gvfs-helper-client: be careful about process entries

The gh_client__find_long_running_process() method returns a
gh_server__process pointer when finding a process. However, that could
be contained within the hashtable of long-running processes _or_ a
brand-new struct due to creating a new process.

This means that we are leaking data in these cases where a struct is
created directly. Add a new signal to say whether or not this pointer
should be removed. Note that there are some error cases in the callers
that already FREE_AND_NULL() the value, but that does not seem to be a
problem in our test scripts.

This change is necessary to help t5799-gvfs-helper.sh pass when compiled
with SANITIZE=leak.

Signed-off-by: Derrick Stolee <[email protected]>

Author: derrickstolee

gvfs-helper-client.c

@@ -371,7 +371,8 @@ static void gh_client__choose_odb(void)
 }
 
 static struct gh_server__process *gh_client__find_long_running_process(
-	unsigned int cap_needed)
+	unsigned int cap_needed,
+	int *must_free)
 {
 	struct gh_server__process *entry;
 	struct strvec argv = STRVEC_INIT;
@@ -416,6 +417,7 @@ static struct gh_server__process *gh_client__find_long_running_process(
 	if (!entry) {
 		entry = xmalloc(sizeof(*entry));
 		entry->supported_capabilities = 0;
+		*must_free = 1;
 
 		if (subprocess_start_strvec(&gh_server__subprocess_map,
 					  &entry->subprocess, 1,
@@ -475,13 +477,14 @@ int gh_client__drain_queue(enum gh_client__created *p_ghc)
 	int nr_loose = 0;
 	int nr_packfile = 0;
 	int err = 0;
+	int must_free = 0;
 
 	*p_ghc = GHC__CREATED__NOTHING;
 
 	if (!gh_client__oidset_count)
 		return 0;
 
-	entry = gh_client__find_long_running_process(CAP_OBJECTS);
+	entry = gh_client__find_long_running_process(CAP_OBJECTS, &must_free);
 	if (!entry)
 		return -1;
 
@@ -511,6 +514,9 @@ int gh_client__drain_queue(enum gh_client__created *p_ghc)
 	oidset_clear(&gh_client__oidset_queued);
 	gh_client__oidset_count = 0;
 
+	if (must_free)
+		FREE_AND_NULL(entry);
+
 	return err;
 }
 
@@ -526,6 +532,7 @@ int gh_client__get_immediate(const struct object_id *oid,
 	int nr_loose = 0;
 	int nr_packfile = 0;
 	int err = 0;
+	int must_free = 0;
 
 	/*
 	 * Keep this trace as a printf only, so that it goes to the
@@ -536,7 +543,7 @@ int gh_client__get_immediate(const struct object_id *oid,
 	if (trace2_is_enabled())
 		trace2_printf("gh_client__get_immediate: %s", oid_to_hex(oid));
 
-	entry = gh_client__find_long_running_process(CAP_OBJECTS);
+	entry = gh_client__find_long_running_process(CAP_OBJECTS, &must_free);
 	if (!entry)
 		return -1;
 
@@ -561,6 +568,9 @@ int gh_client__get_immediate(const struct object_id *oid,
 
 	trace2_region_leave("gh-client", "objects/get", the_repository);
 
+	if (must_free)
+		FREE_AND_NULL(entry);
+
 	return err;
 }
 
@@ -580,8 +590,9 @@ int gh_client__prefetch(timestamp_t seconds_since_epoch,
 	int nr_loose = 0;
 	int nr_packfile = 0;
 	int err = 0;
+	int must_free = 0;
 
-	entry = gh_client__find_long_running_process(CAP_OBJECTS);
+	entry = gh_client__find_long_running_process(CAP_OBJECTS, &must_free);
 	if (!entry)
 		return -1;
 
@@ -613,5 +624,8 @@ int gh_client__prefetch(timestamp_t seconds_since_epoch,
 	if (nr_packfiles_received)
 		*nr_packfiles_received = nr_packfile;
 
+	if (must_free)
+		FREE_AND_NULL(entry);
+
 	return err;
 }