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