Re: [libvirt] [PATCH 3/5] virStorageBackendIQNFound: Rework iscsiadm output parsing

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(a)redhat.com&gt; > --- > src/util/viriscsi.c | 85 +++++++++++++++++++++-------------------------------- > 1 file changed, 34 insertions(+), 51 deletions(-) > I assume virCommandSetOutputBuffer didn't exist when this code was created.

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.

> 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,

but at least it's for other purposes and perhaps less susceptible to the line && *line adjustment.