vi: don't overwrite existing file

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@pobox.com>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 7 insertions, 0 deletions

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