Use COMSPEC env var, not hard-coded CMD.EXE path.

It is with some reluctance I make this change, due to the security
implications of relying on environment variables. But we can't have a
hard-coded path.

* winsup/cygwin/include/paths.h (_PATH_CMDEXE): Macro removed.

* winsup/cygwin/spawn.cc (av::setup): Use COMSPEC environment
variable instead of hard-coded path. If missing, bail with
errno set to EOPNOTSUPP.

* winsup/cygwin/syscalls.cc (system): Use COMSPEC environment
variable. If missing, return -1.
(getusershell): Eliminate static array of shell names. If
shell_index is zero, return value of COMSPEC env var,
if it exists, and increment shell_index to 1.
(popen): Use COMSPEC and if that is missing, set errno to
EOPNOTSUPP and return NULL.

1 files changed, 4 insertions, 1 deletions

diff --git a/winsup/cygwin/spawn.cc b/winsup/cygwin/spawn.cc
index 87cfb3a69..ec0272739 100644
--- a/winsup/cygwin/spawn.cc
+++ b/winsup/cygwin/spawn.cc
@@ -1178,7 +1178,10 @@ av::setup (const char *prog_arg, path_conv& real_path, const char *ext,
 	      }
 	    if (ascii_strcasematch (ext, ".com"))
 	      break;
-	    pgm = (char *) _PATH_CMDEXE;
+	    if ((pgm = getenv("COMSPEC")) == NULL) {
+	      set_errno (EOPNOTSUPP);
+	      return -1;
+	    }
 	    arg1 = NULL;
 	  }