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fs: make it possible to read the filesystem UUID

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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>
This commit is contained in:
Christian Gmeiner
2014-11-12 14:35:04 +01:00
committed by Tom Rini
parent 1b51d32c0f
commit 59e890ef7b
7 changed files with 94 additions and 0 deletions
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43
fs/fs.c
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@@ -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;
}