1 files changed, 152 insertions, 0 deletions
diff --git a/lib/canonicalize.c b/lib/canonicalize.c
new file mode 100644
index 000000000..b888fbb8e
--- /dev/null
+++ b/lib/canonicalize.c
@@ -0,0 +1,152 @@
+/*
+ * canonicalize.c -- canonicalize pathname by removing symlinks
+ * Copyright (C) 1993 Rick Sladkey <jrs@world.std.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Library 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 Library Public License for more details.
+ *
+ */
+
+/*
+ * This routine is part of libc.  We include it nevertheless,
+ * since the libc version has some security flaws.
+ *
+ * TODO: use canonicalize_file_name() when exist in glibc
+ */
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <stdlib.h>
+
+#include "canonicalize.h"
+
+#ifndef MAXSYMLINKS
+# define MAXSYMLINKS 256
+#endif
+
+static char *
+myrealpath(const char *path, char *resolved_path, int maxreslth) {
+	int readlinks = 0;
+	char *npath;
+	char link_path[PATH_MAX+1];
+	int n;
+	char *buf = NULL;
+
+	npath = resolved_path;
+
+	/* If it's a relative pathname use getcwd for starters. */
+	if (*path != '/') {
+		if (!getcwd(npath, maxreslth-2))
+			return NULL;
+		npath += strlen(npath);
+		if (npath[-1] != '/')
+			*npath++ = '/';
+	} else {
+		*npath++ = '/';
+		path++;
+	}
+
+	/* Expand each slash-separated pathname component. */
+	while (*path != '\0') {
+		/* Ignore stray "/" */
+		if (*path == '/') {
+			path++;
+			continue;
+		}
+		if (*path == '.' && (path[1] == '\0' || path[1] == '/')) {
+			/* Ignore "." */
+			path++;
+			continue;
+		}
+		if (*path == '.' && path[1] == '.' &&
+		    (path[2] == '\0' || path[2] == '/')) {
+			/* Backup for ".." */
+			path += 2;
+			while (npath > resolved_path+1 &&
+			       (--npath)[-1] != '/')
+				;
+			continue;
+		}
+		/* Safely copy the next pathname component. */
+		while (*path != '\0' && *path != '/') {
+			if (npath-resolved_path > maxreslth-2) {
+				errno = ENAMETOOLONG;
+				goto err;
+			}
+			*npath++ = *path++;
+		}
+
+		/* Protect against infinite loops. */
+		if (readlinks++ > MAXSYMLINKS) {
+			errno = ELOOP;
+			goto err;
+		}
+
+		/* See if last pathname component is a symlink. */
+		*npath = '\0';
+		n = readlink(resolved_path, link_path, PATH_MAX);
+		if (n < 0) {
+			/* EINVAL means the file exists but isn't a symlink. */
+			if (errno != EINVAL)
+				goto err;
+		} else {
+			int m;
+			char *newbuf;
+
+			/* Note: readlink doesn't add the null byte. */
+			link_path[n] = '\0';
+			if (*link_path == '/')
+				/* Start over for an absolute symlink. */
+				npath = resolved_path;
+			else
+				/* Otherwise back up over this component. */
+				while (*(--npath) != '/')
+					;
+
+			/* Insert symlink contents into path. */
+			m = strlen(path);
+			newbuf = malloc(m + n + 1);
+			if (!newbuf)
+				goto err;
+			memcpy(newbuf, link_path, n);
+			memcpy(newbuf + n, path, m + 1);
+			free(buf);
+			path = buf = newbuf;
+		}
+		*npath++ = '/';
+	}
+	/* Delete trailing slash but don't whomp a lone slash. */
+	if (npath != resolved_path+1 && npath[-1] == '/')
+		npath--;
+	/* Make sure it's null terminated. */
+	*npath = '\0';
+
+	free(buf);
+	return resolved_path;
+
+ err:
+	free(buf);
+	return NULL;
+}
+
+char *
+canonicalize_path(const char *path) {
+	char canonical[PATH_MAX+2];
+
+	if (path == NULL)
+		return NULL;
+
+	if (myrealpath (path, canonical, PATH_MAX+1))
+		return strdup(canonical);
+
+	return strdup(path);
+}
+
+