btrfs-progs: simplify empty stirngs check

We can do a strlen(str) == 0 in a simpler way.

Signed-off-by: David Sterba <dsterba@suse.com>

btrfs-convert.c

@@ -1449,7 +1449,7 @@ static struct btrfs_root * link_subvol(struct btrfs_root *root,
 	int ret;
 
 	len = strlen(base);
-	if (len < 1 || len > BTRFS_NAME_LEN)
+	if (len == 0 || len > BTRFS_NAME_LEN)
 		return NULL;
 
 	path = btrfs_alloc_path();

btrfs-corrupt-block.c

@@ -1217,7 +1217,7 @@ int main(int ac, char **av)
 	if (inode) {
 		struct btrfs_trans_handle *trans;
 
-		if (!strlen(field))
+		if (*field == 0)
 			print_usage(1);
 
 		trans = btrfs_start_transaction(root, 1);
@@ -1233,13 +1233,13 @@ int main(int ac, char **av)
 		goto out_close;
 	}
 	if (metadata_block) {
-		if (!strlen(field))
+		if (*field == 0)
 			print_usage(1);
 		ret = corrupt_metadata_block(root, metadata_block, field);
 		goto out_close;
 	}
 	if (corrupt_di) {
-		if (!key.objectid || !strlen(field))
+		if (!key.objectid || *field == 0)
 			print_usage(1);
 		ret = corrupt_dir_item(root, &key, field);
 		goto out_close;
@@ -1276,7 +1276,7 @@ int main(int ac, char **av)
 		goto out_close;
 	}
 	if (key.objectid || key.offset || key.type) {
-		if (!strlen(field))
+		if (*field == 0)
 			print_usage(1);
 		ret = corrupt_key(root, &key, field);
 		goto out_close;

cmds-filesystem.c

@@ -233,7 +233,7 @@ static int match_search_item_kernel(__u8 *fsid, char *mnt, char *label,
 	if (!strncmp(uuidbuf, search, search_len))
 		return 1;
 
-	if (strlen(label) && strcmp(label, search) == 0)
+	if (*label && strcmp(label, search) == 0)
 		return 1;
 
 	if (strcmp(mnt, search) == 0)
@@ -403,7 +403,7 @@ static int print_one_fs(struct btrfs_ioctl_fs_info_args *fs_info,
 		return ret;
 
 	uuid_unparse(fs_info->fsid, uuidbuf);
-	if (label && strlen(label))
+	if (label && *label)
 		printf("Label: '%s' ", label);
 	else
 		printf("Label: none ");
@@ -823,7 +823,7 @@ static int cmd_filesystem_show(int argc, char **argv)
 
 	if (argc > optind) {
 		search = argv[optind];
-		if (strlen(search) == 0)
+		if (*search == 0)
 			usage(cmd_filesystem_show_usage);
 		type = check_arg_type(search);
 

cmds-receive.c

@@ -169,7 +169,7 @@ static int process_subvol(const char *path, const u8 *uuid, u64 ctransid,
 	BUG_ON(r->cur_subvol.path);
 	BUG_ON(r->cur_subvol_path[0]);
 
-	if (strlen(r->dest_dir_path) == 0) {
+	if (*r->dest_dir_path == 0) {
 		strncpy_null(r->cur_subvol_path, path);
 	} else {
 		ret = path_cat_out(r->cur_subvol_path, r->dest_dir_path, path);
@@ -229,7 +229,7 @@ static int process_snapshot(const char *path, const u8 *uuid, u64 ctransid,
 	BUG_ON(r->cur_subvol.path);
 	BUG_ON(r->cur_subvol_path[0]);
 
-	if (strlen(r->dest_dir_path) == 0) {
+	if (*r->dest_dir_path == 0) {
 		strncpy_null(r->cur_subvol_path, path);
 	} else {
 		ret = path_cat_out(r->cur_subvol_path, r->dest_dir_path, path);
@@ -326,7 +326,7 @@ static int process_snapshot(const char *path, const u8 *uuid, u64 ctransid,
 		}
 	}*/
 
-	if (strlen(parent_subvol->path) == 0)
+	if (*parent_subvol->path == 0)
 		args_v2.fd = dup(r->mnt_fd);
 	else
 		args_v2.fd = openat(r->mnt_fd, parent_subvol->path,
@@ -1135,7 +1135,7 @@ static int do_receive(struct btrfs_receive *r, const char *tomnt,
 	 * Ok we're inside of a subvol off of the root subvol, we need to
 	 * actually set full_root_path.
 	 */
-	if (strlen(root_subvol_path))
+	if (*root_subvol_path)
 		r->full_root_path = root_subvol_path;
 
 	if (r->dest_dir_chroot) {

string-table.c

@@ -101,7 +101,7 @@ void table_dump(struct string_table *tab)
 				continue;
 
 			len = strlen(tab->cells[idx]) - 1;
-			if (len < 1 || tab->cells[idx][0] == '*')
+			if (len == 0 || tab->cells[idx][0] == '*')
 				continue;
 
 			if (len > sizes[i])

utils.c

@@ -1516,7 +1516,7 @@ int btrfs_register_all_devices(void)
 
 	list_for_each_entry(fs_devices, all_uuids, list) {
 		list_for_each_entry(device, &fs_devices->devices, dev_list) {
-			if (strlen(device->name) != 0) {
+			if (*device->name) {
 				err = btrfs_register_one_device(device->name);
 				if (err < 0)
 					return err;