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  * If tofd is -1 we just drain the incoming socket of count
  34  * bytes without writing to the outgoing fd.
  35  * If a write fails we do the same (to cope with disk full)
  36  * errors.
  37  *
  38  * Returns -1 on short reads from fromfd (read error)
  39  * and sets errno.
  40  *
  41  * Returns number of bytes written to 'tofd'
  42  * or thrown away if 'tofd == -1'.
  43  * return != count then sets errno.
  44  * Returns count if complete success.
  45  */
  46
  47 #ifndef TRANSFER_BUF_SIZE
  48 #define TRANSFER_BUF_SIZE (128*1024)
  49 #endif
  50
  51 static ssize_t default_sys_recvfile(int fromfd,
  52                         int tofd,
  53                         SMB_OFF_T offset,
  54                         size_t count)
  55 {
  56         int saved_errno = 0;
  57         size_t total = 0;
  58         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
  59         size_t total_written = 0;
  60         char *buffer = NULL;
  61
  62         DEBUG(10,("default_sys_recvfile: from = %d, to = %d, "
  63                 "offset=%.0f, count = %lu\n",
  64                 fromfd, tofd, (double)offset,
  65                 (unsigned long)count));
  66
  67         if (count == 0) {
  68                 return 0;
  69         }
  70
  71         if (tofd != -1 && offset != (SMB_OFF_T)-1) {
  72                 if (sys_lseek(tofd, offset, SEEK_SET) == -1) {
  73                         if (errno != ESPIPE) {
  74                                 return -1;
  75                         }
  76                 }
  77         }
  78
  79         buffer = SMB_MALLOC_ARRAY(char, bufsize);
  80         if (buffer == NULL) {
  81                 return -1;
  82         }
  83
  84         while (total < count) {
  85                 size_t num_written = 0;
  86                 ssize_t read_ret;
  87                 size_t toread = MIN(bufsize,count - total);
  88
  89                 /* Read from socket - ignore EINTR. */
  90                 read_ret = sys_read(fromfd, buffer, toread);
  91                 if (read_ret <= 0) {
  92                         /* EOF or socket error. */
  93                         free(buffer);
  94                         return -1;
  95                 }
  96
  97                 num_written = 0;
  98
  99                 while (num_written < read_ret) {
 100                         ssize_t write_ret;
 101
 102                         if (tofd == -1) {
 103                                 write_ret = read_ret;
 104                         } else {
 105                                 /* Write to file - ignore EINTR. */
 106                                 write_ret = sys_write(tofd,
 107                                                 buffer + num_written,
 108                                                 read_ret - num_written);
 109
 110                                 if (write_ret <= 0) {
 111                                         /* write error - stop writing. */
 112                                         tofd = -1;
 113                                         saved_errno = errno;
 114                                         continue;
 115                                 }
 116                         }
 117
 118                         num_written += (size_t)write_ret;
 119                         total_written += (size_t)write_ret;
 120                 }
 121
 122                 total += read_ret;
 123         }
 124
 125         free(buffer);
 126         if (saved_errno) {
 127                 /* Return the correct write error. */
 128                 errno = saved_errno;
 129         }
 130         return (ssize_t)total_written;
 131 }
 132
 133 #if defined(HAVE_LINUX_SPLICE)
 134
 135 /*
 136  * Try and use the Linux system call to do this.
 137  * Remember we only return -1 if the socket read
 138  * failed. Else we return the number of bytes
 139  * actually written. We always read count bytes
 140  * from the network in the case of return != -1.
 141  */
 142
 143
 144 ssize_t sys_recvfile(int fromfd,
 145                         int tofd,
 146                         SMB_OFF_T offset,
 147                         size_t count)
 148 {
 149         static int pipefd[2] = { -1, -1 };
 150         static bool try_splice_call = false;
 151         size_t total_written = 0;
 152         loff_t splice_offset = offset;
 153
 154         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 155                 "offset=%.0f, count = %lu\n",
 156                 fromfd, tofd, (double)offset,
 157                 (unsigned long)count));
 158
 159         if (count == 0) {
 160                 return 0;
 161         }
 162
 163         /*
 164          * Older Linux kernels have splice for sendfile,
 165          * but it fails for recvfile. Ensure we only try
 166          * this once and always fall back to the userspace
 167          * implementation if recvfile splice fails. JRA.
 168          */
 169
 170         if (!try_splice_call) {
 171                 return default_sys_recvfile(fromfd,
 172                                 tofd,
 173                                 offset,
 174                                 count);
 175         }
 176
 177         if ((pipefd[0] == -1) && (pipe(pipefd) == -1)) {
 178                 try_splice_call = false;
 179                 return default_sys_recvfile(fromfd, tofd, offset, count);
 180         }
 181
 182         while (count > 0) {
 183                 int nread, to_write;
 184
 185                 nread = splice(fromfd, NULL, pipefd[1], NULL,
 186                                MIN(count, 16384), SPLICE_F_MOVE);
 187                 if (nread == -1) {
 188                         if (errno == EINTR) {
 189                                 continue;
 190                         }
 191                         if (total_written == 0 &&
 192                             (errno == EBADF || errno == EINVAL)) {
 193                                 try_splice_call = false;
 194                                 return default_sys_recvfile(fromfd, tofd,
 195                                                             offset, count);
 196                         }
 197                         break;
 198                 }
 199
 200                 to_write = nread;
 201                 while (to_write > 0) {
 202                         int thistime;
 203                         thistime = splice(pipefd[0], NULL, tofd,
 204                                           &splice_offset, to_write,
 205                                           SPLICE_F_MOVE);
 206                         if (thistime == -1) {
 207                                 goto done;
 208                         }
 209                         to_write -= thistime;
 210                 }
 211
 212                 total_written += nread;
 213                 count -= nread;
 214         }
 215
 216  done:
 217         if (total_written < count) {
 218                 int saved_errno = errno;
 219                 if (drain_socket(fromfd, count-total_written) !=
 220                                 count-total_written) {
 221                         /* socket is dead. */
 222                         return -1;
 223                 }
 224                 errno = saved_errno;
 225         }
 226
 227         return total_written;
 228 }
 229 #else
 230
 231 /*****************************************************************
 232  No recvfile system call - use the default 128 chunk implementation.
 233 *****************************************************************/
 234
 235 ssize_t sys_recvfile(int fromfd,
 236                         int tofd,
 237                         SMB_OFF_T offset,
 238                         size_t count)
 239 {
 240         return default_sys_recvfile(fromfd, tofd, offset, count);
 241 }
 242 #endif
 243
 244 /*****************************************************************
 245  Throw away "count" bytes from the client socket.
 246 *****************************************************************/
 247
 248 ssize_t drain_socket(int sockfd, size_t count)
 249 {
 250         return default_sys_recvfile(sockfd, -1, (SMB_OFF_T)-1, count);
 251 }