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

[David Bremner]

From: Rob Browning <rlb at defaultvalue.org>

Previously (at least) if the input was exactly 4096 bytes long,
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 at 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 88699e90..30363555 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -855,7 +855,7 @@ 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 e1dd6064..ee78e664 100755
--- a/test/T210-raw.sh
+++ b/test/T210-raw.sh
@@ -42,7 +42,6 @@ output="$((`wc -c < $gen_msg_filename`))"
 test_expect_equal 4096 "$output"
 
 test_begin_subtest "Show a raw message exactly 4096 bytes: no error"
-test_subtest_known_broken
 test_expect_success "notmuch show --format=raw subject:4096 1>/dev/null"
 
 test_begin_subtest "Show a raw message exactly 4096 bytes: correct output"
-- 
2.20.1