File: link.c

package info (click to toggle)
tar 1.30%2Bdfsg-6
  • links: PTS, VCS
  • area: main
  • in suites: buster
  • size: 18,352 kB
  • sloc: ansic: 77,395; sh: 52,669; yacc: 1,842; makefile: 479; sed: 16
file content (211 lines) | stat: -rw-r--r-- 5,684 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
/* Emulate link on platforms that lack it, namely native Windows platforms.

   Copyright (C) 2009-2017 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

#include <unistd.h>

#include <errno.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>

#if !HAVE_LINK
# if (defined _WIN32 || defined __WIN32__) && ! defined __CYGWIN__

#  define WIN32_LEAN_AND_MEAN
#  include <windows.h>

/* CreateHardLink was introduced only in Windows 2000.  */
typedef BOOL (WINAPI * CreateHardLinkFuncType) (LPCTSTR lpFileName,
                                                LPCTSTR lpExistingFileName,
                                                LPSECURITY_ATTRIBUTES lpSecurityAttributes);
static CreateHardLinkFuncType CreateHardLinkFunc = NULL;
static BOOL initialized = FALSE;

static void
initialize (void)
{
  HMODULE kernel32 = GetModuleHandle ("kernel32.dll");
  if (kernel32 != NULL)
    {
      CreateHardLinkFunc =
        (CreateHardLinkFuncType) GetProcAddress (kernel32, "CreateHardLinkA");
    }
  initialized = TRUE;
}

int
link (const char *file1, const char *file2)
{
  char *dir;
  size_t len1 = strlen (file1);
  size_t len2 = strlen (file2);
  if (!initialized)
    initialize ();
  if (CreateHardLinkFunc == NULL)
    {
      /* System does not support hard links.  */
      errno = EPERM;
      return -1;
    }
  /* Reject trailing slashes on non-directories; mingw does not
     support hard-linking directories.  */
  if ((len1 && (file1[len1 - 1] == '/' || file1[len1 - 1] == '\\'))
      || (len2 && (file2[len2 - 1] == '/' || file2[len2 - 1] == '\\')))
    {
      struct stat st;
      if (stat (file1, &st) == 0 && S_ISDIR (st.st_mode))
        errno = EPERM;
      else
        errno = ENOTDIR;
      return -1;
    }
  /* CreateHardLink("b/.","a",NULL) creates file "b", so we must check
     that dirname(file2) exists.  */
  dir = strdup (file2);
  if (!dir)
    return -1;
  {
    struct stat st;
    char *p = strchr (dir, '\0');
    while (dir < p && (*--p != '/' && *p != '\\'));
    *p = '\0';
    if (p != dir && stat (dir, &st) == -1)
      {
        int saved_errno = errno;
        free (dir);
        errno = saved_errno;
        return -1;
      }
    free (dir);
  }
  /* Now create the link.  */
  if (CreateHardLinkFunc (file2, file1, NULL) == 0)
    {
      /* It is not documented which errors CreateHardLink() can produce.
       * The following conversions are based on tests on a Windows XP SP2
       * system. */
      DWORD err = GetLastError ();
      switch (err)
        {
        case ERROR_ACCESS_DENIED:
          errno = EACCES;
          break;

        case ERROR_INVALID_FUNCTION:    /* fs does not support hard links */
          errno = EPERM;
          break;

        case ERROR_NOT_SAME_DEVICE:
          errno = EXDEV;
          break;

        case ERROR_PATH_NOT_FOUND:
        case ERROR_FILE_NOT_FOUND:
          errno = ENOENT;
          break;

        case ERROR_INVALID_PARAMETER:
          errno = ENAMETOOLONG;
          break;

        case ERROR_TOO_MANY_LINKS:
          errno = EMLINK;
          break;

        case ERROR_ALREADY_EXISTS:
          errno = EEXIST;
          break;

        default:
          errno = EIO;
        }
      return -1;
    }

  return 0;
}

# else /* !Windows */

#  error "This platform lacks a link function, and Gnulib doesn't provide a replacement. This is a bug in Gnulib."

# endif /* !Windows */
#else /* HAVE_LINK */

# undef link

/* Create a hard link from FILE1 to FILE2, working around platform bugs.  */
int
rpl_link (char const *file1, char const *file2)
{
  size_t len1;
  size_t len2;
  struct stat st;

  /* Don't allow IRIX to dereference dangling file2 symlink.  */
  if (!lstat (file2, &st))
    {
      errno = EEXIST;
      return -1;
    }

  /* Reject trailing slashes on non-directories.  */
  len1 = strlen (file1);
  len2 = strlen (file2);
  if ((len1 && file1[len1 - 1] == '/')
      || (len2 && file2[len2 - 1] == '/'))
    {
      /* Let link() decide whether hard-linking directories is legal.
         If stat() fails, then link() should fail for the same reason
         (although on Solaris 9, link("file/","oops") mistakenly
         succeeds); if stat() succeeds, require a directory.  */
      if (stat (file1, &st))
        return -1;
      if (!S_ISDIR (st.st_mode))
        {
          errno = ENOTDIR;
          return -1;
        }
    }
  else
    {
      /* Fix Cygwin 1.5.x bug where link("a","b/.") creates file "b".  */
      char *dir = strdup (file2);
      char *p;
      if (!dir)
        return -1;
      /* We already know file2 does not end in slash.  Strip off the
         basename, then check that the dirname exists.  */
      p = strrchr (dir, '/');
      if (p)
        {
          *p = '\0';
          if (stat (dir, &st) == -1)
            {
              int saved_errno = errno;
              free (dir);
              errno = saved_errno;
              return -1;
            }
        }
      free (dir);
    }
  return link (file1, file2);
}
#endif /* HAVE_LINK */