1  /* Tests of readlinkat.
       2     Copyright (C) 2009-2022 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 <stdbool.h>
      29  #include <stdio.h>
      30  #include <stdlib.h>
      31  #include <string.h>
      32  #include <sys/stat.h>
      33  
      34  #include "ignore-value.h"
      35  #include "macros.h"
      36  
      37  #ifndef HAVE_SYMLINK
      38  # define HAVE_SYMLINK 0
      39  #endif
      40  
      41  #define BASE "test-readlinkat.t"
      42  
      43  #include "test-readlink.h"
      44  
      45  static int dfd = AT_FDCWD;
      46  
      47  static ssize_t
      48  do_readlink (char const *name, char *buf, size_t len)
      49  {
      50    return readlinkat (dfd, name, buf, len);
      51  }
      52  
      53  int
      54  main (void)
      55  {
      56    char buf[80];
      57    int result;
      58  
      59    /* Remove any leftovers from a previous partial run.  */
      60    ignore_value (system ("rm -rf " BASE "*"));
      61  
      62    /* Test behaviour for invalid file descriptors.  */
      63    {
      64      errno = 0;
      65      ASSERT (readlinkat (-1, "foo", buf, sizeof buf) == -1);
      66      ASSERT (errno == EBADF);
      67    }
      68    {
      69      close (99);
      70      errno = 0;
      71      ASSERT (readlinkat (99, "foo", buf, sizeof buf) == -1);
      72      ASSERT (errno == EBADF);
      73    }
      74  
      75    /* Perform same checks as counterpart functions.  */
      76    result = test_readlink (do_readlink, false);
      77    dfd = openat (AT_FDCWD, ".", O_RDONLY);
      78    ASSERT (0 <= dfd);
      79    ASSERT (test_readlink (do_readlink, false) == result);
      80  
      81    /* Now perform some cross-directory checks.  Skip everything else on
      82       mingw.  */
      83    if (HAVE_SYMLINK)
      84      {
      85        const char *contents = "don't matter!";
      86        ssize_t exp = strlen (contents);
      87  
      88        /* Create link while cwd is '.', then read it in '..'.  */
      89        ASSERT (symlinkat (contents, AT_FDCWD, BASE "link") == 0);
      90        errno = 0;
      91        ASSERT (symlinkat (contents, dfd, BASE "link") == -1);
      92        ASSERT (errno == EEXIST);
      93        ASSERT (chdir ("..") == 0);
      94        errno = 0;
      95        ASSERT (readlinkat (AT_FDCWD, BASE "link", buf, sizeof buf) == -1);
      96        ASSERT (errno == ENOENT);
      97        ASSERT (readlinkat (dfd, BASE "link", buf, sizeof buf) == exp);
      98        ASSERT (strncmp (contents, buf, exp) == 0);
      99        ASSERT (unlinkat (dfd, BASE "link", 0) == 0);
     100  
     101        /* Create link while cwd is '..', then read it in '.'.  */
     102        ASSERT (symlinkat (contents, dfd, BASE "link") == 0);
     103        ASSERT (fchdir (dfd) == 0);
     104        errno = 0;
     105        ASSERT (symlinkat (contents, AT_FDCWD, BASE "link") == -1);
     106        ASSERT (errno == EEXIST);
     107        buf[0] = '\0';
     108        ASSERT (readlinkat (AT_FDCWD, BASE "link", buf, sizeof buf) == exp);
     109        ASSERT (strncmp (contents, buf, exp) == 0);
     110        buf[0] = '\0';
     111        ASSERT (readlinkat (dfd, BASE "link", buf, sizeof buf) == exp);
     112        ASSERT (strncmp (contents, buf, exp) == 0);
     113        ASSERT (unlink (BASE "link") == 0);
     114      }
     115  
     116    ASSERT (close (dfd) == 0);
     117    if (result == 77)
     118      fputs ("skipping test: symlinks not supported on this file system\n",
     119             stderr);
     120    return result;
     121  }