Re: [libvirt] [PATCH] BZ1072677: Avoid freeing of 0 file descriptor

From: Eric Blake <eblake(a)redhat.com&gt; To: Stefan Berger/Watson/IBM@IBMUS, libvir-list(a)redhat.com, Cc: laine(a)laine.org Date: 03/10/2014 02:24 PM Subject: Re: [libvirt] [PATCH] BZ1072677: Avoid freeing of 0 file

On 03/08/2014 04:29 PM, Stefan Berger wrote: > From: Stefan Berger <stefanb(a)linux.vnet.ibm.com&gt; > > 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(a)linux.vnet.ibm.com&gt; > --- > 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'?

> + > +/* 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().

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.