include/c.h

   1 /*
   2  * Fundamental C definitions.
   3  */
   4
   5 #ifndef UTIL_LINUX_C_H
   6 #define UTIL_LINUX_C_H
   7
   8 #include <limits.h>
   9 #include <stddef.h>
  10 #include <stdint.h>
  11 #include <stdio.h>
  12 #include <unistd.h>
  13 #include <stdarg.h>
  14 #include <stdlib.h>
  15 #include <string.h>
  16 #include <errno.h>
  17
  18 #include <assert.h>
  19
  20 #ifdef HAVE_ERR_H
  21 # include <err.h>
  22 #endif
  23
  24 #ifdef HAVE_SYS_SYSMACROS_H
  25 # include <sys/sysmacros.h>     /* for major, minor */
  26 #endif
  27
  28 #ifndef LOGIN_NAME_MAX
  29 # define LOGIN_NAME_MAX 256
  30 #endif
  31
  32 #ifndef NAME_MAX
  33 # define NAME_MAX PATH_MAX
  34 #endif
  35
  36 /*
  37  * Compiler-specific stuff
  38  */
  39 #ifndef __GNUC_PREREQ
  40 # if defined __GNUC__ && defined __GNUC_MINOR__
  41 #  define __GNUC_PREREQ(maj, min) \
  42         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
  43 # else
  44 #  define __GNUC_PREREQ(maj, min) 0
  45 # endif
  46 #endif
  47
  48 #ifdef __GNUC__
  49
  50 /* &a[0] degrades to a pointer: a different type from an array */
  51 # define __must_be_array(a) \
  52         UL_BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(__typeof__(a), __typeof__(&a[0])))
  53
  54 # define ignore_result(x) __extension__ ({ \
  55         __typeof__(x) __dummy __attribute__((__unused__)) = (x); (void) __dummy; \
  56 })
  57
  58 #else /* !__GNUC__ */
  59 # define __must_be_array(a)     0
  60 # define __attribute__(_arg_)
  61 # define ignore_result(x) ((void) (x))
  62 #endif /* !__GNUC__ */
  63
  64 /*
  65  * Function attributes
  66  */
  67 #ifndef __ul_alloc_size
  68 # if __GNUC_PREREQ (4, 3)
  69 #  define __ul_alloc_size(s) __attribute__((alloc_size(s), warn_unused_result))
  70 # else
  71 #  define __ul_alloc_size(s)
  72 # endif
  73 #endif
  74
  75 #ifndef __ul_calloc_size
  76 # if __GNUC_PREREQ (4, 3)
  77 #  define __ul_calloc_size(n, s) __attribute__((alloc_size(n, s), warn_unused_result))
  78 # else
  79 #  define __ul_calloc_size(n, s)
  80 # endif
  81 #endif
  82
  83 /*
  84  * Force a compilation error if condition is true, but also produce a
  85  * result (of value 0 and type size_t), so the expression can be used
  86  * e.g. in a structure initializer (or wherever else comma expressions
  87  * aren't permitted).
  88  */
  89 #define UL_BUILD_BUG_ON_ZERO(e) __extension__ (sizeof(struct { int:-!!(e); }))
  90 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
  91
  92 #ifndef ARRAY_SIZE
  93 # define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
  94 #endif
  95
  96 #ifndef PATH_MAX
  97 # define PATH_MAX 4096
  98 #endif
  99
 100 #ifndef TRUE
 101 # define TRUE 1
 102 #endif
 103
 104 #ifndef FALSE
 105 # define FALSE 0
 106 #endif
 107
 108 #ifndef min
 109 # define min(x, y) __extension__ ({             \
 110         __typeof__(x) _min1 = (x);              \
 111         __typeof__(y) _min2 = (y);              \
 112         (void) (&_min1 == &_min2);              \
 113         _min1 < _min2 ? _min1 : _min2; })
 114 #endif
 115
 116 #ifndef max
 117 # define max(x, y) __extension__ ({             \
 118         __typeof__(x) _max1 = (x);              \
 119         __typeof__(y) _max2 = (y);              \
 120         (void) (&_max1 == &_max2);              \
 121         _max1 > _max2 ? _max1 : _max2; })
 122 #endif
 123
 124 #ifndef cmp_numbers
 125 # define cmp_numbers(x, y) __extension__ ({     \
 126         __typeof__(x) _a = (x);                 \
 127         __typeof__(y) _b = (y);                 \
 128         (void) (&_a == &_b);                    \
 129         _a == _b ? 0 : _a > _b ? 1 : -1; })
 130 #endif
 131
 132 #ifndef offsetof
 133 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 134 #endif
 135
 136 /*
 137  * container_of - cast a member of a structure out to the containing structure
 138  * @ptr:        the pointer to the member.
 139  * @type:       the type of the container struct this is embedded in.
 140  * @member:     the name of the member within the struct.
 141  */
 142 #ifndef container_of
 143 #define container_of(ptr, type, member) __extension__ ({        \
 144         void *__mptr = (void *)(ptr);                           \
 145         ((type *)(__mptr - offsetof(type, member))); })
 146 #endif
 147
 148 #ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
 149 # ifdef HAVE___PROGNAME
 150 extern char *__progname;
 151 #  define program_invocation_short_name __progname
 152 # else
 153 #  ifdef HAVE_GETEXECNAME
 154 #   define program_invocation_short_name \
 155                 prog_inv_sh_nm_from_file(getexecname(), 0)
 156 #  else
 157 #   define program_invocation_short_name \
 158                 prog_inv_sh_nm_from_file(__FILE__, 1)
 159 #  endif
 160 static char prog_inv_sh_nm_buf[256];
 161 static inline char *
 162 prog_inv_sh_nm_from_file(char *f, char stripext)
 163 {
 164         char *t;
 165
 166         if ((t = strrchr(f, '/')) != NULL)
 167                 t++;
 168         else
 169                 t = f;
 170
 171         strncpy(prog_inv_sh_nm_buf, t, sizeof(prog_inv_sh_nm_buf) - 1);
 172         prog_inv_sh_nm_buf[sizeof(prog_inv_sh_nm_buf) - 1] = '\0';
 173
 174         if (stripext && (t = strrchr(prog_inv_sh_nm_buf, '.')) != NULL)
 175                 *t = '\0';
 176
 177         return prog_inv_sh_nm_buf;
 178 }
 179 # endif
 180 #endif
 181
 182
 183 #ifndef HAVE_ERR_H
 184 static inline void
 185 errmsg(char doexit, int excode, char adderr, const char *fmt, ...)
 186 {
 187         fprintf(stderr, "%s: ", program_invocation_short_name);
 188         if (fmt != NULL) {
 189                 va_list argp;
 190                 va_start(argp, fmt);
 191                 vfprintf(stderr, fmt, argp);
 192                 va_end(argp);
 193                 if (adderr)
 194                         fprintf(stderr, ": ");
 195         }
 196         if (adderr)
 197                 fprintf(stderr, "%m");
 198         fprintf(stderr, "\n");
 199         if (doexit)
 200                 exit(excode);
 201 }
 202
 203 #ifndef HAVE_ERR
 204 # define err(E, FMT...) errmsg(1, E, 1, FMT)
 205 #endif
 206
 207 #ifndef HAVE_ERRX
 208 # define errx(E, FMT...) errmsg(1, E, 0, FMT)
 209 #endif
 210
 211 #ifndef HAVE_WARN
 212 # define warn(FMT...) errmsg(0, 0, 1, FMT)
 213 #endif
 214
 215 #ifndef HAVE_WARNX
 216 # define warnx(FMT...) errmsg(0, 0, 0, FMT)
 217 #endif
 218 #endif /* !HAVE_ERR_H */
 219
 220
 221 /* Don't use inline function to avoid '#include "nls.h"' in c.h
 222  */
 223 #define errtryhelp(eval) __extension__ ({ \
 224         fprintf(stderr, _("Try '%s --help' for more information.\n"), \
 225                         program_invocation_short_name); \
 226         exit(eval); \
 227 })
 228
 229 /* After failed execvp() */
 230 #define EX_EXEC_FAILED          126     /* Program located, but not usable. */
 231 #define EX_EXEC_ENOENT          127     /* Could not find program to exec.  */
 232 #define errexec(name)   err(errno == ENOENT ? EX_EXEC_ENOENT : EX_EXEC_FAILED, \
 233                         _("failed to execute %s"), name)
 234
 235
 236 static inline __attribute__((const)) int is_power_of_2(unsigned long num)
 237 {
 238         return (num != 0 && ((num & (num - 1)) == 0));
 239 }
 240
 241 #ifndef HAVE_LOFF_T
 242 typedef int64_t loff_t;
 243 #endif
 244
 245 #if !defined(HAVE_DIRFD) && (!defined(HAVE_DECL_DIRFD) || HAVE_DECL_DIRFD == 0) && defined(HAVE_DIR_DD_FD)
 246 #include <sys/types.h>
 247 #include <dirent.h>
 248 static inline int dirfd(DIR *d)
 249 {
 250         return d->dd_fd;
 251 }
 252 #endif
 253
 254 /*
 255  * Fallback defines for old versions of glibc
 256  */
 257 #include <fcntl.h>
 258
 259 #ifdef O_CLOEXEC
 260 #define UL_CLOEXECSTR   "e"
 261 #else
 262 #define UL_CLOEXECSTR   ""
 263 #endif
 264
 265 #ifndef O_CLOEXEC
 266 #define O_CLOEXEC 0
 267 #endif
 268
 269 #ifdef __FreeBSD_kernel__
 270 #ifndef F_DUPFD_CLOEXEC
 271 #define F_DUPFD_CLOEXEC 17      /* Like F_DUPFD, but FD_CLOEXEC is set */
 272 #endif
 273 #endif
 274
 275
 276 #ifndef AI_ADDRCONFIG
 277 #define AI_ADDRCONFIG 0x0020
 278 #endif
 279
 280 #ifndef IUTF8
 281 #define IUTF8 0040000
 282 #endif
 283
 284 /*
 285  * MAXHOSTNAMELEN replacement
 286  */
 287 static inline size_t get_hostname_max(void)
 288 {
 289         long len = sysconf(_SC_HOST_NAME_MAX);
 290
 291         if (0 < len)
 292                 return len;
 293
 294 #ifdef MAXHOSTNAMELEN
 295         return MAXHOSTNAMELEN;
 296 #elif HOST_NAME_MAX
 297         return HOST_NAME_MAX;
 298 #endif
 299         return 64;
 300 }
 301
 302 /*
 303  * The usleep function was marked obsolete in POSIX.1-2001 and was removed
 304  * in POSIX.1-2008.  It was replaced with nanosleep() that provides more
 305  * advantages (like no interaction with signals and other timer functions).
 306  */
 307 #include <time.h>
 308
 309 static inline int xusleep(useconds_t usec)
 310 {
 311 #ifdef HAVE_NANOSLEEP
 312         struct timespec waittime = {
 313                 .tv_sec   =  usec / 1000000L,
 314                 .tv_nsec  = (usec % 1000000L) * 1000
 315         };
 316         return nanosleep(&waittime, NULL);
 317 #elif defined(HAVE_USLEEP)
 318         return usleep(usec);
 319 #else
 320 # error "System with usleep() or nanosleep() required!"
 321 #endif
 322 }
 323
 324 /*
 325  * Constant strings for usage() functions. For more info see
 326  * Documentation/{howto-usage-function.txt,boilerplate.c}
 327  */
 328 #define USAGE_HEADER     _("\nUsage:\n")
 329 #define USAGE_OPTIONS    _("\nOptions:\n")
 330 #define USAGE_FUNCTIONS  _("\nFunctions:\n")
 331 #define USAGE_COMMANDS   _("\nCommands:\n")
 332 #define USAGE_COLUMNS    _("\nAvailable output columns:\n")
 333 #define USAGE_SEPARATOR    "\n"
 334
 335 #define USAGE_OPTSTR_HELP     _("display this help")
 336 #define USAGE_OPTSTR_VERSION  _("display version")
 337
 338 #define USAGE_HELP_OPTIONS(marg_dsc) \
 339                 "%-" #marg_dsc "s%s\n" \
 340                 "%-" #marg_dsc "s%s\n" \
 341                 , " -h, --help",    USAGE_OPTSTR_HELP \
 342                 , " -V, --version", USAGE_OPTSTR_VERSION
 343
 344 #define USAGE_MAN_TAIL(_man)   _("\nFor more details see %s.\n"), _man
 345
 346 #define UTIL_LINUX_VERSION _("%s from %s\n"), program_invocation_short_name, PACKAGE_STRING
 347
 348 /*
 349  * scanf modifiers for "strings allocation"
 350  */
 351 #ifdef HAVE_SCANF_MS_MODIFIER
 352 #define UL_SCNsA        "%ms"
 353 #elif defined(HAVE_SCANF_AS_MODIFIER)
 354 #define UL_SCNsA        "%as"
 355 #endif
 356
 357 /*
 358  * seek stuff
 359  */
 360 #ifndef SEEK_DATA
 361 # define SEEK_DATA      3
 362 #endif
 363 #ifndef SEEK_HOLE
 364 # define SEEK_HOLE      4
 365 #endif
 366
 367
 368 /*
 369  * Macros to convert #define'itions to strings, for example
 370  * #define XYXXY 42
 371  * printf ("%s=%s\n", stringify(XYXXY), stringify_value(XYXXY));
 372  */
 373 #define stringify_value(s) stringify(s)
 374 #define stringify(s) #s
 375
 376 /*
 377  * UL_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
 378  * instrumentation shipped with Clang and GCC) to not instrument the
 379  * annotated function.  Furthermore, it will prevent the compiler from
 380  * inlining the function because inlining currently breaks the blacklisting
 381  * mechanism of AddressSanitizer.
 382  */
 383 #if defined(__has_feature)
 384 # if __has_feature(address_sanitizer)
 385 #  define UL_ASAN_BLACKLIST __attribute__((noinline)) __attribute__((no_sanitize_memory)) __attribute__((no_sanitize_address))
 386 # else
 387 #  define UL_ASAN_BLACKLIST     /* nothing */
 388 # endif
 389 #else
 390 # define UL_ASAN_BLACKLIST      /* nothing */
 391 #endif
 392
 393
 394
 395 /*
 396  * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for
 397  * pwd buffer and in some cases it is not large enough. See POSIX and
 398  * getpwnam_r man page for more details.
 399  */
 400 #define UL_GETPW_BUFSIZ (16 * 1024)
 401
 402 /*
 403  * Darwin or other BSDs may only have MAP_ANON. To get it on Darwin we must
 404  * define _DARWIN_C_SOURCE before including sys/mman.h. We do this in config.h.
 405  */
 406 #if !defined MAP_ANONYMOUS && defined MAP_ANON
 407 # define MAP_ANONYMOUS  (MAP_ANON)
 408 #endif
 409
 410 #endif /* UTIL_LINUX_C_H */