/src/util-linux/include/c.h

Source
/*
 * Fundamental C definitions.
 *
 * No copyright is claimed.  This code is in the public domain; do with
 * it what you wish.
 */
#ifndef UTIL_LINUX_C_H
#define UTIL_LINUX_C_H

#include <limits.h>
#include <stddef.h>
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <unistd.h>
#include <stdarg.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <grp.h>

#include <assert.h>

#ifdef HAVE_ERR_H
# include <err.h>
#endif

#ifdef HAVE_SYS_SYSMACROS_H
# include <sys/sysmacros.h>     /* for major, minor */
#endif

#ifndef LOGIN_NAME_MAX
# define LOGIN_NAME_MAX 256
#endif

#ifndef NAME_MAX
# define NAME_MAX PATH_MAX
#endif

#ifndef HAVE_SYS_AUXV_H
# include <sys/auxv.h>
#endif

#define BIT(n)                 (1 << (n))

/*
 * __GNUC_PREREQ is deprecated in favour of __has_attribute() and
 * __has_feature(). The __has macros are supported by clang and gcc>=5.
 */
#ifndef __GNUC_PREREQ
# if defined __GNUC__ && defined __GNUC_MINOR__
#  define __GNUC_PREREQ(maj, min) \
  ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
# else
#  define __GNUC_PREREQ(maj, min) 0
# endif
#endif

#ifdef __GNUC__

/* &a[0] degrades to a pointer: a different type from an array */
# define __must_be_array(a) \
  UL_BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(__typeof__(a), __typeof__(&a[0])))

# define ignore_result(x) __extension__ ({ \
  __typeof__(x) __dummy __attribute__((__unused__)) = (x); (void) __dummy; \
})

#else /* !__GNUC__ */
# define __must_be_array(a) 0
# define __attribute__(_arg_)
# define ignore_result(x) ((void) (x))
#endif /* !__GNUC__ */


/* "restrict" keyword fallback */
#if __STDC__ != 1
# define restrict __restrict /* use implementation __ format */
#else
# ifndef __STDC_VERSION__
#  define restrict __restrict /* use implementation __ format */
# else
#  if __STDC_VERSION__ < 199901L
#   define restrict __restrict /* use implementation __ format */
#  endif
# endif
#endif

#ifdef __has_attribute
# define UL_HAS_ATTRIBUTE(x) __has_attribute(x)
#else
# define UL_HAS_ATTRIBUTE(x) 0
#endif

/* C-language Attributes are added in C23. */
#if defined(__STDC_VERSION__) && (__STDC_VERSION__ > 201710L) && defined(__has_c_attribute)
# define UL_HAS_C_ATTRIBUTE(x) __has_c_attribute(x)
#else
# define UL_HAS_C_ATTRIBUTE(x) 0
#endif

#if defined(__cplusplus) && defined(__has_cpp_attribute)
# define UL_HAS_CPP_ATTRIBUTE(x) __has_cpp_attribute(x)
#else
# define UL_HAS_CPP_ATTRIBUTE(x) 0
#endif

/*
Define FALLTHROUGH macro for annotating switch case with the 'fallthrough' attribute
introduced in CPP17 and C23.
CPP17 : https://en.cppreference.com/w/cpp/language/attributes/fallthrough
C23   : https://en.cppreference.com/w/c/language/attributes/fallthrough
*/
#if UL_HAS_C_ATTRIBUTE(fallthrough) || UL_HAS_CPP_ATTRIBUTE(fallthrough)
# define FALLTHROUGH [[fallthrough]]
#elif UL_HAS_ATTRIBUTE(__fallthrough__)
# define FALLTHROUGH __attribute__ ((__fallthrough__))
#else
# define FALLTHROUGH /* fallthrough */
#endif


/*
 * It evaluates to 1 if the attribute/feature is supported by the current
 * compilation target. Fallback for old compilers.
 */
#ifndef __has_attribute
  #define __has_attribute(x) 0
#endif

#ifndef __has_feature
  #define __has_feature(x) 0
#endif

#ifndef __has_extension
  #define __has_extension __has_feature
#endif

/*
 * Function attributes
 */
#ifndef __ul_alloc_size
# if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
#  define __ul_alloc_size(s) __attribute__((alloc_size(s), warn_unused_result))
# else
#  define __ul_alloc_size(s)
# endif
#endif

#ifndef __ul_calloc_size
# if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
#  define __ul_calloc_size(n, s) __attribute__((alloc_size(n, s), warn_unused_result))
# else
#  define __ul_calloc_size(n, s)
# endif
#endif

#if __has_attribute(returns_nonnull) || __GNUC_PREREQ (4, 9)
# define __ul_returns_nonnull __attribute__((returns_nonnull))
#else
# define __ul_returns_nonnull
#endif

#if __has_attribute(__nonstring__)
# define __ul_nonstring __attribute__((__nonstring__))
#else
# define __ul_nonstring
#endif

/*
 * Force a compilation error if condition is true, but also produce a
 * result (of value 0 and type size_t), so the expression can be used
 * e.g. in a structure initializer (or wherever else comma expressions
 * aren't permitted).
 */
#define UL_BUILD_BUG_ON_ZERO(e) __extension__ (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))

#if __has_include(<stdcountof.h>)
#include <stdcountof.h>
#define ARRAY_SIZE(arr) countof(arr)
#endif

#if !defined(ARRAY_SIZE) && __has_extension(c_countof)
#define ARRAY_SIZE(arr) _Countof(arr)
#endif

#ifndef ARRAY_SIZE
# define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
#endif

#ifndef PATH_MAX
# define PATH_MAX 4096
#endif

#ifndef TRUE
# define TRUE 1
#endif

#ifndef FALSE
# define FALSE 0
#endif

#ifndef min
# define min(x, y) __extension__ ({    \
  __typeof__(x) _min1 = (x);    \
  __typeof__(y) _min2 = (y);    \
  (void) (&_min1 == &_min2);    \
  _min1 < _min2 ? _min1 : _min2; })
#endif

#ifndef max
# define max(x, y) __extension__ ({    \
  __typeof__(x) _max1 = (x);    \
  __typeof__(y) _max2 = (y);    \
  (void) (&_max1 == &_max2);    \
  _max1 > _max2 ? _max1 : _max2; })
#endif

#ifndef abs_diff
# define abs_diff(x, y) __extension__ ({        \
  __typeof__(x) _a = (x);     \
  __typeof__(y) _b = (y);     \
  (void) (&_a == &_b);      \
  _a > _b ? _a - _b : _b - _a; })
#endif

#ifndef cmp_numbers
# define cmp_numbers(x, y) __extension__ ({ \
  __typeof__(x) _a = (x);     \
  __typeof__(y) _b = (y);     \
  (void) (&_a == &_b);      \
  _a == _b ? 0 : _a > _b ? 1 : -1; })
#endif


#ifndef cmp_timespec
# define cmp_timespec(a, b, CMP)    \
  (((a)->tv_sec == (b)->tv_sec)   \
  ? ((a)->tv_nsec CMP (b)->tv_nsec) \
  : ((a)->tv_sec CMP (b)->tv_sec))
#endif


#ifndef cmp_stat_mtime
# ifdef HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
#  define cmp_stat_mtime(_a, _b, CMP) cmp_timespec(&(_a)->st_mtim, &(_b)->st_mtim, CMP)
# else
#  define cmp_stat_mtime(_a, _b, CMP) ((_a)->st_mtime CMP (_b)->st_mtime)
# endif
#endif


#ifndef offsetof
#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
#endif

#ifndef sizeof_member
#define sizeof_member(TYPE, MEMBER) sizeof(((TYPE *)0)->MEMBER)
#endif

/*
 * container_of - cast a member of a structure out to the containing structure
 * @ptr:  the pointer to the member.
 * @type: the type of the container struct this is embedded in.
 * @member: the name of the member within the struct.
 */
#ifndef container_of
#define container_of(ptr, type, member) __extension__ ({  \
  const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
  (type *)( (char *)__mptr - offsetof(type,member) );})
#endif

#define read_unaligned_member(p, m) __extension__ ({          \
  size_t offset = offsetof(__typeof__(* p), m);         \
  __typeof__(p->m + 0) v;                               \
  memcpy(&v, ((unsigned char *)p) + offset, sizeof(v)); \
  v; })

#define member_ptr(p, m) (((unsigned char *)p) + offsetof(__typeof__(*p), m))

#ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
# ifdef HAVE___PROGNAME
extern char *__progname;
#  define program_invocation_short_name __progname
# else
#  ifdef HAVE_GETEXECNAME
#   define program_invocation_short_name \
    prog_inv_sh_nm_from_file(getexecname(), 0)
#  else
#   define program_invocation_short_name \
    prog_inv_sh_nm_from_file(__FILE__, 1)
#  endif
static char prog_inv_sh_nm_buf[256];
static inline char *
prog_inv_sh_nm_from_file(char *f, char stripext)
{
  char *t;

  if ((t = strrchr(f, '/')) != NULL)
    t++;
  else
    t = f;

  strncpy(prog_inv_sh_nm_buf, t, sizeof(prog_inv_sh_nm_buf) - 1);
  prog_inv_sh_nm_buf[sizeof(prog_inv_sh_nm_buf) - 1] = '\0';

  if (stripext && (t = strrchr(prog_inv_sh_nm_buf, '.')) != NULL)
    *t = '\0';

  return prog_inv_sh_nm_buf;
}
# endif
#endif


#ifndef HAVE_ERR_H
static inline void __attribute__ ((__format__ (__printf__, 4, 5)))
errmsg(char doexit, int excode, char adderr, const char *fmt, ...)
{
  fprintf(stderr, "%s: ", program_invocation_short_name);
  if (fmt != NULL) {
    va_list argp;
    va_start(argp, fmt);
    vfprintf(stderr, fmt, argp);
    va_end(argp);
    if (adderr)
      fprintf(stderr, ": ");
  }
  if (adderr)
    fprintf(stderr, "%m");
  fprintf(stderr, "\n");
  if (doexit)
    exit(excode);
}

#ifndef HAVE_ERR
# define err(E, FMT...) errmsg(1, E, 1, FMT)
#endif

#ifndef HAVE_ERRX
# define errx(E, FMT...) errmsg(1, E, 0, FMT)
#endif

#ifndef HAVE_WARN
# define warn(FMT...) errmsg(0, 0, 1, FMT)
#endif

#ifndef HAVE_WARNX
# define warnx(FMT...) errmsg(0, 0, 0, FMT)
#endif
#endif /* !HAVE_ERR_H */


static inline
__attribute__((__noreturn__))
void __err_oom(const char *file, unsigned int line)
{
  err(EXIT_FAILURE, "%s: %u: cannot allocate memory", file, line);
}
#define err_oom() __err_oom(__FILE__, __LINE__)

#define err_nosys(exitcode, ...) \
  err(errno == ENOSYS ? EXIT_NOTSUPP : exitcode, __VA_ARGS__)


/* Don't use inline function to avoid '#include "nls.h"' in c.h
 */
#define errtryhelp(eval) __extension__ ({ \
  fprintf(stderr, _("Try '%s --help' for more information.\n"), \
      program_invocation_short_name); \
  exit(eval); \
})

/* After failed execvp() */
#define EX_EXEC_FAILED    126 /* Program located, but not usable. */
#define EX_EXEC_ENOENT    127 /* Could not find program to exec.  */
#define errexec(name) err(errno == ENOENT ? EX_EXEC_ENOENT : EX_EXEC_FAILED, \
      _("failed to execute %s"), name)

static inline __attribute__((const)) int is_power_of_2(unsigned long num)
{
  return (num != 0 && ((num & (num - 1)) == 0));
}

#ifndef HAVE_LOFF_T
typedef int64_t loff_t;
#endif

#if !defined(HAVE_DIRFD) \
    && (!defined(HAVE_DECL_DIRFD) || HAVE_DECL_DIRFD == 0) \
    && defined(HAVE_DIR_DD_FD)
#include <dirent.h>
static inline int dirfd(DIR *d)
{
  return d->dd_fd;
}
#endif

/*
 * Fallback defines for old versions of glibc
 */
#include <fcntl.h>

#ifdef O_CLOEXEC
#define UL_CLOEXECSTR "e"
#else
#define UL_CLOEXECSTR ""
#endif

#ifndef O_CLOEXEC
#define O_CLOEXEC 0
#endif

#ifdef __FreeBSD_kernel__
#ifndef F_DUPFD_CLOEXEC
#define F_DUPFD_CLOEXEC 17  /* Like F_DUPFD, but FD_CLOEXEC is set */
#endif
#endif


#ifndef AI_ADDRCONFIG
#define AI_ADDRCONFIG 0x0020
#endif

#ifndef IUTF8
#define IUTF8 0040000
#endif

/*
 * MAXHOSTNAMELEN replacement
 */
static inline size_t get_hostname_max(void)
{
  long len = sysconf(_SC_HOST_NAME_MAX);

  if (0 < len)
    return len;

#ifdef MAXHOSTNAMELEN
  return MAXHOSTNAMELEN;
#elif HOST_NAME_MAX
  return HOST_NAME_MAX;
#endif
  return 64;
}


static inline int drop_permissions(void)
{
  errno = 0;

  /* drop GID */
  if (setgid(getgid()) < 0)
    goto fail;

  /* drop UID */
  if (setuid(getuid()) < 0)
    goto fail;

  return 0;
fail:
  return errno ? -errno : -1;
}

static inline bool is_privileged_execution(void)
{
#if defined(HAVE_GETAUXVAL) && defined(AT_SECURE)
  return getauxval(AT_SECURE) != 0;
#else
  return (geteuid() != getuid()) || (getegid() != getgid());
#endif
}

/*
 * The usleep function was marked obsolete in POSIX.1-2001 and was removed
 * in POSIX.1-2008.  It was replaced with nanosleep() that provides more
 * advantages (like no interaction with signals and other timer functions).
 */
#include <time.h>

static inline int xusleep(useconds_t usec)
{
#ifdef HAVE_NANOSLEEP
  struct timespec waittime = {
    .tv_sec   =  usec / 1000000L,
    .tv_nsec  = (usec % 1000000L) * 1000
  };
  return nanosleep(&waittime, NULL);
#elif defined(HAVE_USLEEP)
  return usleep(usec);
#else
# error "System with usleep() or nanosleep() required!"
#endif
}

/* ul_sig_printf is signal safe as long you don't use floating point formats,
   positional arguments or wide characters.*/
#define ul_sig_printf(fmt, ...) ignore_result(dprintf(STDERR_FILENO, fmt, __VA_ARGS__))

/*
 * warn() for signal handlers
 */
static inline void ul_sig_warn(const char *mesg)
{
  ul_sig_printf("%s: %s\n", program_invocation_short_name, mesg);
}

/*
 * err() for signal handlers
 */
static inline void __attribute__((__noreturn__)) ul_sig_err(int excode, const char *mesg)
{
  ul_sig_warn(mesg);
  _exit(excode);
}

/*
 * Constant strings for usage() functions. For more info see
 * Documentation/{howto-usage-function.txt,boilerplate.c}
 */
#define USAGE_HEADER     _("\nUsage:\n")
#define USAGE_OPTIONS    _("\nOptions:\n")
#define USAGE_FUNCTIONS  _("\nFunctions:\n")
#define USAGE_COMMANDS   _("\nCommands:\n")
#define USAGE_ARGUMENTS   _("\nArguments:\n")
#define USAGE_COLUMNS    _("\nAvailable output columns:\n")
#define USAGE_DEFAULT_COLUMNS _("\nDefault columns:\n")
#define USAGE_SEPARATOR    "\n"

#define USAGE_OPTSTR_LIST_COLUMNS  _("list the available columns")
#define USAGE_OPTSTR_HELP          _("display this help")
#define USAGE_OPTSTR_VERSION       _("display version")

#define USAGE_LIST_COLUMNS_OPTION(marg_dsc) \
    "%-" #marg_dsc "s%s\n" \
    , " -H, --list-columns",    USAGE_OPTSTR_LIST_COLUMNS

#define USAGE_HELP_OPTIONS(marg_dsc) \
    "%-" #marg_dsc "s%s\n" \
    "%-" #marg_dsc "s%s\n" \
    , " -h, --help",    USAGE_OPTSTR_HELP \
    , " -V, --version", USAGE_OPTSTR_VERSION

#define USAGE_ARG_SEPARATOR    "\n"
#define USAGE_ARG_SIZE(_name) \
    _(" Values for %s may be followed by a suffix: KiB, MiB,\n" \
      " GiB, TiB, PiB, EiB, ZiB, or YiB (where the \"iB\" is optional).\n"), _name

#define USAGE_MAN_TAIL(_man)   _("\nFor more details see %s.\n"), _man

#define UTIL_LINUX_VERSION _("%s from %s\n"), program_invocation_short_name, PACKAGE_STRING

#define print_version(eval) __extension__ ({ \
    printf(UTIL_LINUX_VERSION); \
    exit(eval); \
})

static inline void print_features(const char *const*features, const char *prefix)
{
  if (features && *features) {
    const char *const*p = features;
    while (p && *p) {
      if (prefix && p == features)
        printf(" (%s ", prefix);
      else
        fputs(p == features ? " (" : ", ", stdout);
      fputs(*p++, stdout);
    }
    fputc(')', stdout);
  }
}

#define UTIL_LINUX_VERSION_NOBREAK _("%s from %s"), program_invocation_short_name, PACKAGE_STRING

#define print_version_with_features(eval, features) __extension__ ({ \
    printf(UTIL_LINUX_VERSION_NOBREAK); \
    print_features(features, _("features:")); \
    fputc('\n', stdout); \
    exit(eval); \
})

static inline int fputsln(const char *s, FILE *stream) {
  if (fputs(s, stream) == EOF)
    return EOF;
  return fputc('\n', stdout);
}

/*
 * seek stuff
 */
#ifndef SEEK_DATA
# define SEEK_DATA  3
#endif
#ifndef SEEK_HOLE
# define SEEK_HOLE  4
#endif


/*
 * Macros to convert #define'itions to strings, for example
 * #define XYXXY 42
 * printf ("%s=%s\n", stringify(XYXXY), stringify_value(XYXXY));
 */
#define stringify_value(s) stringify(s)
#define stringify(s) #s

/* Detect if we're compiled with Address Sanitizer
 *  - gcc (__SANITIZE_ADDRESS__)
 *  - clang (__has_feature(address_sanitizer))
 */
#if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
#  ifdef __SANITIZE_ADDRESS__
#      define HAS_FEATURE_ADDRESS_SANITIZER 1
#  elif defined(__has_feature)
#    if __has_feature(address_sanitizer)
#      define HAS_FEATURE_ADDRESS_SANITIZER 1
#    endif
#  endif
#  if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
#    define HAS_FEATURE_ADDRESS_SANITIZER 0
#  endif
#endif

/*
 * UL_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
 * instrumentation shipped with Clang and GCC) to not instrument the
 * annotated function.  Furthermore, it will prevent the compiler from
 * inlining the function because inlining currently breaks the blacklisting
 * mechanism of AddressSanitizer.
 */
#if __has_feature(address_sanitizer) && __has_attribute(no_sanitize_memory) && __has_attribute(no_sanitize_address)
# define UL_ASAN_BLACKLIST __attribute__((noinline)) __attribute__((no_sanitize_memory)) __attribute__((no_sanitize_address))
#else
# define UL_ASAN_BLACKLIST  /* nothing */
#endif

/*
 * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for
 * pwd buffer and in some cases it is not large enough. See POSIX and
 * getpwnam_r man page for more details.
 */
#define UL_GETPW_BUFSIZ (16 * 1024)

/*
 * Darwin or other BSDs may only have MAP_ANON. To get it on Darwin we must
 * define _DARWIN_C_SOURCE before including sys/mman.h. We do this in config.h.
 */
#if !defined MAP_ANONYMOUS && defined MAP_ANON
# define MAP_ANONYMOUS  (MAP_ANON)
#endif

#define SINT_MAX(t) (((t)1 << (sizeof(t) * 8 - 2)) - (t)1 + ((t)1 << (sizeof(t) * 8 - 2)))

#ifndef HAVE_REALLOCARRAY
static inline void *reallocarray(void *ptr, size_t nmemb, size_t size)
{
  size_t s = nmemb * size;

  if (nmemb != 0 && s / nmemb != size) {
    errno = ENOMEM;
    return NULL;
  }
  return realloc(ptr, s);
}
#endif

static inline void ul_reset_errno(int *saved_errno) {
        if (*saved_errno < 0)
                return;

        errno = *saved_errno;
}

#define UL_PROTECT_ERRNO __attribute__((__cleanup__(ul_reset_errno))) \
                         __attribute__((__unused__)) int __ul_saved_errno = errno


/*
 * thread-local storage
 */
#ifdef HAVE_TLS
# define THREAD_LOCAL static __thread
#else
# define THREAD_LOCAL static
#endif

#endif /* UTIL_LINUX_C_H */

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Created: 2025-12-10 06:24