[newlib-cygwin/main] Cygwin: cygwin_GetCommandLineW/A: don't rely on __argv[0] content

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=bded8091c438d18e1d259864d773891a747c7576

commit bded8091c438d18e1d259864d773891a747c7576
Author:     Corinna Vinschen <corinna@vinschen.de>
AuthorDate: Wed Jan 31 13:30:05 2024 +0100
Commit:     Corinna Vinschen <corinna@vinschen.de>
CommitDate: Wed Jan 31 20:11:58 2024 +0100

    Cygwin: cygwin_GetCommandLineW/A: don't rely on __argv[0] content
    
    Since it's possible to change the __argv array, we should not rely
    on __argv[0] actually representing the windows executable path in
    any way.  Use the real path stored in global_progname instead.
    
    Fixes: 521953a83a885 ("* common.din: Export GetCommandLine{A,W}.")
    Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

Diff:
---
 winsup/cygwin/kernel32.cc | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/winsup/cygwin/kernel32.cc b/winsup/cygwin/kernel32.cc
index 36951f6a87be..f07f80d59ddc 100644
--- a/winsup/cygwin/kernel32.cc
+++ b/winsup/cygwin/kernel32.cc
@@ -419,14 +419,17 @@ static UNICODE_STRING *
 ucmd ()
 {
   static UNICODE_STRING wcmd;
+  tmp_pathbuf tp;
+
   if (!wcmd.Buffer)
     {
       linebuf cmd;
-      path_conv real_path (__argv[0]);
+      char *win_progname = tp.c_get ();
+      sys_wcstombs (win_progname, NT_MAX_PATH, global_progname);
       av newargv (__argc, __argv);
       if (newargv.argc)
 	{
-	  cmd.fromargv (newargv, real_path.get_win32 (), true);
+	  cmd.fromargv (newargv, win_progname, true);
 	  RtlInitUnicodeString (&wcmd, cmd);
 	}
     }