Merge pull request #12009 from ncteisen/convinient-fuzz

Convenient Fuzz Tracing

doc/environment_variables.md

@@ -102,6 +102,9 @@ some configuration as environment variables that can be set.
   - INFO - log INFO and ERROR message
   - ERROR - log only errors
 
+* GRPC_TRACE_FUZZER
+  if set, the fuzzers will output trace (it is usually supressed).
+
 * GRPC_DNS_RESOLVER
   Declares which DNS resolver to use. The default is ares if gRPC is built with
   c-ares support. Otherwise, the value of this environment variable is ignored.

test/core/end2end/fuzzers/api_fuzzer.c

@@ -34,6 +34,7 @@
 #include "src/core/lib/iomgr/timer.h"
 #include "src/core/lib/iomgr/timer_manager.h"
 #include "src/core/lib/slice/slice_internal.h"
+#include "src/core/lib/support/env.h"
 #include "src/core/lib/surface/server.h"
 #include "src/core/lib/transport/metadata.h"
 #include "test/core/end2end/data/ssl_test_data.h"
@@ -731,7 +732,9 @@ static validator *make_finished_batch_validator(call_state *cs,
 
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
   grpc_test_only_set_slice_hash_seed(0);
-  if (squelch) gpr_set_log_function(dont_log);
+  char *grpc_trace_fuzzer = gpr_getenv("GRPC_TRACE_FUZZER");
+  if (squelch && grpc_trace_fuzzer == NULL) gpr_set_log_function(dont_log);
+  gpr_free(grpc_trace_fuzzer);
   input_stream inp = {data, data + size};
   grpc_tcp_client_connect_impl = my_tcp_client_connect;
   gpr_now_impl = now_impl;