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host-validate: Be more careful when checking for cgroup support

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Simply checking whether the cgroup name appears somewhere inside
/proc/self/cgroup is enough most of the time, but there are some
corner cases that require a more mindful parsing.
This commit is contained in:
Andrea Bolognani 2016-04-08 14:13:10 +02:00
parent ccf58bd72a
commit 5143429303
1 changed files with 38 additions and 7 deletions
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45
tools/virt-host-validate-common.c
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@ -303,17 +303,48 @@ static int virHostValidateCGroupSupport(const char *hvname,
goto error;
while ((ret = getline(&line, &len, fp)) >= 0 && !matched) {
char *tmp = strstr(line, cg_name);
if (!tmp)
char **cgroups;
char *start;
char *end;
size_t ncgroups;
size_t i;
/* Each line in this file looks like
*
* 4:cpu,cpuacct:/machine.slice/machine-qemu\x2dtest.scope/emulator
*
* Since multiple cgroups can be part of the same line and some cgroup
* names can appear as part of other cgroup names (eg. 'cpu' is a
* prefix for both 'cpuacct' and 'cpuset'), it's not enough to simply
* check whether the cgroup name is present somewhere inside the file.
*
* Moreover, there's nothing stopping the cgroup name from appearing
* in an unrelated mount point name as well */
/* Look for the first colon.
* The part we're interested in starts right after it */
if (!(start = strchr(line, ':')))
continue;
start++;
/* Look for the second colon.
* The part we're interested in ends exactly there */
if (!(end = strchr(start, ':')))
continue;
*end = '\0';
if (!(cgroups = virStringSplitCount(start, ",", 0, &ncgroups)))
continue;
tmp += strlen(cg_name);
if (*tmp != ',' &&
*tmp != ':')
continue;
/* Look for the matching cgroup */
for (i = 0; i < ncgroups; i++) {
if (STREQ(cgroups[i], cg_name))
matched = true;
}
matched = true;
virStringFreeListCount(cgroups, ncgroups);
}
VIR_FREE(line);
VIR_FORCE_FCLOSE(fp);
if (!matched)