE_CPPFLAGS,${_RELEASE}}
+export RELEASE_CFLAGS=${RELEASE_CFLAGS,${_RELEASE}}
+
+# Set a variable
+SETVAR = printf '%s := %s\n' >>$@
+
+# Append to a variable, if non-empty
+APPEND = append() { test -z "$$2" || printf '%s += %s\n' "$$1" "$$2" >>$@; }; append
+
+gen/flags.mk::
+	${MSG} "[ GEN] $@"
+	printf '# %s\n' "$@" >$@
+	${SETVAR} CPPFLAGS "$$BFS_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$TSAN_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$LINT_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$RELEASE_CPPFLAGS"
+	${APPEND} CPPFLAGS "$$XCPPFLAGS"
+	${APPEND} CPPFLAGS "$$EXTRA_CPPFLAGS"
+	${SETVAR} CFLAGS "$$BFS_CFLAGS"
+	${APPEND} CFLAGS "$$ASAN_CFLAGS"
+	${APPEND} CFLAGS "$$LSAN_CFLAGS"
+	${APPEND} CFLAGS "$$MSAN_CFLAGS"
+	${APPEND} CFLAGS "$$TSAN_CFLAGS"
+	${APPEND} CFLAGS "$$UBSAN_CFLAGS"
+	${APPEND} CFLAGS "$$SAN_CFLAGS"
+	${APPEND} CFLAGS "$$GCOV_CFLAGS"
+	${APPEND} CFLAGS "$$LINT_CFLAGS"
+	${APPEND} CFLAGS "$$RELEASE_CFLAGS"
+	${APPEND} CFLAGS "$$XCFLAGS"
+	${APPEND} CFLAGS "$$EXTRA_CFLAGS"
+	${SETVAR} LDFLAGS "$$XLDFLAGS"
+	${SETVAR} LDLIBS "$$XLDLIBS"
+	${APPEND} LDLIBS "$$EXTRA_LDLIBS"
+	${APPEND} LDLIBS "$$BFS_LDLIBS"
+	${SETVAR} NOLIBS "$$XNOLIBS"
+	test "${OS}-${SAN}" != FreeBSD-y || printf 'POSTLINK = elfctl -e +noaslr $$@\n' >>$@
+	${VCAT} $@
diff --git a/build/has/acl-get-entry.c b/build/has/acl-get-entry.c
new file mode 100644
index 0000000..3cce771
--- /dev/null
+++ b/build/has/acl-get-entry.c
@@ -0,0 +1,8 @@
+#include <sys/types.h>
+#include <sys/acl.h>
+
+int main(void) {
+	acl_t acl = acl_get_file(".", ACL_TYPE_DEFAULT);
+	acl_entry_t entry;
+	return acl_get_entry(acl, ACL_FIRST_ENTRY, &entry);
+}
diff --git a/build/has/acl-get-file.c b/build/has/acl-get-file.c
new file mode 100644
index 0000000..89fbf23
--- /dev/null
+++ b/build/has/acl-get-file.c
@@ -0,0 +1,8 @@
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/acl.h>
+
+int main(void) {
+	acl_t acl = acl_get_file(".", ACL_TYPE_DEFAULT);
+	return acl == (acl_t)NULL;
+}
diff --git a/build/has/acl-get-tag-type.c b/build/has/acl-get-tag-type.c
new file mode 100644
index 0000000..2901956
--- /dev/null
+++ b/build/has/acl-get-tag-type.c
@@ -0,0 +1,10 @@
+#include <string.h>
+#include <sys/types.h>
+#include <sys/acl.h>
+
+int main(void) {
+	acl_entry_t entry;
+	memset(&entry, 0, sizeof(entry));
+	acl_tag_t tag;
+	return acl_get_tag_type(entry, &tag);
+}
diff --git a/build/has/acl-is-trivial-np.c b/build/has/acl-is-trivial-np.c
new file mode 100644
index 0000000..9ca9fc7
--- /dev/null
+++ b/build/has/acl-is-trivial-np.c
@@ -0,0 +1,12 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/types.h>
+#include <sys/acl.h>
+
+int main(void) {
+	acl_t acl = acl_get_fd(3);
+	int trivial;
+	acl_is_trivial_np(acl, &trivial);
+	return 0;
+}
diff --git a/build/has/acl-trivial.c b/build/has/acl-trivial.c
new file mode 100644
index 0000000..7efc838
--- /dev/null
+++ b/build/has/acl-trivial.c
@@ -0,0 +1,8 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/acl.h>
+
+int main(void) {
+	return acl_trivial(".");
+}
diff --git a/build/has/aligned-alloc.c b/build/has/aligned-alloc.c
new file mode 100644
index 0000000..4460038
--- /dev/null
+++ b/build/has/aligned-alloc.c
@@ -0,0 +1,8 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stdlib.h>
+
+int main(void) {
+	return !aligned_alloc(_Alignof(void *), sizeof(void *));
+}
diff --git a/build/has/confstr.c b/build/has/confstr.c
new file mode 100644
index 0000000..58280b4
--- /dev/null
+++ b/build/has/confstr.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <unistd.h>
+
+int main(void) {
+	confstr(_CS_PATH, NULL, 0);
+	return 0;
+}
diff --git a/build/has/extattr-get-file.c b/build/has/extattr-get-file.c
new file mode 100644
index 0000000..ac9cf96
--- /dev/null
+++ b/build/has/extattr-get-file.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_get_file("file", EXTATTR_NAMESPACE_USER, "xattr", NULL, 0);
+}
diff --git a/build/has/extattr-get-link.c b/build/has/extattr-get-link.c
new file mode 100644
index 0000000..c35be5b
--- /dev/null
+++ b/build/has/extattr-get-link.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_get_link("link", EXTATTR_NAMESPACE_USER, "xattr", NULL, 0);
+}
diff --git a/build/has/extattr-list-file.c b/build/has/extattr-list-file.c
new file mode 100644
index 0000000..e68a8bb
--- /dev/null
+++ b/build/has/extattr-list-file.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_list_file("file", EXTATTR_NAMESPACE_USER, NULL, 0);
+}
diff --git a/build/has/extattr-list-link.c b/build/has/extattr-list-link.c
new file mode 100644
index 0000000..49f0ec2
--- /dev/null
+++ b/build/has/extattr-list-link.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+#include <sys/types.h>
+#include <sys/extattr.h>
+
+int main(void) {
+	return extattr_list_link("link", EXTATTR_NAMESPACE_USER, NULL, 0);
+}
diff --git a/build/has/fdclosedir.c b/build/has/fdclosedir.c
new file mode 100644
index 0000000..f4ad1f5
--- /dev/null
+++ b/build/has/fdclosedir.c
@@ -0,0 +1,8 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <dirent.h>
+
+int main(void) {
+	return fdclosedir(opendir("."));
+}
diff --git a/build/has/getdents.c b/build/has/getdents.c
new file mode 100644
index 0000000..d0d4228
--- /dev/null
+++ b/build/has/getdents.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <dirent.h>
+
+int main(void) {
+	struct dirent de;
+	getdents(3, &de, 1024);
+	return 0;
+}
diff --git a/build/has/getdents64-syscall.c b/build/has/getdents64-syscall.c
new file mode 100644
index 0000000..4838c14
--- /dev/null
+++ b/build/has/getdents64-syscall.c
@@ -0,0 +1,12 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <dirent.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+int main(void) {
+	struct dirent64 de;
+	syscall(SYS_getdents64, 3, &de, 1024);
+	return 0;
+}
diff --git a/build/has/getdents64.c b/build/has/getdents64.c
new file mode 100644
index 0000000..1abf36d
--- /dev/null
+++ b/build/has/getdents64.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <dirent.h>
+
+int main(void) {
+	struct dirent64 de;
+	getdents64(3, &de, 1024);
+	return 0;
+}
diff --git a/build/has/getprogname-gnu.c b/build/has/getprogname-gnu.c
new file mode 100644
index 0000000..6b97c5e
--- /dev/null
+++ b/build/has/getprogname-gnu.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <errno.h>
+
+int main(void) {
+	const char *str = program_invocation_short_name;
+	return str[0];
+}
diff --git a/build/has/getprogname.c b/build/has/getprogname.c
new file mode 100644
index 0000000..83dc8e8
--- /dev/null
+++ b/build/has/getprogname.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stdlib.h>
+
+int main(void) {
+	const char *str = getprogname();
+	return str[0];
+}
diff --git a/build/has/max-align-t.c b/build/has/max-align-t.c
new file mode 100644
index 0000000..96165ce
--- /dev/null
+++ b/build/has/max-align-t.c
@@ -0,0 +1,8 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <stddef.h>
+
+int main(void) {
+	return _Alignof(max_align_t);
+}
diff --git a/build/has/pipe2.c b/build/has/pipe2.c
new file mode 100644
index 0000000..4cb43b5
--- /dev/null
+++ b/build/has/pipe2.c
@@ -0,0 +1,10 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <fcntl.h>
+#include <unistd.h>
+
+int main(void) {
+	int fds[2];
+	return pipe2(fds, O_CLOEXEC);
+}
diff --git a/build/has/posix-spawn-addfchdir-np.c b/build/has/posix-spawn-addfchdir-np.c
new file mode 100644
index 0000000..b870a53
--- /dev/null
+++ b/build/has/posix-spawn-addfchdir-np.c
@@ -0,0 +1,11 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <spawn.h>
+
+int main(void) {
+	posix_spawn_file_actions_t actions;
+	posix_spawn_file_actions_init(&actions);
+	posix_spawn_file_actions_addfchdir_np(&actions, 3);
+	return 0;
+}
diff --git a/build/has/posix-spawn-addfchdir.c b/build/has/posix-spawn-addfchdir.c
new file mode 100644
index 0000000..c52ff81
--- /dev/null
+++ b/build/has/posix-spawn-addfchdir.c
@@ -0,0 +1,11 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <spawn.h>
+
+int main(void) {
+	posix_spawn_file_actions_t actions;
+	posix_spawn_file_actions_init(&actions);
+	posix_spawn_file_actions_addfchdir(&actions, 3);
+	return 0;
+}
diff --git a/build/has/st-acmtim.c b/build/has/st-acmtim.c
new file mode 100644
index 0000000..d687ab0
--- /dev/null
+++ b/build/has/st-acmtim.c
@@ -0,0 +1,12 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/stat.h>
+
+int main(void) {
+	struct stat sb = {0};
+	unsigned int a = sb.st_atim.tv_sec;
+	unsigned int c = sb.st_ctim.tv_sec;
+	unsigned int m = sb.st_mtim.tv_sec;
+	return a + c + m;
+}
diff --git a/build/has/st-acmtimespec.c b/build/has/st-acmtimespec.c
new file mode 100644
index 0000000..f747bc0
--- /dev/null
+++ b/build/has/st-acmtimespec.c
@@ -0,0 +1,12 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/stat.h>
+
+int main(void) {
+	struct stat sb = {0};
+	unsigned int a = sb.st_atimespec.tv_sec;
+	unsigned int c = sb.st_ctimespec.tv_sec;
+	unsigned int m = sb.st_mtimespec.tv_sec;
+	return a + c + m;
+}
diff --git a/build/has/st-birthtim.c b/build/has/st-birthtim.c
new file mode 100644
index 0000000..4964571
--- /dev/null
+++ b/build/has/st-birthtim.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/stat.h>
+
+int main(void) {
+	struct stat sb = {0};
+	return sb.st_birthtim.tv_sec;
+}
diff --git a/build/has/st-birthtimespec.c b/build/has/st-birthtimespec.c
new file mode 100644
index 0000000..91a613f
--- /dev/null
+++ b/build/has/st-birthtimespec.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/stat.h>
+
+int main(void) {
+	struct stat sb = {0};
+	return sb.st_birthtimespec.tv_sec;
+}
diff --git a/build/has/st-flags.c b/build/has/st-flags.c
new file mode 100644
index 0000000..b1d0c32
--- /dev/null
+++ b/build/has/st-flags.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/stat.h>
+
+int main(void) {
+	struct stat sb = {0};
+	return sb.st_flags;
+}
diff --git a/build/has/statx-syscall.c b/build/has/statx-syscall.c
new file mode 100644
index 0000000..87ec869
--- /dev/null
+++ b/build/has/statx-syscall.c
@@ -0,0 +1,13 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <fcntl.h>
+#include <linux/stat.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+int main(void) {
+	struct statx sb;
+	syscall(SYS_statx, AT_FDCWD, ".", 0, STATX_BASIC_STATS, &sb);
+	return 0;
+}
diff --git a/build/has/statx.c b/build/has/statx.c
new file mode 100644
index 0000000..65f1674
--- /dev/null
+++ b/build/has/statx.c
@@ -0,0 +1,11 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <fcntl.h>
+#include <sys/stat.h>
+
+int main(void) {
+	struct statx sb;
+	statx(AT_FDCWD, ".", 0, STATX_BASIC_STATS, &sb);
+	return 0;
+}
diff --git a/build/has/strerror-l.c b/build/has/strerror-l.c
new file mode 100644
index 0000000..3dcc4d7
--- /dev/null
+++ b/build/has/strerror-l.c
@@ -0,0 +1,11 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <errno.h>
+#include <locale.h>
+#include <string.h>
+
+int main(void) {
+	locale_t locale = duplocale(LC_GLOBAL_LOCALE);
+	return !strerror_l(ENOMEM, locale);
+}
diff --git a/build/has/strerror-r-gnu.c b/build/has/strerror-r-gnu.c
new file mode 100644
index 0000000..26ca0ee
--- /dev/null
+++ b/build/has/strerror-r-gnu.c
@@ -0,0 +1,11 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <errno.h>
+#include <string.h>
+
+int main(void) {
+	char buf[256];
+	// Check that strerror_r() returns a pointer
+	return *strerror_r(ENOMEM, buf, sizeof(buf));
+}
diff --git a/build/has/strerror-r-posix.c b/build/has/strerror-r-posix.c
new file mode 100644
index 0000000..41b2d30
--- /dev/null
+++ b/build/has/strerror-r-posix.c
@@ -0,0 +1,11 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <errno.h>
+#include <string.h>
+
+int main(void) {
+	char buf[256];
+	// Check that strerror_r() returns an integer
+	return 2 * strerror_r(ENOMEM, buf, sizeof(buf));
+}
diff --git a/build/has/tm-gmtoff.c b/build/has/tm-gmtoff.c
new file mode 100644
index 0000000..543df48
--- /dev/null
+++ b/build/has/tm-gmtoff.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <time.h>
+
+int main(void) {
+	struct tm tm = {0};
+	return tm.tm_gmtoff;
+}
diff --git a/build/has/uselocale.c b/build/has/uselocale.c
new file mode 100644
index 0000000..a712ff8
--- /dev/null
+++ b/build/has/uselocale.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <locale.h>
+
+int main(void) {
+	locale_t locale = uselocale((locale_t)0);
+	return locale == LC_GLOBAL_LOCALE;
+}
diff --git a/build/header.mk b/build/header.mk
new file mode 100644
index 0000000..3f77ca5
--- /dev/null
+++ b/build/header.mk
@@ -0,0 +1,69 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that generates gen/config.h
+
+include build/prelude.mk
+include gen/config.mk
+include build/exports.mk
+
+# All header fragments we generate
+HEADERS := \
+    gen/has/acl-get-entry.h \
+    gen/has/acl-get-file.h \
+    gen/has/acl-get-tag-type.h \
+    gen/has/acl-is-trivial-np.h \
+    gen/has/acl-trivial.h \
+    gen/has/aligned-alloc.h \
+    gen/has/confstr.h \
+    gen/has/extattr-get-file.h \
+    gen/has/extattr-get-link.h \
+    gen/has/extattr-list-file.h \
+    gen/has/extattr-list-link.h \
+    gen/has/fdclosedir.h \
+    gen/has/getdents.h \
+    gen/has/getdents64.h \
+    gen/has/getdents64-syscall.h \
+    gen/has/getprogname.h \
+    gen/has/getprogname-gnu.h \
+    gen/has/max-align-t.h \
+    gen/has/pipe2.h \
+    gen/has/posix-spawn-addfchdir.h \
+    gen/has/posix-spawn-addfchdir-np.h \
+    gen/has/st-acmtim.h \
+    gen/has/st-acmtimespec.h \
+    gen/has/st-birthtim.h \
+    gen/has/st-birthtimespec.h \
+    gen/has/st-flags.h \
+    gen/has/statx.h \
+    gen/has/statx-syscall.h \
+    gen/has/strerror-l.h \
+    gen/has/strerror-r-gnu.h \
+    gen/has/strerror-r-posix.h \
+    gen/has/tm-gmtoff.h \
+    gen/has/uselocale.h
+
+# Previously generated by pkgs.mk
+PKG_HEADERS := ${ALL_PKGS:%=gen/use/%.h}
+
+gen/config.h: ${PKG_HEADERS} ${HEADERS}
+	${MSG} "[ GEN] $@"
+	printf '// %s\n' "$@" >$@
+	printf '#ifndef BFS_CONFIG_H\n' >>$@
+	printf '#define BFS_CONFIG_H\n' >>$@
+	cat ${.ALLSRC} >>$@
+	printf '#endif // BFS_CONFIG_H\n' >>$@
+	cat ${.ALLSRC:%=%.log} >$@.log
+	${VCAT} $@
+.PHONY: gen/config.h
+
+# The short name of the config test
+SLUG = ${@:gen/%.h=%}
+
+${HEADERS}::
+	${MKDIR} ${@D}
+	if build/define-if.sh ${SLUG} build/cc.sh build/${SLUG}.c >$@ 2>$@.log; then \
+	    test "${IS_V}" || printf '[ CC ] %-${MSG_WIDTH}s  ✔\n' ${SLUG}.c; \
+	else \
+	    test "${IS_V}" || printf '[ CC ] %-${MSG_WIDTH}s  ✘\n' ${SLUG}.c; \
+	fi
diff --git a/build/pkgconf.sh b/build/pkgconf.sh
new file mode 100755
index 0000000..96e4bf1
--- /dev/null
+++ b/build/pkgconf.sh
@@ -0,0 +1,100 @@
+#!/bin/sh
+
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# pkg-config wrapper with hardcoded fallbacks
+
+set -eu
+
+MODE=
+case "${1:-}" in
+    --*)
+        MODE="$1"
+        shift
+esac
+
+if [ $# -lt 1 ]; then
+    exit
+fi
+
+case "$XNOLIBS" in
+    y|1)
+        exit 1
+esac
+
+if [ -z "$MODE" ]; then
+    # Check whether the libraries exist at all
+    for LIB; do
+        # Check ${USE_$LIB}
+        USE_LIB="USE_$(printf '%s' "$LIB" | tr 'a-z-' 'A-Z_')"
+        eval "USE=\"\${$USE_LIB:-}\""
+        case "$USE" in
+            y|1)
+                continue
+                ;;
+            n|0)
+                exit 1
+                ;;
+        esac
+
+        CFLAGS=$("$0" --cflags "$LIB") || exit 1
+        LDFLAGS=$("$0" --ldflags "$LIB") || exit 1
+        LDLIBS=$("$0" --ldlibs "$LIB") || exit 1
+        build/cc.sh $CFLAGS $LDFLAGS build/use/$LIB.c $LDLIBS || exit 1
+    done
+fi
+
+# Defer to pkg-config if possible
+if command -v "${XPKG_CONFIG:-}" >/dev/null 2>&1; then
+    case "$MODE" in
+        --cflags)
+            "$XPKG_CONFIG" --cflags "$@"
+            ;;
+        --ldflags)
+            "$XPKG_CONFIG" --libs-only-L --libs-only-other "$@"
+            ;;
+        --ldlibs)
+            "$XPKG_CONFIG" --libs-only-l "$@"
+            ;;
+    esac
+
+    exit
+fi
+
+# pkg-config unavailable, emulate it ourselves
+CFLAGS=""
+LDFLAGS=""
+LDLIBS=""
+
+for LIB; do
+    case "$LIB" in
+        libacl)
+            LDLIB=-lacl
+            ;;
+        libcap)
+            LDLIB=-lcap
+            ;;
+        libselinux)
+            LDLIB=-lselinux
+            ;;
+        liburing)
+            LDLIB=-luring
+            ;;
+        oniguruma)
+            LDLIB=-lonig
+            ;;
+        *)
+            printf 'error: Unknown package %s\n' "$LIB" >&2
+            exit 1
+            ;;
+    esac
+
+    LDLIBS="$LDLIBS$LDLIB "
+done
+
+case "$MODE" in
+    --ldlibs)
+        printf '%s\n' "$LDLIBS"
+    ;;
+esac
diff --git a/build/pkgs.mk b/build/pkgs.mk
new file mode 100644
index 0000000..51ca664
--- /dev/null
+++ b/build/pkgs.mk
@@ -0,0 +1,36 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Makefile that generates gen/pkgs.mk
+
+include build/prelude.mk
+include gen/vars.mk
+include gen/flags.mk
+include build/exports.mk
+
+HEADERS := ${ALL_PKGS:%=gen/use/%.h}
+
+gen/pkgs.mk: ${HEADERS}
+	${MSG} "[ GEN] $@"
+	printf '# %s\n' "$@" >$@
+	gen() { \
+	    printf 'PKGS := %s\n' "$$*"; \
+	    printf 'CFLAGS += %s\n' "$$(build/pkgconf.sh --cflags "$$@")"; \
+	    printf 'LDFLAGS += %s\n' "$$(build/pkgconf.sh --ldflags "$$@")"; \
+	    printf 'LDLIBS := %s $${LDLIBS}\n' "$$(build/pkgconf.sh --ldlibs "$$@")"; \
+	}; \
+	gen $$(grep -l ' true$$' ${.ALLSRC} | sed 's|.*/\(.*\)\.h|\1|') >>$@
+	${VCAT} $@
+
+.PHONY: gen/pkgs.mk
+
+# Convert gen/use/foo.h to foo
+PKG = ${@:gen/use/%.h=%}
+
+${HEADERS}::
+	${MKDIR} ${@D}
+	if build/define-if.sh use/${PKG} build/pkgconf.sh ${PKG} >$@ 2>$@.log; then \
+	    test "${IS_V}" || printf '[ CC ] %-${MSG_WIDTH}s  ✔\n' use/${PKG}.c; \
+	else \
+	    test "${IS_V}" || printf '[ CC ] %-${MSG_WIDTH}s  ✘\n' use/${PKG}.c; \
+	fi
diff --git a/build/prelude.mk b/build/prelude.mk
new file mode 100644
index 0000000..b235fa9
--- /dev/null
+++ b/build/prelude.mk
@@ -0,0 +1,133 @@
+# Copyright © Tavian Barnes <tavianator@tavianator.com>
+# SPDX-License-Identifier: 0BSD
+
+# Common makefile utilities.  Compatible with both GNU make and most BSD makes.
+
+# BSD make will chdir into ${.OBJDIR} by default, unless we tell it not to
+.OBJDIR: .
+
+# We don't use any suffix rules
+.SUFFIXES:
+
+# GNU make has $^ for the full list of targets, while BSD make has $> and the
+# long-form ${.ALLSRC}.  We could write $^ $> to get them both, but that would
+# break if one of them implemented support for the other.  So instead, bring
+# BSD's ${.ALLSRC} to GNU.
+.ALLSRC ?= $^
+
+# Installation paths
+DESTDIR ?=
+PREFIX ?= /usr
+MANDIR ?= ${PREFIX}/share/man
+
+# Configurable executables
+CC ?= cc
+INSTALL ?= install
+MKDIR ?= mkdir -p
+PKG_CONFIG ?= pkg-config
+RM ?= rm -f
+
+# GNU and BSD make have incompatible syntax for conditionals, but we can do a
+# lot with just nested variable expansion.  We use "y" as the canonical
+# truthy value, and "" (the empty string) as the canonical falsey value.
+#
+# To normalize a boolean, use ${TRUTHY,${VAR}}, which expands like this:
+#
+#     VAR=y      ${TRUTHY,${VAR}} => ${TRUTHY,y}     => y
+#     VAR=1      ${TRUTHY,${VAR}} => ${TRUTHY,1}     => y
+#     VAR=n      ${TRUTHY,${VAR}} => ${TRUTHY,n}     =>   [empty]
+#     VAR=other  ${TRUTHY,${VAR}} => ${TRUTHY,other} =>   [empty]
+#     VAR=       ${TRUTHY,${VAR}} => ${TRUTHY,}      =>   [emtpy]
+#
+# Inspired by https://github.com/wahern/autoguess
+TRUTHY,y := y
+TRUTHY,1 := y
+
+# Boolean operators are also implemented with nested expansion
+NOT,  := y
+
+# Normalize ${V} to either "y" or ""
+IS_V := ${TRUTHY,${V}}
+
+# Suppress output unless V=1
+Q, := @
+Q  := ${Q,${IS_V}}
+
+# Show full commands with `make V=1`, otherwise short summaries
+MSG = @msg() { \
+          MSG="$$1"; \
+          shift; \
+          test "${IS_V}" || printf '%s\n' "$$MSG"; \
+          test "$${1:-}" || return 0; \
+          test "${IS_V}" && printf '%s\n' "$$*"; \
+          "$$@"; \
+      }; \
+      msg
+
+# Maximum width of a short message, to align the ✔/✘
+MSG_WIDTH := 30
+
+# cat a file if V=1
+VCAT,y := @cat
+VCAT,  := @:
+VCAT   := ${VCAT,${IS_V}}
+
+# All external dependencies
+ALL_PKGS := \
+    libacl \
+    libcap \
+    libselinux \
+    liburing \
+    oniguruma
+
+# List all object files here, as they're needed by both `./configure` and `make`
+
+# All object files except the entry point
+LIBBFS := \
+    obj/src/alloc.o \
+    obj/src/bar.o \
+    obj/src/bfstd.o \
+    obj/src/bftw.o \
+    obj/src/color.o \
+    obj/src/ctx.o \
+    obj/src/diag.o \
+    obj/src/dir.o \
+    obj/src/dstring.o \
+    obj/src/eval.o \
+    obj/src/exec.o \
+    obj/src/expr.o \
+    obj/src/fsade.o \
+    obj/src/ioq.o \
+    obj/src/mtab.o \
+    obj/src/opt.o \
+    obj/src/parse.o \
+    obj/src/printf.o \
+    obj/src/pwcache.o \
+    obj/src/stat.o \
+    obj/src/thread.o \
+    obj/src/trie.o \
+    obj/src/typo.o \
+    obj/src/xregex.o \
+    obj/src/xspawn.o \
+    obj/src/xtime.o \
+    obj/gen/version.o
+
+# Unit test objects
+UNIT_OBJS := \
+    obj/tests/alloc.o \
+    obj/tests/bfstd.o \
+    obj/tests/bit.o \
+    obj/tests/ioq.o \
+    obj/tests/main.o \
+    obj/tests/trie.o \
+    obj/tests/xspawn.o \
+    obj/tests/xtime.o
+
+# All object files
+OBJS := \
+    obj/src/main.o \
+    obj/tests/mksock.o \
+    obj/tests/xspawnee.o \
+    obj/tests/xtouch.o \
+    ${LIBBFS} \
+    ${UNIT_OBJS}
diff --git a/build/use/libacl.c b/build/use/libacl.c
new file mode 100644
index 0000000..de1fe50
--- /dev/null
+++ b/build/use/libacl.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/acl.h>
+
+int main(void) {
+	acl_free(0);
+	return 0;
+}
diff --git a/build/use/libcap.c b/build/use/libcap.c
new file mode 100644
index 0000000..58e832c
--- /dev/null
+++ b/build/use/libcap.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <sys/capability.h>
+
+int main(void) {
+	cap_free(0);
+	return 0;
+}
diff --git a/build/use/libselinux.c b/build/use/libselinux.c
new file mode 100644
index 0000000..bca409d
--- /dev/null
+++ b/build/use/libselinux.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <selinux/selinux.h>
+
+int main(void) {
+	freecon(0);
+	return 0;
+}
diff --git a/build/use/liburing.c b/build/use/liburing.c
new file mode 100644
index 0000000..bea499a
--- /dev/null
+++ b/build/use/liburing.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <liburing.h>
+
+int main(void) {
+	io_uring_free_probe(0);
+	return 0;
+}
diff --git a/build/use/oniguruma.c b/build/use/oniguruma.c
new file mode 100644
index 0000000..cb17596
--- /dev/null
+++ b/build/use/oniguruma.c
@@ -0,0 +1,9 @@
+// Copyright © Tavian Barnes <tavianator@tavianator.com>
+// SPDX-License-Identifier: 0BSD
+
+#include <oniguruma.h>
+
+int main(void) {
+	onig_free(0);
+	return 0;
+}