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Re: [Qemu-devel] [PATCH] pci-assign: avoid pointless stat
From: |
Eric Blake |
Subject: |
Re: [Qemu-devel] [PATCH] pci-assign: avoid pointless stat |
Date: |
Wed, 4 Jan 2017 11:05:51 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 |
On 01/04/2017 09:05 AM, Paolo Bonzini wrote:
> Just check the errno value after fopen and follow it with fstat.
> This shuts up Coverity's complaint about TOC/TOU violation.
>
> Signed-off-by: Paolo Bonzini <address@hidden>
> ---
> hw/i386/pci-assign-load-rom.c | 16 ++++++++--------
> 1 file changed, 8 insertions(+), 8 deletions(-)
Reviewed-by: Eric Blake <address@hidden>
>
> diff --git a/hw/i386/pci-assign-load-rom.c b/hw/i386/pci-assign-load-rom.c
> index 0d8e4b2..fd59076 100644
> --- a/hw/i386/pci-assign-load-rom.c
> +++ b/hw/i386/pci-assign-load-rom.c
> @@ -39,19 +39,19 @@ void *pci_assign_dev_load_option_rom(PCIDevice *dev,
> struct Object *owner,
> "/sys/bus/pci/devices/%04x:%02x:%02x.%01x/rom",
> domain, bus, slot, function);
>
> - if (stat(rom_file, &st)) {
> - if (errno != ENOENT) {
> - error_report("pci-assign: Invalid ROM.");
> - }
> - return NULL;
> - }
> -
> /* Write "1" to the ROM file to enable it */
> fp = fopen(rom_file, "r+");
> if (fp == NULL) {
> - error_report("pci-assign: Cannot open %s: %s", rom_file,
> strerror(errno));
> + if (errno != ENOENT) {
> + error_report("pci-assign: Cannot open %s: %s", rom_file,
> strerror(errno));
> + }
> return NULL;
> }
> + if (fstat(fileno(fp), &st) == -1) {
> + error_report("pci-assign: Cannot stat %s: %s", rom_file,
> strerror(errno));
> + goto close_rom;
fstat() failure after fopen() success is quite unlikely, but I suppose
it is still possible in some weird situations.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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