source3/lib/recvfile.c

   1 /*
   2  Unix SMB/Netbios implementation.
   3  Version 3.2.x
   4  recvfile implementations.
   5  Copyright (C) Jeremy Allison 2007.
   6
   7  This program is free software; you can redistribute it and/or modify
   8  it under the terms of the GNU General Public License as published by
   9  the Free Software Foundation; either version 3 of the License, or
  10  (at your option) any later version.
  11  This program is distributed in the hope that it will be useful,
  12  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  GNU General Public License for more details.
  15
  16  You should have received a copy of the GNU General Public License
  17  along with this program; if not, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /*
  21  * This file handles the OS dependent recvfile implementations.
  22  * The API is such that it returns -1 on error, else returns the
  23  * number of bytes written.
  24  */
  25
  26 #include "includes.h"
  27 #include "system/filesys.h"
  28
  29 /* Do this on our own in TRANSFER_BUF_SIZE chunks.
  30  * It's safe to make direct syscalls to lseek/write here
  31  * as we're below the Samba vfs layer.
  32  *
  33  * Returns -1 on short reads from fromfd (read error)
  34  * and sets errno.
  35  *
  36  * Returns number of bytes written to 'tofd'
  37  * return != count then sets errno.
  38  * Returns count if complete success.
  39  */
  40
  41 #ifndef TRANSFER_BUF_SIZE
  42 #define TRANSFER_BUF_SIZE (128*1024)
  43 #endif
  44
  45 static ssize_t default_sys_recvfile(int fromfd,
  46                         int tofd,
  47                         off_t offset,
  48                         size_t count)
  49 {
  50         int saved_errno = 0;
  51         size_t total = 0;
  52         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
  53         size_t total_written = 0;
  54         char buffer[bufsize];
  55
  56         DEBUG(10,("default_sys_recvfile: from = %d, to = %d, "
  57                 "offset=%.0f, count = %lu\n",
  58                 fromfd, tofd, (double)offset,
  59                 (unsigned long)count));
  60
  61         if (count == 0) {
  62                 return 0;
  63         }
  64
  65         if (tofd != -1 && offset != (off_t)-1) {
  66                 if (lseek(tofd, offset, SEEK_SET) == -1) {
  67                         if (errno != ESPIPE) {
  68                                 return -1;
  69                         }
  70                 }
  71         }
  72
  73         while (total < count) {
  74                 size_t num_written = 0;
  75                 ssize_t read_ret;
  76                 size_t toread = MIN(bufsize,count - total);
  77
  78                 /* Read from socket - ignore EINTR. */
  79                 read_ret = sys_read(fromfd, buffer, toread);
  80                 if (read_ret <= 0) {
  81                         /* EOF or socket error. */
  82                         return -1;
  83                 }
  84
  85                 num_written = 0;
  86
  87                 /* Don't write any more after a write error. */
  88                 while (tofd != -1 && (num_written < read_ret)) {
  89                         ssize_t write_ret;
  90
  91                         /* Write to file - ignore EINTR. */
  92                         write_ret = sys_write(tofd,
  93                                         buffer + num_written,
  94                                         read_ret - num_written);
  95
  96                         if (write_ret <= 0) {
  97                                 /* write error - stop writing. */
  98                                 tofd = -1;
  99                                 if (total_written == 0) {
 100                                         /* Ensure we return
 101                                            -1 if the first
 102                                            write failed. */
 103                                         total_written = -1;
 104                                 }
 105                                 saved_errno = errno;
 106                                 break;
 107                         }
 108
 109                         num_written += (size_t)write_ret;
 110                         total_written += (size_t)write_ret;
 111                 }
 112
 113                 total += read_ret;
 114         }
 115
 116         if (saved_errno) {
 117                 /* Return the correct write error. */
 118                 errno = saved_errno;
 119         }
 120         return (ssize_t)total_written;
 121 }
 122
 123 #if defined(HAVE_LINUX_SPLICE)
 124
 125 /*
 126  * Try and use the Linux system call to do this.
 127  * Remember we only return -1 if the socket read
 128  * failed. Else we return the number of bytes
 129  * actually written. We always read count bytes
 130  * from the network in the case of return != -1.
 131  */
 132
 133
 134 ssize_t sys_recvfile(int fromfd,
 135                         int tofd,
 136                         off_t offset,
 137                         size_t count)
 138 {
 139         static int pipefd[2] = { -1, -1 };
 140         static bool try_splice_call = false;
 141         size_t total_written = 0;
 142         loff_t splice_offset = offset;
 143
 144         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 145                 "offset=%.0f, count = %lu\n",
 146                 fromfd, tofd, (double)offset,
 147                 (unsigned long)count));
 148
 149         if (count == 0) {
 150                 return 0;
 151         }
 152
 153         /*
 154          * Older Linux kernels have splice for sendfile,
 155          * but it fails for recvfile. Ensure we only try
 156          * this once and always fall back to the userspace
 157          * implementation if recvfile splice fails. JRA.
 158          */
 159
 160         if (!try_splice_call) {
 161                 return default_sys_recvfile(fromfd,
 162                                 tofd,
 163                                 offset,
 164                                 count);
 165         }
 166
 167         if ((pipefd[0] == -1) && (pipe(pipefd) == -1)) {
 168                 try_splice_call = false;
 169                 return default_sys_recvfile(fromfd, tofd, offset, count);
 170         }
 171
 172         while (count > 0) {
 173                 int nread, to_write;
 174
 175                 nread = splice(fromfd, NULL, pipefd[1], NULL,
 176                                MIN(count, 16384), SPLICE_F_MOVE);
 177                 if (nread == -1) {
 178                         if (errno == EINTR) {
 179                                 continue;
 180                         }
 181                         if (total_written == 0 &&
 182                             (errno == EBADF || errno == EINVAL)) {
 183                                 try_splice_call = false;
 184                                 return default_sys_recvfile(fromfd, tofd,
 185                                                             offset, count);
 186                         }
 187                         break;
 188                 }
 189
 190                 to_write = nread;
 191                 while (to_write > 0) {
 192                         int thistime;
 193                         thistime = splice(pipefd[0], NULL, tofd,
 194                                           &splice_offset, to_write,
 195                                           SPLICE_F_MOVE);
 196                         if (thistime == -1) {
 197                                 goto done;
 198                         }
 199                         to_write -= thistime;
 200                 }
 201
 202                 total_written += nread;
 203                 count -= nread;
 204         }
 205
 206  done:
 207         if (count) {
 208                 int saved_errno = errno;
 209                 if (drain_socket(fromfd, count) != count) {
 210                         /* socket is dead. */
 211                         return -1;
 212                 }
 213                 errno = saved_errno;
 214         }
 215
 216         return total_written;
 217 }
 218 #else
 219
 220 /*****************************************************************
 221  No recvfile system call - use the default 128 chunk implementation.
 222 *****************************************************************/
 223
 224 ssize_t sys_recvfile(int fromfd,
 225                         int tofd,
 226                         off_t offset,
 227                         size_t count)
 228 {
 229         return default_sys_recvfile(fromfd, tofd, offset, count);
 230 }
 231 #endif
 232
 233 /*****************************************************************
 234  Throw away "count" bytes from the client socket.
 235  Returns count or -1 on error.
 236  Must only operate on a blocking socket.
 237 *****************************************************************/
 238
 239 ssize_t drain_socket(int sockfd, size_t count)
 240 {
 241         size_t total = 0;
 242         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
 243         char buffer[bufsize];
 244         int old_flags = 0;
 245
 246         if (count == 0) {
 247                 return 0;
 248         }
 249
 250         old_flags = fcntl(sockfd, F_GETFL, 0);
 251         if (set_blocking(sockfd, true) == -1) {
 252                 return -1;
 253         }
 254
 255         while (total < count) {
 256                 ssize_t read_ret;
 257                 size_t toread = MIN(bufsize,count - total);
 258
 259                 /* Read from socket - ignore EINTR. */
 260                 read_ret = sys_read(sockfd, buffer, toread);
 261                 if (read_ret <= 0) {
 262                         /* EOF or socket error. */
 263                         count = (size_t)-1;
 264                         goto out;
 265                 }
 266                 total += read_ret;
 267         }
 268
 269   out:
 270
 271         if (fcntl(sockfd, F_SETFL, old_flags) == -1) {
 272                 return -1;
 273         }
 274         return count;
 275 }