1  /* Tests of readlink.
       2     Copyright (C) 2009-2023 Free Software Foundation, Inc.
       3  
       4     This program is free software: you can redistribute it and/or modify
       5     it under the terms of the GNU General Public License as published by
       6     the Free Software Foundation, either version 3 of the License, or
       7     (at your option) any later version.
       8  
       9     This program 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 General Public License for more details.
      13  
      14     You should have received a copy of the GNU General Public License
      15     along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
      16  
      17  /* Written by Eric Blake <ebb9@byu.net>, 2009.  */
      18  
      19  /* This file is designed to test both readlink(a,b,c) and
      20     readlinkat(AT_FDCWD,a,b,c).  FUNC is the function to test.  Assumes
      21     that BASE and ASSERT are already defined, and that appropriate
      22     headers are already included.  If PRINT, warn before skipping
      23     symlink tests with status 77.  */
      24  
      25  static int
      26  test_readlink (ssize_t (*func) (char const *, char *, size_t), bool print)
      27  {
      28    char buf[80];
      29  
      30    /* Sanity checks of failures.  Mingw lacks symlink, but readlink can
      31       still distinguish between various errors.  */
      32    memset (buf, 0xff, sizeof buf);
      33    errno = 0;
      34    ASSERT (func ("no_such", buf, sizeof buf) == -1);
      35    ASSERT (errno == ENOENT);
      36    errno = 0;
      37    ASSERT (func ("no_such/", buf, sizeof buf) == -1);
      38    ASSERT (errno == ENOENT);
      39    errno = 0;
      40    ASSERT (func ("", buf, sizeof buf) == -1);
      41    ASSERT (errno == ENOENT || errno == EINVAL);
      42    errno = 0;
      43    ASSERT (func (".", buf, sizeof buf) == -1);
      44    ASSERT (errno == EINVAL);
      45    errno = 0;
      46    ASSERT (func ("./", buf, sizeof buf) == -1);
      47    ASSERT (errno == EINVAL);
      48    ASSERT (close (creat (BASE "file", 0600)) == 0);
      49    errno = 0;
      50    ASSERT (func (BASE "file", buf, sizeof buf) == -1);
      51    ASSERT (errno == EINVAL);
      52    errno = 0;
      53    ASSERT (func (BASE "file/", buf, sizeof buf) == -1);
      54    ASSERT (errno == ENOTDIR || errno == EINVAL); /* AIX yields EINVAL */
      55  
      56    /* Now test actual symlinks.  */
      57    if (symlink (BASE "dir", BASE "link"))
      58      {
      59        ASSERT (unlink (BASE "file") == 0);
      60        if (print)
      61          fputs ("skipping test: symlinks not supported on this file system\n",
      62                 stderr);
      63        return 77;
      64      }
      65    ASSERT (mkdir (BASE "dir", 0700) == 0);
      66    errno = 0;
      67    ASSERT (func (BASE "link/", buf, sizeof buf) == -1);
      68    ASSERT (errno == EINVAL);
      69    ASSERT (symlink (BASE "link", BASE "link2") == 0);
      70    errno = 0;
      71    ASSERT (func (BASE "link2/", buf, sizeof buf) == -1);
      72    ASSERT (errno == EINVAL);
      73    ASSERT (unlink (BASE "link2") == 0);
      74    ASSERT (symlink (BASE "file", BASE "link2") == 0);
      75    errno = 0;
      76    ASSERT (func (BASE "link2/", buf, sizeof buf) == -1);
      77    ASSERT (errno == ENOTDIR || errno == EINVAL); /* AIX yields EINVAL */
      78    ASSERT (unlink (BASE "file") == 0);
      79    ASSERT (unlink (BASE "link2") == 0);
      80    {
      81      /* Up till now, no readlink has been successful, so buf should be
      82         unchanged.  */
      83      int i;
      84      for (i = 0; i < sizeof buf; i++)
      85        ASSERT (buf[i] == (char) 0xff);
      86    }
      87    {
      88      size_t len = strlen (BASE "dir");
      89      /* When passing too small of a buffer, expect the truncated
      90         length, or an ERANGE failure.  However, a size of 0 is not
      91         portable enough to test.  */
      92      ssize_t result;
      93      errno = 0;
      94      result = readlink (BASE "link", buf, 1);
      95      if (result == -1)
      96        {
      97          ASSERT (errno == ERANGE);
      98          ASSERT (buf[0] == (char) 0xff);
      99        }
     100      else
     101        {
     102          ASSERT (result == 1);
     103          ASSERT (buf[0] == BASE[0]);
     104        }
     105      ASSERT (buf[1] == (char) 0xff);
     106      ASSERT (func (BASE "link", buf, len) == len);
     107      ASSERT (strncmp (buf, BASE "dir", len) == 0);
     108      ASSERT (buf[len] == (char) 0xff);
     109      ASSERT (func (BASE "link", buf, sizeof buf) == len);
     110      ASSERT (strncmp (buf, BASE "dir", len) == 0);
     111      /* POSIX says rest of buf is unspecified; but in practice, it is
     112         either left alone, or NUL-terminated.  */
     113      ASSERT (buf[len] == '\0' || buf[len] == (char) 0xff);
     114    }
     115    ASSERT (rmdir (BASE "dir") == 0);
     116    ASSERT (unlink (BASE "link") == 0);
     117  
     118    return 0;
     119  }