124 lines
2.9 KiB
C
124 lines
2.9 KiB
C
/*
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* Copyright (c) 2014, 2015
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* The President and Fellows of Harvard College.
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* Written by David A. Holland.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* XXX this code is mostly copied from usemtest; it should go in a
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* library.
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <unistd.h>
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#include <err.h>
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#include "usem.h"
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void
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usem_init(struct usem *sem, const char *namefmt, ...)
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{
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va_list ap;
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va_start(ap, namefmt);
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vsnprintf(sem->name, sizeof(sem->name), namefmt, ap);
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va_end(ap);
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sem->fd = open(sem->name, O_RDWR|O_CREAT|O_TRUNC, 0664);
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if (sem->fd < 0) {
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err(1, "%s: create", sem->name);
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}
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close(sem->fd);
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sem->fd = -1;
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}
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void
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usem_open(struct usem *sem)
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{
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sem->fd = open(sem->name, O_RDWR);
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if (sem->fd < 0) {
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err(1, "%s: open", sem->name);
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}
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}
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void
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usem_close(struct usem *sem)
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{
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if (close(sem->fd) == -1) {
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warn("%s: close", sem->name);
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}
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}
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void
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usem_cleanup(struct usem *sem)
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{
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(void)remove(sem->name);
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}
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void
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Pn(struct usem *sem, unsigned count)
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{
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ssize_t r;
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char c;
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r = read(sem->fd, &c, count);
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if (r < 0) {
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err(1, "%s: read", sem->name);
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}
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if ((size_t)r < count) {
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errx(1, "%s: read: unexpected EOF", sem->name);
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}
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}
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void
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P(struct usem *sem)
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{
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Pn(sem, 1);
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}
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void
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Vn(struct usem *sem, unsigned count)
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{
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ssize_t r;
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char c;
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r = write(sem->fd, &c, count);
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if (r < 0) {
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err(1, "%s: write", sem->name);
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}
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if ((size_t)r < count) {
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errx(1, "%s: write: Short count", sem->name);
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}
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}
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void
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V(struct usem *sem)
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{
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Vn(sem, 1);
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}
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