libbrillo: Fix timeout for libbrillo_http_form_data_fuzzer

This was timing out when it was consuming the stream it had generated
through fuzzing. Reading that stream is now more optimized to avoid
hitting the timeout.

BUG=chromium:1014980
TEST=Fuzzer no longer times out on test case

Change-Id: Ie658a428f42f59d92ea803fd84e087cb87207466
Reviewed-on: https://chromium-review.googlesource.com/1869261
Tested-by: Jeffrey Kardatzke <jkardatzke@google.com>
Commit-Ready: Jeffrey Kardatzke <jkardatzke@google.com>
Legacy-Commit-Queue: Commit Bot <commit-bot@chromium.org>
Reviewed-by: Eric Caruso <ejcaruso@chromium.org>
Cr-Mirrored-From: https://chromium.googlesource.com/chromiumos/platform2
Cr-Mirrored-Commit: 0fc62ad016075a449bcf16c7d0d4f99d449ec747

1 files changed, 4 insertions, 4 deletions

diff --git a/brillo/http/http_form_data_fuzzer.cc b/brillo/http/http_form_data_fuzzer.cc
index e252b47..f5ae4b7 100644
--- a/brillo/http/http_form_data_fuzzer.cc
+++ b/brillo/http/http_form_data_fuzzer.cc
@@ -108,11 +108,11 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
   if (!form_stream)
     return 0;
 
-  uint8_t buffer[512];
-  size_t size_read;
+  // We need to use a decent sized buffer and call ReadAllBlocking to avoid
+  // excess overhead with reading here that can make the fuzzer timeout.
+  uint8_t buffer[32768];
   while (form_stream->GetRemainingSize() > 0) {
-    if (!form_stream->ReadBlocking(buffer, sizeof(buffer), &size_read,
-                                   nullptr)) {
+    if (!form_stream->ReadAllBlocking(buffer, sizeof(buffer), nullptr)) {
       // If there's an error reading from the stream, then bail since we'd
       // likely just see repeated errors and never exit.
       break;