[Spice-devel] reds: Assure we don't have stale statistic files before trying to create a new one

Submitted by Frediano Ziglio on July 15, 2015, 10:05 a.m.

Details

Message ID 1436954711-15007-1-git-send-email-fziglio@redhat.com
State Accepted
Commit 40537f6a3e3389b8377b0ae790c62ea0da8aa6d8
Headers show

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Commit Message

Frediano Ziglio July 15, 2015, 10:05 a.m.
If a previous Qemu executable is not able to delete the statistic file
on the next creation with same name (statitics file are based on pid
numbers so if pid get reused for another Qemu process you get the same
name) it fails as you can't open a file with 0444 permissions (these
are the permission used to create these files).
This patch assure there are no stale file trying to remove it before the
creation of the new one. As file is based on pid and name used for spice
you are not deleting another file.

Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
---
 server/reds.c | 1 +
 1 file changed, 1 insertion(+)

Patch hide | download patch | download mbox

diff --git a/server/reds.c b/server/reds.c
index 0867edb..d1edc06 100644
--- a/server/reds.c
+++ b/server/reds.c
@@ -3291,6 +3291,7 @@  static int do_spice_init(SpiceCoreInterface *core_interface)
     shm_name_len = strlen(SPICE_STAT_SHM_NAME) + 20;
     reds->stat_shm_name = (char *)spice_malloc(shm_name_len);
     snprintf(reds->stat_shm_name, shm_name_len, SPICE_STAT_SHM_NAME, getpid());
+    shm_unlink(reds->stat_shm_name);
     if ((fd = shm_open(reds->stat_shm_name, O_CREAT | O_RDWR, 0444)) == -1) {
         spice_error("statistics shm_open failed, %s", strerror(errno));
     }

Comments

Hi Frediano,

On 07/15/2015 01:05 PM, Frediano Ziglio wrote:
> If a previous Qemu executable is not able to delete the statistic file
> on the next creation with same name (statitics file are based on pid
> numbers so if pid get reused for another Qemu process you get the same
> name) it fails as you can't open a file with 0444 permissions (these
> are the permission used to create these files).
> This patch assure there are no stale file trying to remove it before the
> creation of the new one. As file is based on pid and name used for spice
> you are not deleting another file.

You can add a reference to the bug:

Fixes: rhbz#1177326

Ack.

Thanks,
     Uri.

>
> Signed-off-by: Frediano Ziglio <fziglio@redhat.com>
> ---
>   server/reds.c | 1 +
>   1 file changed, 1 insertion(+)
>
> diff --git a/server/reds.c b/server/reds.c
> index 0867edb..d1edc06 100644
> --- a/server/reds.c
> +++ b/server/reds.c
> @@ -3291,6 +3291,7 @@ static int do_spice_init(SpiceCoreInterface *core_interface)
>       shm_name_len = strlen(SPICE_STAT_SHM_NAME) + 20;
>       reds->stat_shm_name = (char *)spice_malloc(shm_name_len);
>       snprintf(reds->stat_shm_name, shm_name_len, SPICE_STAT_SHM_NAME, getpid());
> +    shm_unlink(reds->stat_shm_name);
>       if ((fd = shm_open(reds->stat_shm_name, O_CREAT | O_RDWR, 0444)) == -1) {
>           spice_error("statistics shm_open failed, %s", strerror(errno));
>       }
>