1/* Copyright (C) 2011-2022 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.  */
28typedef 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
45char *
46rpl_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
128