rerere: factor out handle_conflict function

Factor out the handle_conflict function, which handles a single
conflict in a path.  This is in preparation for a subsequent commit,
where this function will be re-used.

Note that this does change the behaviour of 'git rerere' slightly.
Where previously we'd consider all files where an unmatched conflict
marker is found as invalid, we now only consider files invalid when
the "ours" conflict marker ("<<<<<<< <text>") is unmatched, not when
other conflict markers (e.g. "=======") is unmatched.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

rerere.c

@@ -384,6 +384,58 @@ static int is_cmarker(char *buf, int marker_char, int marker_size)
 	return isspace(*buf);
 }
 
+static int handle_conflict(struct rerere_io *io, int marker_size, git_SHA_CTX *ctx)
+{
+	enum {
+		RR_SIDE_1 = 0, RR_SIDE_2, RR_ORIGINAL
+	} hunk = RR_SIDE_1;
+	struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
+	struct strbuf buf = STRBUF_INIT;
+	int has_conflicts = -1;
+
+	while (!io->getline(&buf, io)) {
+		if (is_cmarker(buf.buf, '<', marker_size)) {
+			break;
+		} else if (is_cmarker(buf.buf, '|', marker_size)) {
+			if (hunk != RR_SIDE_1)
+				break;
+			hunk = RR_ORIGINAL;
+		} else if (is_cmarker(buf.buf, '=', marker_size)) {
+			if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
+				break;
+			hunk = RR_SIDE_2;
+		} else if (is_cmarker(buf.buf, '>', marker_size)) {
+			if (hunk != RR_SIDE_2)
+				break;
+			if (strbuf_cmp(&one, &two) > 0)
+				strbuf_swap(&one, &two);
+			has_conflicts = 1;
+			rerere_io_putconflict('<', marker_size, io);
+			rerere_io_putmem(one.buf, one.len, io);
+			rerere_io_putconflict('=', marker_size, io);
+			rerere_io_putmem(two.buf, two.len, io);
+			rerere_io_putconflict('>', marker_size, io);
+			if (ctx) {
+				git_SHA1_Update(ctx, one.buf ? one.buf : "",
+					    one.len + 1);
+				git_SHA1_Update(ctx, two.buf ? two.buf : "",
+					    two.len + 1);
+			}
+			break;
+		} else if (hunk == RR_SIDE_1)
+			strbuf_addbuf(&one, &buf);
+		else if (hunk == RR_ORIGINAL)
+			; /* discard */
+		else if (hunk == RR_SIDE_2)
+			strbuf_addbuf(&two, &buf);
+	}
+	strbuf_release(&one);
+	strbuf_release(&two);
+	strbuf_release(&buf);
+
+	return has_conflicts;
+}
+
 /*
  * Read contents a file with conflicts, normalize the conflicts
  * by (1) discarding the common ancestor version in diff3-style,
@@ -399,70 +451,25 @@ static int is_cmarker(char *buf, int marker_char, int marker_size)
 static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 {
 	git_SHA_CTX ctx;
-	int has_conflicts = 0;
-	enum {
-		RR_CONTEXT = 0, RR_SIDE_1, RR_SIDE_2, RR_ORIGINAL
-	} hunk = RR_CONTEXT;
-	struct strbuf one = STRBUF_INIT, two = STRBUF_INIT;
 	struct strbuf buf = STRBUF_INIT;
-
+	int has_conflicts = 0;
 	if (sha1)
 		git_SHA1_Init(&ctx);
 
 	while (!io->getline(&buf, io)) {
 		if (is_cmarker(buf.buf, '<', marker_size)) {
-			if (hunk != RR_CONTEXT)
-				goto bad;
-			hunk = RR_SIDE_1;
-		} else if (is_cmarker(buf.buf, '|', marker_size)) {
-			if (hunk != RR_SIDE_1)
-				goto bad;
-			hunk = RR_ORIGINAL;
-		} else if (is_cmarker(buf.buf, '=', marker_size)) {
-			if (hunk != RR_SIDE_1 && hunk != RR_ORIGINAL)
-				goto bad;
-			hunk = RR_SIDE_2;
-		} else if (is_cmarker(buf.buf, '>', marker_size)) {
-			if (hunk != RR_SIDE_2)
-				goto bad;
-			if (strbuf_cmp(&one, &two) > 0)
-				strbuf_swap(&one, &two);
-			has_conflicts = 1;
-			hunk = RR_CONTEXT;
-			rerere_io_putconflict('<', marker_size, io);
-			rerere_io_putmem(one.buf, one.len, io);
-			rerere_io_putconflict('=', marker_size, io);
-			rerere_io_putmem(two.buf, two.len, io);
-			rerere_io_putconflict('>', marker_size, io);
-			if (sha1) {
-				git_SHA1_Update(&ctx, one.buf ? one.buf : "",
-					    one.len + 1);
-				git_SHA1_Update(&ctx, two.buf ? two.buf : "",
-					    two.len + 1);
-			}
-			strbuf_reset(&one);
-			strbuf_reset(&two);
-		} else if (hunk == RR_SIDE_1)
-			strbuf_addbuf(&one, &buf);
-		else if (hunk == RR_ORIGINAL)
-			; /* discard */
-		else if (hunk == RR_SIDE_2)
-			strbuf_addbuf(&two, &buf);
-		else
+			has_conflicts = handle_conflict(io, marker_size,
+							sha1 ? &ctx : NULL);
+			if (has_conflicts < 0)
+				break;
+		} else
 			rerere_io_putstr(buf.buf, io);
-		continue;
-	bad:
-		hunk = 99; /* force error exit */
-		break;
 	}
-	strbuf_release(&one);
-	strbuf_release(&two);
 	strbuf_release(&buf);
 
 	if (sha1)
 		git_SHA1_Final(sha1, &ctx);
-	if (hunk != RR_CONTEXT)
-		return -1;
+
 	return has_conflicts;
 }