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
  28 /* Do this on our own in TRANSFER_BUF_SIZE chunks.
  29  * It's safe to make direct syscalls to lseek/write here
  30  * as we're below the Samba vfs layer.
  31  *
  32  * If tofd is -1 we just drain the incoming socket of count
  33  * bytes without writing to the outgoing fd.
  34  * If a write fails we do the same (to cope with disk full)
  35  * errors.
  36  *
  37  * Returns -1 on short reads from fromfd (read error)
  38  * and sets errno.
  39  *
  40  * Returns number of bytes written to 'tofd'
  41  * or thrown away if 'tofd == -1'.
  42  * return != count then sets errno.
  43  * Returns count if complete success.
  44  */
  45
  46 #ifndef TRANSFER_BUF_SIZE
  47 #define TRANSFER_BUF_SIZE (128*1024)
  48 #endif
  49
  50 static ssize_t default_sys_recvfile(int fromfd,
  51                         int tofd,
  52                         SMB_OFF_T offset,
  53                         size_t count)
  54 {
  55         int saved_errno = 0;
  56         size_t total = 0;
  57         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
  58         size_t total_written = 0;
  59         char *buffer = NULL;
  60
  61         DEBUG(10,("default_sys_recvfile: from = %d, to = %d, "
  62                 "offset=%.0f, count = %lu\n",
  63                 fromfd, tofd, (double)offset,
  64                 (unsigned long)count));
  65
  66         if (count == 0) {
  67                 return 0;
  68         }
  69
  70         if (tofd != -1 && offset != (SMB_OFF_T)-1) {
  71                 if (sys_lseek(tofd, offset, SEEK_SET) == -1) {
  72                         if (errno != ESPIPE) {
  73                                 return -1;
  74                         }
  75                 }
  76         }
  77
  78         buffer = SMB_MALLOC_ARRAY(char, bufsize);
  79         if (buffer == NULL) {
  80                 return -1;
  81         }
  82
  83         while (total < count) {
  84                 size_t num_written = 0;
  85                 ssize_t read_ret;
  86                 size_t toread = MIN(bufsize,count - total);
  87
  88                 /* Read from socket - ignore EINTR. */
  89                 read_ret = sys_read(fromfd, buffer, toread);
  90                 if (read_ret <= 0) {
  91                         /* EOF or socket error. */
  92                         free(buffer);
  93                         return -1;
  94                 }
  95
  96                 num_written = 0;
  97
  98                 while (num_written < read_ret) {
  99                         ssize_t write_ret;
 100
 101                         if (tofd == -1) {
 102                                 write_ret = read_ret;
 103                         } else {
 104                                 /* Write to file - ignore EINTR. */
 105                                 write_ret = sys_write(tofd,
 106                                                 buffer + num_written,
 107                                                 read_ret - num_written);
 108
 109                                 if (write_ret <= 0) {
 110                                         /* write error - stop writing. */
 111                                         tofd = -1;
 112                                         saved_errno = errno;
 113                                         continue;
 114                                 }
 115                         }
 116
 117                         num_written += (size_t)write_ret;
 118                         total_written += (size_t)write_ret;
 119                 }
 120
 121                 total += read_ret;
 122         }
 123
 124         free(buffer);
 125         if (saved_errno) {
 126                 /* Return the correct write error. */
 127                 errno = saved_errno;
 128         }
 129         return (ssize_t)total_written;
 130 }
 131
 132 #if defined(HAVE_LINUX_SPLICE)
 133
 134 /*
 135  * Try and use the Linux system call to do this.
 136  * Remember we only return -1 if the socket read
 137  * failed. Else we return the number of bytes
 138  * actually written. We always read count bytes
 139  * from the network in the case of return != -1.
 140  */
 141
 142
 143 ssize_t sys_recvfile(int fromfd,
 144                         int tofd,
 145                         SMB_OFF_T offset,
 146                         size_t count)
 147 {
 148         static int pipefd[2] = { -1, -1 };
 149         static bool try_splice_call = false;
 150         size_t total_written = 0;
 151
 152         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 153                 "offset=%.0f, count = %lu\n",
 154                 fromfd, tofd, (double)offset,
 155                 (unsigned long)count));
 156
 157         if (count == 0) {
 158                 return 0;
 159         }
 160
 161         /*
 162          * Older Linux kernels have splice for sendfile,
 163          * but it fails for recvfile. Ensure we only try
 164          * this once and always fall back to the userspace
 165          * implementation if recvfile splice fails. JRA.
 166          */
 167
 168         if (!try_splice_call) {
 169                 return default_sys_recvfile(fromfd,
 170                                 tofd,
 171                                 offset,
 172                                 count);
 173         }
 174
 175         if ((pipefd[0] == -1) && (pipe(pipefd) == -1)) {
 176                 try_splice_call = false;
 177                 return default_sys_recvfile(fromfd, tofd, offset, count);
 178         }
 179
 180         while (count > 0) {
 181                 int nread, to_write;
 182
 183                 nread = splice(fromfd, NULL, pipefd[1], NULL, count, 0);
 184                 if (nread == -1) {
 185                         if (errno == EINTR) {
 186                                 continue;
 187                         }
 188                         if (total_written == 0 &&
 189                             (errno == EBADF || errno == EINVAL)) {
 190                                 try_splice_call = false;
 191                                 return default_sys_recvfile(fromfd, tofd,
 192                                                             offset, count);
 193                         }
 194                         break;
 195                 }
 196
 197                 to_write = nread;
 198                 while (to_write > 0) {
 199                         int thistime;
 200                         thistime = splice(pipefd[0], NULL, tofd, &offset,
 201                                           to_write, 0);
 202                         if (thistime == -1) {
 203                                 goto done;
 204                         }
 205                         offset += thistime;
 206                         to_write -= thistime;
 207                 }
 208
 209                 total_written += nread;
 210                 count -= nread;
 211         }
 212
 213  done:
 214         if (total_written < count) {
 215                 int saved_errno = errno;
 216                 if (drain_socket(fromfd, count-total_written) !=
 217                                 count-total_written) {
 218                         /* socket is dead. */
 219                         return -1;
 220                 }
 221                 errno = saved_errno;
 222         }
 223
 224         return total_written;
 225 }
 226 #else
 227
 228 /*****************************************************************
 229  No recvfile system call - use the default 128 chunk implementation.
 230 *****************************************************************/
 231
 232 ssize_t sys_recvfile(int fromfd,
 233                         int tofd,
 234                         SMB_OFF_T offset,
 235                         size_t count)
 236 {
 237         return default_sys_recvfile(fromfd, tofd, offset, count);
 238 }
 239 #endif
 240
 241 /*****************************************************************
 242  Throw away "count" bytes from the client socket.
 243 *****************************************************************/
 244
 245 ssize_t drain_socket(int sockfd, size_t count)
 246 {
 247         return default_sys_recvfile(sockfd, -1, (SMB_OFF_T)-1, count);
 248 }