[Bug-gnulib] addition: pathname.h, concatpath.c

[Bruno Haible]

A new module from GNU gettext: pathname.h, containing various pathname
utility functions. For the moment this module has only one function:

   concatenated_pathname (directory, filename, suffix)

This function is an extension of Jim's path-concat.[hc] function.
In gettext, it is used 8 times with suffix != NULL and 7 times with
suffix == NULL, for a total of 15 calls. Which shows that this
function is worth having.

Any comments or objections?

Bruno


============================== pathname.h ===============================
/* Pathname support.
   Copyright (C) 2001-2002 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#ifndef _PATHNAME_H
#define _PATHNAME_H

/* Pathname support.
   ISSLASH(C)           tests whether C is a directory separator character.
   IS_ABSOLUTE_PATH(P)  tests whether P is an absolute path.  If it is not,
                        it may be concatenated to a directory pathname.
   IS_PATH_WITH_DIR(P)  tests whether P contains a directory specification.
 */
#if defined _WIN32 || defined __WIN32__ || defined __EMX__ || defined __DJGPP__
  /* Win32, OS/2, DOS */
# define ISSLASH(C) ((C) == '/' || (C) == '\\')
# define HAS_DEVICE(P) \
    ((((P)[0] >= 'A' && (P)[0] <= 'Z') || ((P)[0] >= 'a' && (P)[0] <= 'z')) \
     && (P)[1] == ':')
# define IS_ABSOLUTE_PATH(P) (ISSLASH ((P)[0]) || HAS_DEVICE (P))
# define IS_PATH_WITH_DIR(P) \
    (strchr (P, '/') != NULL || strchr (P, '\\') != NULL || HAS_DEVICE (P))
# define FILESYSTEM_PREFIX_LEN(P) (HAS_DEVICE (P) ? 2 : 0)
#else
  /* Unix */
# define ISSLASH(C) ((C) == '/')
# define IS_ABSOLUTE_PATH(P) ISSLASH ((P)[0])
# define IS_PATH_WITH_DIR(P) (strchr (P, '/') != NULL)
# define FILESYSTEM_PREFIX_LEN(P) 0
#endif

/* Concatenate a directory pathname, a relative pathname and an optional
   suffix.  Return a freshly allocated pathname.  */
extern char *concatenated_pathname (const char *directory,
                                    const char *filename, const char *suffix);

#endif /* _PATHNAME_H */
============================= concatpath.c ==============================
/* Construct a full pathname from a directory and a filename.
   Copyright (C) 2001-2002 Free Software Foundation, Inc.

   This program is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by the
   Free Software Foundation; either version 2, or (at your option) any
   later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
   USA.  */

/* Written by Bruno Haible <address@hidden>.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

/* Specification.  */
#include "pathname.h"

#include <string.h>

#include "xmalloc.h"
#include "stpcpy.h"

/* Concatenate a directory pathname, a relative pathname and an optional
   suffix.  The directory may end with the directory separator.  The second
   argument may not start with the directory separator (it is relative).
   Return a freshly allocated pathname.  */
char *
concatenated_pathname (const char *directory, const char *filename,
                       const char *suffix)
{
  char *result;
  char *p;

  if (strcmp (directory, ".") == 0)
    {
      /* No need to prepend the directory.  */
      result = (char *) xmalloc (strlen (filename)
                                 + (suffix != NULL ? strlen (suffix) : 0)
                                 + 1);
      p = result;
    }
  else
    {
      size_t directory_len = strlen (directory);
      int need_slash =
        (directory_len > FILESYSTEM_PREFIX_LEN (directory)
         && !ISSLASH (directory[directory_len - 1]));
      result = (char *) xmalloc (directory_len + need_slash
                                 + strlen (filename)
                                 + (suffix != NULL ? strlen (suffix) : 0)
                                 + 1);
      memcpy (result, directory, directory_len);
      p = result + directory_len;
      if (need_slash)
        *p++ = '/';
    }
  p = stpcpy (p, filename);
  if (suffix != NULL)
    stpcpy (p, suffix);
  return result;
}