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                 /*
  79                  * Read from socket - ignore EINTR.
  80                  * Can't use sys_read() as that also
  81                  * ignores EAGAIN and EWOULDBLOCK.
  82                  */
  83                 do {
  84                         read_ret = read(fromfd, buffer, toread);
  85                 } while (read_ret == -1 && errno == EINTR);
  86
  87                 if (read_ret == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
  88                         /*
  89                          * fromfd socket is in non-blocking mode.
  90                          * If we already read some and wrote
  91                          * it successfully, return that.
  92                          * Only return -1 if this is the first read
  93                          * attempt. Caller will handle both cases.
  94                          */
  95                         if (total_written != 0) {
  96                                 return total_written;
  97                         }
  98                         return -1;
  99                 }
 100
 101                 if (read_ret <= 0) {
 102                         /* EOF or socket error. */
 103                         return -1;
 104                 }
 105
 106                 num_written = 0;
 107
 108                 /* Don't write any more after a write error. */
 109                 while (tofd != -1 && (num_written < read_ret)) {
 110                         ssize_t write_ret;
 111
 112                         /* Write to file - ignore EINTR. */
 113                         write_ret = sys_write(tofd,
 114                                         buffer + num_written,
 115                                         read_ret - num_written);
 116
 117                         if (write_ret <= 0) {
 118                                 /* write error - stop writing. */
 119                                 tofd = -1;
 120                                 if (total_written == 0) {
 121                                         /* Ensure we return
 122                                            -1 if the first
 123                                            write failed. */
 124                                         total_written = -1;
 125                                 }
 126                                 saved_errno = errno;
 127                                 break;
 128                         }
 129
 130                         num_written += (size_t)write_ret;
 131                         total_written += (size_t)write_ret;
 132                 }
 133
 134                 total += read_ret;
 135         }
 136
 137         if (saved_errno) {
 138                 /* Return the correct write error. */
 139                 errno = saved_errno;
 140         }
 141         return (ssize_t)total_written;
 142 }
 143
 144 #if defined(HAVE_LINUX_SPLICE)
 145
 146 /*
 147  * Try and use the Linux system call to do this.
 148  * Remember we only return -1 if the socket read
 149  * failed. Else we return the number of bytes
 150  * actually written. We always read count bytes
 151  * from the network in the case of return != -1.
 152  */
 153
 154
 155 ssize_t sys_recvfile(int fromfd,
 156                         int tofd,
 157                         off_t offset,
 158                         size_t count)
 159 {
 160         static int pipefd[2] = { -1, -1 };
 161         static bool try_splice_call = false;
 162         size_t total_written = 0;
 163         loff_t splice_offset = offset;
 164
 165         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 166                 "offset=%.0f, count = %lu\n",
 167                 fromfd, tofd, (double)offset,
 168                 (unsigned long)count));
 169
 170         if (count == 0) {
 171                 return 0;
 172         }
 173
 174         /*
 175          * Older Linux kernels have splice for sendfile,
 176          * but it fails for recvfile. Ensure we only try
 177          * this once and always fall back to the userspace
 178          * implementation if recvfile splice fails. JRA.
 179          */
 180
 181         if (!try_splice_call) {
 182                 return default_sys_recvfile(fromfd,
 183                                 tofd,
 184                                 offset,
 185                                 count);
 186         }
 187
 188         if ((pipefd[0] == -1) && (pipe(pipefd) == -1)) {
 189                 try_splice_call = false;
 190                 return default_sys_recvfile(fromfd, tofd, offset, count);
 191         }
 192
 193         while (count > 0) {
 194                 int nread, to_write;
 195
 196                 nread = splice(fromfd, NULL, pipefd[1], NULL,
 197                                MIN(count, 16384), SPLICE_F_MOVE);
 198                 if (nread == -1) {
 199                         if (errno == EINTR) {
 200                                 continue;
 201                         }
 202                         if (total_written == 0 &&
 203                             (errno == EBADF || errno == EINVAL)) {
 204                                 try_splice_call = false;
 205                                 return default_sys_recvfile(fromfd, tofd,
 206                                                             offset, count);
 207                         }
 208                         if (errno == EAGAIN || errno == EWOULDBLOCK) {
 209                                 /*
 210                                  * fromfd socket is in non-blocking mode.
 211                                  * If we already read some and wrote
 212                                  * it successfully, return that.
 213                                  * Only return -1 if this is the first read
 214                                  * attempt. Caller will handle both cases.
 215                                  */
 216                                 if (total_written != 0) {
 217                                         return total_written;
 218                                 }
 219                                 return -1;
 220                         }
 221                         break;
 222                 }
 223
 224                 to_write = nread;
 225                 while (to_write > 0) {
 226                         int thistime;
 227                         thistime = splice(pipefd[0], NULL, tofd,
 228                                           &splice_offset, to_write,
 229                                           SPLICE_F_MOVE);
 230                         if (thistime == -1) {
 231                                 goto done;
 232                         }
 233                         to_write -= thistime;
 234                 }
 235
 236                 total_written += nread;
 237                 count -= nread;
 238         }
 239
 240  done:
 241         if (count) {
 242                 int saved_errno = errno;
 243                 if (drain_socket(fromfd, count) != count) {
 244                         /* socket is dead. */
 245                         return -1;
 246                 }
 247                 errno = saved_errno;
 248         }
 249
 250         return total_written;
 251 }
 252 #else
 253
 254 /*****************************************************************
 255  No recvfile system call - use the default 128 chunk implementation.
 256 *****************************************************************/
 257
 258 ssize_t sys_recvfile(int fromfd,
 259                         int tofd,
 260                         off_t offset,
 261                         size_t count)
 262 {
 263         return default_sys_recvfile(fromfd, tofd, offset, count);
 264 }
 265 #endif
 266
 267 /*****************************************************************
 268  Throw away "count" bytes from the client socket.
 269  Returns count or -1 on error.
 270  Must only operate on a blocking socket.
 271 *****************************************************************/
 272
 273 ssize_t drain_socket(int sockfd, size_t count)
 274 {
 275         size_t total = 0;
 276         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
 277         char buffer[bufsize];
 278         int old_flags = 0;
 279
 280         if (count == 0) {
 281                 return 0;
 282         }
 283
 284         old_flags = fcntl(sockfd, F_GETFL, 0);
 285         if (set_blocking(sockfd, true) == -1) {
 286                 return -1;
 287         }
 288
 289         while (total < count) {
 290                 ssize_t read_ret;
 291                 size_t toread = MIN(bufsize,count - total);
 292
 293                 /* Read from socket - ignore EINTR. */
 294                 read_ret = sys_read(sockfd, buffer, toread);
 295                 if (read_ret <= 0) {
 296                         /* EOF or socket error. */
 297                         count = (size_t)-1;
 298                         goto out;
 299                 }
 300                 total += read_ret;
 301         }
 302
 303   out:
 304
 305         if (fcntl(sockfd, F_SETFL, old_flags) == -1) {
 306                 return -1;
 307         }
 308         return count;
 309 }