thr_writev.c revision 75369
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: head/lib/libkse/thread/thr_writev.c 75369 2001-04-10 04:19:21Z deischen $ 33 * 34 */ 35#include <sys/types.h> 36#include <sys/fcntl.h> 37#include <sys/uio.h> 38#include <errno.h> 39#include <stdlib.h> 40#include <string.h> 41#include <unistd.h> 42#include <pthread.h> 43#include "pthread_private.h" 44 45__weak_reference(_writev, writev); 46 47ssize_t 48_writev(int fd, const struct iovec * iov, int iovcnt) 49{ 50 struct pthread *curthread = _get_curthread(); 51 int blocking; 52 int idx = 0; 53 int type; 54 ssize_t cnt; 55 ssize_t n; 56 ssize_t num = 0; 57 ssize_t ret; 58 struct iovec liov[20]; 59 struct iovec *p_iov = liov; 60 61 /* Check if the array size exceeds to compiled in size: */ 62 if (iovcnt > (sizeof(liov) / sizeof(struct iovec))) { 63 /* Allocate memory for the local array: */ 64 if ((p_iov = (struct iovec *) 65 malloc(iovcnt * sizeof(struct iovec))) == NULL) { 66 /* Insufficient memory: */ 67 errno = ENOMEM; 68 return (-1); 69 } 70 } 71 72 /* Copy the caller's array so that it can be modified locally: */ 73 memcpy(p_iov,iov,iovcnt * sizeof(struct iovec)); 74 75 /* Lock the file descriptor for write: */ 76 if ((ret = _FD_LOCK(fd, FD_WRITE, NULL)) == 0) { 77 /* Get the read/write mode type: */ 78 type = _thread_fd_table[fd]->flags & O_ACCMODE; 79 80 /* Check if the file is not open for write: */ 81 if (type != O_WRONLY && type != O_RDWR) { 82 /* File is not open for write: */ 83 errno = EBADF; 84 _FD_UNLOCK(fd, FD_WRITE); 85 return (-1); 86 } 87 88 /* Check if file operations are to block */ 89 blocking = ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0); 90 91 /* 92 * Loop while no error occurs and until the expected number 93 * of bytes are written if performing a blocking write: 94 */ 95 while (ret == 0) { 96 /* Perform a non-blocking write syscall: */ 97 n = __sys_writev(fd, &p_iov[idx], iovcnt - idx); 98 99 /* Check if one or more bytes were written: */ 100 if (n > 0) { 101 /* 102 * Keep a count of the number of bytes 103 * written: 104 */ 105 num += n; 106 107 /* 108 * Enter a loop to check if a short write 109 * occurred and move the index to the 110 * array entry where the short write 111 * ended: 112 */ 113 cnt = n; 114 while (cnt > 0 && idx < iovcnt) { 115 /* 116 * If the residual count exceeds 117 * the size of this vector, then 118 * it was completely written: 119 */ 120 if (cnt >= p_iov[idx].iov_len) 121 /* 122 * Decrement the residual 123 * count and increment the 124 * index to the next array 125 * entry: 126 */ 127 cnt -= p_iov[idx++].iov_len; 128 else { 129 /* 130 * This entry was only 131 * partially written, so 132 * adjust it's length 133 * and base pointer ready 134 * for the next write: 135 */ 136 p_iov[idx].iov_len -= cnt; 137 p_iov[idx].iov_base += cnt; 138 cnt = 0; 139 } 140 } 141 } else if (n == 0) { 142 /* 143 * Avoid an infinite loop if the last iov_len is 144 * 0. 145 */ 146 while (idx < iovcnt && p_iov[idx].iov_len == 0) 147 idx++; 148 149 if (idx == iovcnt) { 150 ret = num; 151 break; 152 } 153 } 154 155 /* 156 * If performing a blocking write, check if the 157 * write would have blocked or if some bytes 158 * were written but there are still more to 159 * write: 160 */ 161 if (blocking && ((n < 0 && (errno == EWOULDBLOCK || 162 errno == EAGAIN)) || (n >= 0 && idx < iovcnt))) { 163 curthread->data.fd.fd = fd; 164 _thread_kern_set_timeout(NULL); 165 166 /* Reset the interrupted operation flag: */ 167 curthread->interrupted = 0; 168 169 _thread_kern_sched_state(PS_FDW_WAIT, 170 __FILE__, __LINE__); 171 172 /* 173 * Check if the operation was 174 * interrupted by a signal 175 */ 176 if (curthread->interrupted) { 177 /* Return an error: */ 178 ret = -1; 179 } 180 181 /* 182 * If performing a non-blocking write or if an 183 * error occurred, just return whatever the write 184 * syscall did: 185 */ 186 } else if (!blocking || n < 0) { 187 /* A non-blocking call might return zero: */ 188 ret = n; 189 break; 190 191 /* Check if the write has completed: */ 192 } else if (idx == iovcnt) 193 /* Return the number of bytes written: */ 194 ret = num; 195 } 196 _FD_UNLOCK(fd, FD_RDWR); 197 } 198 199 /* If memory was allocated for the array, free it: */ 200 if (p_iov != liov) 201 free(p_iov); 202 203 return (ret); 204} 205