Switch to modern realpath()

Assume everywhere that the realpath() implementation has the
POSIX.1-2008 behaviour, i.e. allowing NULL as second parameter and thus
returning a newly allocated buffer; it is not just a GNU extension,
and supported already by modern libc's on other OSes.

menu_canonicalize_file_name() is always called with FALSE as second
parameter, so it is replaced directly by realpath(); this allows the
complete removal of canonicalize.{c,h}.

This is a forward-port of the same changes done in gnome-menus, see:
https://gitlab.gnome.org/GNOME/gnome-menus/merge_requests/4

6 files changed, 7 insertions, 374 deletions

diff --git a/libmenu/Makefile.am b/libmenu/Makefile.am
index e6e20e7..34150f2 100644
--- a/libmenu/Makefile.am
+++ b/libmenu/Makefile.am
@@ -13,7 +13,6 @@ libmate_menu_include_HEADERS = \
 	matemenu-tree.h
 
 libmate_menu_sources = \
-	canonicalize.c \
 	desktop-entries.c \
 	entry-directories.c \
 	matemenu-tree.c \
@@ -23,7 +22,6 @@ libmate_menu_sources = \
 
 libmate_menu_la_SOURCES = \
 	$(libmate_menu_sources) \
-	canonicalize.h \
 	desktop-entries.h \
 	entry-directories.h \
 	matemenu-tree.h \
diff --git a/libmenu/canonicalize.c b/libmenu/canonicalize.c
deleted file mode 100644
index 1a29ae9..0000000
--- a/libmenu/canonicalize.c
+++ /dev/null
@@ -1,330 +0,0 @@
-/* Return the canonical absolute name of a given file.
- * Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
- * This file is part of the GNU C Library.
- *
- * Copyright (C) 2002 Red Hat, Inc. (trivial port to GLib)
- *
- * The GNU C Library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * The GNU C Library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with the GNU C Library; if not, write to the Free
- * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
- * 02110-1301 USA.
- */
-
-#include <config.h>
-
-#include "canonicalize.h"
-
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <limits.h>
-#include <sys/param.h>
-#include <sys/stat.h>
-#include <errno.h>
-#include <stddef.h>
-
-#ifndef MAXSYMLINKS
-#define MAXSYMLINKS sysconf(_SC_SYMLOOP_MAX)
-#endif
-
-/* Return the canonical absolute name of file NAME.  A canonical name
-   does not contain any `.', `..' components nor any repeated path
-   separators ('/') or symlinks.  All path components must exist.  If
-   RESOLVED is null, the result is malloc'd; otherwise, if the
-   canonical name is PATH_MAX chars or more, returns null with `errno'
-   set to ENAMETOOLONG; if the name fits in fewer than PATH_MAX chars,
-   returns the name in RESOLVED.  If the name cannot be resolved and
-   RESOLVED is non-NULL, it contains the path of the first component
-   that cannot be resolved.  If the path can be resolved, RESOLVED
-   holds the same value as the value returned.  */
-
-static char* menu_realpath(const char* name, char* resolved)
-{
-	char* rpath = NULL;
-	char* dest = NULL;
-	char* extra_buf = NULL;
-	const char* start;
-	const char* end;
-	const char* rpath_limit;
-	long int path_max;
-	int num_links = 0;
-
-	if (name == NULL)
-	{
-		/* As per Single Unix Specification V2 we must return an error if
-		 * either parameter is a null pointer.  We extend this to allow
-		 * the RESOLVED parameter to be NULL in case the we are expected to
-		 * allocate the room for the return value.  */
-		errno = EINVAL;
-		return NULL;
-	}
-
-	if (name[0] == '\0')
-	{
-		/* As per Single Unix Specification V2 we must return an error if
-		 * the name argument points to an empty string.  */
-		errno = ENOENT;
-		return NULL;
-	}
-
-	#ifdef PATH_MAX
-		path_max = PATH_MAX;
-	#else
-		path_max = pathconf(name, _PC_PATH_MAX);
-
-		if (path_max <= 0)
-		{
-			path_max = 1024;
-		}
-	#endif
-
-	rpath = resolved ? g_alloca(path_max) : g_malloc(path_max);
-	rpath_limit = rpath + path_max;
-
-	if (name[0] != G_DIR_SEPARATOR)
-	{
-		if (!getcwd(rpath, path_max))
-		{
-			rpath[0] = '\0';
-			goto error;
-		}
-
-		dest = strchr(rpath, '\0');
-	}
-	else
-	{
-		rpath[0] = G_DIR_SEPARATOR;
-		dest = rpath + 1;
-	}
-
-	for (start = end = name; *start; start = end)
-    {
-		struct stat st;
-		int n;
-
-		/* Skip sequence of multiple path-separators.  */
-		while (*start == G_DIR_SEPARATOR)
-		{
-			++start;
-		}
-
-		/* Find end of path component.  */
-		for (end = start; *end && *end != G_DIR_SEPARATOR; ++end)
-		{
-			/* Nothing.  */;
-		}
-
-		if (end - start == 0)
-		{
-			break;
-		}
-		else if (end - start == 1 && start[0] == '.')
-		{
-			/* nothing */;
-		}
-		else if (end - start == 2 && start[0] == '.' && start[1] == '.')
-        {
-			/* Back up to previous component, ignore if at root already.  */
-			if (dest > rpath + 1)
-			{
-				while ((--dest)[-1] != G_DIR_SEPARATOR)
-				{
-					/* Nothing.  */;
-				}
-			}
-        }
-		else
-        {
-			size_t new_size;
-
-			if (dest[-1] != G_DIR_SEPARATOR)
-			{
-				*dest++ = G_DIR_SEPARATOR;
-			}
-
-			if (dest + (end - start) >= rpath_limit)
-            {
-				char* new_rpath;
-				ptrdiff_t dest_offset = dest - rpath;
-
-				if (resolved)
-				{
-					#ifdef ENAMETOOLONG
-					  errno = ENAMETOOLONG;
-					#else
-					  /* Uh... just pick something */
-					  errno = EINVAL;
-					#endif
-
-					if (dest > rpath + 1)
-					{
-						dest--;
-					}
-
-					*dest = '\0';
-					goto error;
-                }
-
-				new_size = rpath_limit - rpath;
-
-				if (end - start + 1 > path_max)
-				{
-					new_size += end - start + 1;
-				}
-				else
-				{
-					new_size += path_max;
-				}
-
-				new_rpath = (char*) realloc(rpath, new_size);
-
-				if (new_rpath == NULL)
-				{
-					goto error;
-				}
-
-				rpath = new_rpath;
-				rpath_limit = rpath + new_size;
-
-				dest = rpath + dest_offset;
-            }
-
-			memcpy(dest, start, end - start);
-			dest = dest + (end - start);
-			*dest = '\0';
-
-			if (stat(rpath, &st) < 0)
-			{
-				goto error;
-			}
-
-			if (S_ISLNK(st.st_mode))
-			{
-				char* buf = alloca(path_max);
-				size_t len;
-
-				if (++num_links > MAXSYMLINKS)
-				{
-					errno = ELOOP;
-					goto error;
-				}
-
-				n = readlink(rpath, buf, path_max);
-
-				if (n < 0)
-				{
-					goto error;
-				}
-
-				buf[n] = '\0';
-
-
-
-				if (!extra_buf)
-				{
-					extra_buf = g_alloca(path_max);
-				}
-
-				len = strlen(end);
-
-				if ((long int) (n + len) >= path_max)
-                {
-					#ifdef ENAMETOOLONG
-					  errno = ENAMETOOLONG;
-					#else
-					  /* Uh... just pick something */
-					  errno = EINVAL;
-					#endif
-
-					goto error;
-                }
-
-				/* Careful here, end may be a pointer into extra_buf... */
-				g_memmove(&extra_buf[n], end, len + 1);
-				name = end = memcpy(extra_buf, buf, n);
-
-				if (buf[0] == G_DIR_SEPARATOR)
-				{
-					dest = rpath + 1;       /* It's an absolute symlink */
-				}
-				else
-				{
-					/* Back up to previous component, ignore if at root already: */
-					if (dest > rpath + 1)
-					{
-						while ((--dest)[-1] != G_DIR_SEPARATOR)
-						{
-							/* Nothing.  */;
-						}
-					}
-				}
-            }
-        }
-    }
-
-	if (dest > rpath + 1 && dest[-1] == G_DIR_SEPARATOR)
-	{
-		--dest;
-	}
-
-	*dest = '\0';
-
-	return resolved ? memcpy(resolved, rpath, dest - rpath + 1) : rpath;
-
-	error:
-
-	if (resolved)
-	{
-		strcpy(resolved, rpath);
-	}
-	else
-	{
-		g_free(rpath);
-	}
-
-	return NULL;
-}
-
-char* menu_canonicalize_file_name(const char* name, gboolean allow_missing_basename)
-{
-	char* retval;
-
-	retval = menu_realpath(name, NULL);
-
-	/* We could avoid some system calls by using the second
-	 * argument to realpath() instead of doing realpath
-	 * all over again, but who cares really. we'll see if
-	 * it's ever in a profile.
-	 */
-	if (allow_missing_basename && retval == NULL)
-	{
-		char* dirname;
-		char* canonical_dirname;
-
-		dirname = g_path_get_dirname(name);
-		canonical_dirname = menu_realpath(dirname, NULL);
-		g_free(dirname);
-
-		if (canonical_dirname)
-		{
-			char* basename;
-
-			basename = g_path_get_basename(name);
-			retval = g_build_filename(canonical_dirname, basename, NULL);
-			g_free(basename);
-			g_free(canonical_dirname);
-		}
-	}
-
-	return retval;
-}
diff --git a/libmenu/canonicalize.h b/libmenu/canonicalize.h
deleted file mode 100644
index bb291cf..0000000
--- a/libmenu/canonicalize.h
+++ /dev/null
@@ -1,34 +0,0 @@
-/* Return the canonical absolute name of a given file.
- * Copyright (C) 1996-2001, 2002 Free Software Foundation, Inc.
- * This file is part of the GNU C Library.
- *
- * Copyright (C) 2002 Red Hat, Inc. (trivial port to GLib)
- *
- * The GNU C Library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * The GNU C Library 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
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with the GNU C Library; if not, write to the Free
- * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
- * 02110-1301 USA.
- */
-
-#ifndef MATE_CANONICALIZE_H
-#define MATE_CANONICALIZE_H
-
-#include <glib.h>
-
-G_BEGIN_DECLS
-
-char* menu_canonicalize_file_name(const char* name, gboolean allow_missing_basename);
-
-G_END_DECLS
-
-#endif /* MATE_CANONICALIZE_H */
diff --git a/libmenu/entry-directories.c b/libmenu/entry-directories.c
index 2a21807..33b68eb 100644
--- a/libmenu/entry-directories.c
+++ b/libmenu/entry-directories.c
@@ -25,10 +25,10 @@
 #include <errno.h>
 #include <sys/types.h>
 #include <dirent.h>
+#include <stdlib.h>
 
 #include "menu-util.h"
 #include "menu-monitor.h"
-#include "canonicalize.h"
 
 typedef struct CachedDir CachedDir;
 typedef struct CachedDirMonitor CachedDirMonitor;
@@ -731,7 +731,7 @@ static EntryDirectory* entry_directory_new_full(DesktopEntryType entry_type, con
                 path,
                 is_legacy ? "<yes>" : "<no>");
 
-  canonical = menu_canonicalize_file_name (path, FALSE);
+  canonical = realpath (path, NULL);
   if (canonical == NULL)
     {
       menu_verbose ("Failed to canonicalize \"%s\": %s\n",
diff --git a/libmenu/matemenu-tree.c b/libmenu/matemenu-tree.c
index 4ce4d55..f65a2be 100644
--- a/libmenu/matemenu-tree.c
+++ b/libmenu/matemenu-tree.c
@@ -24,11 +24,11 @@
 #include <gio/gio.h>
 #include <string.h>
 #include <errno.h>
+#include <stdlib.h>
 
 #include "menu-layout.h"
 #include "menu-monitor.h"
 #include "menu-util.h"
-#include "canonicalize.h"
 
 /* private */
 typedef struct MateMenuTreeItem MateMenuTreeItem;
@@ -333,7 +333,7 @@ static gboolean
 canonicalize_path (MateMenuTree  *tree,
                    const char *path)
 {
-  tree->canonical_path = menu_canonicalize_file_name (path, FALSE);
+  tree->canonical_path = realpath (path, NULL);
   if (tree->canonical_path)
     {
       tree->canonical = TRUE;
@@ -1887,7 +1887,7 @@ load_merge_file (MateMenuTree      *tree,
 
   if (!is_canonical)
     {
-      canonical = freeme = menu_canonicalize_file_name (filename, FALSE);
+      canonical = freeme = realpath (filename, NULL);
       if (canonical == NULL)
         {
 	  if (add_monitor)
@@ -1982,7 +1982,7 @@ compare_basedir_to_config_dir (const char *canonical_basedir,
 
   retval = FALSE;
 
-  canonical_menus_dir = menu_canonicalize_file_name (dirname, FALSE);
+  canonical_menus_dir = realpath (dirname, NULL);
   if (canonical_menus_dir != NULL &&
       strcmp (canonical_basedir, canonical_menus_dir) == 0)
     {
@@ -2056,7 +2056,7 @@ static gboolean load_parent_merge_file(MateMenuTree* tree, GHashTable* loaded_me
 	basedir   = menu_layout_node_root_get_basedir(root);
 	menu_name = menu_layout_node_root_get_name(root);
 
-	canonical_basedir = menu_canonicalize_file_name(basedir, FALSE);
+	canonical_basedir = realpath (basedir, NULL);
 
 	if (canonical_basedir == NULL)
 	{
diff --git a/libmenu/menu-layout.c b/libmenu/menu-layout.c
index 30d11b3..93ee6db 100644
--- a/libmenu/menu-layout.c
+++ b/libmenu/menu-layout.c
@@ -29,7 +29,6 @@
 #include <unistd.h>
 #include <errno.h>
 
-#include "canonicalize.h"
 #include "entry-directories.h"
 #include "menu-util.h"