rev-list: handle %x00 NUL in user format

The code paths for showing commits in "git log" and "git
rev-list --graph" correctly handle embedded NULs by looking
only at the resulting strbuf's length, and never treating it
as a C string. The code path for regular rev-list, however,
used printf("%s"), which resulted in truncated output. This
patch uses fwrite instead, like the --graph code path.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/rev-list.c

@@ -147,8 +147,10 @@ static void show_commit(struct commit *commit, void *data)
 			}
 		} else {
 			if (revs->commit_format != CMIT_FMT_USERFORMAT ||
-			    buf.len)
+			    buf.len) {
-				printf("%s%c", buf.buf, info->hdr_termination);
+				fwrite(buf.buf, 1, buf.len, stdout);
+				putchar(info->hdr_termination);
+			}
 		}
 		strbuf_release(&buf);
 	} else {

t/t4012-diff-binary.sh

@@ -77,10 +77,6 @@ test_expect_success 'apply binary patch' \
 	 tree1=`git write-tree` &&
 	 test "$tree1" = "$tree0"'
 
-nul_to_q() {
-	perl -pe 'y/\000/Q/'
-}
-
 test_expect_success 'diff --no-index with binary creation' '
 	echo Q | q_to_nul >binary &&
 	(: hide error code from diff, which just indicates differences

t/t6006-rev-list-format.sh

@@ -162,6 +162,14 @@ commit 131a310eb913d107dd3c09a65d1651175898735d
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
 EOF
 
+test_expect_success '%x00 shows NUL' '
+	echo  >expect commit f58db70b055c5718631e5c61528b28b12090cdea &&
+	echo >>expect fooQbar &&
+	git rev-list -1 --format=foo%x00bar HEAD >actual.nul &&
+	nul_to_q <actual.nul >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success '%ad respects --date=' '
 	echo 2005-04-07 >expect.ad-short &&
 	git log -1 --date=short --pretty=tformat:%ad >output.ad-short master &&

t/test-lib.sh

@@ -248,6 +248,10 @@ test_decode_color () {
 		-e 's/.\[m/<RESET>/g'
 }
 
+nul_to_q () {
+	perl -pe 'y/\000/Q/'
+}
+
 q_to_nul () {
 	perl -pe 'y/Q/\000/'
 }