The mock fopen() function will abort if "/proc/mounts" is requested with "r" permissions and VIR_CGROUP_MOCK_FILENAME env var is not set. Unfortunately this is triggering by the libselinux library constructor when it tries to read /proc/mounts to find out if selinuxfs is mounted in an unusual place. This, however, only affects libselinux in Debian as that opens with "r", while in Fedora / RHEL it opens "re" and thus luckily never triggered the abort(), instead getting an EACCESS. Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; --- tests/vircgroupmock.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/tests/vircgroupmock.c b/tests/vircgroupmock.c index 06bd0a5f29..9c67a44b0d 100644 --- a/tests/vircgroupmock.c +++ b/tests/vircgroupmock.c @@ -460,8 +460,10 @@ FILE *fopen(const char *path, const char *mode) } if (type) { - if (!filename) - abort(); + if (!filename) { + errno = EACCES; + return NULL; + } if (virAsprintfQuiet(&filepath, "%s/vircgroupdata/%s.%s", abs_srcdir, filename, type) < 0) { abort();

On Wed, Mar 27, 2019 at 12:55:18PM +0100, Michal Privoznik wrote: > On 3/27/19 11:31 AM, Daniel P. Berrangé wrote: >> The mock fopen() function will abort if "/proc/mounts" is >> requested with "r" permissions and VIR_CGROUP_MOCK_FILENAME >> env var is not set. >> >> Unfortunately this is triggering by the libselinux library >> constructor when it tries to read /proc/mounts to find out >> if selinuxfs is mounted in an unusual place. >> >> This, however, only affects libselinux in Debian as that >> opens with "r", while in Fedora / RHEL it opens "re" and >> thus luckily never triggered the abort(), instead getting >> an EACCESS. >> >> Signed-off-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; >> --- >> tests/vircgroupmock.c | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/tests/vircgroupmock.c b/tests/vircgroupmock.c >> index 06bd0a5f29..9c67a44b0d 100644 >> --- a/tests/vircgroupmock.c >> +++ b/tests/vircgroupmock.c >> @@ -460,8 +460,10 @@ FILE *fopen(const char *path, const char *mode) >> } >> if (type) { >> - if (!filename) >> - abort(); >> + if (!filename) { >> + errno = EACCES; >> + return NULL; >> + } >> if (virAsprintfQuiet(&filepath, "%s/vircgroupdata/%s.%s", >> abs_srcdir, filename, type) < 0) { >> abort(); >> > > How about: > > diff --git i/tests/vircgroupmock.c w/tests/vircgroupmock.c > index 06bd0a5f29..83f43e72bf 100644 > --- i/tests/vircgroupmock.c > +++ w/tests/vircgroupmock.c > @@ -459,9 +459,7 @@ FILE *fopen(const char *path, const char *mode) > } > } > > - if (type) { > - if (!filename) > - abort(); > + if (filename && type) { > if (virAsprintfQuiet(&filepath, "%s/vircgroupdata/%s.%s", > abs_srcdir, filename, type) < 0) { > abort(); That will cause it to try to open the real /proc/mounts, which feels like an undesirable thing as it means the test could silently start relying on host state by mistake.