lib/libc_r/uthread/uthread_write.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. Neither the name of the author nor the names of any co-contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * $FreeBSD$
  30  *
  31  */
  32 #include <sys/types.h>
  33 #include <sys/fcntl.h>
  34 #include <sys/uio.h>
  35 #include <errno.h>
  36 #include <unistd.h>
  37 #include <pthread.h>
  38 #include "pthread_private.h"
  39
  40 __weak_reference(__write, write);
  41
  42 ssize_t
  43 _write(int fd, const void *buf, size_t nbytes)
  44 {
  45         struct pthread  *curthread = _get_curthread();
  46         int     blocking;
  47         int     type;
  48         ssize_t n;
  49         ssize_t num = 0;
  50         ssize_t ret;
  51
  52         /* POSIX says to do just this: */
  53         if (nbytes == 0)
  54                 return (0);
  55
  56         /* Lock the file descriptor for write: */
  57         if ((ret = _FD_LOCK(fd, FD_WRITE, NULL)) == 0) {
  58                 /* Get the read/write mode type: */
  59                 type = _thread_fd_getflags(fd) & O_ACCMODE;
  60
  61                 /* Check if the file is not open for write: */
  62                 if (type != O_WRONLY && type != O_RDWR) {
  63                         /* File is not open for write: */
  64                         errno = EBADF;
  65                         _FD_UNLOCK(fd, FD_WRITE);
  66                         return (-1);
  67                 }
  68
  69                 /* Check if file operations are to block */
  70                 blocking = ((_thread_fd_getflags(fd) & O_NONBLOCK) == 0);
  71
  72                 /*
  73                  * Loop while no error occurs and until the expected number
  74                  * of bytes are written if performing a blocking write:
  75                  */
  76                 while (ret == 0) {
  77                         /* Perform a non-blocking write syscall: */
  78                         n = __sys_write(fd, (const char *)buf + num,
  79                             nbytes - num);
  80
  81                         /* Check if one or more bytes were written: */
  82                         if (n > 0)
  83                                 /*
  84                                  * Keep a count of the number of bytes
  85                                  * written:
  86                                  */
  87                                 num += n;
  88
  89                         /*
  90                          * If performing a blocking write, check if the
  91                          * write would have blocked or if some bytes
  92                          * were written but there are still more to
  93                          * write:
  94                          */
  95                         if (blocking && ((n < 0 && (errno == EWOULDBLOCK ||
  96                             errno == EAGAIN)) || (n > 0 && num < nbytes))) {
  97                                 curthread->data.fd.fd = fd;
  98                                 _thread_kern_set_timeout(NULL);
  99
 100                                 /* Reset the interrupted operation flag: */
 101                                 curthread->interrupted = 0;
 102
 103                                 _thread_kern_sched_state(PS_FDW_WAIT,
 104                                     __FILE__, __LINE__);
 105
 106                                 /*
 107                                  * Check if the operation was
 108                                  * interrupted by a signal
 109                                  */
 110                                 if (curthread->interrupted) {
 111                                         if (num > 0) {
 112                                                 /* Return partial success: */
 113                                                 ret = num;
 114                                         } else {
 115                                                 /* Return an error: */
 116                                                 errno = EINTR;
 117                                                 ret = -1;
 118                                         }
 119                                 }
 120
 121                         /*
 122                          * If performing a non-blocking write,
 123                          * just return whatever the write syscall did:
 124                          */
 125                         } else if (!blocking) {
 126                                 /* A non-blocking call might return zero: */
 127                                 ret = n;
 128                                 break;
 129
 130                         /*
 131                          * If there was an error, return partial success
 132                          * (if any bytes were written) or else the error:
 133                          */
 134                         } else if (n <= 0) {
 135                                 if (num > 0)
 136                                         ret = num;
 137                                 else
 138                                         ret = n;
 139                                 if (n == 0)
 140                                         break;
 141
 142                         /* Check if the write has completed: */
 143                         } else if (num >= nbytes)
 144                                 /* Return the number of bytes written: */
 145                                 ret = num;
 146                 }
 147                 _FD_UNLOCK(fd, FD_WRITE);
 148         }
 149         return (ret);
 150 }
 151
 152 ssize_t
 153 __write(int fd, const void *buf, size_t nbytes)
 154 {
 155         ssize_t ret;
 156
 157         _thread_enter_cancellation_point();
 158         ret = _write(fd, buf, nbytes);
 159         _thread_leave_cancellation_point();
 160
 161         return ret;
 162 }