510 lines
13 KiB
C
510 lines
13 KiB
C
/* ==== fd.c ============================================================
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* Copyright (c) 1993 by Chris Provenzano, proven@mit.edu
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* All rights reserved.
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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. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Chris Provenzano.
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* 4. The name of Chris Provenzano may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* 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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* Description : All the syscalls dealing with fds.
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*
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* 1.00 93/08/14 proven
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* -Started coding this file.
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*
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* 1.01 93/11/13 proven
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* -The functions readv() and writev() added.
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*/
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#include <pthread.h>
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#include <sys/types.h>
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#include <sys/uio.h>
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#include <stdarg.h>
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#include <fcntl.h>
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#include <errno.h>
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#include <pthread/posix.h>
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/*
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* These first functions really should not be called by the user.
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*
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* I really should dynamically figure out what the table size is.
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*/
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int dtablesize = 64;
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static struct fd_table_entry fd_entry[64];
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/* ==========================================================================
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* fd_init()
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*/
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void fd_init(void)
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{
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int i;
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for (i = 0; i < dtablesize; i++) {
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fd_table[i] = &fd_entry[i];
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fd_table[i]->ops = NULL;
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fd_table[i]->type = FD_NT;
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fd_table[i]->fd.i = NOTOK;
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fd_table[i]->flags = 0;
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fd_table[i]->count = 0;
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pthread_queue_init(&(fd_table[i]->r_queue));
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pthread_queue_init(&(fd_table[i]->w_queue));
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fd_table[i]->r_owner = NULL;
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fd_table[i]->w_owner = NULL;
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fd_table[i]->lock = SEMAPHORE_CLEAR;
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fd_table[i]->next = NULL;
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fd_table[i]->lockcount = 0;
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}
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/* Currently only initialize first 3 fds. */
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fd_kern_init(0);
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fd_kern_init(1);
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fd_kern_init(2);
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}
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/* ==========================================================================
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* fd_allocate()
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*/
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int fd_allocate()
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{
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semaphore *lock;
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int i;
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for (i = 0; i < dtablesize; i++) {
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lock = &(fd_table[i]->lock);
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while (SEMAPHORE_TEST_AND_SET(lock)) {
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continue;
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}
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if (fd_table[i]->count || fd_table[i]->r_owner
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|| fd_table[i]->w_owner) {
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SEMAPHORE_RESET(lock);
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continue;
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}
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if (fd_table[i]->type == FD_NT) {
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/* Test to see if the kernel version is in use */
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/* If so continue; */
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}
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fd_table[i]->count++;
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SEMAPHORE_RESET(lock);
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return(i);
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}
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pthread_run->error = ENFILE;
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return(NOTOK);
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}
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/* ==========================================================================
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* fd_free()
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*
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* Assumes fd is locked and owner by pthread_run
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* Don't clear the queues, fd_unlock will do that.
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*/
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int fd_free(int fd)
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{
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struct fd_table_entry *fd_valid;
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int ret;
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if (ret = --fd_table[fd]->count) {
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/* Separate pthread queue into two distinct queues. */
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fd_valid = fd_table[fd];
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fd_table[fd] = fd_table[fd]->next;
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fd_valid->next = fd_table[fd]->next;
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}
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fd_table[fd]->type = FD_NIU;
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fd_table[fd]->fd.i = NOTOK;
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fd_table[fd]->next = NULL;
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fd_table[fd]->flags = 0;
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fd_table[fd]->count = 0;
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return(ret);
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}
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/* ==========================================================================
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* fd_basic_unlock()
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*
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* The real work of unlock without the locking of fd_table[fd].lock.
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*/
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void fd_basic_unlock(int fd, int lock_type)
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{
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struct pthread *pthread;
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semaphore *plock;
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if (fd_table[fd]->r_owner == pthread_run) {
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if (pthread = pthread_queue_get(&fd_table[fd]->r_queue)) {
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plock = &(pthread->lock);
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while (SEMAPHORE_TEST_AND_SET(plock)) {
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pthread_yield();
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}
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pthread_queue_deq(&fd_table[fd]->r_queue);
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fd_table[fd]->r_owner = pthread;
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pthread->state = PS_RUNNING;
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SEMAPHORE_RESET(plock);
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} else {
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fd_table[fd]->r_owner = NULL;
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}
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}
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if (fd_table[fd]->w_owner == pthread_run) {
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if (pthread = pthread_queue_get(&fd_table[fd]->w_queue)) {
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plock = &(pthread->lock);
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while (SEMAPHORE_TEST_AND_SET(plock)) {
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pthread_yield();
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}
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pthread_queue_deq(&fd_table[fd]->r_queue);
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fd_table[fd]->w_owner = pthread;
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pthread->state = PS_RUNNING;
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SEMAPHORE_RESET(plock);
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} else {
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fd_table[fd]->w_owner = NULL;
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}
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}
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}
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/* ==========================================================================
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* fd_unlock()
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* If there is a lock count then the function fileunlock will do
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* the unlocking, just return.
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*/
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void fd_unlock(int fd, int lock_type)
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{
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semaphore *lock;
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if (!(fd_table[fd]->lockcount)) {
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lock = &(fd_table[fd]->lock);
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while (SEMAPHORE_TEST_AND_SET(lock)) {
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pthread_yield();
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}
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fd_basic_unlock(fd, lock_type);
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SEMAPHORE_RESET(lock);
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}
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}
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/* ==========================================================================
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* fd_basic_lock()
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*
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* The real work of lock without the locking of fd_table[fd].lock.
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* Be sure to leave the lock the same way you found it. i.e. locked.
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*/
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int fd_basic_lock(unsigned int fd, int lock_type, semaphore * lock)
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{
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semaphore *plock;
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/* If not in use return EBADF error */
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if (fd_table[fd]->type == FD_NIU) {
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return(NOTOK);
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}
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/* If not tested, test it and see if it is valid */
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if (fd_table[fd]->type == FD_NT) {
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/* If not ok return EBADF error */
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if (fd_kern_init(fd) != OK) {
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return(NOTOK);
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}
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}
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if ((fd_table[fd]->type == FD_HALF_DUPLEX) ||
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(lock_type & FD_READ)) {
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if (fd_table[fd]->r_owner) {
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if (fd_table[fd]->r_owner != pthread_run) {
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plock = &(pthread_run->lock);
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while (SEMAPHORE_TEST_AND_SET(plock)) {
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pthread_yield();
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}
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pthread_queue_enq(&fd_table[fd]->r_queue, pthread_run);
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SEMAPHORE_RESET(lock);
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/* Reschedule will unlock pthread_run */
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reschedule(PS_FDLR_WAIT);
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while(SEMAPHORE_TEST_AND_SET(lock)) {
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pthread_yield();
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}
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} else {
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if (!fd_table[fd]->lockcount) {
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PANIC();
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}
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}
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}
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fd_table[fd]->r_owner = pthread_run;
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}
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if ((fd_table[fd]->type != FD_HALF_DUPLEX) &&
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(lock_type & FD_WRITE)) {
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if (fd_table[fd]->w_owner) {
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if (fd_table[fd]->w_owner != pthread_run) {
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plock = &(pthread_run->lock);
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while (SEMAPHORE_TEST_AND_SET(plock)) {
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pthread_yield();
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}
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pthread_queue_enq(&fd_table[fd]->w_queue, pthread_run);
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SEMAPHORE_RESET(lock);
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/* Reschedule will unlock pthread_run */
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reschedule(PS_FDLW_WAIT);
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while(SEMAPHORE_TEST_AND_SET(lock)) {
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pthread_yield();
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}
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}
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}
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fd_table[fd]->w_owner = pthread_run;
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}
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if (!fd_table[fd]->count) {
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fd_basic_unlock(fd, lock_type);
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return(NOTOK);
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}
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return(OK);
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}
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/* ==========================================================================
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* fd_lock()
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*/
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int fd_lock(unsigned int fd, int lock_type)
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{
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semaphore *lock;
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int error;
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if (fd < dtablesize) {
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lock = &(fd_table[fd]->lock);
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while (SEMAPHORE_TEST_AND_SET(lock)) {
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pthread_yield();
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}
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error = fd_basic_lock(fd, lock_type, lock);
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SEMAPHORE_RESET(lock);
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return(error);
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}
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return(NOTOK);
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}
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/* ==========================================================================
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* ======================================================================= */
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/* ==========================================================================
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* read()
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*/
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ssize_t read(int fd, void *buf, size_t nbytes)
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{
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int ret;
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if ((ret = fd_lock(fd, FD_READ)) == OK) {
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ret = fd_table[fd]->ops->read(fd_table[fd]->fd,
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fd_table[fd]->flags, buf, nbytes);
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fd_unlock(fd, FD_READ);
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}
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return(ret);
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}
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/* ==========================================================================
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* readv()
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*/
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int readv(int fd, const struct iovec *iov, int iovcnt)
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{
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int ret;
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if ((ret = fd_lock(fd, FD_READ)) == OK) {
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ret = fd_table[fd]->ops->readv(fd_table[fd]->fd,
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fd_table[fd]->flags, iov, iovcnt);
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fd_unlock(fd, FD_READ);
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}
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return(ret);
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}
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/* ==========================================================================
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* write()
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*/
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ssize_t write(int fd, const void *buf, size_t nbytes)
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{
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int ret;
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if ((ret = fd_lock(fd, FD_WRITE)) == OK) {
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ret = fd_table[fd]->ops->write(fd_table[fd]->fd,
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fd_table[fd]->flags, buf, nbytes);
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fd_unlock(fd, FD_WRITE);
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}
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return(ret);
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}
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/* ==========================================================================
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* writev()
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*/
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int writev(int fd, const struct iovec *iov, int iovcnt)
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{
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int ret;
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if ((ret = fd_lock(fd, FD_WRITE)) == OK) {
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ret = fd_table[fd]->ops->writev(fd_table[fd]->fd,
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fd_table[fd]->flags, iov, iovcnt);
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fd_unlock(fd, FD_WRITE);
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}
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return(ret);
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}
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/* ==========================================================================
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* close()
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*
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* The whole close procedure is a bit odd and needs a bit of a rethink.
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* For now close() locks the fd, calls fd_free() which checks to see if
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* there are any other fd values poinging to the same real fd. If so
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* It breaks the wait queue into two sections those that are waiting on fd
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* and those waiting on other fd's. Those that are waiting on fd are connected
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* to the fd_table[fd] queue, and the count is set to zero, (BUT THE LOCK IS NOT
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* RELEASED). close() then calls fd_unlock which give the fd to the next queued
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* element which determins that the fd is closed and then calls fd_unlock etc...
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*/
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int close(int fd)
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{
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union fd_data realfd;
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int ret, flags;
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if ((ret = fd_lock(fd, FD_RDWR)) == OK) {
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flags = fd_table[fd]->flags;
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realfd = fd_table[fd]->fd;
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if (fd_free(fd) == OK) {
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ret = fd_table[fd]->ops->close(realfd, flags);
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}
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fd_unlock(fd, FD_RDWR);
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}
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return(ret);
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}
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/* ==========================================================================
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* fd_basic_dup()
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*
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* Might need to do more than just what's below.
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*/
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static inline void fd_basic_dup(int fd, int newfd)
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{
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fd_table[newfd]->next = fd_table[fd]->next;
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fd_table[fd]->next = fd_table[newfd];
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fd_table[fd]->count++;
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}
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/* ==========================================================================
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* dup2()
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*/
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int dup2(fd, newfd)
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{
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union fd_data realfd;
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semaphore *lock;
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int ret, flags;
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if ((ret = fd_lock(fd, FD_RDWR)) == OK) {
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/* Need to lock the newfd by hand */
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if (newfd < dtablesize) {
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lock = &(fd_table[newfd]->lock);
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while(SEMAPHORE_TEST_AND_SET(lock)) {
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pthread_yield();
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}
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/* Is it inuse */
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if (fd_basic_lock(newfd, FD_RDWR, lock) == OK) {
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/* free it and check close status */
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flags = fd_table[fd]->flags;
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realfd = fd_table[fd]->fd;
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if (fd_free(fd) == OK) {
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ret = fd_table[fd]->ops->close(realfd, flags);
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}
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}
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fd_basic_dup(fd, newfd);
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}
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fd_unlock(fd, FD_RDWR);
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}
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return(ret);
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}
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/* ==========================================================================
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* dup()
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*/
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int dup(int fd)
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{
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int ret;
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if ((ret = fd_lock(fd, FD_RDWR)) == OK) {
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ret = fd_allocate();
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fd_basic_dup(fd, ret);
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fd_unlock(fd, FD_RDWR);
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}
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return(ret);
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}
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/* ==========================================================================
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* fcntl()
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*/
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int fcntl(int fd, int cmd, ...)
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{
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int ret, realfd, flags;
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struct flock *flock;
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semaphore *plock;
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va_list ap;
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flags = 0;
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if ((ret = fd_lock(fd, FD_RDWR)) == OK) {
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va_start(ap, cmd);
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switch(cmd) {
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case F_DUPFD:
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ret = fd_allocate();
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fd_basic_dup(va_arg(ap, int), ret);
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break;
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case F_SETFD:
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flags = va_arg(ap, int);
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case F_GETFD:
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ret = fd_table[fd]->ops->fcntl(fd_table[fd]->fd,
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fd_table[fd]->flags, cmd, flags | __FD_NONBLOCK);
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break;
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case F_GETFL:
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ret = fd_table[fd]->flags;
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break;
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case F_SETFL:
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flags = va_arg(ap, int);
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if ((ret = fd_table[fd]->ops->fcntl(fd_table[fd]->fd,
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fd_table[fd]->flags, cmd, flags | __FD_NONBLOCK)) == OK) {
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fd_table[fd]->flags = flags;
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}
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break;
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/* case F_SETLKW: */
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/*
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* Do the same as SETLK but if it fails with EACCES or EAGAIN
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* block the thread and try again later, not implemented yet
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*/
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/* case F_SETLK: */
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/* case F_GETLK:
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flock = va_arg(ap, struct flock*);
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ret = fd_table[fd]->ops->fcntl(fd_table[fd]->fd,
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fd_table[fd]->flags, cmd, flock);
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break; */
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default:
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/* Might want to make va_arg use a union */
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ret = fd_table[fd]->ops->fcntl(fd_table[fd]->fd,
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fd_table[fd]->flags, cmd, va_arg(ap, void*));
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break;
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}
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va_end(ap);
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fd_unlock(fd, FD_RDWR);
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}
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return(ret);
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}
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