builtin/apply: make parse_single_patch() return -1 on error

To libify `git apply` functionality we have to signal errors to the
caller instead of die()ing.

To do that in a compatible manner with the rest of the error handling
in builtin/apply.c, parse_single_patch() should return a negative
integer instead of calling die().

Let's do that by using error() and let's adjust the related test
cases accordingly.

Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/apply.c

@@ -1671,6 +1671,10 @@ static int parse_fragment(struct apply_state *state,
  *
  * The (fragment->patch, fragment->size) pair points into the memory given
  * by the caller, not a copy, when we return.
+ *
+ * Returns:
+ *   -1 in case of error,
+ *   the number of bytes in the patch otherwise.
  */
 static int parse_single_patch(struct apply_state *state,
 			      const char *line,
@@ -1688,8 +1692,10 @@ static int parse_single_patch(struct apply_state *state,
 		fragment = xcalloc(1, sizeof(*fragment));
 		fragment->linenr = state->linenr;
 		len = parse_fragment(state, line, size, patch, fragment);
-		if (len <= 0)
-			die(_("corrupt patch at line %d"), state->linenr);
+		if (len <= 0) {
+			free(fragment);
+			return error(_("corrupt patch at line %d"), state->linenr);
+		}
 		fragment->patch = line;
 		fragment->size = len;
 		oldlines += fragment->oldlines;
@@ -1725,9 +1731,9 @@ static int parse_single_patch(struct apply_state *state,
 		patch->is_delete = 0;
 
 	if (0 < patch->is_new && oldlines)
-		die(_("new file %s depends on old contents"), patch->new_name);
+		return error(_("new file %s depends on old contents"), patch->new_name);
 	if (0 < patch->is_delete && newlines)
-		die(_("deleted file %s still has contents"), patch->old_name);
+		return error(_("deleted file %s still has contents"), patch->old_name);
 	if (!patch->is_delete && !newlines && context)
 		fprintf_ln(stderr,
 			   _("** warning: "
@@ -2029,6 +2035,9 @@ static int parse_chunk(struct apply_state *state, char *buffer, unsigned long si
 				       size - offset - hdrsize,
 				       patch);
 
+	if (patchsize < 0)
+		return -128;
+
 	if (!patchsize) {
 		static const char git_binary[] = "GIT binary patch\n";
 		int hd = hdrsize + offset;

t/t4012-diff-binary.sh

@@ -68,7 +68,7 @@ test_expect_success C_LOCALE_OUTPUT 'apply detecting corrupt patch correctly' '
 	sed -e "s/-CIT/xCIT/" <output >broken &&
 	test_must_fail git apply --stat --summary broken 2>detected &&
 	detected=$(cat detected) &&
-	detected=$(expr "$detected" : "fatal.*at line \\([0-9]*\\)\$") &&
+	detected=$(expr "$detected" : "error.*at line \\([0-9]*\\)\$") &&
 	detected=$(sed -ne "${detected}p" broken) &&
 	test "$detected" = xCIT
 '
@@ -77,7 +77,7 @@ test_expect_success C_LOCALE_OUTPUT 'apply detecting corrupt patch correctly' '
 	git diff --binary | sed -e "s/-CIT/xCIT/" >broken &&
 	test_must_fail git apply --stat --summary broken 2>detected &&
 	detected=$(cat detected) &&
-	detected=$(expr "$detected" : "fatal.*at line \\([0-9]*\\)\$") &&
+	detected=$(expr "$detected" : "error.*at line \\([0-9]*\\)\$") &&
 	detected=$(sed -ne "${detected}p" broken) &&
 	test "$detected" = xCIT
 '