On 07/03/2018 01:18 AM, John Ferlan wrote:
>
>
> On 06/29/2018 11:01 AM, Michal Privoznik wrote:
>> Firstly, we can utilize virCommandSetOutputBuffer() API which
>> will collect the command output for us. Secondly, sscanf()-ing
>> through each line is easier to understand (and more robust) than
>> jumping over a string with strchr().
>>
>> Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx>
>> ---
>> src/util/viriscsi.c | 85 +++++++++++++++++++++--------------------------------
>> 1 file changed, 34 insertions(+), 51 deletions(-)
>>
>
> I assume virCommandSetOutputBuffer didn't exist when this code was created.
Perhaps. Let me check git log. .. .. And yes, you are right.
virCommandSetOutputBuffer was introduced among with other basic
virCommand* APIs by Dan in late 2010 (f16ad06fb2aeb5e5c9974). But this
function was introduced by Dave in Jan 2010 so he couldn't have used it.
>
> Also, why do I have this recollection related to portability of sscanf?
> I know we use it elsewhere, but some oddball issue that someone like
> Eric may recollect or know about.
I don't know about anything. But since we use it in our code pretty
freely I assumed there is no problem with it.
>
>> diff --git a/src/util/viriscsi.c b/src/util/viriscsi.c
>> index 2e55b3c10b..44788056fd 100644
>> --- a/src/util/viriscsi.c
>> +++ b/src/util/viriscsi.c
>> @@ -108,7 +108,6 @@ virISCSIGetSession(const char *devpath,
>>
>>
>>
>> -#define LINE_SIZE 4096
>> #define IQN_FOUND 1
>> #define IQN_MISSING 0
>> #define IQN_ERROR -1
>> @@ -117,71 +116,56 @@ static int
>> virStorageBackendIQNFound(const char *initiatoriqn,
>> char **ifacename)
>> {
>> - int ret = IQN_ERROR, fd = -1;
>> - char ebuf[64];
>> - FILE *fp = NULL;
>> - char *line = NULL, *newline = NULL, *iqn = NULL, *token = NULL;
>> + int ret = IQN_ERROR;
>> + char *outbuf = NULL;
>> + char *line = NULL;
>> + char *iface = NULL;
>> + char *iqn = NULL;
>> virCommandPtr cmd = virCommandNewArgList(ISCSIADM,
>> "--mode", "iface", NULL);
>>
>> *ifacename = NULL;
>>
>> - if (VIR_ALLOC_N(line, LINE_SIZE) != 0) {
>> - virReportError(VIR_ERR_INTERNAL_ERROR,
>> - _("Could not allocate memory for output of '%s'"),
>> - ISCSIADM);
>> + virCommandSetOutputBuffer(cmd, &outbuf);
>> + if (virCommandRun(cmd, NULL) < 0)
>> goto cleanup;
>> - }
>>
>> - memset(line, 0, LINE_SIZE);
>> + /* Example of data we are dealing with:
>> + * default tcp,<empty>,<empty>,<empty>,<empty>
>> + * iser iser,<empty>,<empty>,<empty>,<empty>
>> + * libvirt-iface-253db048 tcp,<empty>,<empty>,<empty>,iqn.2017-03.com.user:client
>> + */
>
> Nice to have an example especially since this is a bit of a edge case...
>
> Another option - virStringSplitCount on the "\n" to get the number of
> lines and then on each line again using "," to tear apart the pieces.
> This I assume works as I don't have a initiatoriqn set up to test.
>
> Any thoughts/recollections about sscanf? I assume it'll be felt that
> virStringSplit might be overkill,
Indeed.
> but at least it's for other purposes
> and perhaps less susceptible to the line && *line adjustment.
I like sscanf() more because it's fewer lines of code, the variables I
need are assigned value immediately and also memory footprint is smaller
(I guess) since there's no need to store multiple arrays.
Michal
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