gnu/make/misc.c

   1 /* Miscellaneous generic support functions for GNU Make.
   2 Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1997,
   3 2002 Free Software Foundation, Inc.
   4 This file is part of GNU Make.
   5
   6 GNU Make is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Make is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Make; see the file COPYING.  If not, write to
  18 the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19 Boston, MA 02111-1307, USA.  */
  20
  21 #include "make.h"
  22 #include "dep.h"
  23 #include "debug.h"
  24
  25 /* Variadic functions.  We go through contortions to allow proper function
  26    prototypes for both ANSI and pre-ANSI C compilers, and also for those
  27    which support stdarg.h vs. varargs.h, and finally those which have
  28    vfprintf(), etc. and those who have _doprnt... or nothing.
  29
  30    This fancy stuff all came from GNU fileutils, except for the VA_PRINTF and
  31    VA_END macros used here since we have multiple print functions.  */
  32
  33 #if USE_VARIADIC
  34 # if HAVE_STDARG_H
  35 #  include <stdarg.h>
  36 #  define VA_START(args, lastarg) va_start(args, lastarg)
  37 # else
  38 #  include <varargs.h>
  39 #  define VA_START(args, lastarg) va_start(args)
  40 # endif
  41 # if HAVE_VPRINTF
  42 #  define VA_PRINTF(fp, lastarg, args) vfprintf((fp), (lastarg), (args))
  43 # else
  44 #  define VA_PRINTF(fp, lastarg, args) _doprnt((lastarg), (args), (fp))
  45 # endif
  46 # define VA_END(args) va_end(args)
  47 #else
  48 /* We can't use any variadic interface! */
  49 # define va_alist a1, a2, a3, a4, a5, a6, a7, a8
  50 # define va_dcl char *a1, *a2, *a3, *a4, *a5, *a6, *a7, *a8;
  51 # define VA_START(args, lastarg)
  52 # define VA_PRINTF(fp, lastarg, args) fprintf((fp), (lastarg), va_alist)
  53 # define VA_END(args)
  54 #endif
  55
  56
  57 /* Compare strings *S1 and *S2.
  58    Return negative if the first is less, positive if it is greater,
  59    zero if they are equal.  */
  60
  61 int
  62 alpha_compare (const void *v1, const void *v2)
  63 {
  64   const char *s1 = *((char **)v1);
  65   const char *s2 = *((char **)v2);
  66
  67   if (*s1 != *s2)
  68     return *s1 - *s2;
  69   return strcmp (s1, s2);
  70 }
  71 \f
  72 /* Discard each backslash-newline combination from LINE.
  73    Backslash-backslash-newline combinations become backslash-newlines.
  74    This is done by copying the text at LINE into itself.  */
  75
  76 void
  77 collapse_continuations (char *line)
  78 {
  79   char *in, *out, *p;
  80   int backslash;
  81   unsigned int bs_write;
  82
  83   in = strchr (line, '\n');
  84   if (in == 0)
  85     return;
  86
  87   out = in;
  88   while (out > line && out[-1] == '\\')
  89     --out;
  90
  91   while (*in != '\0')
  92     {
  93       /* BS_WRITE gets the number of quoted backslashes at
  94          the end just before IN, and BACKSLASH gets nonzero
  95          if the next character is quoted.  */
  96       backslash = 0;
  97       bs_write = 0;
  98       for (p = in - 1; p >= line && *p == '\\'; --p)
  99         {
 100           if (backslash)
 101             ++bs_write;
 102           backslash = !backslash;
 103
 104           /* It should be impossible to go back this far without exiting,
 105              but if we do, we can't get the right answer.  */
 106           if (in == out - 1)
 107             abort ();
 108         }
 109
 110       /* Output the appropriate number of backslashes.  */
 111       while (bs_write-- > 0)
 112         *out++ = '\\';
 113
 114       /* Skip the newline.  */
 115       ++in;
 116
 117       /* If the newline is quoted, discard following whitespace
 118          and any preceding whitespace; leave just one space.  */
 119       if (backslash)
 120         {
 121           in = next_token (in);
 122           while (out > line && isblank ((unsigned char)out[-1]))
 123             --out;
 124           *out++ = ' ';
 125         }
 126       else
 127         /* If the newline isn't quoted, put it in the output.  */
 128         *out++ = '\n';
 129
 130       /* Now copy the following line to the output.
 131          Stop when we find backslashes followed by a newline.  */
 132       while (*in != '\0')
 133         if (*in == '\\')
 134           {
 135             p = in + 1;
 136             while (*p == '\\')
 137               ++p;
 138             if (*p == '\n')
 139               {
 140                 in = p;
 141                 break;
 142               }
 143             while (in < p)
 144               *out++ = *in++;
 145           }
 146         else
 147           *out++ = *in++;
 148     }
 149
 150   *out = '\0';
 151 }
 152
 153
 154 /* Remove comments from LINE.
 155    This is done by copying the text at LINE onto itself.  */
 156
 157 void
 158 remove_comments (char *line)
 159 {
 160   char *comment;
 161
 162   comment = find_char_unquote (line, '#', 0, 0);
 163
 164   if (comment != 0)
 165     /* Cut off the line at the #.  */
 166     *comment = '\0';
 167 }
 168 \f
 169 /* Print N spaces (used in debug for target-depth).  */
 170
 171 void
 172 print_spaces (unsigned int n)
 173 {
 174   while (n-- > 0)
 175     putchar (' ');
 176 }
 177
 178 \f
 179 /* Return a newly-allocated string whose contents
 180    concatenate those of s1, s2, s3.  */
 181
 182 char *
 183 concat (const char *s1, const char *s2, const char *s3)
 184 {
 185   unsigned int len1, len2, len3;
 186   char *result;
 187
 188   len1 = *s1 != '\0' ? strlen (s1) : 0;
 189   len2 = *s2 != '\0' ? strlen (s2) : 0;
 190   len3 = *s3 != '\0' ? strlen (s3) : 0;
 191
 192   result = (char *) xmalloc (len1 + len2 + len3 + 1);
 193
 194   if (*s1 != '\0')
 195     bcopy (s1, result, len1);
 196   if (*s2 != '\0')
 197     bcopy (s2, result + len1, len2);
 198   if (*s3 != '\0')
 199     bcopy (s3, result + len1 + len2, len3);
 200   *(result + len1 + len2 + len3) = '\0';
 201
 202   return result;
 203 }
 204 \f
 205 /* Print a message on stdout.  */
 206
 207 void
 208 #if HAVE_ANSI_COMPILER && USE_VARIADIC && HAVE_STDARG_H
 209 message (int prefix, const char *fmt, ...)
 210 #else
 211 message (prefix, fmt, va_alist)
 212      int prefix;
 213      const char *fmt;
 214      va_dcl
 215 #endif
 216 {
 217 #if USE_VARIADIC
 218   va_list args;
 219 #endif
 220
 221   log_working_directory (1);
 222
 223   if (fmt != 0)
 224     {
 225       if (prefix)
 226         {
 227           if (makelevel == 0)
 228             printf ("%s: ", program);
 229           else
 230             printf ("%s[%u]: ", program, makelevel);
 231         }
 232       VA_START (args, fmt);
 233       VA_PRINTF (stdout, fmt, args);
 234       VA_END (args);
 235       putchar ('\n');
 236     }
 237
 238   fflush (stdout);
 239 }
 240
 241 /* Print an error message.  */
 242
 243 void
 244 #if HAVE_ANSI_COMPILER && USE_VARIADIC && HAVE_STDARG_H
 245 error (const struct floc *flocp, const char *fmt, ...)
 246 #else
 247 error (flocp, fmt, va_alist)
 248      const struct floc *flocp;
 249      const char *fmt;
 250      va_dcl
 251 #endif
 252 {
 253 #if USE_VARIADIC
 254   va_list args;
 255 #endif
 256
 257   log_working_directory (1);
 258
 259   if (flocp && flocp->filenm)
 260     fprintf (stderr, "%s:%lu: ", flocp->filenm, flocp->lineno);
 261   else if (makelevel == 0)
 262     fprintf (stderr, "%s: ", program);
 263   else
 264     fprintf (stderr, "%s[%u]: ", program, makelevel);
 265
 266   VA_START(args, fmt);
 267   VA_PRINTF (stderr, fmt, args);
 268   VA_END (args);
 269
 270   putc ('\n', stderr);
 271   fflush (stderr);
 272 }
 273
 274 /* Print an error message and exit.  */
 275
 276 void
 277 #if HAVE_ANSI_COMPILER && USE_VARIADIC && HAVE_STDARG_H
 278 fatal (const struct floc *flocp, const char *fmt, ...)
 279 #else
 280 fatal (flocp, fmt, va_alist)
 281      const struct floc *flocp;
 282      const char *fmt;
 283      va_dcl
 284 #endif
 285 {
 286 #if USE_VARIADIC
 287   va_list args;
 288 #endif
 289
 290   log_working_directory (1);
 291
 292   if (flocp && flocp->filenm)
 293     fprintf (stderr, "%s:%lu: *** ", flocp->filenm, flocp->lineno);
 294   else if (makelevel == 0)
 295     fprintf (stderr, "%s: *** ", program);
 296   else
 297     fprintf (stderr, "%s[%u]: *** ", program, makelevel);
 298
 299   VA_START(args, fmt);
 300   VA_PRINTF (stderr, fmt, args);
 301   VA_END (args);
 302
 303   fputs (_(".  Stop.\n"), stderr);
 304
 305   die (2);
 306 }
 307
 308 #ifndef HAVE_STRERROR
 309
 310 #undef  strerror
 311
 312 char *
 313 strerror (int errnum)
 314 {
 315   extern int errno, sys_nerr;
 316 #ifndef __DECC
 317   extern char *sys_errlist[];
 318 #endif
 319   static char buf[] = "Unknown error 12345678901234567890";
 320
 321   if (errno < sys_nerr)
 322     return sys_errlist[errnum];
 323
 324   sprintf (buf, _("Unknown error %d"), errnum);
 325   return buf;
 326 }
 327 #endif
 328
 329 /* Print an error message from errno.  */
 330
 331 void
 332 perror_with_name (const char *str, const char *name)
 333 {
 334   error (NILF, _("%s%s: %s"), str, name, strerror (errno));
 335 }
 336
 337 /* Print an error message from errno and exit.  */
 338
 339 void
 340 pfatal_with_name (const char *name)
 341 {
 342   fatal (NILF, _("%s: %s"), name, strerror (errno));
 343
 344   /* NOTREACHED */
 345 }
 346 \f
 347 /* Like malloc but get fatal error if memory is exhausted.  */
 348 /* Don't bother if we're using dmalloc; it provides these for us.  */
 349
 350 #ifndef HAVE_DMALLOC_H
 351
 352 #undef xmalloc
 353 #undef xrealloc
 354 #undef xstrdup
 355
 356 char *
 357 xmalloc (unsigned int size)
 358 {
 359   /* Make sure we don't allocate 0, for pre-ANSI libraries.  */
 360   char *result = (char *) malloc (size ? size : 1);
 361   if (result == 0)
 362     fatal (NILF, _("virtual memory exhausted"));
 363   return result;
 364 }
 365
 366
 367 char *
 368 xrealloc (char *ptr, unsigned int size)
 369 {
 370   char *result;
 371
 372   /* Some older implementations of realloc() don't conform to ANSI.  */
 373   if (! size)
 374     size = 1;
 375   result = ptr ? realloc (ptr, size) : malloc (size);
 376   if (result == 0)
 377     fatal (NILF, _("virtual memory exhausted"));
 378   return result;
 379 }
 380
 381
 382 char *
 383 xstrdup (const char *ptr)
 384 {
 385   char *result;
 386
 387 #ifdef HAVE_STRDUP
 388   result = strdup (ptr);
 389 #else
 390   result = (char *) malloc (strlen (ptr) + 1);
 391 #endif
 392
 393   if (result == 0)
 394     fatal (NILF, _("virtual memory exhausted"));
 395
 396 #ifdef HAVE_STRDUP
 397   return result;
 398 #else
 399   return strcpy(result, ptr);
 400 #endif
 401 }
 402
 403 #endif  /* HAVE_DMALLOC_H */
 404
 405 char *
 406 savestring (const char *str, unsigned int length)
 407 {
 408   register char *out = (char *) xmalloc (length + 1);
 409   if (length > 0)
 410     bcopy (str, out, length);
 411   out[length] = '\0';
 412   return out;
 413 }
 414 \f
 415 /* Search string BIG (length BLEN) for an occurrence of
 416    string SMALL (length SLEN).  Return a pointer to the
 417    beginning of the first occurrence, or return nil if none found.  */
 418
 419 char *
 420 sindex (const char *big, unsigned int blen,
 421         const char *small, unsigned int slen)
 422 {
 423   if (!blen)
 424     blen = strlen (big);
 425   if (!slen)
 426     slen = strlen (small);
 427
 428   if (slen && blen >= slen)
 429     {
 430       register unsigned int b;
 431
 432       /* Quit when there's not enough room left for the small string.  */
 433       --slen;
 434       blen -= slen;
 435
 436       for (b = 0; b < blen; ++b, ++big)
 437         if (*big == *small && strneq (big + 1, small + 1, slen))
 438           return (char *)big;
 439     }
 440
 441   return 0;
 442 }
 443
 444 /* Limited INDEX:
 445    Search through the string STRING, which ends at LIMIT, for the character C.
 446    Returns a pointer to the first occurrence, or nil if none is found.
 447    Like INDEX except that the string searched ends where specified
 448    instead of at the first null.  */
 449
 450 char *
 451 lindex (const char *s, const char *limit, int c)
 452 {
 453   while (s < limit)
 454     if (*s++ == c)
 455       return (char *)(s - 1);
 456
 457   return 0;
 458 }
 459 \f
 460 /* Return the address of the first whitespace or null in the string S.  */
 461
 462 char *
 463 end_of_token (char *s)
 464 {
 465   while (*s != '\0' && !isblank ((unsigned char)*s))
 466     ++s;
 467   return s;
 468 }
 469
 470 #ifdef WINDOWS32
 471 /*
 472  * Same as end_of_token, but take into account a stop character
 473  */
 474 char *
 475 end_of_token_w32 (char *s, char stopchar)
 476 {
 477   register char *p = s;
 478   register int backslash = 0;
 479
 480   while (*p != '\0' && *p != stopchar
 481          && (backslash || !isblank ((unsigned char)*p)))
 482     {
 483       if (*p++ == '\\')
 484         {
 485           backslash = !backslash;
 486           while (*p == '\\')
 487             {
 488               backslash = !backslash;
 489               ++p;
 490             }
 491         }
 492       else
 493         backslash = 0;
 494     }
 495
 496   return p;
 497 }
 498 #endif
 499
 500 /* Return the address of the first nonwhitespace or null in the string S.  */
 501
 502 char *
 503 next_token (const char *s)
 504 {
 505   while (isblank ((unsigned char)*s))
 506     ++s;
 507   return (char *)s;
 508 }
 509
 510 /* Find the next token in PTR; return the address of it, and store the
 511    length of the token into *LENGTHPTR if LENGTHPTR is not nil.  */
 512
 513 char *
 514 find_next_token (char **ptr, unsigned int *lengthptr)
 515 {
 516   char *p = next_token (*ptr);
 517   char *end;
 518
 519   if (*p == '\0')
 520     return 0;
 521
 522   *ptr = end = end_of_token (p);
 523   if (lengthptr != 0)
 524     *lengthptr = end - p;
 525   return p;
 526 }
 527 \f
 528 /* Copy a chain of `struct dep', making a new chain
 529    with the same contents as the old one.  */
 530
 531 struct dep *
 532 copy_dep_chain (struct dep *d)
 533 {
 534   register struct dep *c;
 535   struct dep *firstnew = 0;
 536   struct dep *lastnew = 0;
 537
 538   while (d != 0)
 539     {
 540       c = (struct dep *) xmalloc (sizeof (struct dep));
 541       bcopy ((char *) d, (char *) c, sizeof (struct dep));
 542       if (c->name != 0)
 543         c->name = xstrdup (c->name);
 544       c->next = 0;
 545       if (firstnew == 0)
 546         firstnew = lastnew = c;
 547       else
 548         lastnew = lastnew->next = c;
 549
 550       d = d->next;
 551     }
 552
 553   return firstnew;
 554 }
 555 \f
 556 #ifdef  iAPX286
 557 /* The losing compiler on this machine can't handle this macro.  */
 558
 559 char *
 560 dep_name (struct dep *dep)
 561 {
 562   return dep->name == 0 ? dep->file->name : dep->name;
 563 }
 564 #endif
 565 \f
 566 #ifdef  GETLOADAVG_PRIVILEGED
 567
 568 #ifdef POSIX
 569
 570 /* Hopefully if a system says it's POSIX.1 and has the setuid and setgid
 571    functions, they work as POSIX.1 says.  Some systems (Alpha OSF/1 1.2,
 572    for example) which claim to be POSIX.1 also have the BSD setreuid and
 573    setregid functions, but they don't work as in BSD and only the POSIX.1
 574    way works.  */
 575
 576 #undef HAVE_SETREUID
 577 #undef HAVE_SETREGID
 578
 579 #else   /* Not POSIX.  */
 580
 581 /* Some POSIX.1 systems have the seteuid and setegid functions.  In a
 582    POSIX-like system, they are the best thing to use.  However, some
 583    non-POSIX systems have them too but they do not work in the POSIX style
 584    and we must use setreuid and setregid instead.  */
 585
 586 #undef HAVE_SETEUID
 587 #undef HAVE_SETEGID
 588
 589 #endif  /* POSIX.  */
 590
 591 #ifndef HAVE_UNISTD_H
 592 extern int getuid (), getgid (), geteuid (), getegid ();
 593 extern int setuid (), setgid ();
 594 #ifdef HAVE_SETEUID
 595 extern int seteuid ();
 596 #else
 597 #ifdef  HAVE_SETREUID
 598 extern int setreuid ();
 599 #endif  /* Have setreuid.  */
 600 #endif  /* Have seteuid.  */
 601 #ifdef HAVE_SETEGID
 602 extern int setegid ();
 603 #else
 604 #ifdef  HAVE_SETREGID
 605 extern int setregid ();
 606 #endif  /* Have setregid.  */
 607 #endif  /* Have setegid.  */
 608 #endif  /* No <unistd.h>.  */
 609
 610 /* Keep track of the user and group IDs for user- and make- access.  */
 611 static int user_uid = -1, user_gid = -1, make_uid = -1, make_gid = -1;
 612 #define access_inited   (user_uid != -1)
 613 static enum { make, user } current_access;
 614
 615
 616 /* Under -d, write a message describing the current IDs.  */
 617
 618 static void
 619 log_access (char *flavor)
 620 {
 621   if (! ISDB (DB_JOBS))
 622     return;
 623
 624   /* All the other debugging messages go to stdout,
 625      but we write this one to stderr because it might be
 626      run in a child fork whose stdout is piped.  */
 627
 628   fprintf (stderr, _("%s: user %lu (real %lu), group %lu (real %lu)\n"),
 629            flavor, (unsigned long) geteuid (), (unsigned long) getuid (),
 630            (unsigned long) getegid (), (unsigned long) getgid ());
 631   fflush (stderr);
 632 }
 633
 634
 635 static void
 636 init_access (void)
 637 {
 638 #ifndef VMS
 639   user_uid = getuid ();
 640   user_gid = getgid ();
 641
 642   make_uid = geteuid ();
 643   make_gid = getegid ();
 644
 645   /* Do these ever fail?  */
 646   if (user_uid == -1 || user_gid == -1 || make_uid == -1 || make_gid == -1)
 647     pfatal_with_name ("get{e}[gu]id");
 648
 649   log_access (_("Initialized access"));
 650
 651   current_access = make;
 652 #endif
 653 }
 654
 655 #endif  /* GETLOADAVG_PRIVILEGED */
 656
 657 /* Give the process appropriate permissions for access to
 658    user data (i.e., to stat files, or to spawn a child process).  */
 659 void
 660 user_access (void)
 661 {
 662 #ifdef  GETLOADAVG_PRIVILEGED
 663
 664   if (!access_inited)
 665     init_access ();
 666
 667   if (current_access == user)
 668     return;
 669
 670   /* We are in "make access" mode.  This means that the effective user and
 671      group IDs are those of make (if it was installed setuid or setgid).
 672      We now want to set the effective user and group IDs to the real IDs,
 673      which are the IDs of the process that exec'd make.  */
 674
 675 #ifdef  HAVE_SETEUID
 676
 677   /* Modern systems have the seteuid/setegid calls which set only the
 678      effective IDs, which is ideal.  */
 679
 680   if (seteuid (user_uid) < 0)
 681     pfatal_with_name ("user_access: seteuid");
 682
 683 #else   /* Not HAVE_SETEUID.  */
 684
 685 #ifndef HAVE_SETREUID
 686
 687   /* System V has only the setuid/setgid calls to set user/group IDs.
 688      There is an effective ID, which can be set by setuid/setgid.
 689      It can be set (unless you are root) only to either what it already is
 690      (returned by geteuid/getegid, now in make_uid/make_gid),
 691      the real ID (return by getuid/getgid, now in user_uid/user_gid),
 692      or the saved set ID (what the effective ID was before this set-ID
 693      executable (make) was exec'd).  */
 694
 695   if (setuid (user_uid) < 0)
 696     pfatal_with_name ("user_access: setuid");
 697
 698 #else   /* HAVE_SETREUID.  */
 699
 700   /* In 4BSD, the setreuid/setregid calls set both the real and effective IDs.
 701      They may be set to themselves or each other.  So you have two alternatives
 702      at any one time.  If you use setuid/setgid, the effective will be set to
 703      the real, leaving only one alternative.  Using setreuid/setregid, however,
 704      you can toggle between your two alternatives by swapping the values in a
 705      single setreuid or setregid call.  */
 706
 707   if (setreuid (make_uid, user_uid) < 0)
 708     pfatal_with_name ("user_access: setreuid");
 709
 710 #endif  /* Not HAVE_SETREUID.  */
 711 #endif  /* HAVE_SETEUID.  */
 712
 713 #ifdef  HAVE_SETEGID
 714   if (setegid (user_gid) < 0)
 715     pfatal_with_name ("user_access: setegid");
 716 #else
 717 #ifndef HAVE_SETREGID
 718   if (setgid (user_gid) < 0)
 719     pfatal_with_name ("user_access: setgid");
 720 #else
 721   if (setregid (make_gid, user_gid) < 0)
 722     pfatal_with_name ("user_access: setregid");
 723 #endif
 724 #endif
 725
 726   current_access = user;
 727
 728   log_access (_("User access"));
 729
 730 #endif  /* GETLOADAVG_PRIVILEGED */
 731 }
 732
 733 /* Give the process appropriate permissions for access to
 734    make data (i.e., the load average).  */
 735 void
 736 make_access (void)
 737 {
 738 #ifdef  GETLOADAVG_PRIVILEGED
 739
 740   if (!access_inited)
 741     init_access ();
 742
 743   if (current_access == make)
 744     return;
 745
 746   /* See comments in user_access, above.  */
 747
 748 #ifdef  HAVE_SETEUID
 749   if (seteuid (make_uid) < 0)
 750     pfatal_with_name ("make_access: seteuid");
 751 #else
 752 #ifndef HAVE_SETREUID
 753   if (setuid (make_uid) < 0)
 754     pfatal_with_name ("make_access: setuid");
 755 #else
 756   if (setreuid (user_uid, make_uid) < 0)
 757     pfatal_with_name ("make_access: setreuid");
 758 #endif
 759 #endif
 760
 761 #ifdef  HAVE_SETEGID
 762   if (setegid (make_gid) < 0)
 763     pfatal_with_name ("make_access: setegid");
 764 #else
 765 #ifndef HAVE_SETREGID
 766   if (setgid (make_gid) < 0)
 767     pfatal_with_name ("make_access: setgid");
 768 #else
 769   if (setregid (user_gid, make_gid) < 0)
 770     pfatal_with_name ("make_access: setregid");
 771 #endif
 772 #endif
 773
 774   current_access = make;
 775
 776   log_access (_("Make access"));
 777
 778 #endif  /* GETLOADAVG_PRIVILEGED */
 779 }
 780
 781 /* Give the process appropriate permissions for a child process.
 782    This is like user_access, but you can't get back to make_access.  */
 783 void
 784 child_access (void)
 785 {
 786 #ifdef  GETLOADAVG_PRIVILEGED
 787
 788   if (!access_inited)
 789     abort ();
 790
 791   /* Set both the real and effective UID and GID to the user's.
 792      They cannot be changed back to make's.  */
 793
 794 #ifndef HAVE_SETREUID
 795   if (setuid (user_uid) < 0)
 796     pfatal_with_name ("child_access: setuid");
 797 #else
 798   if (setreuid (user_uid, user_uid) < 0)
 799     pfatal_with_name ("child_access: setreuid");
 800 #endif
 801
 802 #ifndef HAVE_SETREGID
 803   if (setgid (user_gid) < 0)
 804     pfatal_with_name ("child_access: setgid");
 805 #else
 806   if (setregid (user_gid, user_gid) < 0)
 807     pfatal_with_name ("child_access: setregid");
 808 #endif
 809
 810   log_access (_("Child access"));
 811
 812 #endif  /* GETLOADAVG_PRIVILEGED */
 813 }
 814 \f
 815 #ifdef NEED_GET_PATH_MAX
 816 unsigned int
 817 get_path_max (void)
 818 {
 819   static unsigned int value;
 820
 821   if (value == 0)
 822     {
 823       long int x = pathconf ("/", _PC_PATH_MAX);
 824       if (x > 0)
 825         value = x;
 826       else
 827         return MAXPATHLEN;
 828     }
 829
 830   return value;
 831 }
 832 #endif