[libvirt] [PATCH 3/6] storage: fs: Don't attempt directory creation if it already exists
Cole Robinson
crobinso at redhat.com
Wed Apr 29 01:46:24 UTC 2015
On 04/28/2015 08:19 AM, Peter Krempa wrote:
> On Mon, Apr 27, 2015 at 16:48:41 -0400, Cole Robinson wrote:
>> The current code attempts to handle this, but it only catches mkdir
>> failing with EEXIST. However if say trying to build /tmp for an
>> unprivileged qemu:///session, mkdir will fail with EPERM.
>>
>> Rather than catch any errors, just don't attempt mkdir if the directory
>> already exists.
>> ---
>> src/util/virfile.c | 13 +++++++------
>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/src/util/virfile.c b/src/util/virfile.c
>> index 87d121d..23a1655 100644
>> --- a/src/util/virfile.c
>> +++ b/src/util/virfile.c
>> @@ -2289,12 +2289,13 @@ virDirCreateNoFork(const char *path,
>> int ret = 0;
>> struct stat st;
>>
>> - if ((mkdir(path, mode) < 0)
>> - && !((errno == EEXIST) && (flags & VIR_DIR_CREATE_ALLOW_EXIST))) {
>> - ret = -errno;
>> - virReportSystemError(errno, _("failed to create directory '%s'"),
>> - path);
>> - goto error;
>> + if (!(flags & VIR_DIR_CREATE_ALLOW_EXIST) || !virFileExists(path)) {
>
> De Morgan's law allows to optimize this into a more readable form:
> if (!(virFileExists(path) && (flags & VIR_DIR_CREATE_ALLOW_EXIST))) {
>
> It's one set of parentheses more but it's readable.
>
Huh, personally I find that form much less readable. You need to mentally
evaluate the parenthesized expression, then remember to take the opposite.
The first one I can read out loud from left to right:
if not ALLOW_EXIST or not file exists:
stuff
Maybe I've just written too much python :)
Regardless I've applied your suggestion locally, will push after the release.
Thanks,
Cole
>> + if (mkdir(path, mode) < 0) {
>> + ret = -errno;
>> + virReportSystemError(errno, _("failed to create directory '%s'"),
>> + path);
>> + goto error;
>> + }
>
> ACK with the condition made human readable.
>
> Peter
>
More information about the libvir-list
mailing list