1  /* Construct a full filename from a directory and a relative filename.
       2     Copyright (C) 2001-2004, 2006-2022 Free Software Foundation, Inc.
       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  /* Written by Bruno Haible <haible@clisp.cons.org>.  */
      18  
      19  #include <config.h>
      20  
      21  /* Specification.  */
      22  #include "concat-filename.h"
      23  
      24  #include <errno.h>
      25  #include <stdlib.h>
      26  #include <string.h>
      27  
      28  #include "filename.h"
      29  
      30  /* Concatenate a directory filename, a relative filename and an optional
      31     suffix.  The directory may end with the directory separator.  The second
      32     argument may not start with the directory separator (it is relative).
      33     Return a freshly allocated filename.  Return NULL and set errno
      34     upon memory allocation failure.  */
      35  char *
      36  concatenated_filename (const char *directory, const char *filename,
      37                         const char *suffix)
      38  {
      39    char *result;
      40    char *p;
      41  
      42    if (strcmp (directory, ".") == 0)
      43      {
      44        /* No need to prepend the directory.  */
      45        result = (char *) malloc (strlen (filename)
      46                                  + (suffix != NULL ? strlen (suffix) : 0)
      47                                  + 1);
      48        if (result == NULL)
      49          return NULL; /* errno is set here */
      50        p = result;
      51      }
      52    else
      53      {
      54        size_t directory_len = strlen (directory);
      55        int need_slash =
      56          (directory_len > FILE_SYSTEM_PREFIX_LEN (directory)
      57           && !ISSLASH (directory[directory_len - 1]));
      58        result = (char *) malloc (directory_len + need_slash
      59                                  + strlen (filename)
      60                                  + (suffix != NULL ? strlen (suffix) : 0)
      61                                  + 1);
      62        if (result == NULL)
      63          return NULL; /* errno is set here */
      64        memcpy (result, directory, directory_len);
      65        p = result + directory_len;
      66        if (need_slash)
      67          *p++ = '/';
      68      }
      69    p = stpcpy (p, filename);
      70    if (suffix != NULL)
      71      stpcpy (p, suffix);
      72    return result;
      73  }