Check prettify message output buffer after cleanup

This makes the message prettify buffer length check accurate.

1 files changed, 6 insertions, 4 deletions

diff --git a/src/message.c b/src/message.c
index a4aadb28f..a5cc26237 100644
--- a/src/message.c
+++ b/src/message.c
@@ -63,10 +63,7 @@ int git_message_prettify(char *message_out, size_t buffer_size, const char *mess
 {
 	git_buf buf = GIT_BUF_INIT;
 
-	if (strlen(message) + 1 > buffer_size) {	/* We have to account for a potentially missing \n */
-		giterr_set(GITERR_INVALID, "Buffer too short to hold the cleaned message");
-		return -1;
-	}
+	assert(message_out && buffer_size);
 
 	*message_out = '\0';
 
@@ -75,6 +72,11 @@ int git_message_prettify(char *message_out, size_t buffer_size, const char *mess
 		return -1;
 	}
 
+	if (buf.size + 1 > buffer_size) { /* +1 for NUL byte */
+		giterr_set(GITERR_INVALID, "Buffer too short to hold the cleaned message");
+		return -1;
+	}
+
 	git_buf_copy_cstr(message_out, buffer_size, &buf);
 	git_buf_free(&buf);