source/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         if (count == 0) {
  62                 return 0;
  63         }
  64
  65         if (tofd != -1 && offset != (SMB_OFF_T)-1) {
  66                 if (sys_lseek(tofd, offset, SEEK_SET) == -1) {
  67                         if (errno != ESPIPE) {
  68                                 return -1;
  69                         }
  70                 }
  71         }
  72
  73         buffer = SMB_MALLOC_ARRAY(char, bufsize);
  74         if (buffer == NULL) {
  75                 return -1;
  76         }
  77
  78         while (total < count) {
  79                 size_t num_written = 0;
  80                 ssize_t read_ret;
  81                 size_t toread = MIN(bufsize,count - total);
  82
  83                 /* Read from socket - ignore EINTR. */
  84                 read_ret = sys_read(fromfd, buffer, toread);
  85                 if (read_ret <= 0) {
  86                         /* EOF or socket error. */
  87                         free(buffer);
  88                         return -1;
  89                 }
  90
  91                 num_written = 0;
  92
  93                 while (num_written < read_ret) {
  94                         ssize_t write_ret;
  95
  96                         if (tofd == -1) {
  97                                 write_ret = read_ret;
  98                         } else {
  99                                 /* Write to file - ignore EINTR. */
 100                                 write_ret = sys_write(tofd,
 101                                                 buffer + num_written,
 102                                                 read_ret - num_written);
 103
 104                                 if (write_ret <= 0) {
 105                                         /* write error - stop writing. */
 106                                         tofd = -1;
 107                                         saved_errno = errno;
 108                                         continue;
 109                                 }
 110                         }
 111
 112                         num_written += (size_t)write_ret;
 113                         total_written += (size_t)write_ret;
 114                 }
 115
 116                 total += read_ret;
 117         }
 118
 119         free(buffer);
 120         if (saved_errno) {
 121                 /* Return the correct write error. */
 122                 errno = saved_errno;
 123         }
 124         return (ssize_t)total_written;
 125 }
 126
 127 #if defined(HAVE_LINUX_SPLICE)
 128
 129 /*
 130  * Try and use the Linux system call to do this.
 131  * Remember we only return -1 if the socket read
 132  * failed. Else we return the number of bytes
 133  * actually written. We always read count bytes
 134  * from the network in the case of return != -1.
 135  */
 136
 137
 138 ssize_t sys_recvfile(int fromfd,
 139                         int tofd,
 140                         SMB_OFF_T offset,
 141                         size_t count)
 142 {
 143         static bool try_splice_call = true;
 144         size_t total_written = 0;
 145
 146         if (count == 0) {
 147                 return 0;
 148         }
 149
 150         /*
 151          * Older Linux kernels have splice for sendfile,
 152          * but it fails for recvfile. Ensure we only try
 153          * this once and always fall back to the userspace
 154          * implementation if recvfile splice fails. JRA.
 155          */
 156
 157         if (!try_splice_call) {
 158                 return default_sys_recvfile(fromfd,
 159                                 tofd,
 160                                 offset,
 161                                 count);
 162         }
 163
 164         while (total_written < count) {
 165                 ssize_t ret = splice(fromfd,
 166                                         NULL,
 167                                         tofd,
 168                                         &offset,
 169                                         count,
 170                                         0);
 171                 if (ret == -1) {
 172                         if (errno != EINTR) {
 173                                 if (total_written == 0 &&
 174                                                 (errno == EBADF || errno == EINVAL)) {
 175                                         try_splice_call = false;
 176                                         return default_sys_recvfile(fromfd,
 177                                                                 tofd,
 178                                                                 offset,
 179                                                                 count);
 180                                 }
 181                                 break;
 182                         }
 183                         continue;
 184                 }
 185                 total_written += ret;
 186                 count -= ret;
 187         }
 188
 189         if (total_written < count) {
 190                 int saved_errno = errno;
 191                 if (drain_socket(fromfd, count-total_written) !=
 192                                 count-total_written) {
 193                         /* socket is dead. */
 194                         return -1;
 195                 }
 196                 errno = saved_errno;
 197         }
 198
 199         return total_written;
 200 }
 201 #else
 202
 203 /*****************************************************************
 204  No recvfile system call - use the default 128 chunk implementation.
 205 *****************************************************************/
 206
 207 ssize_t sys_recvfile(int fromfd,
 208                         int tofd,
 209                         SMB_OFF_T offset,
 210                         size_t count)
 211 {
 212         return default_sys_recvfile(fromfd, tofd, offset, count);
 213 }
 214 #endif
 215
 216 /*****************************************************************
 217  Throw away "count" bytes from the client socket.
 218 *****************************************************************/
 219
 220 ssize_t drain_socket(int sockfd, size_t count)
 221 {
 222         return default_sys_recvfile(sockfd, -1, (SMB_OFF_T)-1, count);
 223 }