include/c.h

   1 /*
   2  * Fundamental C definitions.
   3  *
   4  * No copyright is claimed.  This code is in the public domain; do with
   5  * it what you wish.
   6  */
   7 #ifndef UTIL_LINUX_C_H
   8 #define UTIL_LINUX_C_H
   9
  10 #include <limits.h>
  11 #include <stddef.h>
  12 #include <stdint.h>
  13 #include <stdio.h>
  14 #include <unistd.h>
  15 #include <stdarg.h>
  16 #include <stdlib.h>
  17 #include <string.h>
  18 #include <errno.h>
  19
  20 #include <assert.h>
  21
  22 #ifdef HAVE_ERR_H
  23 # include <err.h>
  24 #endif
  25
  26 #ifdef HAVE_SYS_SYSMACROS_H
  27 # include <sys/sysmacros.h>     /* for major, minor */
  28 #endif
  29
  30 #ifndef LOGIN_NAME_MAX
  31 # define LOGIN_NAME_MAX 256
  32 #endif
  33
  34 #ifndef NAME_MAX
  35 # define NAME_MAX PATH_MAX
  36 #endif
  37
  38 /*
  39  * __GNUC_PREREQ is deprecated in favour of __has_attribute() and
  40  * __has_feature(). The __has macros are supported by clang and gcc>=5.
  41  */
  42 #ifndef __GNUC_PREREQ
  43 # if defined __GNUC__ && defined __GNUC_MINOR__
  44 #  define __GNUC_PREREQ(maj, min) \
  45         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
  46 # else
  47 #  define __GNUC_PREREQ(maj, min) 0
  48 # endif
  49 #endif
  50
  51 #ifdef __GNUC__
  52
  53 /* &a[0] degrades to a pointer: a different type from an array */
  54 # define __must_be_array(a) \
  55         UL_BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(__typeof__(a), __typeof__(&a[0])))
  56
  57 # define ignore_result(x) __extension__ ({ \
  58         __typeof__(x) __dummy __attribute__((__unused__)) = (x); (void) __dummy; \
  59 })
  60
  61 #else /* !__GNUC__ */
  62 # define __must_be_array(a)     0
  63 # define __attribute__(_arg_)
  64 # define ignore_result(x) ((void) (x))
  65 #endif /* !__GNUC__ */
  66
  67 /*
  68  * It evaluates to 1 if the attribute/feature is supported by the current
  69  * compilation target. Fallback for old compilers.
  70  */
  71 #ifndef __has_attribute
  72   #define __has_attribute(x) 0
  73 #endif
  74
  75 #ifndef __has_feature
  76   #define __has_feature(x) 0
  77 #endif
  78
  79 /*
  80  * Function attributes
  81  */
  82 #ifndef __ul_alloc_size
  83 # if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
  84 #  define __ul_alloc_size(s) __attribute__((alloc_size(s), warn_unused_result))
  85 # else
  86 #  define __ul_alloc_size(s)
  87 # endif
  88 #endif
  89
  90 #ifndef __ul_calloc_size
  91 # if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
  92 #  define __ul_calloc_size(n, s) __attribute__((alloc_size(n, s), warn_unused_result))
  93 # else
  94 #  define __ul_calloc_size(n, s)
  95 # endif
  96 #endif
  97
  98 #if __has_attribute(returns_nonnull) || __GNUC_PREREQ (4, 9)
  99 # define __ul_returns_nonnull __attribute__((returns_nonnull))
 100 #else
 101 # define __ul_returns_nonnull
 102 #endif
 103
 104 /*
 105  * Force a compilation error if condition is true, but also produce a
 106  * result (of value 0 and type size_t), so the expression can be used
 107  * e.g. in a structure initializer (or wherever else comma expressions
 108  * aren't permitted).
 109  */
 110 #define UL_BUILD_BUG_ON_ZERO(e) __extension__ (sizeof(struct { int:-!!(e); }))
 111 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 112
 113 #ifndef ARRAY_SIZE
 114 # define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
 115 #endif
 116
 117 #ifndef PATH_MAX
 118 # define PATH_MAX 4096
 119 #endif
 120
 121 #ifndef TRUE
 122 # define TRUE 1
 123 #endif
 124
 125 #ifndef FALSE
 126 # define FALSE 0
 127 #endif
 128
 129 #ifndef min
 130 # define min(x, y) __extension__ ({             \
 131         __typeof__(x) _min1 = (x);              \
 132         __typeof__(y) _min2 = (y);              \
 133         (void) (&_min1 == &_min2);              \
 134         _min1 < _min2 ? _min1 : _min2; })
 135 #endif
 136
 137 #ifndef max
 138 # define max(x, y) __extension__ ({             \
 139         __typeof__(x) _max1 = (x);              \
 140         __typeof__(y) _max2 = (y);              \
 141         (void) (&_max1 == &_max2);              \
 142         _max1 > _max2 ? _max1 : _max2; })
 143 #endif
 144
 145 #ifndef cmp_numbers
 146 # define cmp_numbers(x, y) __extension__ ({     \
 147         __typeof__(x) _a = (x);                 \
 148         __typeof__(y) _b = (y);                 \
 149         (void) (&_a == &_b);                    \
 150         _a == _b ? 0 : _a > _b ? 1 : -1; })
 151 #endif
 152
 153 #ifndef offsetof
 154 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 155 #endif
 156
 157 /*
 158  * container_of - cast a member of a structure out to the containing structure
 159  * @ptr:        the pointer to the member.
 160  * @type:       the type of the container struct this is embedded in.
 161  * @member:     the name of the member within the struct.
 162  */
 163 #ifndef container_of
 164 #define container_of(ptr, type, member) __extension__ ({        \
 165         const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
 166         (type *)( (char *)__mptr - offsetof(type,member) );})
 167 #endif
 168
 169 #ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
 170 # ifdef HAVE___PROGNAME
 171 extern char *__progname;
 172 #  define program_invocation_short_name __progname
 173 # else
 174 #  ifdef HAVE_GETEXECNAME
 175 #   define program_invocation_short_name \
 176                 prog_inv_sh_nm_from_file(getexecname(), 0)
 177 #  else
 178 #   define program_invocation_short_name \
 179                 prog_inv_sh_nm_from_file(__FILE__, 1)
 180 #  endif
 181 static char prog_inv_sh_nm_buf[256];
 182 static inline char *
 183 prog_inv_sh_nm_from_file(char *f, char stripext)
 184 {
 185         char *t;
 186
 187         if ((t = strrchr(f, '/')) != NULL)
 188                 t++;
 189         else
 190                 t = f;
 191
 192         strncpy(prog_inv_sh_nm_buf, t, sizeof(prog_inv_sh_nm_buf) - 1);
 193         prog_inv_sh_nm_buf[sizeof(prog_inv_sh_nm_buf) - 1] = '\0';
 194
 195         if (stripext && (t = strrchr(prog_inv_sh_nm_buf, '.')) != NULL)
 196                 *t = '\0';
 197
 198         return prog_inv_sh_nm_buf;
 199 }
 200 # endif
 201 #endif
 202
 203
 204 #ifndef HAVE_ERR_H
 205 static inline void
 206 errmsg(char doexit, int excode, char adderr, const char *fmt, ...)
 207 {
 208         fprintf(stderr, "%s: ", program_invocation_short_name);
 209         if (fmt != NULL) {
 210                 va_list argp;
 211                 va_start(argp, fmt);
 212                 vfprintf(stderr, fmt, argp);
 213                 va_end(argp);
 214                 if (adderr)
 215                         fprintf(stderr, ": ");
 216         }
 217         if (adderr)
 218                 fprintf(stderr, "%m");
 219         fprintf(stderr, "\n");
 220         if (doexit)
 221                 exit(excode);
 222 }
 223
 224 #ifndef HAVE_ERR
 225 # define err(E, FMT...) errmsg(1, E, 1, FMT)
 226 #endif
 227
 228 #ifndef HAVE_ERRX
 229 # define errx(E, FMT...) errmsg(1, E, 0, FMT)
 230 #endif
 231
 232 #ifndef HAVE_WARN
 233 # define warn(FMT...) errmsg(0, 0, 1, FMT)
 234 #endif
 235
 236 #ifndef HAVE_WARNX
 237 # define warnx(FMT...) errmsg(0, 0, 0, FMT)
 238 #endif
 239 #endif /* !HAVE_ERR_H */
 240
 241
 242 /* Don't use inline function to avoid '#include "nls.h"' in c.h
 243  */
 244 #define errtryhelp(eval) __extension__ ({ \
 245         fprintf(stderr, _("Try '%s --help' for more information.\n"), \
 246                         program_invocation_short_name); \
 247         exit(eval); \
 248 })
 249
 250 /* After failed execvp() */
 251 #define EX_EXEC_FAILED          126     /* Program located, but not usable. */
 252 #define EX_EXEC_ENOENT          127     /* Could not find program to exec.  */
 253 #define errexec(name)   err(errno == ENOENT ? EX_EXEC_ENOENT : EX_EXEC_FAILED, \
 254                         _("failed to execute %s"), name)
 255
 256
 257 static inline __attribute__((const)) int is_power_of_2(unsigned long num)
 258 {
 259         return (num != 0 && ((num & (num - 1)) == 0));
 260 }
 261
 262 #ifndef HAVE_LOFF_T
 263 typedef int64_t loff_t;
 264 #endif
 265
 266 #if !defined(HAVE_DIRFD) && (!defined(HAVE_DECL_DIRFD) || HAVE_DECL_DIRFD == 0) && defined(HAVE_DIR_DD_FD)
 267 #include <sys/types.h>
 268 #include <dirent.h>
 269 static inline int dirfd(DIR *d)
 270 {
 271         return d->dd_fd;
 272 }
 273 #endif
 274
 275 /*
 276  * Fallback defines for old versions of glibc
 277  */
 278 #include <fcntl.h>
 279
 280 #ifdef O_CLOEXEC
 281 #define UL_CLOEXECSTR   "e"
 282 #else
 283 #define UL_CLOEXECSTR   ""
 284 #endif
 285
 286 #ifndef O_CLOEXEC
 287 #define O_CLOEXEC 0
 288 #endif
 289
 290 #ifdef __FreeBSD_kernel__
 291 #ifndef F_DUPFD_CLOEXEC
 292 #define F_DUPFD_CLOEXEC 17      /* Like F_DUPFD, but FD_CLOEXEC is set */
 293 #endif
 294 #endif
 295
 296
 297 #ifndef AI_ADDRCONFIG
 298 #define AI_ADDRCONFIG 0x0020
 299 #endif
 300
 301 #ifndef IUTF8
 302 #define IUTF8 0040000
 303 #endif
 304
 305 /*
 306  * MAXHOSTNAMELEN replacement
 307  */
 308 static inline size_t get_hostname_max(void)
 309 {
 310         long len = sysconf(_SC_HOST_NAME_MAX);
 311
 312         if (0 < len)
 313                 return len;
 314
 315 #ifdef MAXHOSTNAMELEN
 316         return MAXHOSTNAMELEN;
 317 #elif HOST_NAME_MAX
 318         return HOST_NAME_MAX;
 319 #endif
 320         return 64;
 321 }
 322
 323 /*
 324  * The usleep function was marked obsolete in POSIX.1-2001 and was removed
 325  * in POSIX.1-2008.  It was replaced with nanosleep() that provides more
 326  * advantages (like no interaction with signals and other timer functions).
 327  */
 328 #include <time.h>
 329
 330 static inline int xusleep(useconds_t usec)
 331 {
 332 #ifdef HAVE_NANOSLEEP
 333         struct timespec waittime = {
 334                 .tv_sec   =  usec / 1000000L,
 335                 .tv_nsec  = (usec % 1000000L) * 1000
 336         };
 337         return nanosleep(&waittime, NULL);
 338 #elif defined(HAVE_USLEEP)
 339         return usleep(usec);
 340 #else
 341 # error "System with usleep() or nanosleep() required!"
 342 #endif
 343 }
 344
 345 /*
 346  * Constant strings for usage() functions. For more info see
 347  * Documentation/{howto-usage-function.txt,boilerplate.c}
 348  */
 349 #define USAGE_HEADER     _("\nUsage:\n")
 350 #define USAGE_OPTIONS    _("\nOptions:\n")
 351 #define USAGE_FUNCTIONS  _("\nFunctions:\n")
 352 #define USAGE_COMMANDS   _("\nCommands:\n")
 353 #define USAGE_ARGUMENTS   _("\nArguments:\n")
 354 #define USAGE_COLUMNS    _("\nAvailable output columns:\n")
 355 #define USAGE_SEPARATOR    "\n"
 356
 357 #define USAGE_OPTSTR_HELP     _("display this help")
 358 #define USAGE_OPTSTR_VERSION  _("display version")
 359
 360 #define USAGE_HELP_OPTIONS(marg_dsc) \
 361                 "%-" #marg_dsc "s%s\n" \
 362                 "%-" #marg_dsc "s%s\n" \
 363                 , " -h, --help",    USAGE_OPTSTR_HELP \
 364                 , " -V, --version", USAGE_OPTSTR_VERSION
 365
 366 #define USAGE_ARG_SEPARATOR    "\n"
 367 #define USAGE_ARG_SIZE(_name) \
 368                 _(" %s arguments may be followed by the suffixes for\n" \
 369                   "   GiB, TiB, PiB, EiB, ZiB, and YiB (the \"iB\" is optional)\n"), _name
 370
 371 #define USAGE_MAN_TAIL(_man)   _("\nFor more details see %s.\n"), _man
 372
 373 #define UTIL_LINUX_VERSION _("%s from %s\n"), program_invocation_short_name, PACKAGE_STRING
 374
 375 #define print_version(eval) __extension__ ({ \
 376                 printf(UTIL_LINUX_VERSION); \
 377                 exit(eval); \
 378 })
 379
 380 /*
 381  * scanf modifiers for "strings allocation"
 382  */
 383 #ifdef HAVE_SCANF_MS_MODIFIER
 384 #define UL_SCNsA        "%ms"
 385 #elif defined(HAVE_SCANF_AS_MODIFIER)
 386 #define UL_SCNsA        "%as"
 387 #endif
 388
 389 /*
 390  * seek stuff
 391  */
 392 #ifndef SEEK_DATA
 393 # define SEEK_DATA      3
 394 #endif
 395 #ifndef SEEK_HOLE
 396 # define SEEK_HOLE      4
 397 #endif
 398
 399
 400 /*
 401  * Macros to convert #define'itions to strings, for example
 402  * #define XYXXY 42
 403  * printf ("%s=%s\n", stringify(XYXXY), stringify_value(XYXXY));
 404  */
 405 #define stringify_value(s) stringify(s)
 406 #define stringify(s) #s
 407
 408 /*
 409  * UL_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
 410  * instrumentation shipped with Clang and GCC) to not instrument the
 411  * annotated function.  Furthermore, it will prevent the compiler from
 412  * inlining the function because inlining currently breaks the blacklisting
 413  * mechanism of AddressSanitizer.
 414  */
 415 #if __has_feature(address_sanitizer) && __has_attribute(no_sanitize_memory) && __has_attribute(no_sanitize_address)
 416 # define UL_ASAN_BLACKLIST __attribute__((noinline)) __attribute__((no_sanitize_memory)) __attribute__((no_sanitize_address))
 417 #else
 418 # define UL_ASAN_BLACKLIST      /* nothing */
 419 #endif
 420
 421 /*
 422  * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for
 423  * pwd buffer and in some cases it is not large enough. See POSIX and
 424  * getpwnam_r man page for more details.
 425  */
 426 #define UL_GETPW_BUFSIZ (16 * 1024)
 427
 428 /*
 429  * Darwin or other BSDs may only have MAP_ANON. To get it on Darwin we must
 430  * define _DARWIN_C_SOURCE before including sys/mman.h. We do this in config.h.
 431  */
 432 #if !defined MAP_ANONYMOUS && defined MAP_ANON
 433 # define MAP_ANONYMOUS  (MAP_ANON)
 434 #endif
 435
 436 #endif /* UTIL_LINUX_C_H */