lib/libc_r/uthread/uthread_close.c

   1 /*
   2  * Copyright (c) 1995-1998 John Birrell <jb@cimlogic.com.au>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by John Birrell.
  16  * 4. Neither the name of the author nor the names of any co-contributors
  17  *    may be used to endorse or promote products derived from this software
  18  *    without specific prior written permission.
  19  *
  20  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  30  * SUCH DAMAGE.
  31  *
  32  * $FreeBSD: src/lib/libc_r/uthread/uthread_close.c,v 1.10.2.5 2003/06/13 16:04:59 ru Exp $
  33  * $DragonFly: src/lib/libc_r/uthread/uthread_close.c,v 1.3 2006/08/01 08:25:58 corecode Exp $
  34  */
  35 #include <errno.h>
  36 #include <stdlib.h>
  37 #include <unistd.h>
  38 #include <fcntl.h>
  39 #include <sys/stat.h>
  40 #include <pthread.h>
  41 #include "pthread_private.h"
  42
  43 int
  44 _close(int fd)
  45 {
  46         int             flags;
  47         int             ret;
  48         struct stat     sb;
  49         struct fd_table_entry   *entry;
  50
  51         if ((fd < 0) || (fd >= _thread_dtablesize) ||
  52             (fd == _thread_kern_pipe[0]) || (fd == _thread_kern_pipe[1])) {
  53                 /*
  54                  * Don't allow silly programs to close the kernel pipe.
  55                  *
  56                  * Non-active descriptors are detected by _FD_LOCK below.
  57                  */
  58                 errno = EBADF;
  59                 ret = -1;
  60         }
  61         /*
  62          * Lock the file descriptor while the file is closed and get
  63          * the file descriptor status:
  64          */
  65         else if (((ret = _FD_LOCK(fd, FD_RDWR, NULL)) == 0) &&
  66             ((ret = __sys_fstat(fd, &sb)) == 0)) {
  67                 /*
  68                  * Check if the file should be left as blocking.
  69                  *
  70                  * This is so that the file descriptors shared with a parent
  71                  * process aren't left set to non-blocking if the child
  72                  * closes them prior to exit.  An example where this causes
  73                  * problems with /bin/sh is when a child closes stdin.
  74                  *
  75                  * Setting a file as blocking causes problems if a threaded
  76                  * parent accesses the file descriptor before the child exits.
  77                  * Once the threaded parent receives a SIGCHLD then it resets
  78                  * all of its files to non-blocking, and so it is then safe
  79                  * to access them.
  80                  *
  81                  * Pipes are not set to blocking when they are closed, as
  82                  * the parent and child will normally close the file
  83                  * descriptor of the end of the pipe that they are not
  84                  * using, which would then cause any reads to block
  85                  * indefinitely.
  86                  */
  87                 if ((S_ISREG(sb.st_mode) || S_ISCHR(sb.st_mode))
  88                     && (_thread_fd_getflags(fd) & O_NONBLOCK) == 0) {
  89                         /* Get the current flags: */
  90                         flags = __sys_fcntl(fd, F_GETFL, NULL);
  91                         /* Clear the nonblocking file descriptor flag: */
  92                         __sys_fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
  93                 }
  94
  95                 /* XXX: Assumes well behaved threads. */
  96                 /* XXX: Defer real close to avoid race condition */
  97                 entry = _thread_fd_table[fd];
  98                 _thread_fd_table[fd] = NULL;
  99                 free(entry);
 100
 101                 /* Drop stale pthread stdio descriptor flags. */
 102                 if (fd < 3)
 103                         _pthread_stdio_flags[fd] = -1;
 104
 105                 /* Close the file descriptor: */
 106                 ret = __sys_close(fd);
 107         }
 108         return (ret);
 109 }
 110
 111 int
 112 close(int fd)
 113 {
 114         int     ret;
 115
 116         _thread_enter_cancellation_point();
 117         ret = _close(fd);
 118         _thread_leave_cancellation_point();
 119
 120         return ret;
 121 }