[PATCH v3 09/11] rerere: return strbuf from handle path

[Thomas Gummerer <t.gummerer@gmail.com>]

Currently we write the conflict to disk directly in the handle_path
function.  To make it re-usable for nested conflicts, instead of
writing the conflict out directly, store it in a strbuf and let the
caller write it out.

This does mean some slight increase in memory usage, however that
increase is limited to the size of the largest conflict we've
currently processed.  We already keep one copy of the conflict in
memory, and it shouldn't be too large, so the increase in memory usage
seems acceptable.

As a bonus this lets us get replace the rerere_io_putconflict function
with a trivial two line function.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
---
 rerere.c | 58 ++++++++++++++++++--------------------------------------
 1 file changed, 18 insertions(+), 40 deletions(-)

diff --git a/rerere.c b/rerere.c
index 2d62251943..a35b88916c 100644
--- a/rerere.c
+++ b/rerere.c
@@ -302,38 +302,6 @@ static void rerere_io_putstr(const char *str, struct rerere_io *io)
 		ferr_puts(str, io->output, &io->wrerror);
 }
 
-/*
- * Write a conflict marker to io->output (if defined).
- */
-static void rerere_io_putconflict(int ch, int size, struct rerere_io *io)
-{
-	char buf[64];
-
-	while (size) {
-		if (size <= sizeof(buf) - 2) {
-			memset(buf, ch, size);
-			buf[size] = '\n';
-			buf[size + 1] = '\0';
-			size = 0;
-		} else {
-			int sz = sizeof(buf) - 1;
-
-			/*
-			 * Make sure we will not write everything out
-			 * in this round by leaving at least 1 byte
-			 * for the next round, giving the next round
-			 * a chance to add the terminating LF.  Yuck.
-			 */
-			if (size <= sz)
-				sz -= (sz - size) + 1;
-			memset(buf, ch, sz);
-			buf[sz] = '\0';
-			size -= sz;
-		}
-		rerere_io_putstr(buf, io);
-	}
-}
-
 static void rerere_io_putmem(const char *mem, size_t sz, struct rerere_io *io)
 {
 	if (io->output)
@@ -384,7 +352,14 @@ 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)
+static void rerere_strbuf_putconflict(struct strbuf *buf, int ch, size_t size)
+{
+	strbuf_addchars(buf, ch, size);
+	strbuf_addch(buf, '\n');
+}
+
+static int handle_conflict(struct strbuf *out, struct rerere_io *io,
+			   int marker_size, git_SHA_CTX *ctx)
 {
 	enum {
 		RR_SIDE_1 = 0, RR_SIDE_2, RR_ORIGINAL
@@ -410,11 +385,11 @@ static int handle_conflict(struct rerere_io *io, int marker_size, git_SHA_CTX *c
 			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);
+			rerere_strbuf_putconflict(out, '<', marker_size);
+			strbuf_addbuf(out, &one);
+			rerere_strbuf_putconflict(out, '=', marker_size);
+			strbuf_addbuf(out, &two);
+			rerere_strbuf_putconflict(out, '>', marker_size);
 			if (ctx) {
 				git_SHA1_Update(ctx, one.buf ? one.buf : "",
 					    one.len + 1);
@@ -451,21 +426,24 @@ static int handle_conflict(struct rerere_io *io, int marker_size, git_SHA_CTX *c
 static int handle_path(unsigned char *sha1, struct rerere_io *io, int marker_size)
 {
 	git_SHA_CTX ctx;
-	struct strbuf buf = STRBUF_INIT;
+	struct strbuf buf = STRBUF_INIT, out = STRBUF_INIT;
 	int has_conflicts = 0;
 	if (sha1)
 		git_SHA1_Init(&ctx);
 
 	while (!io->getline(&buf, io)) {
 		if (is_cmarker(buf.buf, '<', marker_size)) {
-			has_conflicts = handle_conflict(io, marker_size,
+			has_conflicts = handle_conflict(&out, io, marker_size,
 							sha1 ? &ctx : NULL);
 			if (has_conflicts < 0)
 				break;
+			rerere_io_putmem(out.buf, out.len, io);
+			strbuf_reset(&out);
 		} else
 			rerere_io_putstr(buf.buf, io);
 	}
 	strbuf_release(&buf);
+	strbuf_release(&out);
 
 	if (sha1)
 		git_SHA1_Final(sha1, &ctx);
-- 
2.17.0.410.g65aef3a6c4