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diff --git a/include/base/fsmutex.h b/include/base/fsmutex.h
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+/** BEGIN COPYRIGHT BLOCK
+ * Copyright 2001 Sun Microsystems, Inc.
+ * Portions copyright 1999, 2001-2003 Netscape Communications Corporation.
+ * All rights reserved.
+ * END COPYRIGHT BLOCK **/
+/*
+ * fsmutex: Mutexes that are filesystem-based so they're available from more
+ * than one process and address space
+ * 
+ * Rob McCool
+ */
+
+
+#ifndef FSMUTEX_H
+#define FSMUTEX_H
+
+#include "netsite.h"
+
+typedef void * FSMUTEX;
+
+
+/* ------------------------------ Prototypes ------------------------------ */
+
+NSPR_BEGIN_EXTERN_C
+
+/* 
+   Flags to fsmutex_init. 
+
+   FSMUTEX_VISIBLE makes a filesystem mutex which can be opened by other
+   programs or processes.
+
+   FSMUTEX_NEEDCRIT specifies that the fsmutex_lock and fsmutex_unlock 
+   functions should also use a critical section to ensure that more than
+   one thread does not acquire the mutex at a time. If this flag is not 
+   specified, it is up to the caller to ensure that only thread within a 
+   process tries to acquire the lock at any given time.
+ */
+#define FSMUTEX_VISIBLE 0x01
+#define FSMUTEX_NEEDCRIT 0x02
+
+
+/*
+   fsmutex_init creates a new filesystem-based mutex. The resulting mutex
+   is part of the filesystem. The name and number parameters are used to
+   create a name for the mutex. If the FSMUTEX_VISIBLE flag is specified, 
+   the mutex will be left in the filesystem for other programs and processes
+   to access. If a mutex with the given name/number combination already
+   exists, the calling process is allowed access to it. If the mutex does
+   not already exist, the mutex is created.
+
+   Returns NULL on failure, a void pointer to a fsmutex structure otherwise.
+   This fsmutex structure is local to the current process.
+ */
+NSAPI_PUBLIC FSMUTEX fsmutex_init(char *name, int number, int flags);
+
+/* 
+   Sets the ownership of the underlying filesystem object to the given
+   uid and gid. Only effective if the server is running as root.
+ */
+#ifdef XP_UNIX
+#include <unistd.h>
+#ifdef __sony
+#include <sys/types.h>
+#endif
+NSAPI_PUBLIC void fsmutex_setowner(FSMUTEX fsm, uid_t uid, gid_t gid);
+#endif
+
+
+
+/*
+   fsmutex_terminate deletes a filesystem-based mutex. A mutex will only
+   be deleted when every process which has an open pointer to the mutex 
+   calls this function.
+ */
+NSAPI_PUBLIC void fsmutex_terminate(FSMUTEX id);
+
+/*
+   fsmutex_lock attempts to acquire the given filesystem-based mutex. If 
+   another process is holding the mutex, or if the FSMUTEX_NEEDCRIT flag
+   was passed to fsmutex_init and another thread in the current process is 
+   holding the mutex, then the calling thread will block until the mutex
+   is available.
+ */
+NSAPI_PUBLIC void fsmutex_lock(FSMUTEX id);
+
+/*
+   fsmutex_unlock releases a filesystem-based mutex previously acquired
+   by fsmutex_lock.
+ */
+NSAPI_PUBLIC void fsmutex_unlock(FSMUTEX id);
+
+NSPR_END_EXTERN_C
+
+#endif