[U-Boot] [PATCH] fs: make it possible to read the filesystem UUID

[Christian Gmeiner]

Some filesystems have a UUID stored in its superblock. To
allow using root=UUID=... for the kernel command line we
need a way to read-out the filesystem UUID.

Hit any key to stop autoboot:  0
=> fsuuid
fsuuid - Look up a filesystem UUID

Usage:
fsuuid <interface> <dev>:<part>
    - print filesystem UUID
fsuuid <interface> <dev>:<part> <varname>
    - set environment variable to filesystem UUID

=> fsuuid mmc 0:1
d9f9fc05-45ae-4a36-a616-fccce0e4f887
=> fsuuid mmc 0:2
eb3db83c-7b28-499f-95ce-9e0bb21cda81
=> fsuuid mmc 0:1 uuid1
=> fsuuid mmc 0:2 uuid2
=> printenv uuid1
uuid1=d9f9fc05-45ae-4a36-a616-fccce0e4f887
=> printenv uuid2
uuid2=eb3db83c-7b28-499f-95ce-9e0bb21cda81
=>

Signed-off-by: Christian Gmeiner <christian.gmeiner at gmail.com>
---
 README           |  1 +
 common/Makefile  |  1 +
 fs/ext4/ext4fs.c | 15 +++++++++++++++
 fs/fs.c          | 39 +++++++++++++++++++++++++++++++++++++++
 include/ext4fs.h |  1 +
 include/fs.h     |  2 ++
 6 files changed, 59 insertions(+)

diff --git a/README b/README
index 7b5538e..53b84a6 100644
--- a/README
+++ b/README
@@ -989,6 +989,7 @@ The following options need to be configured:
 		CONFIG_CMD_EXT4		* ext4 command support
 		CONFIG_CMD_FS_GENERIC	* filesystem commands (e.g. load, ls)
 					  that work for multiple fs types
+		CONFIG_CMD_FS_UUID	* Look up a filesystem UUID
 		CONFIG_CMD_SAVEENV	  saveenv
 		CONFIG_CMD_FDC		* Floppy Disk Support
 		CONFIG_CMD_FAT		* FAT command support
diff --git a/common/Makefile b/common/Makefile
index 6cc4de8..508a0b2 100644
--- a/common/Makefile
+++ b/common/Makefile
@@ -188,6 +188,7 @@ obj-y += usb.o usb_hub.o
 obj-$(CONFIG_USB_STORAGE) += usb_storage.o
 endif
 obj-$(CONFIG_CMD_FASTBOOT) += cmd_fastboot.o
+obj-$(CONFIG_CMD_FS_UUID) += cmd_fs_uuid.o
 
 obj-$(CONFIG_CMD_USB_MASS_STORAGE) += cmd_usb_mass_storage.o
 obj-$(CONFIG_CMD_THOR_DOWNLOAD) += cmd_thordown.o
diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index cbdc220..61b6dc2 100644
--- a/fs/ext4/ext4fs.c
+++ b/fs/ext4/ext4fs.c
@@ -187,6 +187,21 @@ int ext4fs_size(const char *filename)
 	return ext4fs_open(filename);
 }
 
+int ext4fs_uuid(char *uuid_str)
+{
+	if (ext4fs_root == NULL)
+		return -1;
+
+#ifdef CONFIG_LIB_UUID
+	uuid_bin_to_str((unsigned char *)ext4fs_root->sblock.unique_id,
+			uuid_str, UUID_STR_FORMAT_STD);
+
+	return 0;
+#endif
+
+	return -ENOSYS;
+}
+
 int ext4fs_read(char *buf, unsigned len)
 {
 	if (ext4fs_root == NULL || ext4fs_file == NULL)
diff --git a/fs/fs.c b/fs/fs.c
index dd680f3..492d8b1 100644
--- a/fs/fs.c
+++ b/fs/fs.c
@@ -15,6 +15,7 @@
  */
 
 #include <config.h>
+#include <errno.h>
 #include <common.h>
 #include <part.h>
 #include <ext4fs.h>
@@ -86,6 +87,7 @@ struct fstype_info {
 	int (*read)(const char *filename, void *buf, int offset, int len);
 	int (*write)(const char *filename, void *buf, int offset, int len);
 	void (*close)(void);
+	int (*uuid)(char *uuid_str);
 };
 
 static struct fstype_info fstypes[] = {
@@ -113,6 +115,7 @@ static struct fstype_info fstypes[] = {
 		.size = ext4fs_size,
 		.read = ext4_read_file,
 		.write = fs_write_unsupported,
+		.uuid = ext4fs_uuid,
 	},
 #endif
 #ifdef CONFIG_SANDBOX
@@ -206,6 +209,17 @@ static void fs_close(void)
 	fs_type = FS_TYPE_ANY;
 }
 
+int fs_uuid(char *uuid_str)
+{
+	struct fstype_info *info = fs_get_info(fs_type);
+	int ret = -ENOSYS;
+
+	if (info->uuid)
+		ret = info->uuid(uuid_str);
+
+	return ret;
+}
+
 int fs_ls(const char *dirname)
 {
 	int ret;
@@ -443,3 +457,28 @@ int do_save(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 
 	return 0;
 }
+
+int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+		int fstype)
+{
+	int ret;
+	char uuid[37];
+	memset(uuid, 0, sizeof(uuid));
+
+	if (argc < 3 || argc > 4)
+		return CMD_RET_USAGE;
+
+	if (fs_set_blk_dev(argv[1], argv[2], fstype))
+		return 1;
+
+	ret = fs_uuid(uuid);
+	if (ret)
+		return ret;
+
+	if (argc == 4)
+		setenv(argv[3], uuid);
+	else
+		printf("%s\n", uuid);
+
+	return 0;
+}
diff --git a/include/ext4fs.h b/include/ext4fs.h
index 6c419f3..19816de 100644
--- a/include/ext4fs.h
+++ b/include/ext4fs.h
@@ -137,6 +137,7 @@ void ext4fs_reinit_global(void);
 int ext4fs_ls(const char *dirname);
 int ext4fs_exists(const char *filename);
 int ext4fs_size(const char *filename);
+int ext4fs_uuid(char *uuid_str);
 void ext4fs_free_node(struct ext2fs_node *node, struct ext2fs_node *currroot);
 int ext4fs_devread(lbaint_t sector, int byte_offset, int byte_len, char *buf);
 void ext4fs_set_blk_dev(block_dev_desc_t *rbdd, disk_partition_t *info);
diff --git a/include/fs.h b/include/fs.h
index 06a45f2..41082b3 100644
--- a/include/fs.h
+++ b/include/fs.h
@@ -92,5 +92,7 @@ int file_exists(const char *dev_type, const char *dev_part, const char *file,
 		int fstype);
 int do_save(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
 		int fstype);
+int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+		int fstype);
 
 #endif /* _FS_H */
-- 
1.9.3