Merge branch 'rb/no-dev-zero-in-test'

* rb/no-dev-zero-in-test:
  t5562: replace /dev/zero with a pipe from generate_zero_bytes
  t5318: replace use of /dev/zero with generate_zero_bytes
  test-lib-functions.sh: add generate_zero_bytes function

Author: gitster

t/t5318-commit-graph.sh

@@ -383,7 +383,7 @@ corrupt_graph_and_verify() {
 	cp $objdir/info/commit-graph commit-graph-backup &&
 	printf "$data" | dd of="$objdir/info/commit-graph" bs=1 seek="$pos" conv=notrunc &&
 	dd of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" count=0 &&
-	dd if=/dev/zero of="$objdir/info/commit-graph" bs=1 seek="$zero_pos" count=$(($orig_size - $zero_pos)) &&
+	generate_zero_bytes $(($orig_size - $zero_pos)) >>"$objdir/info/commit-graph" &&
 	test_must_fail git commit-graph verify 2>test_err &&
 	grep -v "^+" test_err >err &&
 	test_i18ngrep "$grepstr" err

t/t5562-http-backend-content-length.sh

@@ -143,14 +143,14 @@ test_expect_success GZIP 'push gzipped empty' '
 
 test_expect_success 'CONTENT_LENGTH overflow ssite_t' '
 	NOT_FIT_IN_SSIZE=$(ssize_b100dots) &&
-	env \
+	generate_zero_bytes infinity  | env \
 		CONTENT_TYPE=application/x-git-upload-pack-request \
 		QUERY_STRING=/repo.git/git-upload-pack \
 		PATH_TRANSLATED="$PWD"/.git/git-upload-pack \
 		GIT_HTTP_EXPORT_ALL=TRUE \
 		REQUEST_METHOD=POST \
 		CONTENT_LENGTH="$NOT_FIT_IN_SSIZE" \
-		git http-backend </dev/zero >/dev/null 2>err &&
+		git http-backend >/dev/null 2>err &&
 	grep "fatal:.*CONTENT_LENGTH" err
 '
 

t/test-lib-functions.sh

@@ -116,6 +116,19 @@ remove_cr () {
 	tr '\015' Q | sed -e 's/Q$//'
 }
 
+# Generate an output of $1 bytes of all zeroes (NULs, not ASCII zeroes).
+# If $1 is 'infinity', output forever or until the receiving pipe stops reading,
+# whichever comes first.
+generate_zero_bytes () {
+	perl -e 'if ($ARGV[0] == "infinity") {
+		while (-1) {
+			print "\0"
+		}
+	} else {
+		print "\0" x $ARGV[0]
+	}' "$@"
+}
+
 # In some bourne shell implementations, the "unset" builtin returns
 # nonzero status when a variable to be unset was not set in the first
 # place.