bug#18745: 24.3; MS Windows, `call-process-shell-command' fails on `shell-quote-argument'ed bat file with quoted args

[Noam Postavsky <npostavs@users.sourceforge.net>]

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On Thu, Oct 16, 2014 at 5:30 PM, Noam Postavsky
<npostavs@users.sourceforge.net> wrote:
> On Thu, Oct 16, 2014 at 1:06 PM, Eli Zaretskii <eliz@gnu.org> wrote:
>> GNU Make overcomes this by detecting these cases, and invoking
>> CreateProcess in a special way (NULL as the first argument), see the
>> function process_begin there, around line 710 of sub_proc.c in the GNU
>> Make sources.  If you can come up with a way to do the same in Emacs,
>> by some suitable patch to cmdproxy.c, such a patch will be welcome
>> (assuming either the patch is small, or you will agree to sign legal
>> papers necessary for submitting substantial patches to FSF projects).
>
> I'll take a look (btw I have already signed for Emacs).

Patching cmdproxy.c fixes the call-process-shell-command case:

  (call-process-shell-command
   "\"c:/path with space/foo-bar.bat\" \"x &y\"" nil '(t t) t)

To fix the call-process case:

  (call-process
   "c:/path with space/foo-bar.bat" nil '(t t) t "x &y")

required a patch to w32proc.c. This is my first patch to Emacs proper;
hopefully I got everything in the right format.

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2014-10-21  Noam Postavsky  <npostavs@users.sourceforget.net>

	Paper over MS Windows CreateProcess deficiencies (Bug#18745).

	* nt/cmdproxy.c (batch_file_p): new function.
	(spawn): if calling a quoted batch file pass NULL for progname.
	* src/w32proc.c (create_child): if calling a quoted batch file
	pass NULL for exe.

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--- org/nt/cmdproxy.c	Tue Oct 21 20:39:39 2014
+++ new/nt/cmdproxy.c	Tue Oct 21 20:27:08 2014
@@ -220,6 +220,28 @@
   return o - buf;
 }
 
+/* Return TRUE if PROGNAME is a batch file */
+BOOL
+batch_file_p (const char *progname)
+{
+  const char *exts[] = {".bat", ".cmd"};
+  int n_exts = sizeof (exts) / sizeof (char *);
+  int i;
+
+  const char *ext = strrchr(progname, '.');
+
+  if (ext)
+    {
+      for (i = 0; i < n_exts; i++)
+        {
+          if (stricmp(ext, exts[i]) == 0)
+            return TRUE;
+        }
+    }
+
+  return FALSE;
+}
+
 /* Search for EXEC file in DIR.  If EXEC does not have an extension,
    DIR is searched for EXEC with the standard extensions appended.  */
 int
@@ -469,6 +491,13 @@
 
   memset (&start, 0, sizeof (start));
   start.cb = sizeof (start);
+
+  /* CreateProcess handles batch files as progname specially. This
+     special handling fails when both the batch file and arguments are
+     quoted. We pass NULL as progname to avoid the special
+     handling. */
+  if (progname != NULL && cmdline[0] == '"' && batch_file_p(progname))
+      progname = NULL;
 
   if (CreateProcess (progname, cmdline, &sec_attrs, NULL, TRUE,
 		     0, envblock, dir, &start, &child))
--- org/src/w32proc.c	Tue Oct 21 20:39:43 2014
+++ new/src/w32proc.c	Tue Oct 21 20:27:08 2014
@@ -1078,6 +1078,7 @@
   DWORD flags;
   char dir[ MAX_PATH ];
   char *p;
+  const char *ext;
 
   if (cp == NULL) emacs_abort ();
 
@@ -1115,6 +1116,15 @@
   for (p = dir; *p; p = CharNextA (p))
     if (*p == '/')
       *p = '\\';
+
+  /* CreateProcess handles batch files as exe specially. This special
+     handling fails when both the batch file and arguments are
+     quoted. We pass NULL as exe to avoid the special handling. */
+  if (exe && cmdline[0] == '"' &&
+      (ext = strrchr(exe, '.')) &&
+      (xstrcasecmp (ext, ".bat") == 0
+       || xstrcasecmp (ext, ".cmd") == 0))
+      exe = NULL;
 
   flags = (!NILP (Vw32_start_process_share_console)
 	   ? CREATE_NEW_PROCESS_GROUP