fs: make it possible to read the filesystem UUID

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.

changes rfc -> v1:
 - make the environment variable an option parameter. If not
   given, the UUID is printed out. If given, it is stored in the env
   variable.
 - corrected typos
 - return error codes

changes v1 -> v2:
 - fix return code of do_fs_uuid(..)
 - document do_fs_uuid(..)
 - implement fs_uuid_unsuported(..) be more consistent with the
   way other optional functionality works

changes v2 -> v3:
 - change ext4fs_uuid(..) to make use of #if .. #else .. #endif
   construct to get rid of unreachable code

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@gmail.com>
Acked-by: Stephen Warren <swarren@nvidia.com>

diff --git a/README b/README
index 837dca0c931852d5592047fe19012ffeb3e3e6a3..380656563fe4f8b8fa01d46e5c9f409b57e3a309 100644 (file)
--- 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 6cc4de8a73f6ab24a20760ded2d64e395b65a94f..508a0b28f5ad325ad4059d539a1fad3257884040 100644 (file)
--- 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/common/cmd_fs_uuid.c b/common/cmd_fs_uuid.c
new file mode 100644 (file)
index 0000000..613f3a4
--- /dev/null
+++ b/common/cmd_fs_uuid.c
@@ -0,0 +1,26 @@
+/*
+ * cmd_fs_uuid.c -- fsuuid command
+ *
+ * Copyright (C) 2014, Bachmann electronic GmbH
+ *
+ * SPDX-License-Identifier:    GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <fs.h>
+
+static int do_fs_uuid_wrapper(cmd_tbl_t *cmdtp, int flag,
+       int argc, char * const argv[])
+{
+       return do_fs_uuid(cmdtp, flag, argc, argv, FS_TYPE_ANY);
+}
+
+U_BOOT_CMD(
+       fsuuid, 4, 1, do_fs_uuid_wrapper,
+       "Look up a filesystem UUID",
+       "<interface> <dev>:<part>\n"
+       "    - print filesystem UUID\n"
+       "fsuuid <interface> <dev>:<part> <varname>\n"
+       "    - set environment variable to filesystem UUID\n"
+);

diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index cbdc22026deb63a24968cbd3c0078407940bc5a2..87d51285184ae28c693a01fe9666e60fa1be55ce 100644 (file)
--- a/fs/ext4/ext4fs.c
+++ b/fs/ext4/ext4fs.c
@@ -231,3 +231,18 @@ int ext4_read_file(const char *filename, void *buf, int offset, int len)
 
        return len_read;
 }
+
+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;
+#else
+       return -ENOSYS;
+#endif
+}

diff --git a/fs/fs.c b/fs/fs.c
index dd680f39c9ca60472ea91f37a7a325f95da3b672..e4ad6bc3308d77dab534bc1fcd969ad68d037fb8 100644 (file)
--- 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>
@@ -67,6 +68,11 @@ static inline void fs_close_unsupported(void)
 {
 }
 
+static inline int fs_uuid_unsupported(char *uuid_str)
+{
+       return -1;
+}
+
 struct fstype_info {
        int fstype;
        /*
@@ -86,6 +92,7 @@ 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[] = {
@@ -100,6 +107,7 @@ static struct fstype_info fstypes[] = {
                .size = fat_size,
                .read = fat_read_file,
                .write = fs_write_unsupported,
+               .uuid = fs_uuid_unsupported,
        },
 #endif
 #ifdef CONFIG_FS_EXT4
@@ -113,6 +121,7 @@ static struct fstype_info fstypes[] = {
                .size = ext4fs_size,
                .read = ext4_read_file,
                .write = fs_write_unsupported,
+               .uuid = ext4fs_uuid,
        },
 #endif
 #ifdef CONFIG_SANDBOX
@@ -126,6 +135,7 @@ static struct fstype_info fstypes[] = {
                .size = sandbox_fs_size,
                .read = fs_read_sandbox,
                .write = fs_write_sandbox,
+               .uuid = fs_uuid_unsupported,
        },
 #endif
        {
@@ -138,6 +148,7 @@ static struct fstype_info fstypes[] = {
                .size = fs_size_unsupported,
                .read = fs_read_unsupported,
                .write = fs_write_unsupported,
+               .uuid = fs_uuid_unsupported,
        },
 };
 
@@ -206,6 +217,13 @@ 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);
+
+       return info->uuid(uuid_str);
+}
+
 int fs_ls(const char *dirname)
 {
        int ret;
@@ -443,3 +461,28 @@ 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 CMD_RET_FAILURE;
+
+       if (argc == 4)
+               setenv(argv[3], uuid);
+       else
+               printf("%s\n", uuid);
+
+       return CMD_RET_SUCCESS;
+}

diff --git a/include/ext4fs.h b/include/ext4fs.h
index 6c419f3a233759c7e0998a1e5a25d7792a00bcfe..38970e4817775ed3341a37271cf2c0f48c0b95f4 100644 (file)
--- a/include/ext4fs.h
+++ b/include/ext4fs.h
@@ -145,4 +145,5 @@ int ext4fs_probe(block_dev_desc_t *fs_dev_desc,
                 disk_partition_t *fs_partition);
 int ext4_read_file(const char *filename, void *buf, int offset, int len);
 int ext4_read_superblock(char *buffer);
+int ext4fs_uuid(char *uuid_str);
 #endif

diff --git a/include/fs.h b/include/fs.h
index 06a45f2788323b5d0fef4debf677bcf942cebe4d..491c60a7cb909114f5b63064157d1cde400dd02b 100644 (file)
--- a/include/fs.h
+++ b/include/fs.h
@@ -93,4 +93,11 @@ int file_exists(const char *dev_type, const char *dev_part, const char *file,
 int do_save(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
                int fstype);
 
+/*
+ * Determine the UUID of the specified filesystem and print it. Optionally it is
+ * possible to store the UUID directly in env.
+ */
+int do_fs_uuid(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[],
+               int fstype);
+
 #endif /* _FS_H */