util: Check for errors in virLogSetFromEnv

And make callers check the return value as well.  This helps error out early for
invalid environment variables.

That is desirable because it could lead to deadlocks.  This can happen when
resetting logging after fork() reports translated errors because gettext
functions are not reentrant.  Well, it is not limited to resetting logging after
fork(), it can be any translation at that phase, but parsing environment
variables is easy to make fail on purpose to show the result, it can also happen
just due to a typo.

Before this commit it is possible to deadlock the daemon on startup
with something like:

LIBVIRT_LOG_FILTERS='1:*' LIBVIRT_LOG_OUTPUTS=1:stdout libvirtd

where filters are used to enable more logging and hence make the race less rare
and outputs are set to invalid

Combined with the previous patches this changes
the following from:

...
<deadlock>

to:

...
libvirtd: initialisation failed

The error message is improved in future commits and is also possible thanks to
this patch.

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>

src/admin/libvirt-admin.c

@@ -55,7 +55,8 @@ virAdmGlobalInit(void)
     if (virErrorInitialize() < 0)
         goto error;
 
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        goto error;
 
 #ifdef WITH_LIBINTL_H
     if (!bindtextdomain(PACKAGE, LOCALEDIR))

src/libvirt.c

@@ -232,7 +232,8 @@ virGlobalInit(void)
         goto error;
     }
 
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        goto error;
 
     virNetTLSInit();
 

src/lxc/lxc_controller.c

@@ -2503,7 +2503,8 @@ int main(int argc, char *argv[])
     }
 
     /* Initialize logging */
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        exit(EXIT_FAILURE);
 
     while (1) {
         int c;

src/remote/remote_ssh_helper.c

@@ -402,7 +402,8 @@ int main(int argc, char **argv)
     virFileActivateDirOverrideForProg(argv[0]);
 
     /* Initialize the log system */
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        exit(EXIT_FAILURE);
 
     uri_str = argv[1];
     VIR_DEBUG("Using URI %s", uri_str);

src/security/virt-aa-helper.c

@@ -1449,7 +1449,8 @@ main(int argc, char **argv)
     virFileActivateDirOverrideForProg(argv[0]);
 
     /* Initialize the log system */
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        exit(EXIT_FAILURE);
 
     /* clear the environment */
     environ = NULL;

src/util/vircommand.c

@@ -751,7 +751,8 @@ virExec(virCommand *cmd)
     VIR_FORCE_CLOSE(null);
 
     /* Initialize full logging for a while */
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        goto fork_error;
 
     if (cmd->pidfile &&
         virPipe(pipesync) < 0)

src/util/virdaemon.c

@@ -183,7 +183,8 @@ virDaemonSetupLogging(const char *daemon_name,
         return -1;
 
     /* If there are some environment variables defined, use those instead */
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        return -1;
 
     /*
      * Command line override for --verbose

src/util/virlog.c

@@ -1200,24 +1200,34 @@ virLogParseDefaultPriority(const char *priority)
  *
  * Sets virLogDefaultPriority, virLogFilters and virLogOutputs based on
  * environment variables.
+ *
+ * This function might fail which should also make the caller fail.
  */
-void
+int
 virLogSetFromEnv(void)
 {
     const char *debugEnv;
 
     if (virLogInitialize() < 0)
-        return;
+        return -1;
 
     debugEnv = getenv("LIBVIRT_DEBUG");
-    if (debugEnv && *debugEnv)
-        virLogSetDefaultPriority(virLogParseDefaultPriority(debugEnv));
+    if (debugEnv && *debugEnv) {
+        int priority = virLogParseDefaultPriority(debugEnv);
+        if (priority < 0 ||
+            virLogSetDefaultPriority(priority) < 0)
+            return -1;
+    }
     debugEnv = getenv("LIBVIRT_LOG_FILTERS");
-    if (debugEnv && *debugEnv)
-        virLogSetFilters(debugEnv);
+    if (debugEnv && *debugEnv &&
+        virLogSetFilters(debugEnv))
+        return -1;
     debugEnv = getenv("LIBVIRT_LOG_OUTPUTS");
-    if (debugEnv && *debugEnv)
-        virLogSetOutputs(debugEnv);
+    if (debugEnv && *debugEnv &&
+        virLogSetOutputs(debugEnv))
+        return -1;
+
+    return 0;
 }
 
 

src/util/virlog.h

@@ -146,7 +146,7 @@ char *virLogGetFilters(void);
 char *virLogGetOutputs(void);
 virLogPriority virLogGetDefaultPriority(void);
 int virLogSetDefaultPriority(virLogPriority priority);
-void virLogSetFromEnv(void);
+int virLogSetFromEnv(void) G_GNUC_WARN_UNUSED_RESULT;
 void virLogOutputFree(virLogOutput *output);
 void virLogOutputListFree(virLogOutput **list, int count);
 void virLogFilterFree(virLogFilter *filter);

tests/testutils.c

@@ -835,7 +835,9 @@ int virTestMain(int argc,
     if (virErrorInitialize() < 0)
         return EXIT_FAILURE;
 
-    virLogSetFromEnv();
+    if (virLogSetFromEnv() < 0)
+        return EXIT_FAILURE;
+
     if (!getenv("LIBVIRT_DEBUG") && !virLogGetNbOutputs()) {
         if (!(output = virLogOutputNew(virtTestLogOutput, virtTestLogClose,
                                        &testLog, VIR_LOG_DEBUG,