runner/resultgen: Explain why json creation might have failed

Sometimes creating the string representation fails. This usually happens
when we have a huge logs (e.g.: something was spamming the dmesg) or the
result generation was run on a very low-end system (e.g. embedded board
with 256 megs of RAM).

Sadly json-c call returns us NULL and provides no explanation
whatsoever. Let's fix a NULL pointer dereference in such cases and print
a mesage that should help people make sense out of what have just
happened.

Cc: Swati Sharma <swati2.sharma@intel.com>
Cc: Petri Latvala <petri.latvala@intel.com>
Signed-off-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>

1 files changed, 13 insertions, 0 deletions

diff --git a/runner/resultgen.c b/runner/resultgen.c
index add4aad5..e2e162b0 100644
--- a/runner/resultgen.c
+++ b/runner/resultgen.c
@@ -1661,6 +1661,19 @@ bool generate_results(int dirfd)
 	}
 
 	json_string = json_object_to_json_string_ext(obj, JSON_C_TO_STRING_PRETTY);
+
+	if (json_string == NULL) {
+		fprintf(stderr, "resultgen: Failed to create json representation of the results.\n");
+		fprintf(stderr, "           This usually means that the results are too big\n");
+		fprintf(stderr, "           to fit in the memory as the text representation\n");
+		fprintf(stderr, "           is being created.\n\n");
+		fprintf(stderr, "           Either something was spamming the logs or your\n");
+		fprintf(stderr, "           system is very low on free mem.\n");
+
+		close(resultsfd);
+		return false;
+	}
+
 	write(resultsfd, json_string, strlen(json_string));
 	close(resultsfd);
 	return true;