io.c

   1 /*
   2    Copyright (C) Andrew Tridgell 1996
   3    Copyright (C) Paul Mackerras 1996
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2 of the License, or
   8    (at your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software
  17    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  18 */
  19
  20 /*
  21   Utilities used in rsync
  22
  23   tridge, June 1996
  24   */
  25 #include "rsync.h"
  26
  27 /* if no timeout is specified then use a 60 second select timeout */
  28 #define SELECT_TIMEOUT 60
  29
  30 static int io_multiplexing_out;
  31 static int io_multiplexing_in;
  32 static int multiplex_in_fd;
  33 static int multiplex_out_fd;
  34 static time_t last_io;
  35 static int eof_error=1;
  36 extern int verbose;
  37 extern int io_timeout;
  38 extern struct stats stats;
  39
  40 static int buffer_f_in = -1;
  41
  42 void setup_readbuffer(int f_in)
  43 {
  44         buffer_f_in = f_in;
  45 }
  46
  47 static void check_timeout(void)
  48 {
  49         time_t t;
  50
  51         if (!io_timeout) return;
  52
  53         if (!last_io) {
  54                 last_io = time(NULL);
  55                 return;
  56         }
  57
  58         t = time(NULL);
  59
  60         if (last_io && io_timeout && (t-last_io) >= io_timeout) {
  61                 rprintf(FERROR,"io timeout after %d second - exiting\n",
  62                         (int)(t-last_io));
  63                 exit_cleanup(1);
  64         }
  65 }
  66
  67
  68 static char *read_buffer;
  69 static char *read_buffer_p;
  70 static int read_buffer_len;
  71 static int read_buffer_size;
  72 static int no_flush;
  73 static int no_flush_read;
  74
  75 /* read from a socket with IO timeout. return the number of
  76    bytes read. If no bytes can be read then exit, never return
  77    a number <= 0 */
  78 static int read_timeout(int fd, char *buf, int len)
  79 {
  80         int n, ret=0;
  81
  82         no_flush_read++;
  83         io_flush();
  84         no_flush_read--;
  85
  86         while (ret == 0) {
  87                 fd_set fds;
  88                 struct timeval tv;
  89
  90                 FD_ZERO(&fds);
  91                 FD_SET(fd, &fds);
  92                 tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
  93                 tv.tv_usec = 0;
  94
  95                 if (select(fd+1, &fds, NULL, NULL, &tv) != 1) {
  96                         check_timeout();
  97                         continue;
  98                 }
  99
 100                 n = read(fd, buf, len);
 101
 102                 if (n > 0) {
 103                         stats.total_read += n;
 104                         buf += n;
 105                         len -= n;
 106                         ret += n;
 107                         if (io_timeout)
 108                                 last_io = time(NULL);
 109                         continue;
 110                 }
 111
 112                 if (n == -1 && errno == EINTR) {
 113                         continue;
 114                 }
 115
 116                 if (n == -1 &&
 117                     (errno == EAGAIN || errno == EWOULDBLOCK)) {
 118                         /* this shouldn't happen, if it does then
 119                            sleep for a short time to prevent us
 120                            chewing too much CPU */
 121                         u_sleep(100);
 122                         continue;
 123                 }
 124
 125                 if (n == 0) {
 126                         if (eof_error) {
 127                                 rprintf(FERROR,"unexpected EOF in read_timeout\n");
 128                         }
 129                         exit_cleanup(1);
 130                 }
 131
 132                 rprintf(FERROR,"read error: %s\n", strerror(errno));
 133                 exit_cleanup(1);
 134         }
 135
 136         return ret;
 137 }
 138
 139 /* continue trying to read len bytes - don't return until len
 140    has been read */
 141 static void read_loop(int fd, char *buf, int len)
 142 {
 143         while (len) {
 144                 int n = read_timeout(fd, buf, len);
 145
 146                 buf += n;
 147                 len -= n;
 148         }
 149 }
 150
 151 /* read from the file descriptor handling multiplexing -
 152    return number of bytes read
 153    never return <= 0 */
 154 static int read_unbuffered(int fd, char *buf, int len)
 155 {
 156         static int remaining;
 157         char ibuf[4];
 158         int tag, ret=0;
 159         char line[1024];
 160
 161         if (!io_multiplexing_in || fd != multiplex_in_fd)
 162                 return read_timeout(fd, buf, len);
 163
 164         while (ret == 0) {
 165                 if (remaining) {
 166                         len = MIN(len, remaining);
 167                         read_loop(fd, buf, len);
 168                         remaining -= len;
 169                         ret = len;
 170                         continue;
 171                 }
 172
 173                 read_loop(fd, ibuf, 4);
 174                 tag = IVAL(ibuf, 0);
 175
 176                 remaining = tag & 0xFFFFFF;
 177                 tag = tag >> 24;
 178
 179                 if (tag == MPLEX_BASE) continue;
 180
 181                 tag -= MPLEX_BASE;
 182
 183                 if (tag != FERROR && tag != FINFO) {
 184                         rprintf(FERROR,"unexpected tag %d\n", tag);
 185                         exit_cleanup(1);
 186                 }
 187
 188                 if (remaining > sizeof(line)-1) {
 189                         rprintf(FERROR,"multiplexing overflow %d\n\n",
 190                                 remaining);
 191                         exit_cleanup(1);
 192                 }
 193
 194                 read_loop(fd, line, remaining);
 195                 line[remaining] = 0;
 196
 197                 rprintf(tag,"%s", line);
 198                 remaining = 0;
 199         }
 200
 201         return ret;
 202 }
 203
 204
 205
 206 /* This function was added to overcome a deadlock problem when using
 207  * ssh.  It looks like we can't allow our receive queue to get full or
 208  * ssh will clag up. Uggh.  */
 209 static void read_check(int f)
 210 {
 211         int n = 8192;
 212
 213         if (f == -1) return;
 214
 215         if (read_buffer_len == 0) {
 216                 read_buffer_p = read_buffer;
 217         }
 218
 219         if (n > MAX_READ_BUFFER/4)
 220                 n = MAX_READ_BUFFER/4;
 221
 222         if (read_buffer_p != read_buffer) {
 223                 memmove(read_buffer,read_buffer_p,read_buffer_len);
 224                 read_buffer_p = read_buffer;
 225         }
 226
 227         if (n > (read_buffer_size - read_buffer_len)) {
 228                 read_buffer_size += n;
 229                 read_buffer = (char *)Realloc(read_buffer,read_buffer_size);
 230                 if (!read_buffer) out_of_memory("read check");
 231                 read_buffer_p = read_buffer;
 232         }
 233
 234         n = read_unbuffered(f,read_buffer+read_buffer_len,n);
 235         read_buffer_len += n;
 236 }
 237
 238
 239 /* do a buffered read from fd. don't return until all N bytes
 240    have been read. If all N can't be read then exit with an error */
 241 static void readfd(int fd,char *buffer,int N)
 242 {
 243         int  ret;
 244         int total=0;
 245
 246         if ((read_buffer_len < N) && (N < 1024)) {
 247                 read_check(buffer_f_in);
 248         }
 249
 250         while (total < N) {
 251                 if (read_buffer_len > 0 && buffer_f_in == fd) {
 252                         ret = MIN(read_buffer_len,N-total);
 253                         memcpy(buffer+total,read_buffer_p,ret);
 254                         read_buffer_p += ret;
 255                         read_buffer_len -= ret;
 256                         total += ret;
 257                         continue;
 258                 }
 259
 260                 no_flush_read++;
 261                 io_flush();
 262                 no_flush_read--;
 263
 264                 ret = read_unbuffered(fd,buffer + total,N-total);
 265                 total += ret;
 266         }
 267 }
 268
 269
 270 int32 read_int(int f)
 271 {
 272         char b[4];
 273         readfd(f,b,4);
 274         return IVAL(b,0);
 275 }
 276
 277 int64 read_longint(int f)
 278 {
 279         extern int remote_version;
 280         int64 ret;
 281         char b[8];
 282         ret = read_int(f);
 283
 284         if ((int32)ret != (int32)0xffffffff) return ret;
 285
 286 #ifdef NO_INT64
 287         rprintf(FERROR,"Integer overflow - attempted 64 bit offset\n");
 288         exit_cleanup(1);
 289 #else
 290         if (remote_version >= 16) {
 291                 readfd(f,b,8);
 292                 ret = IVAL(b,0) | (((int64)IVAL(b,4))<<32);
 293         }
 294 #endif
 295
 296         return ret;
 297 }
 298
 299 void read_buf(int f,char *buf,int len)
 300 {
 301         readfd(f,buf,len);
 302 }
 303
 304 void read_sbuf(int f,char *buf,int len)
 305 {
 306         read_buf(f,buf,len);
 307         buf[len] = 0;
 308 }
 309
 310 unsigned char read_byte(int f)
 311 {
 312         unsigned char c;
 313         read_buf(f,(char *)&c,1);
 314         return c;
 315 }
 316
 317
 318
 319 /* write len bytes to fd, possibly reading from buffer_f_in if set
 320    in order to unclog the pipe. don't return until all len
 321    bytes have been written */
 322 static void writefd_unbuffered(int fd,char *buf,int len)
 323 {
 324         int total = 0;
 325         fd_set w_fds, r_fds;
 326         int fd_count, count;
 327         struct timeval tv;
 328         int reading=0;
 329         int blocked=0;
 330
 331         no_flush++;
 332
 333         while (total < len) {
 334                 FD_ZERO(&w_fds);
 335                 FD_ZERO(&r_fds);
 336                 FD_SET(fd,&w_fds);
 337                 fd_count = fd+1;
 338
 339                 if (!no_flush_read) {
 340                         reading = (buffer_f_in != -1 &&
 341                                    read_buffer_len < MAX_READ_BUFFER);
 342                 }
 343
 344                 if (reading) {
 345                         FD_SET(buffer_f_in,&r_fds);
 346                         if (buffer_f_in > fd)
 347                                 fd_count = buffer_f_in+1;
 348                 }
 349
 350                 tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
 351                 tv.tv_usec = 0;
 352
 353                 count = select(fd_count,
 354                                reading?&r_fds:NULL,
 355                                &w_fds,NULL,
 356                                &tv);
 357
 358                 if (count <= 0) {
 359                         check_timeout();
 360                         continue;
 361                 }
 362
 363                 if (reading && FD_ISSET(buffer_f_in, &r_fds)) {
 364                         read_check(buffer_f_in);
 365                 }
 366
 367                 if (FD_ISSET(fd, &w_fds)) {
 368                         int n = (len-total)>>blocked;
 369                         int ret = write(fd,buf+total,n?n:1);
 370
 371                         if (ret == -1 && errno == EINTR) {
 372                                 continue;
 373                         }
 374
 375                         if (ret == -1 &&
 376                             (errno == EAGAIN || errno == EWOULDBLOCK)) {
 377                                 blocked++;
 378                                 continue;
 379                         }
 380
 381                         if (ret <= 0) {
 382                                 rprintf(FERROR,"erroring writing %d bytes - exiting\n", len);
 383                                 exit_cleanup(1);
 384                         }
 385
 386                         blocked = 0;
 387                         total += ret;
 388                         stats.total_written += ret;
 389
 390                         if (io_timeout)
 391                                 last_io = time(NULL);
 392                 }
 393         }
 394
 395         no_flush--;
 396 }
 397
 398
 399 static char *io_buffer;
 400 static int io_buffer_count;
 401
 402 void io_start_buffering(int fd)
 403 {
 404         if (io_buffer) return;
 405         multiplex_out_fd = fd;
 406         io_buffer = (char *)malloc(IO_BUFFER_SIZE+4);
 407         if (!io_buffer) out_of_memory("writefd");
 408         io_buffer_count = 0;
 409
 410         /* leave room for the multiplex header in case it's needed */
 411         io_buffer += 4;
 412 }
 413
 414 void io_flush(void)
 415 {
 416         int fd = multiplex_out_fd;
 417         if (!io_buffer_count || no_flush) return;
 418
 419         if (io_multiplexing_out) {
 420                 SIVAL(io_buffer-4, 0, (MPLEX_BASE<<24) + io_buffer_count);
 421                 writefd_unbuffered(fd, io_buffer-4, io_buffer_count+4);
 422         } else {
 423                 writefd_unbuffered(fd, io_buffer, io_buffer_count);
 424         }
 425         io_buffer_count = 0;
 426 }
 427
 428 void io_end_buffering(int fd)
 429 {
 430         io_flush();
 431         if (!io_multiplexing_out) {
 432                 free(io_buffer-4);
 433                 io_buffer = NULL;
 434         }
 435 }
 436
 437 static void writefd(int fd,char *buf,int len)
 438 {
 439         if (!io_buffer) {
 440                 writefd_unbuffered(fd, buf, len);
 441                 return;
 442         }
 443
 444         while (len) {
 445                 int n = MIN(len, IO_BUFFER_SIZE-io_buffer_count);
 446                 if (n > 0) {
 447                         memcpy(io_buffer+io_buffer_count, buf, n);
 448                         buf += n;
 449                         len -= n;
 450                         io_buffer_count += n;
 451                 }
 452
 453                 if (io_buffer_count == IO_BUFFER_SIZE) io_flush();
 454         }
 455 }
 456
 457
 458 void write_int(int f,int32 x)
 459 {
 460         char b[4];
 461         SIVAL(b,0,x);
 462         writefd(f,b,4);
 463 }
 464
 465 void write_longint(int f, int64 x)
 466 {
 467         extern int remote_version;
 468         char b[8];
 469
 470         if (remote_version < 16 || x <= 0x7FFFFFFF) {
 471                 write_int(f, (int)x);
 472                 return;
 473         }
 474
 475         write_int(f, -1);
 476         SIVAL(b,0,(x&0xFFFFFFFF));
 477         SIVAL(b,4,((x>>32)&0xFFFFFFFF));
 478
 479         writefd(f,b,8);
 480 }
 481
 482 void write_buf(int f,char *buf,int len)
 483 {
 484         writefd(f,buf,len);
 485 }
 486
 487 /* write a string to the connection */
 488 void write_sbuf(int f,char *buf)
 489 {
 490         write_buf(f, buf, strlen(buf));
 491 }
 492
 493
 494 void write_byte(int f,unsigned char c)
 495 {
 496         write_buf(f,(char *)&c,1);
 497 }
 498
 499 int read_line(int f, char *buf, int maxlen)
 500 {
 501         eof_error = 0;
 502
 503         while (maxlen) {
 504                 buf[0] = 0;
 505                 read_buf(f, buf, 1);
 506                 if (buf[0] == 0) return 0;
 507                 if (buf[0] == '\n') {
 508                         buf[0] = 0;
 509                         break;
 510                 }
 511                 if (buf[0] != '\r') {
 512                         buf++;
 513                         maxlen--;
 514                 }
 515         }
 516         if (maxlen == 0) {
 517                 *buf = 0;
 518                 return 0;
 519         }
 520
 521         eof_error = 1;
 522
 523         return 1;
 524 }
 525
 526
 527 void io_printf(int fd, const char *format, ...)
 528 {
 529         va_list ap;
 530         char buf[1024];
 531         int len;
 532
 533         va_start(ap, format);
 534         len = vslprintf(buf, sizeof(buf)-1, format, ap);
 535         va_end(ap);
 536
 537         if (len < 0) exit_cleanup(1);
 538
 539         write_sbuf(fd, buf);
 540 }
 541
 542
 543 /* setup for multiplexing an error stream with the data stream */
 544 void io_start_multiplex_out(int fd)
 545 {
 546         multiplex_out_fd = fd;
 547         io_flush();
 548         io_start_buffering(fd);
 549         io_multiplexing_out = 1;
 550 }
 551
 552 /* setup for multiplexing an error stream with the data stream */
 553 void io_start_multiplex_in(int fd)
 554 {
 555         multiplex_in_fd = fd;
 556         io_flush();
 557         if (read_buffer_len) {
 558                 fprintf(stderr,"ERROR: data in read buffer at mplx start\n");
 559                 exit_cleanup(1);
 560         }
 561
 562         io_multiplexing_in = 1;
 563 }
 564
 565 /* write an message to the error stream */
 566 int io_multiplex_write(int f, char *buf, int len)
 567 {
 568         if (!io_multiplexing_out) return 0;
 569
 570         io_flush();
 571
 572         SIVAL(io_buffer-4, 0, ((MPLEX_BASE + f)<<24) + len);
 573         memcpy(io_buffer, buf, len);
 574
 575         writefd_unbuffered(multiplex_out_fd, io_buffer-4, len+4);
 576         return 1;
 577 }
 578
 579 void io_close_input(int fd)
 580 {
 581         buffer_f_in = -1;
 582 }