On 06.12.2012 13:29, Laine Stump wrote:
On 12/06/2012 06:34 AM, Michal Privoznik wrote:
If the debugging is enabled, the virCommand subsystem catches debug messages in the command output as well. In that case, we can't assume the string corresponding to command's stdout will start with specific prefix. But the prefix can be moved deeper in the string. This bug shows itself when parsing dnsmasq output:
2012-12-06 11:18:11.445+0000: 18491: error : dnsmasqCapsSetFromBuffer:664 : internal error cannot parse /usr/sbin/dnsmasq version number in '2012-12-06 11:11:02.232+0000: 18492: debug : virFileClose:72 : Closed fd 22'
We can clearly see that the output of dnsmasq --version doesn't start with expected "Dnsmasq version " string but a libvirt debug output.
This is a bug in virCommand, and should also affect qemuCapsParseHelpStr(). Is there no way to fix it at the source, rather than working around it like this?
Oh, right. The reason why this doesn't get exposed with qemuCapsParseHelpStr() is - we are not keeping stderr when executing 'qemu --help' but we are doing that for dnsmasq. So I guess this patch is obsolete and should be instead replaced by: diff --git a/src/util/dnsmasq.c b/src/util/dnsmasq.c index 4f210d2..bee3b61 100644 --- a/src/util/dnsmasq.c +++ b/src/util/dnsmasq.c @@ -715,7 +715,6 @@ dnsmasqCapsRefreshInternal(dnsmasqCapsPtr caps, bool force) cmd = virCommandNewArgList(caps->binaryPath, "--version", NULL); virCommandSetOutputBuffer(cmd, &version); - virCommandSetErrorBuffer(cmd, &version); virCommandAddEnvPassCommon(cmd); virCommandClearCaps(cmd); if (virCommandRun(cmd, NULL) < 0) { @@ -727,7 +726,6 @@ dnsmasqCapsRefreshInternal(dnsmasqCapsPtr caps, bool force) cmd = virCommandNewArgList(caps->binaryPath, "--help", NULL); virCommandSetOutputBuffer(cmd, &help); - virCommandSetErrorBuffer(cmd, &help); virCommandAddEnvPassCommon(cmd); virCommandClearCaps(cmd); if (virCommandRun(cmd, NULL) < 0) {
--- src/util/dnsmasq.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/src/util/dnsmasq.c b/src/util/dnsmasq.c index 4f210d2..de0293a 100644 --- a/src/util/dnsmasq.c +++ b/src/util/dnsmasq.c @@ -641,9 +641,9 @@ dnsmasqCapsSetFromBuffer(dnsmasqCapsPtr caps, const char *buf)
caps->noRefresh = true;
- p = STRSKIP(buf, DNSMASQ_VERSION_STR); - if (!p) + if (!(p = strstr(buf, DNSMASQ_VERSION_STR))) goto fail; + p += sizeof(DNSMASQ_VERSION_STR) - 1;
Why -1 ? That happens to work, but wouldn't if the version string didn't end with a space.
sizeof(const char[]) counts '\0' at the end. We don't want that here.
virSkipSpaces(&p); if (virParseVersionString(p, &caps->version, true) < 0) goto fail;
I'd rather make sure that nobody has a bright idea on how to fix virCommand before pushing this.
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