commit 437eabd0399a9293ba6c4501de293c51794cd70a
author Adam Langley <alangley@gmail.com> Tue Sep 29 10:55:09 2020 -0700
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> Tue Sep 29 18:37:22 2020 +0000
tree 2e6878d038909c74e8454c13776c700f67871833
parent bb72a8d649232a74951401a22a9d99fcc5407a3a

modulewrapper: fix sending empty spans.

Sending empty spans tripped up the code because it never considered
the iovec to have been sent. Instead, filter out empty iovecs in the
first place.

Change-Id: I48ea2a887ca64c73051346f3096735c30507525a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/43124
Commit-Queue: Adam Langley <alangley@gmail.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: David Benjamin <davidben@google.com>

util/fipstools/acvp/modulewrapper/modulewrapper.cc

diff --git a/util/fipstools/acvp/modulewrapper/modulewrapper.cc b/util/fipstools/acvp/modulewrapper/modulewrapper.cc
index 5de8b5d..219fe7e 100644
--- a/util/fipstools/acvp/modulewrapper/modulewrapper.cc
+++ b/util/fipstools/acvp/modulewrapper/modulewrapper.cc
@@ -78,14 +78,19 @@
   iovs[0].iov_base = nums;
   iovs[0].iov_len = sizeof(uint32_t) * (1 + spans.size());
 
+  size_t num_iov = 1;
   for (size_t i = 0; i < spans.size(); i++) {
     const auto &span = spans[i];
     nums[i + 1] = span.size();
-    iovs[i + 1].iov_base = const_cast<uint8_t *>(span.data());
-    iovs[i + 1].iov_len = span.size();
+    if (span.size() == 0) {
+      continue;
+    }
+
+    iovs[num_iov].iov_base = const_cast<uint8_t *>(span.data());
+    iovs[num_iov].iov_len = span.size();
+    num_iov++;
   }
 
-  const size_t num_iov = spans.size() + 1;
   size_t iov_done = 0;
   while (iov_done < num_iov) {
     ssize_t r;
@@ -98,7 +103,7 @@
     }
 
     size_t written = r;
-    for (size_t i = iov_done; written > 0 && i < num_iov; i++) {
+    for (size_t i = iov_done; i < num_iov && written > 0; i++) {
       iovec &iov = iovs[i];
 
       size_t done = written;