1  /* Copyright (C) 2011-2023 Free Software Foundation, Inc.
       2     This file is part of gnulib.
       3  
       4     This file is free software: you can redistribute it and/or modify
       5     it under the terms of the GNU Lesser General Public License as
       6     published by the Free Software Foundation; either version 2.1 of the
       7     License, or (at your option) any later version.
       8  
       9     This file 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
      12     GNU Lesser General Public License for more details.
      13  
      14     You should have received a copy of the GNU Lesser General Public License
      15     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      16  
      17  #include <config.h>
      18  
      19  /* Specification */
      20  #include <unistd.h>
      21  
      22  #include <errno.h>
      23  #include <stdlib.h>
      24  #include <string.h>
      25  
      26  #if GNULIB_GETCWD
      27  /* Favor GPL getcwd.c if both getcwd and getcwd-lgpl modules are in use.  */
      28  typedef int dummy;
      29  #else
      30  
      31  /* Get the name of the current working directory, and put it in SIZE
      32     bytes of BUF.  Returns NULL if the directory couldn't be determined
      33     (perhaps because the absolute name was longer than PATH_MAX, or
      34     because of missing read/search permissions on parent directories)
      35     or SIZE was too small.  If successful, returns BUF.  If BUF is
      36     NULL, an array is allocated with 'malloc'; the array is SIZE bytes
      37     long, unless SIZE == 0, in which case it is as big as
      38     necessary.  */
      39  
      40  # undef getcwd
      41  # if defined _WIN32 && !defined __CYGWIN__
      42  #  define getcwd _getcwd
      43  # endif
      44  
      45  char *
      46  rpl_getcwd (char *buf, size_t size)
      47  {
      48    char *ptr;
      49    char *result;
      50  
      51    /* Handle single size operations.  */
      52    if (buf)
      53      {
      54        if (!size)
      55          {
      56            errno = EINVAL;
      57            return NULL;
      58          }
      59        return getcwd (buf, size);
      60      }
      61  
      62    if (size)
      63      {
      64        buf = malloc (size);
      65        if (!buf)
      66          {
      67            errno = ENOMEM;
      68            return NULL;
      69          }
      70        result = getcwd (buf, size);
      71        if (!result)
      72          free (buf);
      73        return result;
      74      }
      75  
      76    /* Flexible sizing requested.  Avoid over-allocation for the common
      77       case of a name that fits within a 4k page, minus some space for
      78       local variables, to be sure we don't skip over a guard page.  */
      79    {
      80      char tmp[4032];
      81      size = sizeof tmp;
      82      ptr = getcwd (tmp, size);
      83      if (ptr)
      84        {
      85          result = strdup (ptr);
      86          if (!result)
      87            errno = ENOMEM;
      88          return result;
      89        }
      90      if (errno != ERANGE)
      91        return NULL;
      92    }
      93  
      94    /* My what a large directory name we have.  */
      95    do
      96      {
      97        size <<= 1;
      98        ptr = realloc (buf, size);
      99        if (ptr == NULL)
     100          {
     101            free (buf);
     102            errno = ENOMEM;
     103            return NULL;
     104          }
     105        buf = ptr;
     106        result = getcwd (buf, size);
     107      }
     108    while (!result && errno == ERANGE);
     109  
     110    if (!result)
     111      free (buf);
     112    else
     113      {
     114        /* Here result == buf.  */
     115        /* Shrink result before returning it.  */
     116        size_t actual_size = strlen (result) + 1;
     117        if (actual_size < size)
     118          {
     119            char *shrinked_result = realloc (result, actual_size);
     120            if (shrinked_result != NULL)
     121              result = shrinked_result;
     122          }
     123      }
     124    return result;
     125  }
     126  
     127  #endif