libbb: fix another tab-completion corner case

Commit 90f35327c (libbb: avoid problems with quoted characters in
tab completion) avoided a conflict between the code to quote
special characters and that to display case-preserved filenames.
Here's another one.

I'd installed a third-party binary on Microsoft Windows and wanted
to execute it from a busybox-w32 shell which didn't have it in its
path.  No problem:

   $ c:/prog<tab>
   $ c:/Program<tab>
   Program Files/  ProgramData
   $ c:/Program\<tab>
   $ c:/PProgram

I was too quick to enter the final <tab>, I'd meant to add a space.

A trailing backslash is effectively removed by the tab completion
matching code but it remains on the display.  This confuses the
code to display case-preserved filenames.

Upstream BusyBox just ends up with a spurious backslash in the name.
Bash rewrites the command line to remove the surplus backslash.

Fix the issue in busybox-w32 by leaving the backslash in the name,
even for matching purposes.  This will never result in a match,
thus affording the user a change to correct their mistake.

1 files changed, 6 insertions, 0 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 205044630..c20436270 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -1046,7 +1046,13 @@ static NOINLINE int build_match_prefix(char *match_buf)
 
         /* Mark every \c as "quoted c" */
         for (i = 0; int_buf[i]; i++) {
+#if ENABLE_PLATFORM_MINGW32
+                /* Trailing backslash is effectively removed which confuses
+                 * the code to display case-preserved filenames. */
+                if (int_buf[i] == '\\' && int_buf[i+1] != '\0') {
+#else
                 if (int_buf[i] == '\\') {
+#endif
                         remove_chunk(int_buf, i, i + 1);
                         int_buf[i] |= QUOT;
                 }