win32: handle Unix-style absolute paths for executables

As noted in commit 548ec7045 (win32: interpret absolute paths as
relative to %SYSTEMDRIVE%) a path starting with a '/' in the Unix
world is treated as relative to the current drive by Windows.
To avoid ambiguity that commit considered certain such paths to
be relative to %SYSTEMDRIVE%.  Extend this to paths representing
executables.

Add the functions need_system_drive() and auto_add_system_drive()
to detect the need for a system drive prefix and to add it if
necessary.  Use these functions in:

- the 'which' applet
- the find_executable() function
- tab-completion code
- PATH look-up, shellexec(), describe_command() and find_command() in ash
- parse_interpreter() and mingw_spawn_1()

With these changes executable paths starting with a slash are
handled consistently, whatever the current drive.

1 files changed, 9 insertions, 1 deletions

diff --git a/libbb/lineedit.c b/libbb/lineedit.c
index a36a1647d..f6577e372 100644
--- a/libbb/lineedit.c
+++ b/libbb/lineedit.c
@@ -913,8 +913,12 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                 struct dirent *next;
                 struct stat st;
                 char *found;
-
+#if ENABLE_PLATFORM_MINGW32
+                char *lpath = auto_add_system_drive(paths[i]);
+                dir = opendir(lpath);
+#else
                 dir = opendir(paths[i]);
+#endif
                 if (!dir)
                         continue; /* don't print an error */
 
@@ -929,7 +933,11 @@ static NOINLINE unsigned complete_cmd_dir_file(const char *command, int type)
                         if (!is_prefixed_with(name_found, pfind))
                                 continue; /* no */
 
+#if ENABLE_PLATFORM_MINGW32
+                        found = concat_path_file(lpath, name_found);
+#else
                         found = concat_path_file(paths[i], name_found);
+#endif
                         /* NB: stat() first so that we see is it a directory;
                          * but if that fails, use lstat() so that
                          * we still match dangling links */