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 = NULL;
  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         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                 /* Don't write any more after a write error. */
  94                 while (tofd != -1 && (num_written < read_ret)) {
  95                         ssize_t write_ret;
  96
  97                         /* Write to file - ignore EINTR. */
  98                         write_ret = sys_write(tofd,
  99                                         buffer + num_written,
 100                                         read_ret - num_written);
 101
 102                         if (write_ret <= 0) {
 103                                 /* write error - stop writing. */
 104                                 tofd = -1;
 105                                 if (total_written == 0) {
 106                                         /* Ensure we return
 107                                            -1 if the first
 108                                            write failed. */
 109                                         total_written = -1;
 110                                 }
 111                                 saved_errno = errno;
 112                                 break;
 113                         }
 114
 115                         num_written += (size_t)write_ret;
 116                         total_written += (size_t)write_ret;
 117                 }
 118
 119                 total += read_ret;
 120         }
 121
 122         free(buffer);
 123         if (saved_errno) {
 124                 /* Return the correct write error. */
 125                 errno = saved_errno;
 126         }
 127         return (ssize_t)total_written;
 128 }
 129
 130 #if defined(HAVE_LINUX_SPLICE)
 131
 132 /*
 133  * Try and use the Linux system call to do this.
 134  * Remember we only return -1 if the socket read
 135  * failed. Else we return the number of bytes
 136  * actually written. We always read count bytes
 137  * from the network in the case of return != -1.
 138  */
 139
 140
 141 ssize_t sys_recvfile(int fromfd,
 142                         int tofd,
 143                         off_t offset,
 144                         size_t count)
 145 {
 146         static int pipefd[2] = { -1, -1 };
 147         static bool try_splice_call = false;
 148         size_t total_written = 0;
 149         loff_t splice_offset = offset;
 150
 151         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 152                 "offset=%.0f, count = %lu\n",
 153                 fromfd, tofd, (double)offset,
 154                 (unsigned long)count));
 155
 156         if (count == 0) {
 157                 return 0;
 158         }
 159
 160         /*
 161          * Older Linux kernels have splice for sendfile,
 162          * but it fails for recvfile. Ensure we only try
 163          * this once and always fall back to the userspace
 164          * implementation if recvfile splice fails. JRA.
 165          */
 166
 167         if (!try_splice_call) {
 168                 return default_sys_recvfile(fromfd,
 169                                 tofd,
 170                                 offset,
 171                                 count);
 172         }
 173
 174         if ((pipefd[0] == -1) && (pipe(pipefd) == -1)) {
 175                 try_splice_call = false;
 176                 return default_sys_recvfile(fromfd, tofd, offset, count);
 177         }
 178
 179         while (count > 0) {
 180                 int nread, to_write;
 181
 182                 nread = splice(fromfd, NULL, pipefd[1], NULL,
 183                                MIN(count, 16384), SPLICE_F_MOVE);
 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,
 201                                           &splice_offset, to_write,
 202                                           SPLICE_F_MOVE);
 203                         if (thistime == -1) {
 204                                 goto done;
 205                         }
 206                         to_write -= thistime;
 207                 }
 208
 209                 total_written += nread;
 210                 count -= nread;
 211         }
 212
 213  done:
 214         if (count) {
 215                 int saved_errno = errno;
 216                 if (drain_socket(fromfd, count) != count) {
 217                         /* socket is dead. */
 218                         return -1;
 219                 }
 220                 errno = saved_errno;
 221         }
 222
 223         return total_written;
 224 }
 225 #else
 226
 227 /*****************************************************************
 228  No recvfile system call - use the default 128 chunk implementation.
 229 *****************************************************************/
 230
 231 ssize_t sys_recvfile(int fromfd,
 232                         int tofd,
 233                         off_t offset,
 234                         size_t count)
 235 {
 236         return default_sys_recvfile(fromfd, tofd, offset, count);
 237 }
 238 #endif
 239
 240 /*****************************************************************
 241  Throw away "count" bytes from the client socket.
 242  Returns count or -1 on error.
 243 *****************************************************************/
 244
 245 ssize_t drain_socket(int sockfd, size_t count)
 246 {
 247         size_t total = 0;
 248         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
 249         char *buffer = NULL;
 250
 251         if (count == 0) {
 252                 return 0;
 253         }
 254
 255         buffer = SMB_MALLOC_ARRAY(char, bufsize);
 256         if (buffer == NULL) {
 257                 return -1;
 258         }
 259
 260         while (total < count) {
 261                 ssize_t read_ret;
 262                 size_t toread = MIN(bufsize,count - total);
 263
 264                 /* Read from socket - ignore EINTR. */
 265                 read_ret = sys_read(sockfd, buffer, toread);
 266                 if (read_ret <= 0) {
 267                         /* EOF or socket error. */
 268                         free(buffer);
 269                         return -1;
 270                 }
 271                 total += read_ret;
 272         }
 273
 274         free(buffer);
 275         return count;
 276 }