sysdeps/posix/getcwd.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 96 Free Software Foundation, Inc.
   2 This file is part of the GNU C Library.
   3
   4 The GNU C Library is free software; you can redistribute it and/or
   5 modify it under the terms of the GNU Library General Public License as
   6 published by the Free Software Foundation; either version 2 of the
   7 License, or (at your option) any later version.
   8
   9 The GNU C Library is distributed in the hope that it will be useful,
  10 but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12 Library General Public License for more details.
  13
  14 You should have received a copy of the GNU Library General Public
  15 License along with the GNU C Library; see the file COPYING.LIB.  If
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 /* Wants:
  20    AC_STDC_HEADERS
  21    AC_DIR_HEADER
  22    AC_UNISTD_H
  23    AC_MEMORY_H
  24    AC_CONST
  25    AC_ALLOCA
  26  */
  27
  28 /* AIX requires this to be the first thing in the file.  */
  29 #if defined (_AIX) && !defined (__GNUC__)
  30  #pragma alloca
  31 #endif
  32
  33 #ifdef  HAVE_CONFIG_H
  34 #include "config.h"
  35 #endif
  36
  37 #include <errno.h>
  38 #include <sys/types.h>
  39 #include <sys/stat.h>
  40
  41 #ifdef  STDC_HEADERS
  42 #include <stddef.h>
  43 #endif
  44
  45 #if !defined(__GNU_LIBRARY__) && !defined(STDC_HEADERS)
  46 extern int errno;
  47 #endif
  48 #ifndef __set_errno
  49 #define __set_errno(val) errno = (val)
  50 #endif
  51
  52 #ifndef NULL
  53 #define NULL    0
  54 #endif
  55
  56 #if defined (USGr3) && !defined (DIRENT)
  57 #define DIRENT
  58 #endif /* USGr3 */
  59 #if defined (Xenix) && !defined (SYSNDIR)
  60 #define SYSNDIR
  61 #endif /* Xenix */
  62
  63 #if defined (POSIX) || defined (DIRENT) || defined (__GNU_LIBRARY__)
  64 #include <dirent.h>
  65 #ifndef __GNU_LIBRARY__
  66 #define D_NAMLEN(d) strlen((d)->d_name)
  67 #else
  68 #define HAVE_D_NAMLEN
  69 #define D_NAMLEN(d) ((d)->d_namlen)
  70 #endif
  71 #else /* not POSIX or DIRENT */
  72 #define dirent          direct
  73 #define D_NAMLEN(d)     ((d)->d_namlen)
  74 #define HAVE_D_NAMLEN
  75 #if defined (USG) && !defined (sgi)
  76 #if defined (SYSNDIR)
  77 #include <sys/ndir.h>
  78 #else /* Not SYSNDIR */
  79 #include "ndir.h"
  80 #endif /* SYSNDIR */
  81 #else /* not USG */
  82 #include <sys/dir.h>
  83 #endif /* USG */
  84 #endif /* POSIX or DIRENT or __GNU_LIBRARY__ */
  85
  86 #if     defined (HAVE_UNISTD_H) || defined (__GNU_LIBRARY__)
  87 #include <unistd.h>
  88 #endif
  89
  90 #if     (defined (STDC_HEADERS) || defined (__GNU_LIBRARY__) \
  91          || defined (POSIX))
  92 #include <stdlib.h>
  93 #include <string.h>
  94 #define ANSI_STRING
  95 #else   /* No standard headers.  */
  96
  97 #ifdef  USG
  98
  99 #include <string.h>
 100 #ifdef  NEED_MEMORY_H
 101 #include <memory.h>
 102 #endif
 103 #define ANSI_STRING
 104
 105 #else   /* Not USG.  */
 106
 107 #ifdef  NeXT
 108
 109 #include <string.h>
 110
 111 #else   /* Not NeXT.  */
 112
 113 #include <strings.h>
 114
 115 #ifndef bcmp
 116 extern int bcmp ();
 117 #endif
 118 #ifndef bzero
 119 extern void bzero ();
 120 #endif
 121 #ifndef bcopy
 122 extern void bcopy ();
 123 #endif
 124
 125 #endif  /* NeXT. */
 126
 127 #endif  /* USG.  */
 128
 129 extern char *malloc (), *realloc ();
 130 extern void free ();
 131
 132 #endif /* Standard headers.  */
 133
 134 #ifndef ANSI_STRING
 135 #define memcpy(d, s, n) bcopy((s), (d), (n))
 136 #define memmove memcpy
 137 #endif  /* Not ANSI_STRING.  */
 138
 139 #if     !defined(__alloca) && !defined(__GNU_LIBRARY__)
 140
 141 #ifdef  __GNUC__
 142 #undef  alloca
 143 #define alloca(n)       __builtin_alloca (n)
 144 #else   /* Not GCC.  */
 145 #if     defined (sparc) || defined (HAVE_ALLOCA_H)
 146 #include <alloca.h>
 147 #else   /* Not sparc or HAVE_ALLOCA_H.  */
 148 #ifndef _AIX
 149 extern char *alloca ();
 150 #endif  /* Not _AIX.  */
 151 #endif  /* sparc or HAVE_ALLOCA_H.  */
 152 #endif  /* GCC.  */
 153
 154 #define __alloca        alloca
 155
 156 #endif
 157
 158 #if (defined (HAVE_LIMITS_H) || defined (STDC_HEADERS) || \
 159      defined (__GNU_LIBRARY__))
 160 #include <limits.h>
 161 #else
 162 #include <sys/param.h>
 163 #endif
 164
 165 #ifndef PATH_MAX
 166 #ifdef  MAXPATHLEN
 167 #define PATH_MAX MAXPATHLEN
 168 #else
 169 #define PATH_MAX 1024
 170 #endif
 171 #endif
 172
 173 #if !defined (STDC_HEADERS) && !defined (__GNU_LIBRARY__)
 174 #undef  size_t
 175 #define size_t  unsigned int
 176 #endif
 177
 178 #if !__STDC__ && !defined (const)
 179 #define const
 180 #endif
 181
 182 #ifndef __GNU_LIBRARY__
 183 #define __lstat stat
 184 #endif
 185 \f
 186 #ifndef _LIBC
 187 #define __getcwd getcwd
 188 #endif
 189
 190 /* Get the pathname of the current working directory, and put it in SIZE
 191    bytes of BUF.  Returns NULL if the directory couldn't be determined or
 192    SIZE was too small.  If successful, returns BUF.  In GNU, if BUF is
 193    NULL, an array is allocated with `malloc'; the array is SIZE bytes long,
 194    unless SIZE <= 0, in which case it is as big as necessary.  */
 195
 196 char *
 197 __getcwd (buf, size)
 198      char *buf;
 199      size_t size;
 200 {
 201   static const char dots[]
 202     = "../../../../../../../../../../../../../../../../../../../../../../../\
 203 ../../../../../../../../../../../../../../../../../../../../../../../../../../\
 204 ../../../../../../../../../../../../../../../../../../../../../../../../../..";
 205   const char *dotp, *dotlist;
 206   size_t dotsize;
 207   dev_t rootdev, thisdev;
 208   ino_t rootino, thisino;
 209   char *path;
 210   register char *pathp;
 211   struct stat st;
 212
 213   if (size == 0)
 214     {
 215       if (buf != NULL)
 216         {
 217           __set_errno (EINVAL);
 218           return NULL;
 219         }
 220
 221       size = PATH_MAX + 1;
 222     }
 223
 224   if (buf != NULL)
 225     path = buf;
 226   else
 227     {
 228       path = malloc (size);
 229       if (path == NULL)
 230         return NULL;
 231     }
 232
 233   pathp = path + size;
 234   *--pathp = '\0';
 235
 236   if (__lstat (".", &st) < 0)
 237     return NULL;
 238   thisdev = st.st_dev;
 239   thisino = st.st_ino;
 240
 241   if (__lstat ("/", &st) < 0)
 242     return NULL;
 243   rootdev = st.st_dev;
 244   rootino = st.st_ino;
 245
 246   dotsize = sizeof (dots) - 1;
 247   dotp = &dots[sizeof (dots)];
 248   dotlist = dots;
 249   while (!(thisdev == rootdev && thisino == rootino))
 250     {
 251       register DIR *dirstream;
 252       register struct dirent *d;
 253       dev_t dotdev;
 254       ino_t dotino;
 255       char mount_point;
 256
 257       /* Look at the parent directory.  */
 258       if (dotp == dotlist)
 259         {
 260           /* My, what a deep directory tree you have, Grandma.  */
 261           char *new;
 262           if (dotlist == dots)
 263             {
 264               new = malloc (dotsize * 2 + 1);
 265               if (new == NULL)
 266                 return NULL;
 267               memcpy (new, dots, dotsize);
 268             }
 269           else
 270             {
 271               new = realloc ((__ptr_t) dotlist, dotsize * 2 + 1);
 272               if (new == NULL)
 273                 goto lose;
 274             }
 275           memcpy (&new[dotsize], new, dotsize);
 276           dotp = &new[dotsize];
 277           dotsize *= 2;
 278           new[dotsize] = '\0';
 279           dotlist = new;
 280         }
 281
 282       dotp -= 3;
 283
 284       /* Figure out if this directory is a mount point.  */
 285       if (__lstat (dotp, &st) < 0)
 286         goto lose;
 287       dotdev = st.st_dev;
 288       dotino = st.st_ino;
 289       mount_point = dotdev != thisdev;
 290
 291       /* Search for the last directory.  */
 292       dirstream = __opendir (dotp);
 293       if (dirstream == NULL)
 294         goto lose;
 295       while ((d = __readdir (dirstream)) != NULL)
 296         {
 297           if (d->d_name[0] == '.' &&
 298               (d->d_name[1] == '\0' ||
 299                (d->d_name[1] == '.' && d->d_name[2] == '\0')))
 300             continue;
 301           if (mount_point || (ino_t) d->d_ino == thisino)
 302             {
 303               char name[dotlist + dotsize - dotp + 1 + _D_ALLOC_NAMLEN (d)];
 304               memcpy (name, dotp, dotlist + dotsize - dotp);
 305               name[dotlist + dotsize - dotp] = '/';
 306               strcpy (&name[dotlist + dotsize - dotp + 1], d->d_name);
 307               if (__lstat (name, &st) < 0)
 308                 {
 309                   int save = errno;
 310                   (void) __closedir (dirstream);
 311                   __set_errno (save);
 312                   goto lose;
 313                 }
 314               if (st.st_dev == thisdev && st.st_ino == thisino)
 315                 break;
 316             }
 317         }
 318       if (d == NULL)
 319         {
 320           int save = errno;
 321           (void) __closedir (dirstream);
 322           __set_errno (save);
 323           goto lose;
 324         }
 325       else
 326         {
 327           size_t namlen = _D_EXACT_NAMLEN (d);
 328
 329           if ((size_t) (pathp - path) < namlen)
 330             {
 331               if (buf != NULL)
 332                 {
 333                   __set_errno (ERANGE);
 334                   return NULL;
 335                 }
 336               else
 337                 {
 338                   size *= 2;
 339                   buf = realloc (path, size);
 340                   if (buf == NULL)
 341                     {
 342                       (void) __closedir (dirstream);
 343                       free (path);
 344                       __set_errno (ENOMEM);/* closedir might have changed it.*/
 345                       return NULL;
 346                     }
 347                   pathp = &buf[pathp - path];
 348                   path = buf;
 349                 }
 350             }
 351           pathp -= namlen;
 352           (void) memcpy (pathp, d->d_name, namlen);
 353           *--pathp = '/';
 354           (void) __closedir (dirstream);
 355         }
 356
 357       thisdev = dotdev;
 358       thisino = dotino;
 359     }
 360
 361   if (pathp == &path[size - 1])
 362     *--pathp = '/';
 363
 364   if (dotlist != dots)
 365     free ((__ptr_t) dotlist);
 366
 367   memmove (path, pathp, path + size - pathp);
 368   return path;
 369
 370  lose:
 371   if (dotlist != dots)
 372     free ((__ptr_t) dotlist);
 373   return NULL;
 374 }
 375
 376 #ifdef _LIBC
 377 weak_alias (__getcwd, getcwd)
 378 #endif