src/common/fd.h

/*****************************************************************************\
 *  $Id$
 *****************************************************************************
 *  Copyright (C) 2001-2006 The Regents of the University of California.
 *  Produced at Lawrence Livermore National Laboratory (cf, DISCLAIMER).
 *  Written by Chris Dunlap <cdunlap@llnl.gov>.
 *  UCRL-CODE-2002-009.
 *  
 *  This file is part of ConMan, a remote console management program.
 *  For details, see <http://www.llnl.gov/linux/conman/>.
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\*****************************************************************************/


#ifndef _FD_H
#define _FD_H


#ifdef HAVE_CONFIG_H
#  include "config.h"
#endif /* HAVE_CONFIG_H */

#include <sys/types.h>
#include <unistd.h>

#include "src/common/macros.h"

void fd_set_close_on_exec(int fd);
/*
 *  Sets the file descriptor (fd) to be closed on exec().
 */

void fd_set_noclose_on_exec(int fd);
/*
 *  Sets the file descriptor (fd) to NOT be closed on exec().
 */

void fd_set_nonblocking(int fd);
/*
 *  Sets the file descriptor (fd) for non-blocking I/O.
 */

void fd_set_blocking(int fd);
/*
 * Sets the file descriptor (fd) for blocking I/O.
 */

int fd_get_read_lock(int fd);
/*
 *  Obtain a read lock on the file specified by (fd).
 *  Returns 0 on success, or -1 if prevented from obtaining the lock.
 */

int fd_get_readw_lock(int fd);
/*
 *  Obtain a read lock on the file specified by (fd),
 *    blocking until one becomes available.
 *  Returns 0 on success, or -1 on error.
 */

int fd_get_write_lock(int fd);
/*
 *  Obtain a write lock on the file specified by (fd).
 *  Returns 0 on success, or -1 if prevented from obtaining the lock.
 */

int fd_get_writew_lock(int fd);
/*
 *  Obtain a write lock on the file specified by (fd),
 *    blocking until one becomes available.
 *  Returns 0 on success, or -1 on error.
 */

int fd_release_lock(int fd);
/*
 *  Release a lock held on the file specified by (fd).
 *  Returns 0 on success, or -1 on error.
 */

pid_t fd_is_read_lock_blocked(int fd);
/*
 *  If a lock exists the would block a request for a read-lock
 *    (ie, if a write-lock is already being held on the file),
 *    returns the pid of the process holding the lock; o/w, returns 0.
 */

pid_t fd_is_write_lock_blocked(int fd);
/*
 *  If a lock exists the would block a request for a write-lock
 *    (ie, if any lock is already being held on the file),
 *    returns the pid of a process holding the lock; o/w, returns 0.
 */

ssize_t fd_read_n(int fd, void *buf, size_t n);
/*
 *  Reads up to (n) bytes from (fd) into (buf).
 *  Returns the number of bytes read, 0 on EOF, or -1 on error.
 */

ssize_t fd_write_n(int fd, void *buf, size_t n);
/*
 *  Writes (n) bytes from (buf) to (fd).
 *  Returns the number of bytes written, or -1 on error.
 */

ssize_t fd_read_line(int fd, void *buf, size_t maxlen);
/*
 *  Reads at most (maxlen-1) bytes up to a newline from (fd) into (buf).
 *  The (buf) is guaranteed to be NUL-terminated and will contain the
 *    newline if it is encountered within (maxlen-1) bytes.
 *  Returns the number of bytes read, 0 on EOF, or -1 on error.
 */

int fd_is_blocking(int fd);
/*
 * Return 1 if the file specified by the file descriptor is blocking.
 * Return 0 otherwise.
 */

#endif /* !_FD_H */