Eric Blake <eblake@redhat.com> wrote on 03/10/2014 02:09:58 PM:
From: Eric Blake <eblake@redhat.com> To: Stefan Berger/Watson/IBM@IBMUS, libvir-list@redhat.com, Cc: laine@laine.org Date: 03/10/2014 02:24 PM Subject: Re: [libvirt] [PATCH] BZ1072677: Avoid freeing of 0 file descriptor
On 03/08/2014 04:29 PM, Stefan Berger wrote:
From: Stefan Berger <stefanb@linux.vnet.ibm.com>
Avoid the freeing of an array of zero file descriptors in case of error. Introduce a macro VIR_INIT_N_FD to initialize such an array's elements to -1.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com> --- src/qemu/qemu_hotplug.c | 14 +++++++++++--- src/util/virfile.h | 12 ++++++++++++ 2 files changed, 23 insertions(+), 3 deletions(-)
+++ b/src/util/virfile.h @@ -75,6 +75,18 @@ FILE *virFileFdopen(int *fdptr, const char *mode) ATTRIBUTE_RETURN_CHECK; VIR_FILE_CLOSE_PRESERVE_ERRNO | \ VIR_FILE_CLOSE_DONT_LOG))
+static inline void vir_init_n_int(int *ptr, int count, int value) +{ + int i; + + for (i = 0; i < count; i++) + ptr[i] = value; +}
Do we ever plan on using this for values other than '-1'?
It's probably too general for the fd purpose here only.
+ +/* Initialize an array of file descriptors to -1 */ +# define VIR_INIT_N_FD(ptr, count) \ + vir_init_n_int(ptr, count, -1)
Could also be spelled:
memset(ptr, -1, sizeof(*ptr) * count))
which goes back to why we need vir_init_n_int().
Also this would be possible.
I agree that the fix to qemu_hotplug.c to not close fd 0 on failure is needed, but am not sure about the complexity of the virfile.h addition.
So a simple memset() would do? Having a macro for VIR_ALLOC_N_FD() would probably be too much, eh? Stefan