From e217832c4c4d8dba3c13af35b1d107851271b77d Mon Sep 17 00:00:00 2001
From: Corinna Vinschen <corinna@vinschen.de>
Date: Wed, 22 Oct 2003 10:07:59 +0000
Subject: 	* Makefile.in: Add $(LIBSERVER) rule. 	* cygserver.h: Moved
 from include/cygwin to here. 	* cygserver_ipc.h: Moved from ../cygserver to
 here. 	* cygserver_shm.h: Ditto. 	* cygwin.din: Add shmat, shmctl, shmdt
 and shmget. 	* fhandler_tty.cc (fhandler_tty_slave::open): Don't warn about
 handle 	dup'ing if not build with USE_SERVER. 	* shm.cc: Include
 cygerrno.h unconditionally. 	(shmat): Set errno to ENOSYS and return -1 if
 not build with 	USE_SERVER. 	(shmctl): Ditto. 	(shmdt):
 Ditto. 	(shmget): Ditto. 	* woutsup.h: Remove. 	*
 include/cygwin/cygserver_process.h: Moved to ../cygserver directory. 	*
 include/cygwin/cygserver_transport.h: Ditto. 	*
 include/cygwin/cygserver_transport_pipes.h: Ditto. 	*
 include/cygwin/cygserver_transport_sockets.h: Ditto. 	*
 include/cygwin/version.h: Bump API minor number.

---
 winsup/cygwin/cygserver_ipc.h | 84 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 84 insertions(+)
 create mode 100644 winsup/cygwin/cygserver_ipc.h

(limited to 'winsup/cygwin/cygserver_ipc.h')

diff --git a/winsup/cygwin/cygserver_ipc.h b/winsup/cygwin/cygserver_ipc.h
new file mode 100644
index 000000000..0d0ebbc76
--- /dev/null
+++ b/winsup/cygwin/cygserver_ipc.h
@@ -0,0 +1,84 @@
+/* cygserver_ipc.h
+
+   Copyright 2002 Red Hat, Inc.
+
+   Originally written by Conrad Scott <conrad.scott@dsl.pipex.com>
+
+This file is part of Cygwin.
+
+This software is a copyrighted work licensed under the terms of the
+Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
+details. */
+
+#ifndef __CYGSERVER_IPC_H__
+#define __CYGSERVER_IPC_H__
+
+#include <assert.h>
+#include <limits.h>		/* For OPEN_MAX. */
+
+/*
+ * The sysv ipc id's (msgid, semid, shmid) are integers arranged such
+ * that they no subsystem will generate the same id as some other
+ * subsystem; nor do these ids overlap file descriptors (the other
+ * common integer ids).  Since Cygwin can allocate more than OPEN_MAX
+ * file descriptors, it can't be guaranteed not to overlap, but it
+ * should help catch some errors.
+ *
+ * msgid's: OPEN_MAX,     OPEN_MAX + 3, OPEN_MAX + 6, . . .
+ * semid's: OPEN_MAX + 1, OPEN_MAX + 4, OPEN_MAX + 7, . . .
+ * shmid's: OPEN_MAX + 2, OPEN_MAX + 5, OPEN_MAX + 8, . . .
+ *
+ * To further ensure that ids are unique, if ipc objects are created
+ * and destroyed and then re-created, they are given new ids by
+ * munging the basic id (as above) with a sequence number.
+ *
+ * Internal ipc id's, which are 0, 1, ... within each subsystem (and
+ * not munged with a sequence number), are used solely by the ipcs(8)
+ * interface.
+ */
+
+enum ipc_subsys_t
+  {
+    IPC_MSGOP = 0,
+    IPC_SEMOP = 1,
+    IPC_SHMOP = 2,
+    IPC_SUBSYS_COUNT
+  };
+
+/*
+ * IPCMNI - The absolute maximum number of simultaneous ipc ids for
+ * any one subsystem.
+ */
+
+enum
+  {
+    IPCMNI = 0x10000		// Must be a power of two.
+  };
+
+inline int
+ipc_int2ext (const int intid, const ipc_subsys_t subsys, long & sequence)
+{
+  assert (0 <= intid && intid < IPCMNI);
+
+  const long tmp = InterlockedIncrement (&sequence);
+
+  return (((tmp & 0x7fff) << 16)
+	  | (OPEN_MAX + (intid * IPC_SUBSYS_COUNT) + subsys));
+}
+
+inline int
+ipc_ext2int_subsys (const int extid)
+{
+  return ((extid & (IPCMNI - 1)) - OPEN_MAX) % IPC_SUBSYS_COUNT;
+}
+
+inline int
+ipc_ext2int (const int extid, const ipc_subsys_t subsys)
+{
+  if (ipc_ext2int_subsys (extid) != subsys)
+    return -1;
+  else
+    return ((extid & (IPCMNI - 1)) - OPEN_MAX) / IPC_SUBSYS_COUNT;
+}
+
+#endif /* __CYGSERVER_IPC_H__ */
-- 
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