Fix escaping issues in open-process on Windows.

This can now execute programs with spaces in their path names.
Arguments can contain embedded double quotes, and other characters
that are special to cmd.exe, like &, |, (, ), ^ and others.

* stream.c (string_extend_count, win_escape_cmd): New static functions.
(win_escape_arg): Fix and extend escaping scheme to cover not only
the argument processing scheme implemented by programs which use Microsoft's
C library, but also to smuggle the command line through cmd.exe.
(win_make_cmdline): Use win_escape_cmd to wrap the command.
Escape the quotes which are placed around arguments, so cmd.exe
doesn't interpret them, which will cause it to suppress its processing
of the caret escapes.

2 files changed, 64 insertions, 12 deletions

diff --git a/ChangeLog b/ChangeLog
index e2d223b0..b06f0dab 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,22 @@
 2015-04-15  Kaz Kylheku  <kaz@kylheku.com>
 
+	Fix escaping issues in open-process on Windows.
+
+	This can now execute programs with spaces in their path names.
+	Arguments can contain embedded double quotes, and other characters
+	that are special to cmd.exe, like &, |, (, ), ^ and others.
+
+	* stream.c (string_extend_count, win_escape_cmd): New static functions.
+	(win_escape_arg): Fix and extend escaping scheme to cover not only
+	the argument processing scheme implemented by programs which use Microsoft's
+	C library, but also to smuggle the command line through cmd.exe.
+	(win_make_cmdline): Use win_escape_cmd to wrap the command.
+	Escape the quotes which are placed around arguments, so cmd.exe
+	doesn't interpret them, which will cause it to suppress its processing
+	of the caret escapes.
+
+2015-04-15  Kaz Kylheku  <kaz@kylheku.com>
+
 	Allow quasiquotes in braces and quasiliterals, and quotes in braces.
 
 	* parser.l: Consolidate rules for recognizing quote, unquote, and
diff --git a/stream.c b/stream.c
index ef91a07d..7187749a 100644
--- a/stream.c
+++ b/stream.c
@@ -2452,6 +2452,33 @@ val open_process(val name, val mode_str, val args)
 }
 #else
 
+static void string_extend_count(int count, val out, val tail)
+{
+  int i;
+  for (i = 0; i < count; i++)
+    string_extend(out, tail);
+}
+
+static val win_escape_cmd(val str)
+{
+  const wchar_t *s;
+  val out = string(L"");
+
+  for (s = c_str(str); *s; s++) {
+    switch (*s) {
+    case ' ': case '\t':
+      string_extend(out, lit("\""));
+      string_extend(out, chr(*s));
+      string_extend(out, lit("\""));
+      break;
+    default:
+      string_extend(out, chr(*s));
+    }
+  }
+
+  return out;
+}
+
 static val win_escape_arg(val str)
 {
   int bscount = 0, i;
@@ -2461,17 +2488,25 @@ static val win_escape_arg(val str)
   for (s = c_str(str); *s; s++) {
     switch (*s) {
     case '"':
-      for (i = 0; i < bscount; i++)
-        string_extend(out, lit("\\\\"));
-      string_extend(out, lit("\\\""));
+      string_extend_count(bscount, out, lit("\\\\"));
+      string_extend(out, lit("\\^\""));
       bscount = 0;
       break;
     case '\\':
       bscount++;
       break;
+    case '^': case '%': case '!':
+    case '\n': case '&': case '|':
+    case '<': case '>':
+    case '(': case ')':
+      for (i = 0; i < bscount; i++)
+        string_extend_count(bscount, out, lit("\\"));
+      string_extend(out, chr('^'));
+      string_extend(out, chr(*s));
+      break;
     default:
       for (i = 0; i < bscount; i++)
-        string_extend(out, lit("\\"));
+        string_extend_count(bscount, out, lit("\\"));
       string_extend(out, chr(*s));
       bscount = 0;
       break;
@@ -2488,16 +2523,16 @@ static val win_make_cmdline(val args)
 {
   val out = string(L"");
 
-  string_extend(out, pop(&args));
-  string_extend(out, lit(" "));
+  string_extend(out, win_escape_cmd(pop(&args)));
+  string_extend(out, chr(' '));
 
-  for (; args; args = cdr(args)) {
-    string_extend(out, lit("\""));
-    string_extend(out, win_escape_arg(car(args)));
-    if (cdr(args))
-      string_extend(out, lit("\" "));
+  while (args) {
+    string_extend(out, lit("^\""));
+    string_extend(out, win_escape_arg(pop(&args)));
+    if (args)
+      string_extend(out, lit("^\" "));
     else
-      string_extend(out, lit("\""));
+      string_extend(out, lit("^\""));
   }
 
   return out;