* [Qemu-devel] [PATCH v2 1/1] vvfat: add a label option
2015-06-19 9:35 [Qemu-devel] [PATCH v2 0/1] vvfat label option updated Wolfgang Bumiller
@ 2015-06-19 9:35 ` Wolfgang Bumiller
2015-06-19 12:48 ` Eric Blake
2015-06-19 12:50 ` [Qemu-devel] [PATCH v2 0/1] vvfat label option updated Stefan Hajnoczi
1 sibling, 1 reply; 4+ messages in thread
From: Wolfgang Bumiller @ 2015-06-19 9:35 UTC (permalink / raw)
To: qemu-devel
Until now the vvfat volume label was hardcoded to be
"QEMU VVFAT", now you can pass a file.label=labelname option
to the -drive to change it.
The FAT structure defines the volume label to be limited to
11 bytes and is filled up spaces when shorter than that. The
trailing spaces however aren't exposed to the user by
operating systems.
Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
block/vvfat.c | 25 ++++++++++++++++++++++---
qapi/block-core.json | 6 +++++-
2 files changed, 27 insertions(+), 4 deletions(-)
diff --git a/block/vvfat.c b/block/vvfat.c
index e803589..1f8a240 100644
--- a/block/vvfat.c
+++ b/block/vvfat.c
@@ -322,6 +322,7 @@ typedef struct BDRVVVFATState {
int fat_type; /* 16 or 32 */
array_t fat,directory,mapping;
+ char volume_label[11];
unsigned int cluster_size;
unsigned int sectors_per_cluster;
@@ -859,7 +860,7 @@ static int init_directories(BDRVVVFATState* s,
{
direntry_t* entry=array_get_next(&(s->directory));
entry->attributes=0x28; /* archive | volume label */
- memcpy(entry->name, "QEMU VVFAT ", sizeof(entry->name));
+ memcpy(entry->name, s->volume_label, sizeof(entry->name));
}
/* Now build FAT, and write back information into directory */
@@ -968,7 +969,8 @@ static int init_directories(BDRVVVFATState* s,
bootsector->u.fat16.signature=0x29;
bootsector->u.fat16.id=cpu_to_le32(0xfabe1afd);
- memcpy(bootsector->u.fat16.volume_label,"QEMU VVFAT ",11);
+ memcpy(bootsector->u.fat16.volume_label, s->volume_label,
+ sizeof(bootsector->u.fat16.volume_label));
memcpy(bootsector->fat_type,(s->fat_type==12?"FAT12 ":s->fat_type==16?"FAT16 ":"FAT32 "),8);
bootsector->magic[0]=0x55; bootsector->magic[1]=0xaa;
@@ -1008,6 +1010,11 @@ static QemuOptsList runtime_opts = {
.help = "Create a floppy rather than a hard disk image",
},
{
+ .name = "label",
+ .type = QEMU_OPT_STRING,
+ .help = "Use a volume label other than QEMU VVFAT",
+ },
+ {
.name = "rw",
.type = QEMU_OPT_BOOL,
.help = "Make the image writable",
@@ -1069,7 +1076,7 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
BDRVVVFATState *s = bs->opaque;
int cyls, heads, secs;
bool floppy;
- const char *dirname;
+ const char *dirname, *label;
QemuOpts *opts;
Error *local_err = NULL;
int ret;
@@ -1096,6 +1103,18 @@ static int vvfat_open(BlockDriverState *bs, QDict *options, int flags,
s->fat_type = qemu_opt_get_number(opts, "fat-type", 0);
floppy = qemu_opt_get_bool(opts, "floppy", false);
+ memset(s->volume_label, ' ', sizeof(s->volume_label));
+ label = qemu_opt_get(opts, "label");
+ if (label) {
+ size_t label_length = strlen(label);
+ if (label_length > 11) {
+ error_setg(errp, "vvfat label cannot be longer than 11 bytes");
+ ret = -EINVAL;
+ goto fail;
+ }
+ memcpy(s->volume_label, label, label_length);
+ }
+
if (floppy) {
/* 1.44MB or 2.88MB floppy. 2.88MB can be FAT12 (default) or FAT16. */
if (!s->fat_type) {
diff --git a/qapi/block-core.json b/qapi/block-core.json
index afa9d3d..feb9e4f 100644
--- a/qapi/block-core.json
+++ b/qapi/block-core.json
@@ -1453,13 +1453,17 @@
# @fat-type: #optional FAT type: 12, 16 or 32
# @floppy: #optional whether to export a floppy image (true) or
# partitioned hard disk (false; default)
+# @label: #optional set the volume label, limited to 11 bytes. FAT16 and
+ FAT32 traditionally have some restrictions on labels, which are
+ ignored by most operating systems. Defaults to "QEMU VVFAT".
+ (since 2.4)
# @rw: #optional whether to allow write operations (default: false)
#
# Since: 1.7
##
{ 'struct': 'BlockdevOptionsVVFAT',
'data': { 'dir': 'str', '*fat-type': 'int', '*floppy': 'bool',
- '*rw': 'bool' } }
+ '*label': 'str', '*rw': 'bool' } }
##
# @BlockdevOptionsGenericFormat
--
2.1.4
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [Qemu-devel] [PATCH v2 0/1] vvfat label option updated
2015-06-19 9:35 [Qemu-devel] [PATCH v2 0/1] vvfat label option updated Wolfgang Bumiller
2015-06-19 9:35 ` [Qemu-devel] [PATCH v2 1/1] vvfat: add a label option Wolfgang Bumiller
@ 2015-06-19 12:50 ` Stefan Hajnoczi
1 sibling, 0 replies; 4+ messages in thread
From: Stefan Hajnoczi @ 2015-06-19 12:50 UTC (permalink / raw)
To: Wolfgang Bumiller; +Cc: qemu-devel
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On Fri, Jun 19, 2015 at 11:35:28AM +0200, Wolfgang Bumiller wrote:
> * Till/Until changed
> * Added (since 2.4) to json file
> * Added the 11-byte limit description. Without mentioning the trailing
> spaces in the json file since the guest OS doesn't expose them to
> the user. However, I mentioned it in the commit message.
>
> The limit comes from the FAT structure, but for completeness' sake I
> looked up the FAT descriptions a little more. Turns out at least
> FAT32 labels are "supposed" to be stored with uppercase letters, and
> seem to have some theoretical restrictions on the used characters, but
> neither linux nor windows guests seem to care on the OS side. And at
> least mkfs.vfat's -n option only warns about lowercase letters, but
> doesn't error. Theoretically you're also not allowed to start a label
> with a space, while mkfs.vfat neither warns nor errors about this.
> So I decided to not add any additional checks and only mentioned it in
> the json's doc string.
>
> Wolfgang Bumiller (1):
> vvfat: add a label option
>
> block/vvfat.c | 25 ++++++++++++++++++++++---
> qapi/block-core.json | 6 +++++-
> 2 files changed, 27 insertions(+), 4 deletions(-)
>
> --
> 2.1.4
>
>
>
Thanks, applied to my block tree:
https://github.com/stefanha/qemu/commits/block
Stefan
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^ permalink raw reply [flat|nested] 4+ messages in thread