[PATCH 2/2] cli/show: avoid empty write to stdout in format_part_raw

[David Bremner <david@tethera.net>]

From: Rob Browning <rlb@defaultvalue.org>

Previously if the input was exactly a multiple of the internal buffer
size, notmuch would attempt to fwrite nothing to stdout, but still
expected fwrite to return 1, causing a failure that looked like this:

  $ notmuch show --format=raw id:87o96f1cya.fsf@codeaurora.org
    ...entire message shown as expected..
  Error: Write failed
  $ echo $?
  1

To fix the problem don't call fwrite at all when there's nothing to
write.
---
 notmuch-show.c   | 2 +-
 test/T210-raw.sh | 1 -
 2 files changed, 1 insertion(+), 2 deletions(-)

diff --git a/notmuch-show.c b/notmuch-show.c
index c3a3783a..98b85352 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -851,7 +851,7 @@ format_part_raw (unused (const void *ctx), unused (sprinter_t *sp),
 		return NOTMUCH_STATUS_FILE_ERROR;
 	    }
 
-	    if (fwrite (buf, size, 1, stdout) != 1) {
+	    if (size > 0 && fwrite (buf, size, 1, stdout) != 1) {
 		fprintf (stderr, "Error: Write failed\n");
 		fclose (file);
 		return NOTMUCH_STATUS_FILE_ERROR;
diff --git a/test/T210-raw.sh b/test/T210-raw.sh
index 0d57deb5..93944491 100755
--- a/test/T210-raw.sh
+++ b/test/T210-raw.sh
@@ -61,7 +61,6 @@ for pow in $(seq 12 20); do
     notmuch show --format=raw subject:$size > OUTPUT
     test_expect_equal_file mail/size-$size OUTPUT
     test_begin_subtest "return value, message of size $size"
-    test_subtest_known_broken
     test_expect_success  "notmuch show --format=raw subject:$size > /dev/null"
 done
 
-- 
2.20.1