win32: improved support for c:path path names

Microsoft Windows permits path names of the form 'c:path', without a
path separator after the colon.  The system records a current directory
for each drive and the path is interpreted relative to that.

Since Windows API calls understand 'c:path' path names many commands
in busybox-w32 already work with them.  This commit adds the following:

- The 'cd' shell built-in interprets 'c:path' path names correctly.
  Previously it treated them as relative to the shell's concept of
  the current working directory, not the current directory of the
  specified drive.

- The 'pwd' shell built-in takes the '-a' option to list the current
  directory for all drives.

- 'c:path' path names are subject to tab-completion.

Paths of the form 'c:path' don't work for mapped network drives or
paths that have been associated with a drive using SUBST.

See GitHub issue #147.

1 files changed, 11 insertions, 0 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index 3725dba0d..0d5ce9082 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -843,6 +843,17 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
         path1[0] = (char*)".";
 
         pfind = strrchr(command, '/');
+#if ENABLE_PLATFORM_MINGW32
+        if (!pfind && has_dos_drive_prefix(command) && command[2] != '\0') {
+                char buffer[PATH_MAX];
+
+                /* path is of form c:path with no '/' */
+                if (get_drive_cwd(command, buffer, PATH_MAX)) {
+                        pfind = command + 2;
+                        path1[0] = xstrdup(buffer);
+                }
+        } else
+#endif
         if (!pfind) {
                 if (type == FIND_EXE_ONLY)
                         npaths = path_parse(&paths);