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 #include "lib/util/sys_rw.h"
  29
  30 /* Do this on our own in TRANSFER_BUF_SIZE chunks.
  31  * It's safe to make direct syscalls to lseek/write here
  32  * as we're below the Samba vfs layer.
  33  *
  34  * Returns -1 on short reads from fromfd (read error)
  35  * and sets errno.
  36  *
  37  * Returns number of bytes written to 'tofd'
  38  * return != count then sets errno.
  39  * Returns count if complete success.
  40  */
  41
  42 #ifndef TRANSFER_BUF_SIZE
  43 #define TRANSFER_BUF_SIZE (128*1024)
  44 #endif
  45
  46 static ssize_t default_sys_recvfile(int fromfd,
  47                         int tofd,
  48                         off_t offset,
  49                         size_t count)
  50 {
  51         int saved_errno = 0;
  52         size_t total = 0;
  53         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
  54         size_t total_written = 0;
  55         char buffer[bufsize];
  56
  57         DEBUG(10,("default_sys_recvfile: from = %d, to = %d, "
  58                 "offset=%.0f, count = %lu\n",
  59                 fromfd, tofd, (double)offset,
  60                 (unsigned long)count));
  61
  62         if (count == 0) {
  63                 return 0;
  64         }
  65
  66         if (tofd != -1 && offset != (off_t)-1) {
  67                 if (lseek(tofd, offset, SEEK_SET) == -1) {
  68                         if (errno != ESPIPE) {
  69                                 return -1;
  70                         }
  71                 }
  72         }
  73
  74         while (total < count) {
  75                 size_t num_written = 0;
  76                 ssize_t read_ret;
  77                 size_t toread = MIN(bufsize,count - total);
  78
  79                 /*
  80                  * Read from socket - ignore EINTR.
  81                  * Can't use sys_read() as that also
  82                  * ignores EAGAIN and EWOULDBLOCK.
  83                  */
  84                 do {
  85                         read_ret = read(fromfd, buffer, toread);
  86                 } while (read_ret == -1 && errno == EINTR);
  87
  88                 if (read_ret == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
  89                         /*
  90                          * fromfd socket is in non-blocking mode.
  91                          * If we already read some and wrote
  92                          * it successfully, return that.
  93                          * Only return -1 if this is the first read
  94                          * attempt. Caller will handle both cases.
  95                          */
  96                         if (total_written != 0) {
  97                                 return total_written;
  98                         }
  99                         return -1;
 100                 }
 101
 102                 if (read_ret <= 0) {
 103                         /* EOF or socket error. */
 104                         return -1;
 105                 }
 106
 107                 num_written = 0;
 108
 109                 /* Don't write any more after a write error. */
 110                 while (tofd != -1 && (num_written < read_ret)) {
 111                         ssize_t write_ret;
 112
 113                         /* Write to file - ignore EINTR. */
 114                         write_ret = sys_write(tofd,
 115                                         buffer + num_written,
 116                                         read_ret - num_written);
 117
 118                         if (write_ret <= 0) {
 119                                 /* write error - stop writing. */
 120                                 tofd = -1;
 121                                 if (total_written == 0) {
 122                                         /* Ensure we return
 123                                            -1 if the first
 124                                            write failed. */
 125                                         total_written = -1;
 126                                 }
 127                                 saved_errno = errno;
 128                                 break;
 129                         }
 130
 131                         num_written += (size_t)write_ret;
 132                         total_written += (size_t)write_ret;
 133                 }
 134
 135                 total += read_ret;
 136         }
 137
 138         if (saved_errno) {
 139                 /* Return the correct write error. */
 140                 errno = saved_errno;
 141         }
 142         return (ssize_t)total_written;
 143 }
 144
 145 #if defined(HAVE_LINUX_SPLICE)
 146
 147 /*
 148  * Try and use the Linux system call to do this.
 149  * Remember we only return -1 if the socket read
 150  * failed. Else we return the number of bytes
 151  * actually written. We always read count bytes
 152  * from the network in the case of return != -1.
 153  */
 154
 155
 156 ssize_t sys_recvfile(int fromfd,
 157                         int tofd,
 158                         off_t offset,
 159                         size_t count)
 160 {
 161         static int pipefd[2] = { -1, -1 };
 162         static bool try_splice_call = false;
 163         static size_t chunk_size = 16384;
 164         size_t total_written = 0;
 165         loff_t splice_offset = offset;
 166
 167         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 168                 "offset=%.0f, count = %lu\n",
 169                 fromfd, tofd, (double)offset,
 170                 (unsigned long)count));
 171
 172         if (count == 0) {
 173                 return 0;
 174         }
 175
 176         /*
 177          * Older Linux kernels have splice for sendfile,
 178          * but it fails for recvfile. Ensure we only try
 179          * this once and always fall back to the userspace
 180          * implementation if recvfile splice fails. JRA.
 181          */
 182
 183         if (!try_splice_call) {
 184                 return default_sys_recvfile(fromfd,
 185                                 tofd,
 186                                 offset,
 187                                 count);
 188         }
 189
 190         if (pipefd[0] == -1) {
 191                 int ret;
 192
 193                 ret = pipe(pipefd);
 194                 if (ret == -1) {
 195                         try_splice_call = false;
 196                         return default_sys_recvfile(fromfd, tofd, offset, count);
 197                 }
 198
 199 #ifdef F_SETPIPE_SZ
 200                 fcntl(pipefd[1], F_SETPIPE_SZ, 1048576);
 201                 ret = fcntl(pipefd[1], F_GETPIPE_SZ);
 202                 if (ret > chunk_size) {
 203                         chunk_size = ret;
 204                 }
 205 #endif
 206         }
 207
 208         while (count > 0) {
 209                 int nread, to_write;
 210
 211                 nread = splice(fromfd, NULL, pipefd[1], NULL,
 212                                MIN(count, chunk_size), SPLICE_F_MOVE);
 213                 if (nread == -1) {
 214                         if (errno == EINTR) {
 215                                 continue;
 216                         }
 217                         if (total_written == 0 &&
 218                             (errno == EBADF || errno == EINVAL)) {
 219                                 try_splice_call = false;
 220                                 return default_sys_recvfile(fromfd, tofd,
 221                                                             offset, count);
 222                         }
 223                         if (errno == EAGAIN || errno == EWOULDBLOCK) {
 224                                 /*
 225                                  * fromfd socket is in non-blocking mode.
 226                                  * If we already read some and wrote
 227                                  * it successfully, return that.
 228                                  * Only return -1 if this is the first read
 229                                  * attempt. Caller will handle both cases.
 230                                  */
 231                                 if (total_written != 0) {
 232                                         return total_written;
 233                                 }
 234                                 return -1;
 235                         }
 236                         break;
 237                 }
 238
 239                 to_write = nread;
 240                 while (to_write > 0) {
 241                         int thistime;
 242                         thistime = splice(pipefd[0], NULL, tofd,
 243                                           &splice_offset, to_write,
 244                                           SPLICE_F_MOVE);
 245                         if (thistime == -1) {
 246                                 goto done;
 247                         }
 248                         to_write -= thistime;
 249                 }
 250
 251                 total_written += nread;
 252                 count -= nread;
 253         }
 254
 255  done:
 256         if (count) {
 257                 int saved_errno = errno;
 258                 if (drain_socket(fromfd, count) != count) {
 259                         /* socket is dead. */
 260                         return -1;
 261                 }
 262                 errno = saved_errno;
 263         }
 264
 265         return total_written;
 266 }
 267 #else
 268
 269 /*****************************************************************
 270  No recvfile system call - use the default 128 chunk implementation.
 271 *****************************************************************/
 272
 273 ssize_t sys_recvfile(int fromfd,
 274                         int tofd,
 275                         off_t offset,
 276                         size_t count)
 277 {
 278         return default_sys_recvfile(fromfd, tofd, offset, count);
 279 }
 280 #endif
 281
 282 /*****************************************************************
 283  Throw away "count" bytes from the client socket.
 284  Returns count or -1 on error.
 285  Must only operate on a blocking socket.
 286 *****************************************************************/
 287
 288 ssize_t drain_socket(int sockfd, size_t count)
 289 {
 290         size_t total = 0;
 291         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
 292         char buffer[bufsize];
 293         int old_flags = 0;
 294
 295         if (count == 0) {
 296                 return 0;
 297         }
 298
 299         old_flags = fcntl(sockfd, F_GETFL, 0);
 300         if (set_blocking(sockfd, true) == -1) {
 301                 return -1;
 302         }
 303
 304         while (total < count) {
 305                 ssize_t read_ret;
 306                 size_t toread = MIN(bufsize,count - total);
 307
 308                 /* Read from socket - ignore EINTR. */
 309                 read_ret = sys_read(sockfd, buffer, toread);
 310                 if (read_ret <= 0) {
 311                         /* EOF or socket error. */
 312                         count = (size_t)-1;
 313                         goto out;
 314                 }
 315                 total += read_ret;
 316         }
 317
 318   out:
 319
 320         if (fcntl(sockfd, F_SETFL, old_flags) == -1) {
 321                 return -1;
 322         }
 323         return count;
 324 }