[libvirt] [PATCH] qemu driver: use lseek64 for setting position in logfile

[Stefan Berger]

libvir-list-bounces at redhat.com wrote on 01/04/2011 09:46:07 AM:

> 
> While doing some testing with Qemu and creating huge logfiles I 
> encountered the case where the VM could not start anymore due to the 
> lseek() to the end of the Qemu VM's log file failing. The patch below 
> replaces the two occurrences of lseek() in the relevant path with 
> lseek64() and solves this problem. It may be a good idea to look at 
> other occurrences of lseek() as well whether they should be replaced. 
> off_t is 8 bytes long (64 bit), so it doesn't need to be replaced with 
> the explicit off64_t.
> 
> To reproduce this error, you could do the following:
> 
> dd if=/dev/zero of=/var/log/libvirt/qemu/<name of VM>.log bs=1024 
> count=$((1024*2048))
> 
> and you should get an error like this:
> 
> error: Failed to start domain <name of VM>
> error: Unable to seek to -2147482651 in /var/log/libvirt/qemu/<name of 
> VM>.log: Success
> 
> Signed-off-by: Stefan Berger <stefanb at us.ibm.com>
> 
> ---
>   src/qemu/qemu_driver.c |    6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> Index: libvirt-acl/src/qemu/qemu_driver.c
> ===================================================================
> --- libvirt-acl.orig/src/qemu/qemu_driver.c
> +++ libvirt-acl/src/qemu/qemu_driver.c
[...]

> @@ -2624,7 +2624,7 @@ static int qemudStartVMDaemon(virConnect
>                                 enum virVMOperationType vmop) {
>       int ret;
>       unsigned long long qemuCmdFlags;
> -    int pos = -1;
> +    off_t pos = -1;
>       char ebuf[1024];
>       char *pidfile = NULL;
>       int logfile = -1;

... actually this is really the only hunk that's necessary to fix this 
problem.

  Stefan
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