ubifs: Add support for looking up directory and relative symlinks

This patch adds support for resolving symlinks to directories as well as
relative symlinks. Symlinks are now always resolved during file lookup,
so the load stage no longer needs to special-case them.

Signed-off-by: Simon Kagstrom <simon.kagstrom@netinsight.net>
Signed-off-by: Stefan Roese <sr@denx.de>

fs/ubifs/ubifs.c

@@ -379,9 +379,11 @@ static unsigned long ubifs_findfile(struct super_block *sb, char *filename)
 	int ret;
 	char *next;
 	char fpath[128];
+	char symlinkpath[128];
 	char *name = fpath;
 	unsigned long root_inum = 1;
 	unsigned long inum;
+	int symlink_count = 0; /* Don't allow symlink recursion */
 
 	strcpy(fpath, filename);
 
@@ -397,6 +399,9 @@ static unsigned long ubifs_findfile(struct super_block *sb, char *filename)
 		return inum;
 
 	for (;;) {
+		struct inode *inode;
+		struct ubifs_inode *ui;
+
 		/* Extract the actual part from the pathname.  */
 		next = strchr(name, '/');
 		if (next) {
@@ -406,18 +411,48 @@ static unsigned long ubifs_findfile(struct super_block *sb, char *filename)
 		}
 
 		ret = ubifs_finddir(sb, name, root_inum, &inum);
+		if (!ret)
+			return 0;
+		inode = ubifs_iget(sb, inum);
+
+		if (!inode)
+			return 0;
+		ui = ubifs_inode(inode);
+
+		if ((inode->i_mode & S_IFMT) == S_IFLNK) {
+			char link_name[64];
+			char buf[128];
+
+			/* We have some sort of symlink recursion, bail out */
+			if (symlink_count++ > 8) {
+				printf("Symlink recursion, aborting\n");
+				return 0;
+			}
+			memcpy(link_name, ui->data, ui->data_len);
+			link_name[ui->data_len] = '\0';
+
+			if (link_name[0] == '/') {
+				/* Absolute path, redo everything without
+				 * the leading slash */
+				next = name = link_name + 1;
+				root_inum = 1;
+				continue;
+			}
+			/* Relative to cur dir */
+			sprintf(buf, "%s%s",
+					link_name, next == NULL ? "" : next);
+			memcpy(symlinkpath, buf, sizeof(buf));
+			next = name = symlinkpath;
+			continue;
+		}
 
 		/*
 		 * Check if directory with this name exists
 		 */
 
 		/* Found the node!  */
-		if (!next || *next == '\0') {
-			if (ret)
-				return inum;
-
-			break;
-		}
+		if (!next || *next == '\0')
+			return inum;
 
 		root_inum = inum;
 		name = next;
@@ -614,10 +649,10 @@ int ubifs_load(char *filename, u32 addr, u32 size)
 	int err = 0;
 	int i;
 	int count;
-	char link_name[64];
-	struct ubifs_inode *ui;
 
 	c->ubi = ubi_open_volume(c->vi.ubi_num, c->vi.vol_id, UBI_READONLY);
+	/* ubifs_findfile will resolve symlinks, so we know that we get
+	 * the real file here */
 	inum = ubifs_findfile(ubifs_sb, filename);
 	if (!inum) {
 		err = -1;
@@ -634,23 +669,6 @@ int ubifs_load(char *filename, u32 addr, u32 size)
 		goto out;
 	}
 
-	/*
-	 * Check for symbolic link
-	 */
-	ui = ubifs_inode(inode);
-	if (((inode->i_mode & S_IFMT) == S_IFLNK) && ui->data_len) {
-		memcpy(link_name, ui->data, ui->data_len);
-		link_name[ui->data_len] = '\0';
-		printf("%s is linked to %s!\n", filename, link_name);
-		ubifs_iput(inode);
-
-		/*
-		 * Now we have the "real" filename, call ubifs_load()
-		 * again (recursive call) to load this file instead
-		 */
-		return ubifs_load(link_name, addr, size);
-	}
-
 	/*
 	 * If no size was specified or if size bigger than filesize
 	 * set size to filesize