[git commit] vi: correctly detect when a deletion empties the buffer

Denys Vlasenko vda.linux at googlemail.com
Mon Dec 3 09:07:58 UTC 2018


commit: https://git.busybox.net/busybox/commit/?id=d08206dce1291f512d7de9037d9ef1ffbf705cac
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

Michał Berger has reported two issues:

- Repeatedly deleting and undoing the deletion of the last line
  results in characters being lost from the end of the line.

- Deleting the bottom line twice then attempting to undo each of
  these deletions results in a segfault.

The problem seems to be an incorrect test for whether the text buffer
is empty.

Reported-by: Michał Berger <michallinuxstuff at gmail.com>
Signed-off-by: Ron Yorston <rmy at pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 editors/vi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/editors/vi.c b/editors/vi.c
index ee3c7feb2..271529404 100644
--- a/editors/vi.c
+++ b/editors/vi.c
@@ -2364,7 +2364,7 @@ static void undo_push(char *src, unsigned int length, uint8_t u_type)	// Add to
 	// Allocate a new undo object
 	if (u_type == UNDO_DEL || u_type == UNDO_DEL_CHAIN) {
 		// For UNDO_DEL objects, save deleted text
-		if ((src + length) == end)
+		if ((text + length) == end)
 			length--;
 		// If this deletion empties text[], strip the newline. When the buffer becomes
 		// zero-length, a newline is added back, which requires this to compensate.


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