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         size_t total_written = 0;
 164         loff_t splice_offset = offset;
 165
 166         DEBUG(10,("sys_recvfile: from = %d, to = %d, "
 167                 "offset=%.0f, count = %lu\n",
 168                 fromfd, tofd, (double)offset,
 169                 (unsigned long)count));
 170
 171         if (count == 0) {
 172                 return 0;
 173         }
 174
 175         /*
 176          * Older Linux kernels have splice for sendfile,
 177          * but it fails for recvfile. Ensure we only try
 178          * this once and always fall back to the userspace
 179          * implementation if recvfile splice fails. JRA.
 180          */
 181
 182         if (!try_splice_call) {
 183                 return default_sys_recvfile(fromfd,
 184                                 tofd,
 185                                 offset,
 186                                 count);
 187         }
 188
 189         if ((pipefd[0] == -1) && (pipe(pipefd) == -1)) {
 190                 try_splice_call = false;
 191                 return default_sys_recvfile(fromfd, tofd, offset, count);
 192         }
 193
 194         while (count > 0) {
 195                 int nread, to_write;
 196
 197                 nread = splice(fromfd, NULL, pipefd[1], NULL,
 198                                MIN(count, 16384), SPLICE_F_MOVE);
 199                 if (nread == -1) {
 200                         if (errno == EINTR) {
 201                                 continue;
 202                         }
 203                         if (total_written == 0 &&
 204                             (errno == EBADF || errno == EINVAL)) {
 205                                 try_splice_call = false;
 206                                 return default_sys_recvfile(fromfd, tofd,
 207                                                             offset, count);
 208                         }
 209                         if (errno == EAGAIN || errno == EWOULDBLOCK) {
 210                                 /*
 211                                  * fromfd socket is in non-blocking mode.
 212                                  * If we already read some and wrote
 213                                  * it successfully, return that.
 214                                  * Only return -1 if this is the first read
 215                                  * attempt. Caller will handle both cases.
 216                                  */
 217                                 if (total_written != 0) {
 218                                         return total_written;
 219                                 }
 220                                 return -1;
 221                         }
 222                         break;
 223                 }
 224
 225                 to_write = nread;
 226                 while (to_write > 0) {
 227                         int thistime;
 228                         thistime = splice(pipefd[0], NULL, tofd,
 229                                           &splice_offset, to_write,
 230                                           SPLICE_F_MOVE);
 231                         if (thistime == -1) {
 232                                 goto done;
 233                         }
 234                         to_write -= thistime;
 235                 }
 236
 237                 total_written += nread;
 238                 count -= nread;
 239         }
 240
 241  done:
 242         if (count) {
 243                 int saved_errno = errno;
 244                 if (drain_socket(fromfd, count) != count) {
 245                         /* socket is dead. */
 246                         return -1;
 247                 }
 248                 errno = saved_errno;
 249         }
 250
 251         return total_written;
 252 }
 253 #else
 254
 255 /*****************************************************************
 256  No recvfile system call - use the default 128 chunk implementation.
 257 *****************************************************************/
 258
 259 ssize_t sys_recvfile(int fromfd,
 260                         int tofd,
 261                         off_t offset,
 262                         size_t count)
 263 {
 264         return default_sys_recvfile(fromfd, tofd, offset, count);
 265 }
 266 #endif
 267
 268 /*****************************************************************
 269  Throw away "count" bytes from the client socket.
 270  Returns count or -1 on error.
 271  Must only operate on a blocking socket.
 272 *****************************************************************/
 273
 274 ssize_t drain_socket(int sockfd, size_t count)
 275 {
 276         size_t total = 0;
 277         size_t bufsize = MIN(TRANSFER_BUF_SIZE,count);
 278         char buffer[bufsize];
 279         int old_flags = 0;
 280
 281         if (count == 0) {
 282                 return 0;
 283         }
 284
 285         old_flags = fcntl(sockfd, F_GETFL, 0);
 286         if (set_blocking(sockfd, true) == -1) {
 287                 return -1;
 288         }
 289
 290         while (total < count) {
 291                 ssize_t read_ret;
 292                 size_t toread = MIN(bufsize,count - total);
 293
 294                 /* Read from socket - ignore EINTR. */
 295                 read_ret = sys_read(sockfd, buffer, toread);
 296                 if (read_ret <= 0) {
 297                         /* EOF or socket error. */
 298                         count = (size_t)-1;
 299                         goto out;
 300                 }
 301                 total += read_ret;
 302         }
 303
 304   out:
 305
 306         if (fcntl(sockfd, F_SETFL, old_flags) == -1) {
 307                 return -1;
 308         }
 309         return count;
 310 }