[git commit] vi: don't overwrite existing file

[Denys Vlasenko]

commit: https://git.busybox.net/busybox/commit/?id=5ae25f40bdc839e3fb24dcb7ddd6067698bf87b0
branch: https://git.busybox.net/busybox/commit/?id=refs/heads/master

If the name of the file being written doesn't match the current
filename and the output file already exists vi should issue a
warning and not overwrite the file.

Because the test only compares the file names it's somewhat over-
protective.  If the current file name is 'my_text' and the user tries
to save to './my_text' they'll be prevented from doing so.

function                                             old     new   delta
colon                                               3092    3151     +59
.rodata                                           105118  105146     +28
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/0 up/down: 87/0)               Total: 87 bytes

Signed-off-by: Ron Yorston <rmy at pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 editors/vi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/editors/vi.c b/editors/vi.c
index ccf2870ab..47b13b3ca 100644
--- a/editors/vi.c
+++ b/editors/vi.c
@@ -2816,6 +2816,13 @@ static void colon(char *buf)
 
 		// is there a file name to write to?
 		if (args[0]) {
+			struct stat statbuf;
+
+			if (!useforce && (fn == NULL || strcmp(fn, args) != 0) &&
+					stat(args, &statbuf) == 0) {
+				status_line_bold("File exists (:w! overrides)");
+				goto ret;
+			}
 			fn = args;
 		}
 # if ENABLE_FEATURE_VI_READONLY