1 files changed, 108 insertions, 0 deletions
diff --git a/liblock/liblock.h b/liblock/liblock.h
new file mode 100644
index 0000000..db43bd4
--- /dev/null
+++ b/liblock/liblock.h
@@ -0,0 +1,108 @@
+
+#ifndef liblock_h
+#define liblock_h
+
+/*
+** Copyright 1998 - 1999 Double Precision, Inc.  See COPYING for
+** distribution information.
+*/
+
+#ifdef	__cplusplus
+extern "C" {
+#endif
+
+#if	HAVE_CONFIG_H
+#include	"liblock/config.h"
+#endif
+#include	<sys/types.h>
+
+#define	ll_whence_start	0
+#define	ll_whence_curpos 1
+#define	ll_whence_end 2
+
+#define	ll_readlock	0
+#define	ll_writelock	4
+#define	ll_unlock	8
+#define	ll_wait		16
+
+int	ll_lockfd(int,	/* File descriptor */
+		int,	/* ll_ bitmask */
+		LL_OFFSET_TYPE,	/* Start */
+		LL_OFFSET_TYPE);	/* Length */
+
+
+/* Some useful macros: ll_lock_ex - exclusive lock on a file,
+		ll_lock_ex_test - attempt an exclusive lock on a file
+		ll_unlock_ex - unlock a file
+*/
+
+#define	ll_lock_ex(f)	\
+	ll_lockfd( (f), ll_writelock|ll_whence_start|ll_wait, 0, 0)
+
+#define	ll_lock_ex_test(f)	\
+	ll_lockfd( (f), ll_writelock|ll_whence_start, 0, 0)
+
+#define	ll_unlock_ex(f)	\
+	ll_lockfd( (f), ll_unlock|ll_whence_start, 0, 0)
+
+
+/*
+** Value-added: functions that reliably start and stop a daemon process,
+** permitting only one daemon process running.  Utilizes a lock file, and a
+** pidfile.
+*/
+
+int ll_daemon_start(const char *lockfile);
+void ll_daemon_started(const char *pidfile, int fd);
+int ll_daemon_resetio();
+int ll_daemon_stop(const char *lockfile, const char *pidfile);
+int ll_daemon_restart(const char *lockfile, const char *pidfile);
+
+/*
+  The basic scenario
+
+main()
+{
+    if ((fd=ll_daemon_start(lockfilename)) < 0)
+    {
+           error();  exit(1);
+    }
+
+    ... Some custom initialization here ...
+
+    ll_daemon_started(pidfile, fd);
+
+    ll_daemon_resetio();   ... this one is optional
+}
+
+To stop this daemon:
+
+ll_daemon_stop (lockfilename, pidfile)
+
+
+ll_daemon_start attempts to start a daemon process going.  It does only
+a partial setup.  If it detects that the daemon process is already
+running, it itself does an exit(0), not returning to the parent.
+
+If there was a failure starting a daemon process, -1 is return, else
+we return a transparent file descriptor, which will have to be passed as
+the secodn argument to ll_daemon_started().
+
+When ll_daemon_start returns, we're already running in a partially set-up
+daemon process.  The setup isn't complete just yet.  The parent function
+can perform any other custom initialization.  If initialization fails,
+the parent function can simply exit.  Otherwise, if the initialization
+completes, ll_daemon_started must be called in order to save this daemon
+process's pid in the pid file (2nd arg must be the return from ll_daemon_start.
+
+To stop a daemon process, simply call ll_daemon_stop.  Nothing too
+sophisticated here.
+
+To send the daemon process a SIGHUP, call ll_daemon_restart.
+*/
+
+#ifdef	__cplusplus
+}
+#endif
+
+#endif