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/* -*- Mode: C; indent-tabs-mode: t; c-basic-offset: 8; tab-width: 8 -*- */
/* f-utils.h
*
* Copyright (C) 2003 Ettore Perazzoli
*
* 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 of the
* License, 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.
*
* Author: Ettore Perazzoli <ettore@ximian.com>
*/
#include <config.h>
#include "f-utils.h"
#include <glib.h>
char *
f_build_relative_path (const char *start_path,
const char *destination_path)
{
const char *sp, *dp;
GString *relative_path;
gboolean need_separator;
char *retval;
g_return_val_if_fail (g_path_is_absolute (start_path), NULL);
g_return_val_if_fail (g_path_is_absolute (destination_path), NULL);
sp = start_path;
dp = destination_path;
/* Look for a common subpath at the beginning of the paths. */
while (*sp == *dp && *sp != 0) {
sp ++;
dp ++;
}
if (*sp == 0 && *dp == 0)
return g_strdup ("");
/* Roll back to the path element. This is guarranteed to not run past
the beginning of the string because of the g_path_is_absolute()
checks above. */
while (*sp != G_DIR_SEPARATOR && *sp != 0)
sp --;
while (*dp != G_DIR_SEPARATOR && *dp != 0)
dp --;
g_assert (*dp == G_DIR_SEPARATOR || *dp == 0);
g_assert (*sp == G_DIR_SEPARATOR || *sp == 0);
/* Start constructing the string by adding one ".." for each path
component in the source path that is not in the destination
path. */
relative_path = g_string_new ("");
need_separator = FALSE;
while (*sp != 0) {
sp ++;
if (*sp == G_DIR_SEPARATOR || *sp == 0) {
while (*sp == G_DIR_SEPARATOR)
sp ++;
if (need_separator)
g_string_append (relative_path, G_DIR_SEPARATOR_S);
g_string_append (relative_path, "..");
need_separator = TRUE;
}
}
/* Add the rest of the path elements, if any. */
if (*dp != 0) {
/* (Notice that DP is guaranteed to point to either a null character
or to a separator so we don't need to add it ourselves.) */
if (need_separator)
g_string_append (relative_path, dp);
else
g_string_append (relative_path, dp + 1);
}
retval = relative_path->str;
g_string_free (relative_path, FALSE);
return retval;
}
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