From 0931a9f15e7436346e33c66129f3ff822c33f52a Mon Sep 17 00:00:00 2001
From: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Sat, 22 Sep 2012 23:59:21 +0200
Subject: Check that runsystem script exists before trying it.

* init/init.c (launch_something): Check with file_name_lookup that runsystem
script exists before calling start_child.
* daemons/console-run.c (main): Check with file_name_lookup that runsystem
script exists before opening a console for it.
---
 daemons/console-run.c |  7 +++++++
 init/init.c           | 23 +++++++++++++++++++----
 2 files changed, 26 insertions(+), 4 deletions(-)

diff --git a/daemons/console-run.c b/daemons/console-run.c
index aaa1159b..fb879e53 100644
--- a/daemons/console-run.c
+++ b/daemons/console-run.c
@@ -49,6 +49,7 @@ int
 main (int argc, char **argv)
 {
   mach_port_t consdev = get_console ();
+  mach_port_t runsystem;
   char *consname;
 
   if (consdev == MACH_PORT_NULL)
@@ -62,6 +63,12 @@ main (int argc, char **argv)
   if (argc < 2)
     error (1, 0, "Usage: %s PROGRAM [ARG...]", program_invocation_short_name);
 
+  /* Check whether runsystem exists before opening a console for it.  */
+  runsystem = file_name_lookup (argv[1], O_RDONLY, 0);
+  if (runsystem == MACH_PORT_NULL)
+    error (127, errno, "cannot open file `%s' for execution", argv[1]);
+  mach_port_deallocate (mach_task_self (), runsystem);
+
   if (open_console (&consname))
     setenv ("FALLBACK_CONSOLE", consname, 1);
 
diff --git a/init/init.c b/init/init.c
index d66bee0b..edfe1236 100644
--- a/init/init.c
+++ b/init/init.c
@@ -1082,6 +1082,7 @@ start_child (const char *prog, char **progargs)
 static void
 launch_something (const char *why)
 {
+  file_t something;
   static unsigned int try;
   static const char *const tries[] =
   {
@@ -1093,12 +1094,26 @@ launch_something (const char *why)
   if (why)
     error (0, 0, "%s %s", tries[try - 1], why);
 
-  if (try == 0 && start_child (tries[try++], &global_argv[1]) == 0)
-      return;
+  something = file_name_lookup (tries[try], O_EXEC, 0);
+  if (something != MACH_PORT_NULL)
+    {
+      mach_port_deallocate (mach_task_self (), something);
+      if (try == 0 && start_child (tries[try++], &global_argv[1]) == 0)
+        return;
+    }
+  else
+    try++;
 
   while (try < sizeof tries / sizeof tries[0])
-    if (start_child (tries[try++], NULL) == 0)
-      return;
+    {
+      something = file_name_lookup (tries[try], O_EXEC, 0);
+      if (something != MACH_PORT_NULL)
+	{
+	  mach_port_deallocate (mach_task_self (), something);
+	  if (start_child (tries[try++], NULL) == 0)
+	    return;
+	}
+    }
 
   crash_system ();
 }
-- 
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