On Thu, 20 Dec 2007, Linus Torvalds wrote:

And here's the git patch to avoid this optimization when there is 
context.

Actually, the code to finding one '\n' is still needed to avoid the 
(pathological) case of getting a "\No newline", so scrap that one which 
was too aggressive, and use this (simpler) one instead.

Not that it matters in real life, since nobody uses -U0, and "git blame" 
won't care. But let's get it right anyway ;)

This whole function has had more bugs than it has lines.

		Linus

---
 xdiff-interface.c |    7 +++++--
 1 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/xdiff-interface.c b/xdiff-interface.c
index 9ee877c..711029e 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c

@@ -115,15 +115,18 @@ static void trim_common_tail(mmfile_t *a, mmfile_t *b, long ctx)
 	char *bp = b->ptr + b->size;
 	long smaller = (a->size < b->size) ? a->size : b->size;
 
+	if (ctx)
+		return;
+
 	while (blk + trimmed <= smaller && !memcmp(ap - blk, bp - blk, blk)) {
 		trimmed += blk;
 		ap -= blk;
 		bp -= blk;
 	}
 
-	while (recovered < trimmed && 0 <= ctx)
+	while (recovered < trimmed)
 		if (ap[recovered++] == '\n')
-			ctx--;
+			break;
 	a->size -= (trimmed - recovered);
 	b->size -= (trimmed - recovered);
 }