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