From efed709f6967b02a75dafb630d7da7357b7ebda3 Mon Sep 17 00:00:00 2001
From: Matthew Flatt <mflatt@racket-lang.org>
Date: Tue, 12 Apr 2011 10:21:26 -0400
Subject: [PATCH] improve error reporting when using exec

---
 src/racket/src/port.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/racket/src/port.c b/src/racket/src/port.c
index 38fbc345c7..ecef7e53c5 100644
--- a/src/racket/src/port.c
+++ b/src/racket/src/port.c
@@ -8203,12 +8203,20 @@ static Scheme_Object *subprocess(int c, Scheme_Object *args[])
 	END_XFORM_SKIP;
 
 	err = MSC_IZE(execv)(command, argv);
+        if (err)
+          err = errno;
 
 	/* If we get here it failed; give up */
 
         /* using scheme_signal_error will leave us in the forked process,
 	   so use scheme_console_printf instead */
-        scheme_console_printf("racket: exec failed (%d)\n", err);
+        scheme_console_printf("racket: exec failed (%s%serrno=%d)\n", 
+#ifdef NO_STRERROR_AVAILABLE
+                              "", "",
+#else
+                              strerror(err), "; ",
+#endif
+                              err);
 
 	/* back to Racket signal dispositions: */
 	START_XFORM_SKIP;