debugfs: expose a preserve command line switch in rdump command

rdump assumed the user wanted to preserve permissions and ownership when
dumping a filesystem directory recursively with 'rdump'. This is in
opposition with the way the 'dump' or 'dump_inode' command has been
designed, since it expose a '-p' command line switch to allow the end
users to explicitly opt-in for permission and ownership preservation.

The inability to explicitly ask for permission and ownership
preservation would get rdump to default to preservation, which is a
problem when faced with filesystems having directories with the read
flag but not the execute flag, since it would only allow to enumerate
the directory content, but not see the inode details. Therefore getting
debugfs in all kinds of issues trying to set ownership and permissions
of files it can't see.

This fix introduce a 'preserve' ('-p') flag in rdump command so that
users can explicitly opt-in for it, and debugfs will default to a safer
way of operation (no preserve).

Author: qkaiser

debugfs/dump.c

@@ -262,10 +262,15 @@ static void rdump_symlink(ext2_ino_t ino, struct ext2_inode *inode,
 	free(buf);
 }
 
+typedef struct {
+  char* fullname;
+  int preserve;
+} rdump_dirent_private;
+
 static int rdump_dirent(struct ext2_dir_entry *, int, int, char *, void *);
 
 static int rdump_inode(ext2_ino_t ino, struct ext2_inode *inode,
-			const char *name, const char *dumproot)
+			const char *name, const char *dumproot, int preserve)
 {
 	char *fullname;
 	int result = 0;
@@ -290,7 +295,7 @@ static int rdump_inode(ext2_ino_t ino, struct ext2_inode *inode,
 			goto errout;
 		}
 
-		if (dump_file("rdump", ino, fd, 1, fullname) != 0) {
+		if (dump_file("rdump", ino, fd, preserve, fullname) != 0) {
 			result = 1;
 			com_err("rdump", errno, "while dumping %s", fullname);
 		}
@@ -315,14 +320,23 @@ static int rdump_inode(ext2_ino_t ino, struct ext2_inode *inode,
 			goto errout;
 		}
 
+		rdump_dirent_private* entry = malloc(sizeof(rdump_dirent_private));
+		if (entry == NULL) {
+			com_err("rdump", errno, "while allocating entry for %s", fullname);
+			goto errout;
+		}
+		entry->fullname = fullname;
+		entry->preserve = preserve;
+
 		retval = ext2fs_dir_iterate(current_fs, ino, 0, 0,
-					    rdump_dirent, (void *) fullname);
+					    rdump_dirent, (void *) entry);
+		free(entry);
 		if (retval) {
 			com_err("rdump", retval, "while dumping %s", fullname);
 			result = 1;
 		}
-
-		fix_perms("rdump", inode, -1, fullname);
+		if (preserve)
+			fix_perms("rdump", inode, -1, fullname);
 	}
 	/* else do nothing (don't dump device files, sockets, fifos, etc.) */
 
@@ -338,29 +352,42 @@ static int rdump_dirent(struct ext2_dir_entry *dirent,
 {
 	char name[EXT2_NAME_LEN + 1];
 	int thislen;
-	const char *dumproot = private;
 	struct ext2_inode inode;
 
+	rdump_dirent_private *dirent_private = (rdump_dirent_private *) private;
 	thislen = ext2fs_dirent_name_len(dirent);
 	strncpy(name, dirent->name, thislen);
 	name[thislen] = 0;
 
 	if (debugfs_read_inode(dirent->inode, &inode, name))
 		return 0;
 
-	return rdump_inode(dirent->inode, &inode, name, dumproot);
+	return rdump_inode(dirent->inode, &inode, name, dirent_private->fullname, dirent_private->preserve);
 }
 
 void do_rdump(int argc, char **argv, int sci_idx,
 	      void *infop EXT2FS_ATTR((unused)))
 {
 	struct stat st;
 	char *dest_dir;
-	int i;
+	int i, c;
+	int preserve = 0;
+	ext2_ino_t ino;
+	struct ext2_inode inode;
 
-	if (common_args_process(argc, argv, 3, INT_MAX, "rdump",
-				"<directory>... <native directory>", 0))
-		return;
+	reset_getopt();
+	while ((c = getopt(argc, argv, "p")) != EOF) {
+		switch (c) {
+			case 'p':
+				preserve++;
+				break;
+			default:
+				goto print_usage;
+		}
+	}
+
+	if (optind  > argc - 2)
+		goto print_usage;
 
 	/* Pull out last argument */
 	dest_dir = argv[argc - 1];
@@ -376,10 +403,9 @@ void do_rdump(int argc, char **argv, int sci_idx,
 		return;
 	}
 
-	for (i = 1; i < argc; i++) {
+	for (i = optind; i < argc; i++) {
 		char *arg = argv[i], *basename;
-		struct ext2_inode inode;
-		ext2_ino_t ino = string_to_inode(arg);
+		ino = string_to_inode(arg);
 		if (!ino)
 			continue;
 
@@ -392,9 +418,14 @@ void do_rdump(int argc, char **argv, int sci_idx,
 		else
 			basename = arg;
 
-		if (rdump_inode(ino, &inode, basename, dest_dir) != 0)
+		if (rdump_inode(ino, &inode, basename, dest_dir, preserve) != 0)
 			ss_set_exit_status(sci_idx, 1);
 	}
+	print_usage:
+		com_err(argv[0], 0,
+				"Usage: rdump [-p] "
+				"<fs_directory>... <output_file>");
+		ss_set_exit_status(sci_idx, 1);
 }
 
 void do_cat(int argc, char **argv, int sci_idx EXT2FS_ATTR((unused)),