diff options
Diffstat (limited to 'src/prelude.h')
| -rw-r--r-- | src/prelude.h | 391 |
1 files changed, 80 insertions, 311 deletions
diff --git a/src/prelude.h b/src/prelude.h index 3521fe8..a0cc2a1 100644 --- a/src/prelude.h +++ b/src/prelude.h @@ -2,355 +2,124 @@ // SPDX-License-Identifier: 0BSD /** - * Configuration and feature/platform detection. + * Praeludium. + * + * This header is automatically included in every translation unit, before any + * other headers, so it can set feature test macros[1][2]. This sets up our own + * mini-dialect of C, which includes + * + * - Standard C17 and POSIX.1 2024 features + * - Portable and platform-specific extensions + * - Convenience macros like `bool`, `alignof`, etc. + * - Common compiler extensions like __has_include() + * + * Further bfs-specific utilities are defined in "bfs.h". + * + * [1]: https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html + * [2]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/V2_chap02.html */ #ifndef BFS_PRELUDE_H #define BFS_PRELUDE_H -// Possible __STDC_VERSION__ values +// Feature test macros -#define C95 199409L -#define C99 199901L -#define C11 201112L -#define C17 201710L -#define C23 202311L - -// Get the static_assert() definition as well as __GLIBC__ -#include <assert.h> - -#if __STDC_VERSION__ < C23 -# include <stdalign.h> -# include <stdbool.h> -# include <stdnoreturn.h> -#endif +/** + * Linux and BSD handle _POSIX_C_SOURCE differently: on Linux, it enables POSIX + * interfaces that are not visible by default. On BSD, it also *disables* most + * extensions, giving a strict POSIX environment. Since we want the extensions, + * we don't set _POSIX_C_SOURCE. + */ +// #define _POSIX_C_SOURCE 202405L -// bfs packaging configuration +/** openat() etc. */ +#define _ATFILE_SOURCE 1 -#include "config.h" +/** BSD-derived extensions. */ +#define _BSD_SOURCE 1 -#ifndef BFS_COMMAND -# define BFS_COMMAND "bfs" -#endif -#ifndef BFS_HOMEPAGE -# define BFS_HOMEPAGE "https://tavianator.com/projects/bfs.html" -#endif +/** glibc successor to _BSD_SOURCE. */ +#define _DEFAULT_SOURCE 1 -// 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[]; +/** GNU extensions. */ +#define _GNU_SOURCE 1 -// Check for system headers +/** Use 64-bit off_t. */ +#define _FILE_OFFSET_BITS 64 -#ifdef __has_include +/** Use 64-bit time_t. */ +#define _TIME_BITS 64 -#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 +/** macOS extensions. */ +#if __APPLE__ +# define _DARWIN_C_SOURCE 1 #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 +/** Solaris extensions. */ +#if __sun +# define __EXTENSIONS__ 1 +// https://illumos.org/man/3C/getpwnam#standard-conforming +# define _POSIX_PTHREAD_SEMANTICS 1 #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])) +// Get the convenience macros that became standard spellings in C23 +#if __STDC_VERSION__ < 202311L -/** - * 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 +/** _Static_assert() => static_assert() */ +#include <assert.h> +/** _Alignas(), _Alignof() => alignas(), alignof() */ +#include <stdalign.h> +/** _Bool => bool, true, false */ +#include <stdbool.h> /** - * True sharing/constructive interference/smallest cache line size. + * C23 deprecates `noreturn void` in favour of `[[noreturn]] void`, so we expose + * _noreturn instead with the other attributes in "bfs.h". */ -#ifdef __GCC_CONSTRUCTIVE_SIZE -# define TRUE_SHARING_SIZE __GCC_CONSTRUCTIVE_SIZE -#else -# define TRUE_SHARING_SIZE 64 -#endif +// #include <stdnoreturn.h> -/** - * Alignment specifier that avoids false sharing. - */ -#define cache_align alignas(FALSE_SHARING_SIZE) +/** Part of <threads.h>, but we don't use anything else from it. */ +#define thread_local _Thread_local -// Wrappers for attributes +#endif // !C23 -/** - * Silence warnings about switch/case fall-throughs. - */ -#if __has_attribute(fallthrough) -# define fallthru __attribute__((fallthrough)) -#else -# define fallthru ((void)0) -#endif +// Feature detection -/** - * 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 +// https://clang.llvm.org/docs/LanguageExtensions.html#has-attribute +#ifndef __has_attribute +# define __has_attribute(attr) false #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 +// https://clang.llvm.org/docs/LanguageExtensions.html#has-builtin +#ifndef __has_builtin +# define __has_builtin(builtin) false #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) +// https://en.cppreference.com/w/c/language/attributes#Attribute_testing +#ifndef __has_c_attribute +# define __has_c_attribute(attr) false #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) +// https://clang.llvm.org/docs/LanguageExtensions.html#has-feature-and-has-extension +#ifndef __has_feature +# define __has_feature(feat) false #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 +// https://en.cppreference.com/w/c/preprocessor/include +#ifndef __has_include +# define __has_include(header) false #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 +// Sanitizer macros (GCC defines these but Clang does not) -/** - * 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(...) +#if __has_feature(address_sanitizer) && !defined(__SANITIZE_ADDRESS__) +# define __SANITIZE_ADDRESS__ true #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 +#if __has_feature(memory_sanitizer) && !defined(__SANITIZE_MEMORY__) +# define __SANITIZE_MEMORY__ true #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(...) +#if __has_feature(thread_sanitizer) && !defined(__SANITIZE_THREAD__) +# define __SANITIZE_THREAD__ true #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 |