[libvirt] [PATCH 1/2] qemu: blockPeek: Fix filling of the return buffer

[Eric Blake]

On 09/18/2017 09:11 AM, Peter Krempa wrote:
> Commit 3956af495e broke the blockPeek API since virStorageFileRead
> allocates a return buffer and fills it with the data, while the API
> fills a user-provided buffer. This did not get caught by the compiler
> since the API prototype uses a 'void *'.
> 
> Fix it by transferring the data from the allocated buffer to the user
> provided buffer.
> 
> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1491217
> ---
>  src/qemu/qemu_driver.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index e1a0dd553..93a1c6061 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -11415,6 +11415,7 @@ qemuDomainBlockPeek(virDomainPtr dom,
>      virQEMUDriverPtr driver = dom->conn->privateData;
>      virDomainDiskDefPtr disk = NULL;
>      virDomainObjPtr vm;
> +    char *tmpbuf = NULL;
>      int ret = -1;
> 
>      virCheckFlags(0, -1);
> @@ -11444,12 +11445,15 @@ qemuDomainBlockPeek(virDomainPtr dom,
>      if (virStorageFileRead(disk->src, offset, size, buffer) < 0)
>          goto cleanup;
> 
> +    memcpy(buffer, tmpbuf, size);

Umm, where is tmpbuf actually set to a non-null pointer? Shouldn't the
virStorageFileRead() call also be updated?

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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