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 #include <sys/types.h>
  20 #include <grp.h>
  21
  22 #include <assert.h>
  23
  24 #ifdef HAVE_ERR_H
  25 # include <err.h>
  26 #endif
  27
  28 #ifdef HAVE_SYS_SYSMACROS_H
  29 # include <sys/sysmacros.h>     /* for major, minor */
  30 #endif
  31
  32 #ifndef LOGIN_NAME_MAX
  33 # define LOGIN_NAME_MAX 256
  34 #endif
  35
  36 #ifndef NAME_MAX
  37 # define NAME_MAX PATH_MAX
  38 #endif
  39
  40 /*
  41  * __GNUC_PREREQ is deprecated in favour of __has_attribute() and
  42  * __has_feature(). The __has macros are supported by clang and gcc>=5.
  43  */
  44 #ifndef __GNUC_PREREQ
  45 # if defined __GNUC__ && defined __GNUC_MINOR__
  46 #  define __GNUC_PREREQ(maj, min) \
  47         ((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
  48 # else
  49 #  define __GNUC_PREREQ(maj, min) 0
  50 # endif
  51 #endif
  52
  53 #ifdef __GNUC__
  54
  55 /* &a[0] degrades to a pointer: a different type from an array */
  56 # define __must_be_array(a) \
  57         UL_BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(__typeof__(a), __typeof__(&a[0])))
  58
  59 # define ignore_result(x) __extension__ ({ \
  60         __typeof__(x) __dummy __attribute__((__unused__)) = (x); (void) __dummy; \
  61 })
  62
  63 #else /* !__GNUC__ */
  64 # define __must_be_array(a)     0
  65 # define __attribute__(_arg_)
  66 # define ignore_result(x) ((void) (x))
  67 #endif /* !__GNUC__ */
  68
  69
  70 /* "restrict" keyword fallback */
  71 #if __STDC__ != 1
  72 # define restrict __restrict /* use implementation __ format */
  73 #else
  74 # ifndef __STDC_VERSION__
  75 #  define restrict __restrict /* use implementation __ format */
  76 # else
  77 #  if __STDC_VERSION__ < 199901L
  78 #   define restrict __restrict /* use implementation __ format */
  79 #  endif
  80 # endif
  81 #endif
  82
  83
  84 /*
  85  * It evaluates to 1 if the attribute/feature is supported by the current
  86  * compilation target. Fallback for old compilers.
  87  */
  88 #ifndef __has_attribute
  89   #define __has_attribute(x) 0
  90 #endif
  91
  92 #ifndef __has_feature
  93   #define __has_feature(x) 0
  94 #endif
  95
  96 /*
  97  * Function attributes
  98  */
  99 #ifndef __ul_alloc_size
 100 # if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
 101 #  define __ul_alloc_size(s) __attribute__((alloc_size(s), warn_unused_result))
 102 # else
 103 #  define __ul_alloc_size(s)
 104 # endif
 105 #endif
 106
 107 #ifndef __ul_calloc_size
 108 # if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
 109 #  define __ul_calloc_size(n, s) __attribute__((alloc_size(n, s), warn_unused_result))
 110 # else
 111 #  define __ul_calloc_size(n, s)
 112 # endif
 113 #endif
 114
 115 #if __has_attribute(returns_nonnull) || __GNUC_PREREQ (4, 9)
 116 # define __ul_returns_nonnull __attribute__((returns_nonnull))
 117 #else
 118 # define __ul_returns_nonnull
 119 #endif
 120
 121 /*
 122  * Force a compilation error if condition is true, but also produce a
 123  * result (of value 0 and type size_t), so the expression can be used
 124  * e.g. in a structure initializer (or wherever else comma expressions
 125  * aren't permitted).
 126  */
 127 #define UL_BUILD_BUG_ON_ZERO(e) __extension__ (sizeof(struct { int:-!!(e); }))
 128 #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
 129
 130 #ifndef ARRAY_SIZE
 131 # define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
 132 #endif
 133
 134 #ifndef PATH_MAX
 135 # define PATH_MAX 4096
 136 #endif
 137
 138 #ifndef TRUE
 139 # define TRUE 1
 140 #endif
 141
 142 #ifndef FALSE
 143 # define FALSE 0
 144 #endif
 145
 146 #ifndef min
 147 # define min(x, y) __extension__ ({             \
 148         __typeof__(x) _min1 = (x);              \
 149         __typeof__(y) _min2 = (y);              \
 150         (void) (&_min1 == &_min2);              \
 151         _min1 < _min2 ? _min1 : _min2; })
 152 #endif
 153
 154 #ifndef max
 155 # define max(x, y) __extension__ ({             \
 156         __typeof__(x) _max1 = (x);              \
 157         __typeof__(y) _max2 = (y);              \
 158         (void) (&_max1 == &_max2);              \
 159         _max1 > _max2 ? _max1 : _max2; })
 160 #endif
 161
 162 #ifndef abs_diff
 163 # define abs_diff(x, y) __extension__ ({        \
 164         __typeof__(x) _a = (x);                 \
 165         __typeof__(y) _b = (y);                 \
 166         (void) (&_a == &_b);                    \
 167         _a > _b ? _a - _b : _b - _a; })
 168 #endif
 169
 170 #ifndef cmp_numbers
 171 # define cmp_numbers(x, y) __extension__ ({     \
 172         __typeof__(x) _a = (x);                 \
 173         __typeof__(y) _b = (y);                 \
 174         (void) (&_a == &_b);                    \
 175         _a == _b ? 0 : _a > _b ? 1 : -1; })
 176 #endif
 177
 178
 179 #ifndef cmp_timespec
 180 # define cmp_timespec(a, b, CMP)                \
 181         (((a)->tv_sec == (b)->tv_sec)           \
 182         ? ((a)->tv_nsec CMP (b)->tv_nsec)       \
 183         : ((a)->tv_sec CMP (b)->tv_sec))
 184 #endif
 185
 186
 187 #ifndef cmp_stat_mtime
 188 # ifdef HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
 189 #  define cmp_stat_mtime(_a, _b, CMP)   cmp_timespec(&(_a)->st_mtim, &(_b)->st_mtim, CMP)
 190 # else
 191 #  define cmp_stat_mtime(_a, _b, CMP)   ((_a)->st_mtime CMP (_b)->st_mtime)
 192 # endif
 193 #endif
 194
 195
 196 #ifndef offsetof
 197 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 198 #endif
 199
 200 #ifndef sizeof_member
 201 #define sizeof_member(TYPE, MEMBER) sizeof(((TYPE *)0)->MEMBER)
 202 #endif
 203
 204 /*
 205  * container_of - cast a member of a structure out to the containing structure
 206  * @ptr:        the pointer to the member.
 207  * @type:       the type of the container struct this is embedded in.
 208  * @member:     the name of the member within the struct.
 209  */
 210 #ifndef container_of
 211 #define container_of(ptr, type, member) __extension__ ({        \
 212         const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
 213         (type *)( (char *)__mptr - offsetof(type,member) );})
 214 #endif
 215
 216 #define read_unaligned_member(p, m) __extension__ ({          \
 217         size_t offset = offsetof(__typeof__(* p), m);         \
 218         __typeof__(p->m) v;                                   \
 219         memcpy(&v, ((unsigned char *)p) + offset, sizeof(v)); \
 220         v; })
 221
 222 #define member_ptr(p, m) (((unsigned char *)p) + offsetof(__typeof__(*p), m))
 223
 224 #ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
 225 # ifdef HAVE___PROGNAME
 226 extern char *__progname;
 227 #  define program_invocation_short_name __progname
 228 # else
 229 #  ifdef HAVE_GETEXECNAME
 230 #   define program_invocation_short_name \
 231                 prog_inv_sh_nm_from_file(getexecname(), 0)
 232 #  else
 233 #   define program_invocation_short_name \
 234                 prog_inv_sh_nm_from_file(__FILE__, 1)
 235 #  endif
 236 static char prog_inv_sh_nm_buf[256];
 237 static inline char *
 238 prog_inv_sh_nm_from_file(char *f, char stripext)
 239 {
 240         char *t;
 241
 242         if ((t = strrchr(f, '/')) != NULL)
 243                 t++;
 244         else
 245                 t = f;
 246
 247         strncpy(prog_inv_sh_nm_buf, t, sizeof(prog_inv_sh_nm_buf) - 1);
 248         prog_inv_sh_nm_buf[sizeof(prog_inv_sh_nm_buf) - 1] = '\0';
 249
 250         if (stripext && (t = strrchr(prog_inv_sh_nm_buf, '.')) != NULL)
 251                 *t = '\0';
 252
 253         return prog_inv_sh_nm_buf;
 254 }
 255 # endif
 256 #endif
 257
 258
 259 #ifndef HAVE_ERR_H
 260 static inline void __attribute__ ((__format__ (__printf__, 4, 5)))
 261 errmsg(char doexit, int excode, char adderr, const char *fmt, ...)
 262 {
 263         fprintf(stderr, "%s: ", program_invocation_short_name);
 264         if (fmt != NULL) {
 265                 va_list argp;
 266                 va_start(argp, fmt);
 267                 vfprintf(stderr, fmt, argp);
 268                 va_end(argp);
 269                 if (adderr)
 270                         fprintf(stderr, ": ");
 271         }
 272         if (adderr)
 273                 fprintf(stderr, "%m");
 274         fprintf(stderr, "\n");
 275         if (doexit)
 276                 exit(excode);
 277 }
 278
 279 #ifndef HAVE_ERR
 280 # define err(E, FMT...) errmsg(1, E, 1, FMT)
 281 #endif
 282
 283 #ifndef HAVE_ERRX
 284 # define errx(E, FMT...) errmsg(1, E, 0, FMT)
 285 #endif
 286
 287 #ifndef HAVE_WARN
 288 # define warn(FMT...) errmsg(0, 0, 1, FMT)
 289 #endif
 290
 291 #ifndef HAVE_WARNX
 292 # define warnx(FMT...) errmsg(0, 0, 0, FMT)
 293 #endif
 294 #endif /* !HAVE_ERR_H */
 295
 296
 297 static inline
 298 __attribute__((__noreturn__))
 299 void __err_oom(const char *file, unsigned int line)
 300 {
 301         err(EXIT_FAILURE, "%s: %u: cannot allocate memory", file, line);
 302 }
 303 #define err_oom()       __err_oom(__FILE__, __LINE__)
 304
 305 #define err_nosys(exitcode, ...) \
 306         err(errno == ENOSYS ? EXIT_NOTSUPP : exitcode, __VA_ARGS__)
 307
 308
 309 /* Don't use inline function to avoid '#include "nls.h"' in c.h
 310  */
 311 #define errtryhelp(eval) __extension__ ({ \
 312         fprintf(stderr, _("Try '%s --help' for more information.\n"), \
 313                         program_invocation_short_name); \
 314         exit(eval); \
 315 })
 316
 317 /* After failed execvp() */
 318 #define EX_EXEC_FAILED          126     /* Program located, but not usable. */
 319 #define EX_EXEC_ENOENT          127     /* Could not find program to exec.  */
 320 #define errexec(name)   err(errno == ENOENT ? EX_EXEC_ENOENT : EX_EXEC_FAILED, \
 321                         _("failed to execute %s"), name)
 322
 323 static inline __attribute__((const)) int is_power_of_2(unsigned long num)
 324 {
 325         return (num != 0 && ((num & (num - 1)) == 0));
 326 }
 327
 328 #ifndef HAVE_LOFF_T
 329 typedef int64_t loff_t;
 330 #endif
 331
 332 #if !defined(HAVE_DIRFD) \
 333     && (!defined(HAVE_DECL_DIRFD) || HAVE_DECL_DIRFD == 0) \
 334     && defined(HAVE_DIR_DD_FD)
 335 #include <dirent.h>
 336 static inline int dirfd(DIR *d)
 337 {
 338         return d->dd_fd;
 339 }
 340 #endif
 341
 342 /*
 343  * Fallback defines for old versions of glibc
 344  */
 345 #include <fcntl.h>
 346
 347 #ifdef O_CLOEXEC
 348 #define UL_CLOEXECSTR   "e"
 349 #else
 350 #define UL_CLOEXECSTR   ""
 351 #endif
 352
 353 #ifndef O_CLOEXEC
 354 #define O_CLOEXEC 0
 355 #endif
 356
 357 #ifdef __FreeBSD_kernel__
 358 #ifndef F_DUPFD_CLOEXEC
 359 #define F_DUPFD_CLOEXEC 17      /* Like F_DUPFD, but FD_CLOEXEC is set */
 360 #endif
 361 #endif
 362
 363
 364 #ifndef AI_ADDRCONFIG
 365 #define AI_ADDRCONFIG 0x0020
 366 #endif
 367
 368 #ifndef IUTF8
 369 #define IUTF8 0040000
 370 #endif
 371
 372 /*
 373  * MAXHOSTNAMELEN replacement
 374  */
 375 static inline size_t get_hostname_max(void)
 376 {
 377         long len = sysconf(_SC_HOST_NAME_MAX);
 378
 379         if (0 < len)
 380                 return len;
 381
 382 #ifdef MAXHOSTNAMELEN
 383         return MAXHOSTNAMELEN;
 384 #elif HOST_NAME_MAX
 385         return HOST_NAME_MAX;
 386 #endif
 387         return 64;
 388 }
 389
 390
 391 static inline int drop_permissions(void)
 392 {
 393         errno = 0;
 394
 395         /* drop GID */
 396         if (setgid(getgid()) < 0)
 397                 goto fail;
 398
 399         /* drop UID */
 400         if (setuid(getuid()) < 0)
 401                 goto fail;
 402
 403         return 0;
 404 fail:
 405         return errno ? -errno : -1;
 406 }
 407
 408 /*
 409  * The usleep function was marked obsolete in POSIX.1-2001 and was removed
 410  * in POSIX.1-2008.  It was replaced with nanosleep() that provides more
 411  * advantages (like no interaction with signals and other timer functions).
 412  */
 413 #include <time.h>
 414
 415 static inline int xusleep(useconds_t usec)
 416 {
 417 #ifdef HAVE_NANOSLEEP
 418         struct timespec waittime = {
 419                 .tv_sec   =  usec / 1000000L,
 420                 .tv_nsec  = (usec % 1000000L) * 1000
 421         };
 422         return nanosleep(&waittime, NULL);
 423 #elif defined(HAVE_USLEEP)
 424         return usleep(usec);
 425 #else
 426 # error "System with usleep() or nanosleep() required!"
 427 #endif
 428 }
 429
 430
 431 #define ul_err_write(_m) ignore_result( write(STDERR_FILENO, _m, strlen(_m)) )
 432
 433 /*
 434  * warn() for signal handlers
 435  */
 436 static inline void ul_sig_warn(const char *mesg)
 437 {
 438         ul_err_write(program_invocation_short_name);
 439         ul_err_write(": ");
 440         ul_err_write(mesg);
 441         ul_err_write("\n");
 442 }
 443
 444 /*
 445  * err() for signal handlers
 446  */
 447 static inline void __attribute__((__noreturn__)) ul_sig_err(int excode, const char *mesg)
 448 {
 449         ul_sig_warn(mesg);
 450         _exit(excode);
 451 }
 452
 453 /*
 454  * Constant strings for usage() functions. For more info see
 455  * Documentation/{howto-usage-function.txt,boilerplate.c}
 456  */
 457 #define USAGE_HEADER     _("\nUsage:\n")
 458 #define USAGE_OPTIONS    _("\nOptions:\n")
 459 #define USAGE_FUNCTIONS  _("\nFunctions:\n")
 460 #define USAGE_COMMANDS   _("\nCommands:\n")
 461 #define USAGE_ARGUMENTS   _("\nArguments:\n")
 462 #define USAGE_COLUMNS    _("\nAvailable output columns:\n")
 463 #define USAGE_DEFAULT_COLUMNS _("\nDefault columns:\n")
 464 #define USAGE_SEPARATOR    "\n"
 465
 466 #define USAGE_OPTSTR_HELP     _("display this help")
 467 #define USAGE_OPTSTR_VERSION  _("display version")
 468
 469 #define USAGE_HELP_OPTIONS(marg_dsc) \
 470                 "%-" #marg_dsc "s%s\n" \
 471                 "%-" #marg_dsc "s%s\n" \
 472                 , " -h, --help",    USAGE_OPTSTR_HELP \
 473                 , " -V, --version", USAGE_OPTSTR_VERSION
 474
 475 #define USAGE_ARG_SEPARATOR    "\n"
 476 #define USAGE_ARG_SIZE(_name) \
 477                 _(" %s arguments may be followed by the suffixes for\n" \
 478                   "   GiB, TiB, PiB, EiB, ZiB, and YiB (the \"iB\" is optional)\n"), _name
 479
 480 #define USAGE_MAN_TAIL(_man)   _("\nFor more details see %s.\n"), _man
 481
 482 #define UTIL_LINUX_VERSION _("%s from %s\n"), program_invocation_short_name, PACKAGE_STRING
 483
 484 #define print_version(eval) __extension__ ({ \
 485                 printf(UTIL_LINUX_VERSION); \
 486                 exit(eval); \
 487 })
 488
 489 static inline void print_features(const char **features, const char *prefix)
 490 {
 491         if (features && *features) {
 492                 const char **p = features;
 493                 while (p && *p) {
 494                         if (prefix && p == features)
 495                                 printf(" (%s ", prefix);
 496                         else
 497                                 fputs(p == features ? " (" : ", ", stdout);
 498                         fputs(*p++, stdout);
 499                 }
 500                 fputc(')', stdout);
 501         }
 502 }
 503
 504 #define UTIL_LINUX_VERSION_NOBREAK _("%s from %s"), program_invocation_short_name, PACKAGE_STRING
 505
 506 #define print_version_with_features(eval, features) __extension__ ({ \
 507                 printf(UTIL_LINUX_VERSION_NOBREAK); \
 508                 print_features(features, _("features:")); \
 509                 fputc('\n', stdout); \
 510                 exit(eval); \
 511 })
 512
 513 /*
 514  * seek stuff
 515  */
 516 #ifndef SEEK_DATA
 517 # define SEEK_DATA      3
 518 #endif
 519 #ifndef SEEK_HOLE
 520 # define SEEK_HOLE      4
 521 #endif
 522
 523
 524 /*
 525  * Macros to convert #define'itions to strings, for example
 526  * #define XYXXY 42
 527  * printf ("%s=%s\n", stringify(XYXXY), stringify_value(XYXXY));
 528  */
 529 #define stringify_value(s) stringify(s)
 530 #define stringify(s) #s
 531
 532 /* Detect if we're compiled with Address Sanitizer
 533  *  - gcc (__SANITIZE_ADDRESS__)
 534  *  - clang (__has_feature(address_sanitizer))
 535  */
 536 #if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
 537 #  ifdef __SANITIZE_ADDRESS__
 538 #      define HAS_FEATURE_ADDRESS_SANITIZER 1
 539 #  elif defined(__has_feature)
 540 #    if __has_feature(address_sanitizer)
 541 #      define HAS_FEATURE_ADDRESS_SANITIZER 1
 542 #    endif
 543 #  endif
 544 #  if !defined(HAS_FEATURE_ADDRESS_SANITIZER)
 545 #    define HAS_FEATURE_ADDRESS_SANITIZER 0
 546 #  endif
 547 #endif
 548
 549 /*
 550  * UL_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
 551  * instrumentation shipped with Clang and GCC) to not instrument the
 552  * annotated function.  Furthermore, it will prevent the compiler from
 553  * inlining the function because inlining currently breaks the blacklisting
 554  * mechanism of AddressSanitizer.
 555  */
 556 #if __has_feature(address_sanitizer) && __has_attribute(no_sanitize_memory) && __has_attribute(no_sanitize_address)
 557 # define UL_ASAN_BLACKLIST __attribute__((noinline)) __attribute__((no_sanitize_memory)) __attribute__((no_sanitize_address))
 558 #else
 559 # define UL_ASAN_BLACKLIST      /* nothing */
 560 #endif
 561
 562 /*
 563  * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for
 564  * pwd buffer and in some cases it is not large enough. See POSIX and
 565  * getpwnam_r man page for more details.
 566  */
 567 #define UL_GETPW_BUFSIZ (16 * 1024)
 568
 569 /*
 570  * Darwin or other BSDs may only have MAP_ANON. To get it on Darwin we must
 571  * define _DARWIN_C_SOURCE before including sys/mman.h. We do this in config.h.
 572  */
 573 #if !defined MAP_ANONYMOUS && defined MAP_ANON
 574 # define MAP_ANONYMOUS  (MAP_ANON)
 575 #endif
 576
 577 #define SINT_MAX(t) (((t)1 << (sizeof(t) * 8 - 2)) - (t)1 + ((t)1 << (sizeof(t) * 8 - 2)))
 578
 579 #endif /* UTIL_LINUX_C_H */