1  /* Tests of readlinkat.
       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  #include <config.h>
      20  
      21  #include <unistd.h>
      22  
      23  #include "signature.h"
      24  SIGNATURE_CHECK (readlinkat, ssize_t, (int, char const *, char *, size_t));
      25  
      26  #include <fcntl.h>
      27  #include <errno.h>
      28  #include <stdio.h>
      29  #include <stdlib.h>
      30  #include <string.h>
      31  #include <sys/stat.h>
      32  
      33  #include "ignore-value.h"
      34  #include "macros.h"
      35  
      36  #ifndef HAVE_SYMLINK
      37  # define HAVE_SYMLINK 0
      38  #endif
      39  
      40  #define BASE "test-readlinkat.t"
      41  
      42  #include "test-readlink.h"
      43  
      44  static int dfd = AT_FDCWD;
      45  
      46  static ssize_t
      47  do_readlink (char const *name, char *buf, size_t len)
      48  {
      49    return readlinkat (dfd, name, buf, len);
      50  }
      51  
      52  int
      53  main (void)
      54  {
      55    char buf[80];
      56    int result;
      57  
      58    /* Remove any leftovers from a previous partial run.  */
      59    ignore_value (system ("rm -rf " BASE "*"));
      60  
      61    /* Test behaviour for invalid file descriptors.  */
      62    {
      63      errno = 0;
      64      ASSERT (readlinkat (-1, "foo", buf, sizeof buf) == -1);
      65      ASSERT (errno == EBADF);
      66    }
      67    {
      68      close (99);
      69      errno = 0;
      70      ASSERT (readlinkat (99, "foo", buf, sizeof buf) == -1);
      71      ASSERT (errno == EBADF);
      72    }
      73  
      74    /* Perform same checks as counterpart functions.  */
      75    result = test_readlink (do_readlink, false);
      76    dfd = openat (AT_FDCWD, ".", O_RDONLY);
      77    ASSERT (0 <= dfd);
      78    ASSERT (test_readlink (do_readlink, false) == result);
      79  
      80    /* Now perform some cross-directory checks.  Skip everything else on
      81       mingw.  */
      82    if (HAVE_SYMLINK)
      83      {
      84        const char *contents = "don't matter!";
      85        ssize_t exp = strlen (contents);
      86  
      87        /* Create link while cwd is '.', then read it in '..'.  */
      88        ASSERT (symlinkat (contents, AT_FDCWD, BASE "link") == 0);
      89        errno = 0;
      90        ASSERT (symlinkat (contents, dfd, BASE "link") == -1);
      91        ASSERT (errno == EEXIST);
      92        ASSERT (chdir ("..") == 0);
      93        errno = 0;
      94        ASSERT (readlinkat (AT_FDCWD, BASE "link", buf, sizeof buf) == -1);
      95        ASSERT (errno == ENOENT);
      96        ASSERT (readlinkat (dfd, BASE "link", buf, sizeof buf) == exp);
      97        ASSERT (strncmp (contents, buf, exp) == 0);
      98        ASSERT (unlinkat (dfd, BASE "link", 0) == 0);
      99  
     100        /* Create link while cwd is '..', then read it in '.'.  */
     101        ASSERT (symlinkat (contents, dfd, BASE "link") == 0);
     102        ASSERT (fchdir (dfd) == 0);
     103        errno = 0;
     104        ASSERT (symlinkat (contents, AT_FDCWD, BASE "link") == -1);
     105        ASSERT (errno == EEXIST);
     106        buf[0] = '\0';
     107        ASSERT (readlinkat (AT_FDCWD, BASE "link", buf, sizeof buf) == exp);
     108        ASSERT (strncmp (contents, buf, exp) == 0);
     109        buf[0] = '\0';
     110        ASSERT (readlinkat (dfd, BASE "link", buf, sizeof buf) == exp);
     111        ASSERT (strncmp (contents, buf, exp) == 0);
     112        ASSERT (unlink (BASE "link") == 0);
     113      }
     114  
     115    ASSERT (close (dfd) == 0);
     116    if (result == 77)
     117      fputs ("skipping test: symlinks not supported on this file system\n",
     118             stderr);
     119    return result;
     120  }