peer_lock.c File Reference

#include <fcntl.h>
#include <sys/wait.h>
#include <unistd.h>
#include "peer_lock.h"

Functions
int	peer_hold_lock (struct peer *p, const char *path, short type, off_t start, off_t len)
	Fork a peer that holds an fcntl lock until released.
void	peer_release (struct peer *p)
	Release a held peer lock and reap the peer.
int	peer_try_lock (const char *path, short type, off_t start, off_t len)
	Probe a lock range from a forked child.

Function Documentation

peer_hold_lock()

int peer_hold_lock	(	struct peer *	p,
		const char *	path,
		short	type,
		off_t	start,
		off_t	len )

Fork a peer that holds an fcntl lock until released.

F_SETLK/F_GETLK never conflict with or report the calling process's own locks, so a test that needs a genuinely contending lock forks a peer that takes it and parks.

Parameters

[out]	p	filled with the peer's pid and control pipes
[in]	path	file to lock
[in]	type	F_RDLCK or F_WRLCK
[in]	start	first byte of the range
[in]	len	range length (0 = to EOF)

Returns

0 with the lock held by the time this returns, -1 on failure

peer_release()

void peer_release

(

struct peer *

p

)

Release a held peer lock and reap the peer.

Parameters

[in]

p

peer filled by peer_hold_lock()

peer_try_lock()

int peer_try_lock	(	const char *	path,
		short	type,
		off_t	start,
		off_t	len )

Probe a lock range from a forked child.

Cross-process, so it sees locks this process holds (which its own F_GETLK never would).

Parameters

[in]	path	file to probe
[in]	type	F_RDLCK or F_WRLCK
[in]	start	first byte of the range
[in]	len	range length (0 = to EOF)

Returns

1 if the lock was acquired (range free), 0 if it conflicted (range held by another process), -1 on a fork/open error