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.
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.
IDC - let's see if sscanf causes any other recollections before R-by'ing.
John
>
> - virCommandSetOutputFD(cmd, &fd);
> - if (virCommandRunAsync(cmd, NULL) < 0)
> - goto cleanup;
> + line = outbuf;
> + while (line) {
> + char *newline;
> + int num;
>
> - if ((fp = VIR_FDOPEN(fd, "r")) == NULL) {
> - virReportError(VIR_ERR_INTERNAL_ERROR,
> - _("Failed to open stream for file descriptor "
> - "when reading output from '%s': '%s'"),
> - ISCSIADM, virStrerror(errno, ebuf, sizeof(ebuf)));
> - goto cleanup;
> - }
> + if (!(newline = strchr(line, '\n')))
> + break;
>
> - while (fgets(line, LINE_SIZE, fp) != NULL) {
> - newline = strrchr(line, '\n');
> - if (newline == NULL) {
> - virReportError(VIR_ERR_INTERNAL_ERROR,
> - _("Unexpected line > %d characters "
> - "when parsing output of '%s'"),
> - LINE_SIZE, ISCSIADM);
> - goto cleanup;
> - }
> *newline = '\0';
>
> - iqn = strrchr(line, ',');
> - if (iqn == NULL)
> - continue;
> - iqn++;
> + VIR_FREE(iface);
> + VIR_FREE(iqn);
> + num = sscanf(line, "%ms %*[^,],%*[^,],%*[^,],%*[^,],%ms", &iface, &iqn);
> +
> + if (num != 2) {
> + virReportError(VIR_ERR_INTERNAL_ERROR,
> + _("malformed output of %s: %s"),
> + ISCSIADM, line);
> + goto cleanup;
> + }
>
> if (STREQ(iqn, initiatoriqn)) {
> - token = strchr(line, ' ');
> - if (!token) {
> - virReportError(VIR_ERR_INTERNAL_ERROR,
> - _("Missing space when parsing output "
> - "of '%s'"), ISCSIADM);
> - goto cleanup;
> - }
> -
> - if (VIR_STRNDUP(*ifacename, line, token - line) < 0)
> - goto cleanup;
> + VIR_STEAL_PTR(*ifacename, iface);
>
> VIR_DEBUG("Found interface '%s' with IQN '%s'", *ifacename, iqn);
> break;
> }
> - }
>
> - if (virCommandWait(cmd, NULL) < 0)
> - goto cleanup;
> + line = newline + 1;
> + }
>
> ret = *ifacename ? IQN_FOUND : IQN_MISSING;
>
> @@ -189,11 +173,10 @@ virStorageBackendIQNFound(const char *initiatoriqn,
> if (ret != IQN_FOUND)
> VIR_DEBUG("Could not find interface with IQN '%s'", iqn);
>
> - VIR_FREE(line);
> - VIR_FORCE_FCLOSE(fp);
> - VIR_FORCE_CLOSE(fd);
> + VIR_FREE(iqn);
> + VIR_FREE(iface);
> + VIR_FREE(outbuf);
> virCommandFree(cmd);
> -
> return ret;
> }
>
>
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