Change the name "title_mutex" to "tty_mutex" throughout.

* tty.h (tty_list::allocate_tty): Turn argument into a boolean.
* tty.cc (tty_list::init): Protect entire allocation operation with tty_mutex
(formerly title_mutex) to protect against allocation races.

7 files changed, 50 insertions, 42 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index b79d488e2..34a44682b 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,10 @@
+2004-05-17  Christopher Faylor  <cgf@alum.bu.edu>
+
+	Change the name "title_mutex" to "tty_mutex" throughout.
+	* tty.h (tty_list::allocate_tty): Turn argument into a boolean.
+	* tty.cc (tty_list::init): Protect entire allocation operation with
+	tty_mutex (formerly title_mutex) to protect against allocation races.
+
 2004-05-16  Corinna Vinschen  <corinna@vinschen.de>
 
 	* fhandler_socket.cc (fhandler_socket::recvfrom): Use original flags
diff --git a/winsup/cygwin/exceptions.cc b/winsup/cygwin/exceptions.cc
index 3b7be7042..44f37cbbe 100644
--- a/winsup/cygwin/exceptions.cc
+++ b/winsup/cygwin/exceptions.cc
@@ -330,7 +330,7 @@ try_to_debug (bool waitloop)
   /* if any of these mutexes is owned, we will fail to start any cygwin app
      until trapped app exits */
 
-  ReleaseMutex (title_mutex);
+  ReleaseMutex (tty_mutex);
 
   /* prevent recursive exception handling */
   char* rawenv = GetEnvironmentStrings () ;
@@ -1117,22 +1117,22 @@ signal_exit (int rc)
   do_exit (rc);
 }
 
-HANDLE NO_COPY title_mutex = NULL;
+HANDLE NO_COPY tty_mutex = NULL;
 
 void
 events_init (void)
 {
   char *name;
   char mutex_name[CYG_MAX_PATH];
-  /* title_mutex protects modification of console title. It's necessary
+  /* tty_mutex is on while searching for a tty slot. It's necessary
      while finding console window handle */
 
-  if (!(title_mutex = CreateMutex (&sec_all_nih, FALSE,
+  if (!(tty_mutex = CreateMutex (&sec_all_nih, FALSE,
 				   name = shared_name (mutex_name,
-						       "title_mutex", 0))))
+						       "tty_mutex", 0))))
     api_fatal ("can't create title mutex '%s', %E", name);
 
-  ProtectHandle (title_mutex);
+  ProtectHandle (tty_mutex);
   new_muto (mask_sync);
   windows_system_directory[0] = '\0';
   (void) GetSystemDirectory (windows_system_directory, sizeof (windows_system_directory) - 2);
diff --git a/winsup/cygwin/fhandler_console.cc b/winsup/cygwin/fhandler_console.cc
index 616090dfd..242182ec3 100644
--- a/winsup/cygwin/fhandler_console.cc
+++ b/winsup/cygwin/fhandler_console.cc
@@ -1776,10 +1776,10 @@ set_console_title (char *title)
   char buf[257];
   strncpy (buf, title, sizeof (buf) - 1);
   buf[sizeof (buf) - 1] = '\0';
-  if ((rc = WaitForSingleObject (title_mutex, 15000)) != WAIT_OBJECT_0)
+  if ((rc = WaitForSingleObject (tty_mutex, 15000)) != WAIT_OBJECT_0)
     sigproc_printf ("wait for title mutex failed rc %d, %E", rc);
   SetConsoleTitle (buf);
-  ReleaseMutex (title_mutex);
+  ReleaseMutex (tty_mutex);
   debug_printf ("title '%s'", buf);
 }
 
diff --git a/winsup/cygwin/fhandler_tty.cc b/winsup/cygwin/fhandler_tty.cc
index 6233971cb..8b98c2dba 100644
--- a/winsup/cygwin/fhandler_tty.cc
+++ b/winsup/cygwin/fhandler_tty.cc
@@ -1157,7 +1157,7 @@ fhandler_pty_master::fhandler_pty_master ()
 int
 fhandler_pty_master::open (int flags, mode_t)
 {
-  int ntty = cygwin_shared->tty.allocate_tty (0);
+  int ntty = cygwin_shared->tty.allocate_tty (false);
   if (ntty < 0)
     return 0;
 
diff --git a/winsup/cygwin/tty.cc b/winsup/cygwin/tty.cc
index 000de2e6e..6ced84bb0 100644
--- a/winsup/cygwin/tty.cc
+++ b/winsup/cygwin/tty.cc
@@ -121,7 +121,7 @@ attach_tty (int num)
     }
   if (NOTSTATE (myself, PID_USETTY))
     return -1;
-  return cygwin_shared->tty.allocate_tty (1);
+  return cygwin_shared->tty.allocate_tty (true);
 }
 
 void
@@ -196,32 +196,28 @@ tty_list::init (void)
    If flag == 0, just find a free tty.
  */
 int
-tty_list::allocate_tty (int with_console)
+tty_list::allocate_tty (bool with_console)
 {
   HWND console;
+  int freetty = -1;
 
   /* FIXME: This whole function needs a protective mutex. */
 
+  if (WaitForSingleObject (tty_mutex, INFINITE) == WAIT_FAILED)
+    termios_printf ("WFSO for tty_mutex %p failed, %E", tty_mutex);
+
   if (!with_console)
     console = NULL;
   else if (!(console = GetConsoleWindow ()))
     {
-      char *oldtitle = new char [TITLESIZE];
+      char oldtitle[TITLESIZE];
 
-      if (!oldtitle)
-	{
-	  termios_printf ("Can't *allocate console title buffer");
-	  return -1;
-	}
       if (!GetConsoleTitle (oldtitle, TITLESIZE))
 	{
 	  termios_printf ("Can't read console title");
-	  return -1;
+	  goto out;
 	}
 
-      if (WaitForSingleObject (title_mutex, INFINITE) == WAIT_FAILED)
-	termios_printf ("WFSO for title_mutext %p failed, %E", title_mutex);
-
       char buf[40];
 
       __small_sprintf (buf, "cygwin.find.console.%d", myself->pid);
@@ -234,16 +230,15 @@ tty_list::allocate_tty (int with_console)
 	}
       SetConsoleTitle (oldtitle);
       Sleep (40);
-      ReleaseMutex (title_mutex);
       if (console == NULL)
 	{
 	  termios_printf ("Can't find console window");
-	  return -1;
+	  goto out;
 	}
     }
-  /* Is a tty allocated for console? */
 
-  int freetty = -1;
+  HANDLE hmaster = NULL;
+  /* Is a tty allocated for console? */
   for (int i = 0; i < NTTYS; i++)
     {
       if (!ttys[i].exists ())
@@ -254,17 +249,19 @@ tty_list::allocate_tty (int with_console)
 	    break;		/* No.  We've got one. */
 	}
 
+      /* FIXME: Is this right?  We can potentially query a "nonexistent"
+	 tty slot after falling through from the above? */
       if (with_console && ttys[i].gethwnd () == console)
 	{
 	  termios_printf ("console %x already associated with tty%d",
 		console, i);
 	  /* Is the master alive? */
-	  HANDLE hMaster;
-	  hMaster = OpenProcess (PROCESS_DUP_HANDLE, FALSE, ttys[i].master_pid);
-	  if (hMaster)
+	  hmaster = OpenProcess (PROCESS_DUP_HANDLE, FALSE, ttys[i].master_pid);
+	  if (hmaster)
 	    {
-	      CloseHandle (hMaster);
-	      return i;
+	      CloseHandle (hmaster);
+	      freetty = i;
+	      goto out;
 	    }
 	  /* Master is dead */
 	  freetty = i;
@@ -274,23 +271,27 @@ tty_list::allocate_tty (int with_console)
 
   /* There is no tty allocated to console, allocate the first free found */
   if (freetty == -1)
-    {
-      system_printf ("No free ttys available");
-      return -1;
-    }
-  tty *t = ttys + freetty;
+    goto out;
+
+  tty *t;
+  t = ttys + freetty;
   t->init ();
   t->setsid (-1);
   t->setpgid (myself->pgid);
   t->sethwnd (console);
 
-  if (with_console)
+out:
+  if (freetty < 0)
+    system_printf ("No tty allocated");
+  else if (!with_console)
+    termios_printf ("tty%d allocated", freetty);
+  else
     {
-      termios_printf ("console %x associated with tty%d", console, freetty);
-      create_tty_master (freetty);
+      termios_printf ("console %p associated with tty%d", console, freetty);
+      if (!hmaster)
+	create_tty_master (freetty);
     }
-  else
-    termios_printf ("tty%d allocated", freetty);
+  ReleaseMutex (tty_mutex);
   return freetty;
 }
 
diff --git a/winsup/cygwin/tty.h b/winsup/cygwin/tty.h
index d29b2e903..5602a0530 100644
--- a/winsup/cygwin/tty.h
+++ b/winsup/cygwin/tty.h
@@ -125,7 +125,7 @@ class tty_list
 
 public:
   tty * operator [](int n) {return ttys + n;}
-  int allocate_tty (int n); /* n non zero if allocate a tty, pty otherwise */
+  int allocate_tty (bool); /* true if allocate a tty, pty otherwise */
   int connect_tty (int);
   void terminate ();
   void init ();
diff --git a/winsup/cygwin/winsup.h b/winsup/cygwin/winsup.h
index cd698ba56..49a880ea9 100644
--- a/winsup/cygwin/winsup.h
+++ b/winsup/cygwin/winsup.h
@@ -134,7 +134,7 @@ extern int cygserver_running;
 #include "debug.h"
 
 /* Events/mutexes */
-extern HANDLE title_mutex;
+extern HANDLE tty_mutex;
 
 /**************************** Convenience ******************************/