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This class wraps the pidfile_* API from libutil. The destructor calls pidfile_remove() when an object is destroyed. This class is similar to std::unique_ptr<> in that it retains exclusive ownership of the pidfh object. In addition to release and reset methods, write, close, and fileno methods are provided as wrappers for pidfile_*. Sponsored by: Chelsio Communications Pull Request: https://github.com/freebsd/freebsd-src/pull/1794
110 lines
2.2 KiB
Groff
110 lines
2.2 KiB
Groff
.\"
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.\" SPDX-License-Identifier: BSD-2-Clause
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.\"
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.\" Copyright (c) 2025 Chelsio Communications, Inc.
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.\" Written by: John Baldwin <jhb@FreeBSD.org>
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.\"
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.Dd July 31, 2025
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.Dt FREEBSD::STRINGF 3
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.Os
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.Sh NAME
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.Nm freebsd::pidfile
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.Nd own a PID file handle
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.Sh LIBRARY
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.Lb libutil++
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.Sh SYNOPSIS
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.In libutil++.hh
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.Pp
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.Vt class freebsd::pidfile
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{
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.Bd -ragged -offset indent
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.Fn pidfile
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.Fn pidfile "struct pidfh *pfh"
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.Fn pidfile "pidfile &&other"
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.Fn ~pidfile
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.Ft struct pidfh *
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.Fn release
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.Ft void
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.Fn reset "struct pidfh *newpfh = nullptr"
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.Ft int
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.Fn write
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.Ft int
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.Fn close
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.Ft int
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.Fn fileno
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.Ft "pidfile &"
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.Fn operator= "pidfile &&other"
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.Ft "pidfile &"
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.Fn operator= "struct pidfh *pfh"
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.Fn "explicit operator bool"
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.Ed
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};
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.Sh DESCRIPTION
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Each instance of this class owns a PID file handle created by
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.Xr pidfile_open 3 .
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This class is patterned on std::unique_ptr;
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however,
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rather than exporting the raw pointer via a
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.Fn get
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method,
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this class provides wrapper methods for each of the other
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.Xr pidfile 3
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functions.
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The currently-owned PID file is removed by invoking
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.Xr pidfile_remove 3
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when an instance of this class is destroyed.
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The currently-owned PID file is also removed if it is replaced by the
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.Fn reset
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method or assignment operators.
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.Pp
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The
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.Fn release
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method relinquishes ownership of the current PID file handle and returns the
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value of the previously-owned PID file handle.
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.Pp
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The
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.Fn write
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method writes out the PID of the current process to the PID file via
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.Xr pidfile_write 3 .
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.Pp
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The
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.Fn close
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method closes the current PID file without removing it via
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.Xr pidfile_close 3 .
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If the close succeeds, the PID file handle is no longer valid.
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.Pp
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The
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.Fn fileno
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method returns the underlying file descriptor for the current PID file via
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.Xr pidfile_fileno 3 .
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.Pp
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The explicit
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.Vt bool
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conversion operator permits testing the validity of an object.
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The operator returns true if the instance owns a valid PID file handle.
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.Sh EXAMPLES
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.Bd -literal -offset indent
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int
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main()
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{
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freebsd::pidfile pf(pidfile_open("/var/run/daemon.pid",
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0600, NULL));
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if (!pf)
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err(1, "pidfile_open");
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if (daemon(0, 0) == -1) {
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warn("daemon");
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return 1;
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}
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pf->write();
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for (;;) {
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/* Do Work */
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}
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return 0;
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}
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.Ed
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.Sh SEE ALSO
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.Xr pidfile 3
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