external/gpl2/xcvs/dist/lib/filenamecat.c

   1 /* Concatenate two arbitrary file names.
   2
   3    Copyright (C) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005 Free
   4    Software Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 /* Written by Jim Meyering.  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 # include <config.h>
  24 #endif
  25
  26 /* Specification.  */
  27 #include "filenamecat.h"
  28
  29 #include <string.h>
  30
  31 #include "dirname.h"
  32 #include "xalloc.h"
  33
  34 #if ! HAVE_MEMPCPY && ! defined mempcpy
  35 # define mempcpy(D, S, N) ((void *) ((char *) memcpy (D, S, N) + (N)))
  36 #endif
  37
  38 /* Return the longest suffix of F that is a relative file name.
  39    If it has no such suffix, return the empty string.  */
  40
  41 static char const *
  42 longest_relative_suffix (char const *f)
  43 {
  44   for (f += FILE_SYSTEM_PREFIX_LEN (f); ISSLASH (*f); f++)
  45     continue;
  46   return f;
  47 }
  48
  49 /* Concatenate two file name components, DIR and ABASE, in
  50    newly-allocated storage and return the result.
  51    The resulting file name F is such that the commands "ls F" and "(cd
  52    DIR; ls BASE)" refer to the same file, where BASE is ABASE with any
  53    file system prefixes and leading separators removed.
  54    Arrange for a directory separator if necessary between DIR and BASE
  55    in the result, removing any redundant separators.
  56    In any case, if BASE_IN_RESULT is non-NULL, set
  57    *BASE_IN_RESULT to point to the copy of ABASE in the returned
  58    concatenation.  However, if ABASE begins with more than one slash,
  59    set *BASE_IN_RESULT to point to the sole corresponding slash that
  60    is copied into the result buffer.
  61
  62    Report an error if memory is exhausted.  */
  63
  64 char *
  65 file_name_concat (char const *dir, char const *abase, char **base_in_result)
  66 {
  67   char const *dirbase = base_name (dir);
  68   size_t dirbaselen = base_len (dirbase);
  69   size_t dirlen = dirbase - dir + dirbaselen;
  70   size_t needs_separator = (dirbaselen && ! ISSLASH (dirbase[dirbaselen - 1]));
  71
  72   char const *base = longest_relative_suffix (abase);
  73   size_t baselen = strlen (base);
  74
  75   char *p_concat = xmalloc (dirlen + needs_separator + baselen + 1);
  76   char *p;
  77
  78   p = mempcpy (p_concat, dir, dirlen);
  79   *p = DIRECTORY_SEPARATOR;
  80   p += needs_separator;
  81
  82   if (base_in_result)
  83     *base_in_result = p - IS_ABSOLUTE_FILE_NAME (abase);
  84
  85   p = mempcpy (p, base, baselen);
  86   *p = '\0';
  87
  88   return p_concat;
  89 }
  90
  91 #ifdef TEST_FILE_NAME_CONCAT
  92 # include <stdlib.h>
  93 # include <stdio.h>
  94 int
  95 main ()
  96 {
  97   static char const *const tests[][3] =
  98     {
  99       {"a", "b",   "a/b"},
 100       {"a/", "b",  "a/b"},
 101       {"a/", "/b", "a/b"},
 102       {"a", "/b",  "a/b"},
 103
 104       {"/", "b",  "/b"},
 105       {"/", "/b", "/b"},
 106       {"/", "/",  "/"},
 107       {"a", "/",  "a/"},   /* this might deserve a diagnostic */
 108       {"/a", "/", "/a/"},  /* this might deserve a diagnostic */
 109       {"a", "//b",  "a/b"},
 110     };
 111   size_t i;
 112   bool fail = false;
 113   for (i = 0; i < sizeof tests / sizeof tests[0]; i++)
 114     {
 115       char *base_in_result;
 116       char const *const *t = tests[i];
 117       char *res = file_name_concat (t[0], t[1], &base_in_result);
 118       if (strcmp (res, t[2]) != 0)
 119         {
 120           printf ("got %s, expected %s\n", res, t[2]);
 121           fail = true;
 122         }
 123     }
 124   exit (fail ? EXIT_FAILURE : EXIT_SUCCESS);
 125 }
 126 #endif