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xen_disk: cope with missing xenstore "params" node

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When disk is a cdrom and the drive is empty the "params" node in
xenstore might be missing completely: cope with it instead of
segfaulting.

Updated in v2:

- actually removed the strchr(blkdev->params, ':') that caused the
segfault;

- free all the allocated strings from xenstore before returning;

Updated in v3:

- set blkdev fields to NULL after free'ing them.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
This commit is contained in:
Stefano Stabellini 2011-06-27 16:10:01 +01:00 committed by Alexander Graf
parent 37cdfcf194
commit 5ea3c2b405
1 changed files with 27 additions and 7 deletions
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26
hw/xen_disk.c
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@ -616,12 +616,14 @@ static int blk_init(struct XenDevice *xendev)
{
struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
int index, qflags, have_barriers, info = 0;
char *h;
/* read xenstore entries */
if (blkdev->params == NULL) {
char *h = NULL;
blkdev->params = xenstore_read_be_str(&blkdev->xendev, "params");
if (blkdev->params != NULL) {
h = strchr(blkdev->params, ':');
}
if (h != NULL) {
blkdev->fileproto = blkdev->params;
blkdev->filename = h+1;
@ -649,7 +651,7 @@ static int blk_init(struct XenDevice *xendev)
blkdev->mode == NULL ||
blkdev->type == NULL ||
blkdev->dev == NULL) {
return -1;
goto out_error;
}
/* read-only ? */
@ -672,10 +674,15 @@ static int blk_init(struct XenDevice *xendev)
/* setup via xenbus -> create new block driver instance */
xen_be_printf(&blkdev->xendev, 2, "create new bdrv (xenbus setup)\n");
blkdev->bs = bdrv_new(blkdev->dev);
if (blkdev->bs) {
if (bdrv_open(blkdev->bs, blkdev->filename, qflags,
bdrv_find_whitelisted_format(blkdev->fileproto)) != 0) {
bdrv_delete(blkdev->bs);
return -1;
blkdev->bs = NULL;
}
}
if (!blkdev->bs) {
goto out_error;
}
} else {
/* setup via qemu cmdline -> already setup for us */
@ -704,6 +711,19 @@ static int blk_init(struct XenDevice *xendev)
xenstore_write_be_int(&blkdev->xendev, "sectors",
blkdev->file_size / blkdev->file_blk);
return 0;
out_error:
qemu_free(blkdev->params);
blkdev->params = NULL;
qemu_free(blkdev->mode);
blkdev->mode = NULL;
qemu_free(blkdev->type);
blkdev->type = NULL;
qemu_free(blkdev->dev);
blkdev->dev = NULL;
qemu_free(blkdev->devtype);
blkdev->devtype = NULL;
return -1;
}
static int blk_connect(struct XenDevice *xendev)