make.h

   1 /* Miscellaneous global declarations and portability cruft for GNU Make.
   2 Copyright (C) 1988-2012 Free Software Foundation, Inc.
   3 This file is part of GNU Make.
   4
   5 GNU Make is free software; you can redistribute it and/or modify it under the
   6 terms of the GNU General Public License as published by the Free Software
   7 Foundation; either version 3 of the License, or (at your option) any later
   8 version.
   9
  10 GNU Make is distributed in the hope that it will be useful, but WITHOUT ANY
  11 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
  12 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  13
  14 You should have received a copy of the GNU General Public License along with
  15 this program.  If not, see <http://www.gnu.org/licenses/>.  */
  16
  17 /* We use <config.h> instead of "config.h" so that a compilation
  18    using -I. -I$srcdir will use ./config.h rather than $srcdir/config.h
  19    (which it would do because make.h was found in $srcdir).  */
  20 #include <config.h>
  21 #undef  HAVE_CONFIG_H
  22 #define HAVE_CONFIG_H 1
  23
  24 /* Specify we want GNU source code.  This must be defined before any
  25    system headers are included.  */
  26
  27 #define _GNU_SOURCE 1
  28
  29 /* AIX requires this to be the first thing in the file.  */
  30 #if HAVE_ALLOCA_H
  31 # include <alloca.h>
  32 #else
  33 # ifdef _AIX
  34  #pragma alloca
  35 # else
  36 #  if !defined(__GNUC__) && !defined(WINDOWS32)
  37 #   ifndef alloca /* predefined by HP cc +Olibcalls */
  38 char *alloca ();
  39 #   endif
  40 #  endif
  41 # endif
  42 #endif
  43
  44 /* Disable assert() unless we're a maintainer.
  45    Some asserts are compute-intensive.  */
  46 #ifndef MAKE_MAINTAINER_MODE
  47 # define NDEBUG 1
  48 #endif
  49
  50
  51 #ifdef  CRAY
  52 /* This must happen before #include <signal.h> so
  53    that the declaration therein is changed.  */
  54 # define signal bsdsignal
  55 #endif
  56
  57 /* If we're compiling for the dmalloc debugger, turn off string inlining.  */
  58 #if defined(HAVE_DMALLOC_H) && defined(__GNUC__)
  59 # define __NO_STRING_INLINES
  60 #endif
  61
  62 #include <sys/types.h>
  63 #include <sys/stat.h>
  64 #include <signal.h>
  65 #include <stdio.h>
  66 #include <ctype.h>
  67
  68 #ifdef HAVE_SYS_TIMEB_H
  69 /* SCO 3.2 "devsys 4.2" has a prototype for 'ftime' in <time.h> that bombs
  70    unless <sys/timeb.h> has been included first.  */
  71 # include <sys/timeb.h>
  72 #endif
  73 #if TIME_WITH_SYS_TIME
  74 # include <sys/time.h>
  75 # include <time.h>
  76 #else
  77 # if HAVE_SYS_TIME_H
  78 #  include <sys/time.h>
  79 # else
  80 #  include <time.h>
  81 # endif
  82 #endif
  83
  84 #include <errno.h>
  85
  86 #ifndef errno
  87 extern int errno;
  88 #endif
  89
  90 #ifndef isblank
  91 # define isblank(c)     ((c) == ' ' || (c) == '\t')
  92 #endif
  93
  94 #ifdef  HAVE_UNISTD_H
  95 # include <unistd.h>
  96 /* Ultrix's unistd.h always defines _POSIX_VERSION, but you only get
  97    POSIX.1 behavior with 'cc -YPOSIX', which predefines POSIX itself!  */
  98 # if defined (_POSIX_VERSION) && !defined (ultrix) && !defined (VMS)
  99 #  define POSIX 1
 100 # endif
 101 #endif
 102
 103 /* Some systems define _POSIX_VERSION but are not really POSIX.1.  */
 104 #if (defined (butterfly) || defined (__arm) || (defined (__mips) && defined (_SYSTYPE_SVR3)) || (defined (sequent) && defined (i386)))
 105 # undef POSIX
 106 #endif
 107
 108 #if !defined (POSIX) && defined (_AIX) && defined (_POSIX_SOURCE)
 109 # define POSIX 1
 110 #endif
 111
 112 #ifndef RETSIGTYPE
 113 # define RETSIGTYPE     void
 114 #endif
 115
 116 #ifndef sigmask
 117 # define sigmask(sig)   (1 << ((sig) - 1))
 118 #endif
 119
 120 #ifndef HAVE_SA_RESTART
 121 # define SA_RESTART 0
 122 #endif
 123
 124 #ifdef  HAVE_LIMITS_H
 125 # include <limits.h>
 126 #endif
 127 #ifdef  HAVE_SYS_PARAM_H
 128 # include <sys/param.h>
 129 #endif
 130
 131 #ifndef PATH_MAX
 132 # ifndef POSIX
 133 #  define PATH_MAX      MAXPATHLEN
 134 # endif
 135 #endif
 136 #ifndef MAXPATHLEN
 137 # define MAXPATHLEN 1024
 138 #endif
 139
 140 #ifdef  PATH_MAX
 141 # define GET_PATH_MAX   PATH_MAX
 142 # define PATH_VAR(var)  char var[PATH_MAX]
 143 #else
 144 # define NEED_GET_PATH_MAX 1
 145 # define GET_PATH_MAX   (get_path_max ())
 146 # define PATH_VAR(var)  char *var = alloca (GET_PATH_MAX)
 147 unsigned int get_path_max (void);
 148 #endif
 149
 150 #ifndef CHAR_BIT
 151 # define CHAR_BIT 8
 152 #endif
 153
 154 #ifndef USHRT_MAX
 155 # define USHRT_MAX 65535
 156 #endif
 157
 158 /* Nonzero if the integer type T is signed.
 159    Use <= to avoid GCC warnings about always-false expressions.  */
 160 #define INTEGER_TYPE_SIGNED(t) ((t) -1 <= 0)
 161
 162 /* The minimum and maximum values for the integer type T.
 163    Use ~ (t) 0, not -1, for portability to 1's complement hosts.  */
 164 #define INTEGER_TYPE_MINIMUM(t) \
 165   (! INTEGER_TYPE_SIGNED (t) ? (t) 0 : ~ (t) 0 << (sizeof (t) * CHAR_BIT - 1))
 166 #define INTEGER_TYPE_MAXIMUM(t) (~ (t) 0 - INTEGER_TYPE_MINIMUM (t))
 167
 168 #ifndef CHAR_MAX
 169 # define CHAR_MAX INTEGER_TYPE_MAXIMUM (char)
 170 #endif
 171
 172 #ifdef STAT_MACROS_BROKEN
 173 # ifdef S_ISREG
 174 #  undef S_ISREG
 175 # endif
 176 # ifdef S_ISDIR
 177 #  undef S_ISDIR
 178 # endif
 179 #endif  /* STAT_MACROS_BROKEN.  */
 180
 181 #ifndef S_ISREG
 182 # define S_ISREG(mode)  (((mode) & S_IFMT) == S_IFREG)
 183 #endif
 184 #ifndef S_ISDIR
 185 # define S_ISDIR(mode)  (((mode) & S_IFMT) == S_IFDIR)
 186 #endif
 187
 188 #ifdef VMS
 189 # include <types.h>
 190 # include <unixlib.h>
 191 # include <unixio.h>
 192 # include <perror.h>
 193 /* Needed to use alloca on VMS.  */
 194 # include <builtins.h>
 195 #endif
 196
 197 #ifndef __attribute__
 198 /* This feature is available in gcc versions 2.5 and later.  */
 199 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 5) || __STRICT_ANSI__
 200 #  define __attribute__(x)
 201 # endif
 202 /* The __-protected variants of 'format' and 'printf' attributes
 203    are accepted by gcc versions 2.6.4 (effectively 2.7) and later.  */
 204 # if __GNUC__ < 2 || (__GNUC__ == 2 && __GNUC_MINOR__ < 7)
 205 #  define __format__ format
 206 #  define __printf__ printf
 207 # endif
 208 #endif
 209 #define UNUSED  __attribute__ ((unused))
 210
 211 #if defined (STDC_HEADERS) || defined (__GNU_LIBRARY__)
 212 # include <stdlib.h>
 213 # include <string.h>
 214 # define ANSI_STRING 1
 215 #else   /* No standard headers.  */
 216 # ifdef HAVE_STRING_H
 217 #  include <string.h>
 218 #  define ANSI_STRING 1
 219 # else
 220 #  include <strings.h>
 221 # endif
 222 # ifdef HAVE_MEMORY_H
 223 #  include <memory.h>
 224 # endif
 225 # ifdef HAVE_STDLIB_H
 226 #  include <stdlib.h>
 227 # else
 228 void *malloc (int);
 229 void *realloc (void *, int);
 230 void free (void *);
 231
 232 void abort (void) __attribute__ ((noreturn));
 233 void exit (int) __attribute__ ((noreturn));
 234 # endif /* HAVE_STDLIB_H.  */
 235
 236 #endif /* Standard headers.  */
 237
 238 /* These should be in stdlib.h.  Make sure we have them.  */
 239 #ifndef EXIT_SUCCESS
 240 # define EXIT_SUCCESS 0
 241 #endif
 242 #ifndef EXIT_FAILURE
 243 # define EXIT_FAILURE 1
 244 #endif
 245
 246 #ifndef  ANSI_STRING
 247
 248 /* SCO Xenix has a buggy macro definition in <string.h>.  */
 249 #undef  strerror
 250 #if !defined(__DECC)
 251 char *strerror (int errnum);
 252 #endif
 253
 254 #endif  /* !ANSI_STRING.  */
 255 #undef  ANSI_STRING
 256
 257 #if HAVE_INTTYPES_H
 258 # include <inttypes.h>
 259 #endif
 260 #if HAVE_STDINT_H
 261 # include <stdint.h>
 262 #endif
 263 #define FILE_TIMESTAMP uintmax_t
 264
 265 #if !defined(HAVE_STRSIGNAL)
 266 char *strsignal (int signum);
 267 #endif
 268
 269 /* ISDIGIT offers the following features:
 270    - Its arg may be any int or unsigned int; it need not be an unsigned char.
 271    - It's guaranteed to evaluate its argument exactly once.
 272       NOTE!  Make relies on this behavior, don't change it!
 273    - It's typically faster.
 274    POSIX 1003.2-1992 section 2.5.2.1 page 50 lines 1556-1558 says that
 275    only '0' through '9' are digits.  Prefer ISDIGIT to isdigit() unless
 276    it's important to use the locale's definition of 'digit' even when the
 277    host does not conform to POSIX.  */
 278 #define ISDIGIT(c) ((unsigned) (c) - '0' <= 9)
 279
 280 /* Test if two strings are equal. Is this worthwhile?  Should be profiled.  */
 281 #define streq(a, b) \
 282    ((a) == (b) || \
 283     (*(a) == *(b) && (*(a) == '\0' || !strcmp ((a) + 1, (b) + 1))))
 284
 285 /* Test if two strings are equal, but match case-insensitively on systems
 286    which have case-insensitive filesystems.  Should only be used for
 287    filenames!  */
 288 #ifdef HAVE_CASE_INSENSITIVE_FS
 289 # define patheq(a, b) \
 290     ((a) == (b) \
 291      || (tolower((unsigned char)*(a)) == tolower((unsigned char)*(b)) \
 292          && (*(a) == '\0' || !strcasecmp ((a) + 1, (b) + 1))))
 293 #else
 294 # define patheq(a, b) streq(a, b)
 295 #endif
 296
 297 #define strneq(a, b, l) (strncmp ((a), (b), (l)) == 0)
 298
 299 #if defined(__GNUC__) || defined(ENUM_BITFIELDS)
 300 # define ENUM_BITFIELD(bits)    :bits
 301 #else
 302 # define ENUM_BITFIELD(bits)
 303 #endif
 304
 305 /* Handle gettext and locales.  */
 306
 307 #if HAVE_LOCALE_H
 308 # include <locale.h>
 309 #else
 310 # define setlocale(category, locale)
 311 #endif
 312
 313 #include <gettext.h>
 314
 315 #define _(msgid)            gettext (msgid)
 316 #define N_(msgid)           gettext_noop (msgid)
 317 #define S_(msg1,msg2,num)   ngettext (msg1,msg2,num)
 318
 319 /* Handle other OSs.
 320    To overcome an issue parsing paths in a DOS/Windows environment when
 321    built in a unix based environment, override the PATH_SEPARATOR_CHAR
 322    definition unless being built for Cygwin. */
 323 #if defined(HAVE_DOS_PATHS) && !defined(__CYGWIN__)
 324 # undef PATH_SEPARATOR_CHAR
 325 # define PATH_SEPARATOR_CHAR ';'
 326 #elif !defined(PATH_SEPARATOR_CHAR)
 327 # if defined (VMS)
 328 #  define PATH_SEPARATOR_CHAR ','
 329 # else
 330 #  define PATH_SEPARATOR_CHAR ':'
 331 # endif
 332 #endif
 333
 334 /* This is needed for getcwd() and chdir(), on some W32 systems.  */
 335 #if defined(HAVE_DIRECT_H)
 336 # include <direct.h>
 337 #endif
 338
 339 #ifdef WINDOWS32
 340 # include <fcntl.h>
 341 # include <malloc.h>
 342 # define pipe(_p)        _pipe((_p), 512, O_BINARY)
 343 # define kill(_pid,_sig) w32_kill((_pid),(_sig))
 344
 345 void sync_Path_environment (void);
 346 int w32_kill (pid_t pid, int sig);
 347 char *end_of_token_w32 (const char *s, char stopchar);
 348 int find_and_set_default_shell (const char *token);
 349
 350 /* indicates whether or not we have Bourne shell */
 351 extern int no_default_sh_exe;
 352
 353 /* is default_shell unixy? */
 354 extern int unixy_shell;
 355 #endif  /* WINDOWS32 */
 356
 357 #if defined(HAVE_SYS_RESOURCE_H) && defined(HAVE_GETRLIMIT) && defined(HAVE_SETRLIMIT)
 358 # define SET_STACK_SIZE
 359 #endif
 360 #ifdef SET_STACK_SIZE
 361 # include <sys/resource.h>
 362 extern struct rlimit stack_limit;
 363 #endif
 364
 365 struct floc
 366   {
 367     const char *filenm;
 368     unsigned long lineno;
 369   };
 370 #define NILF ((struct floc *)0)
 371
 372 #define CSTRLEN(_s) (sizeof (_s)-1)
 373 #define STRING_SIZE_TUPLE(_s) (_s), CSTRLEN(_s)
 374
 375 \f
 376 /* We have to have stdarg.h or varargs.h AND v*printf or doprnt to use
 377    variadic versions of these functions.  */
 378
 379 #if HAVE_STDARG_H || HAVE_VARARGS_H
 380 # if HAVE_VPRINTF || HAVE_DOPRNT
 381 #  define USE_VARIADIC 1
 382 # endif
 383 #endif
 384
 385 #if HAVE_ANSI_COMPILER && USE_VARIADIC && HAVE_STDARG_H
 386 const char *concat (unsigned int, ...);
 387 void message (int prefix, const char *fmt, ...)
 388               __attribute__ ((__format__ (__printf__, 2, 3)));
 389 void error (const struct floc *flocp, const char *fmt, ...)
 390             __attribute__ ((__format__ (__printf__, 2, 3)));
 391 void fatal (const struct floc *flocp, const char *fmt, ...)
 392                    __attribute__ ((noreturn, __format__ (__printf__, 2, 3)));
 393 #else
 394 const char *concat ();
 395 void message ();
 396 void error ();
 397 void fatal ();
 398 #endif
 399
 400 void die (int) __attribute__ ((noreturn));
 401 void log_working_directory (int);
 402 void pfatal_with_name (const char *) __attribute__ ((noreturn));
 403 void perror_with_name (const char *, const char *);
 404 void *xmalloc (unsigned int);
 405 void *xcalloc (unsigned int);
 406 void *xrealloc (void *, unsigned int);
 407 char *xstrdup (const char *);
 408 char *xstrndup (const char *, unsigned int);
 409 char *find_next_token (const char **, unsigned int *);
 410 char *next_token (const char *);
 411 char *end_of_token (const char *);
 412 void collapse_continuations (char *);
 413 char *lindex (const char *, const char *, int);
 414 int alpha_compare (const void *, const void *);
 415 void print_spaces (unsigned int);
 416 char *find_percent (char *);
 417 const char *find_percent_cached (const char **);
 418 FILE *open_tmpfile (char **, const char *);
 419
 420 #ifndef NO_ARCHIVES
 421 int ar_name (const char *);
 422 void ar_parse_name (const char *, char **, char **);
 423 int ar_touch (const char *);
 424 time_t ar_member_date (const char *);
 425
 426 typedef long int (*ar_member_func_t) (int desc, const char *mem, int truncated,
 427                                       long int hdrpos, long int datapos,
 428                                       long int size, long int date, int uid,
 429                                       int gid, int mode, const void *arg);
 430
 431 long int ar_scan (const char *archive, ar_member_func_t function, const void *arg);
 432 int ar_name_equal (const char *name, const char *mem, int truncated);
 433 #ifndef VMS
 434 int ar_member_touch (const char *arname, const char *memname);
 435 #endif
 436 #endif
 437
 438 int dir_file_exists_p (const char *, const char *);
 439 int file_exists_p (const char *);
 440 int file_impossible_p (const char *);
 441 void file_impossible (const char *);
 442 const char *dir_name (const char *);
 443 void hash_init_directories (void);
 444
 445 void define_default_variables (void);
 446 void set_default_suffixes (void);
 447 void install_default_suffix_rules (void);
 448 void install_default_implicit_rules (void);
 449
 450 void build_vpath_lists (void);
 451 void construct_vpath_list (char *pattern, char *dirpath);
 452 const char *vpath_search (const char *file, FILE_TIMESTAMP *mtime_ptr,
 453                           unsigned int* vpath_index, unsigned int* path_index);
 454 int gpath_search (const char *file, unsigned int len);
 455
 456 void construct_include_path (const char **arg_dirs);
 457
 458 void user_access (void);
 459 void make_access (void);
 460 void child_access (void);
 461
 462 void close_stdout (void);
 463
 464 char *strip_whitespace (const char **begpp, const char **endpp);
 465
 466 /* String caching  */
 467 void strcache_init (void);
 468 void strcache_print_stats (const char *prefix);
 469 int strcache_iscached (const char *str);
 470 const char *strcache_add (const char *str);
 471 const char *strcache_add_len (const char *str, unsigned int len);
 472 int strcache_setbufsize (unsigned int size);
 473
 474 /* Guile support  */
 475 #ifdef HAVE_GUILE
 476 int guile_gmake_setup (const struct floc *flocp);
 477 #endif
 478
 479 /* Loadable object support  */
 480 typedef int (*load_func_t)(const struct floc *flocp);
 481 int load_file (const struct floc *flocp, const char *filename, int noerror);
 482
 483 #ifdef  HAVE_VFORK_H
 484 # include <vfork.h>
 485 #endif
 486
 487 /* We omit these declarations on non-POSIX systems which define _POSIX_VERSION,
 488    because such systems often declare them in header files anyway.  */
 489
 490 #if !defined (__GNU_LIBRARY__) && !defined (POSIX) && !defined (_POSIX_VERSION) && !defined(WINDOWS32)
 491
 492 long int atol ();
 493 # ifndef VMS
 494 long int lseek ();
 495 # endif
 496
 497 #endif  /* Not GNU C library or POSIX.  */
 498
 499 #ifdef  HAVE_GETCWD
 500 # if !defined(VMS) && !defined(__DECC)
 501 char *getcwd ();
 502 # endif
 503 #else
 504 char *getwd ();
 505 # define getcwd(buf, len)       getwd (buf)
 506 #endif
 507
 508 #if !HAVE_STRCASECMP
 509 # if HAVE_STRICMP
 510 #  define strcasecmp stricmp
 511 # elif HAVE_STRCMPI
 512 #  define strcasecmp strcmpi
 513 # else
 514 /* Create our own, in misc.c */
 515 int strcasecmp (const char *s1, const char *s2);
 516 # endif
 517 #endif
 518
 519 #if !HAVE_STRNCASECMP
 520 # if HAVE_STRNICMP
 521 #  define strncasecmp strnicmp
 522 # elif HAVE_STRNCMPI
 523 #  define strncasecmp strncmpi
 524 # else
 525 /* Create our own, in misc.c */
 526 int strncasecmp (const char *s1, const char *s2, int n);
 527 # endif
 528 #endif
 529
 530 extern const struct floc *reading_file;
 531 extern const struct floc **expanding_var;
 532
 533 extern char **environ;
 534
 535 extern int just_print_flag, silent_flag, ignore_errors_flag, keep_going_flag;
 536 extern int print_data_base_flag, question_flag, touch_flag, always_make_flag;
 537 extern int env_overrides, no_builtin_rules_flag, no_builtin_variables_flag;
 538 extern int print_version_flag, print_directory_flag, check_symlink_flag;
 539 extern int warn_undefined_variables_flag, trace_flag, posix_pedantic;
 540 extern int not_parallel, second_expansion, clock_skew_detected;
 541 extern int rebuilding_makefiles, one_shell;
 542
 543 /* can we run commands via 'sh -c xxx' or must we use batch files? */
 544 extern int batch_mode_shell;
 545
 546 /* Resetting the command script introduction prefix character.  */
 547 #define RECIPEPREFIX_NAME          ".RECIPEPREFIX"
 548 #define RECIPEPREFIX_DEFAULT       '\t'
 549 extern char cmd_prefix;
 550
 551 extern unsigned int job_slots;
 552 extern int job_fds[2];
 553 extern int job_rfd;
 554 #ifndef NO_FLOAT
 555 extern double max_load_average;
 556 #else
 557 extern int max_load_average;
 558 #endif
 559
 560 extern char *program;
 561 extern char *starting_directory;
 562 extern unsigned int makelevel;
 563 extern char *version_string, *remote_description, *make_host;
 564
 565 extern unsigned int commands_started;
 566
 567 extern int handling_fatal_signal;
 568
 569
 570 #ifndef MIN
 571 #define MIN(_a,_b) ((_a)<(_b)?(_a):(_b))
 572 #endif
 573 #ifndef MAX
 574 #define MAX(_a,_b) ((_a)>(_b)?(_a):(_b))
 575 #endif
 576
 577 #ifdef VMS
 578 #  define MAKE_SUCCESS 1
 579 #  define MAKE_TROUBLE 2
 580 #  define MAKE_FAILURE 3
 581 #else
 582 #  define MAKE_SUCCESS 0
 583 #  define MAKE_TROUBLE 1
 584 #  define MAKE_FAILURE 2
 585 #endif
 586
 587 /* Set up heap debugging library dmalloc.  */
 588
 589 #ifdef HAVE_DMALLOC_H
 590 #include <dmalloc.h>
 591 #endif
 592
 593 #ifndef initialize_main
 594 # ifdef __EMX__
 595 #  define initialize_main(pargc, pargv) \
 596                           { _wildcard(pargc, pargv); _response(pargc, pargv); }
 597 # else
 598 #  define initialize_main(pargc, pargv)
 599 # endif
 600 #endif
 601
 602 #ifdef __EMX__
 603 # if !defined chdir
 604 #  define chdir _chdir2
 605 # endif
 606 # if !defined getcwd
 607 #  define getcwd _getcwd2
 608 # endif
 609
 610 /* NO_CHDIR2 causes make not to use _chdir2() and _getcwd2() instead of
 611    chdir() and getcwd(). This avoids some error messages for the
 612    make testsuite but restricts the drive letter support. */
 613 # ifdef NO_CHDIR2
 614 #  warning NO_CHDIR2: usage of drive letters restricted
 615 #  undef chdir
 616 #  undef getcwd
 617 # endif
 618 #endif
 619
 620 #ifndef initialize_main
 621 # define initialize_main(pargc, pargv)
 622 #endif
 623
 624
 625 /* Some systems (like Solaris, PTX, etc.) do not support the SA_RESTART flag
 626    properly according to POSIX.  So, we try to wrap common system calls with
 627    checks for EINTR.  Note that there are still plenty of system calls that
 628    can fail with EINTR but this, reportedly, gets the vast majority of
 629    failure cases.  If you still experience failures you'll need to either get
 630    a system where SA_RESTART works, or you need to avoid -j.  */
 631
 632 #define EINTRLOOP(_v,_c)   while (((_v)=_c)==-1 && errno==EINTR)
 633
 634 /* While system calls that return integers are pretty consistent about
 635    returning -1 on failure and setting errno in that case, functions that
 636    return pointers are not always so well behaved.  Sometimes they return
 637    NULL for expected behavior: one good example is readdir() which returns
 638    NULL at the end of the directory--and _doesn't_ reset errno.  So, we have
 639    to do it ourselves here.  */
 640
 641 #define ENULLLOOP(_v,_c)   do { errno = 0; (_v) = _c; } \
 642                            while((_v)==0 && errno==EINTR)