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