gdbserver/hostio.cc

   1 /* Host file transfer support for gdbserver.
   2    Copyright (C) 2007-2020 Free Software Foundation, Inc.
   3
   4    Contributed by CodeSourcery.
   5
   6    This file is part of GDB.
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 #include "server.h"
  22 #include "gdb/fileio.h"
  23 #include "hostio.h"
  24
  25 #include <fcntl.h>
  26 #include <limits.h>
  27 #include <unistd.h>
  28 #include <sys/types.h>
  29 #include <sys/stat.h>
  30 #include "gdbsupport/fileio.h"
  31
  32 struct fd_list
  33 {
  34   int fd;
  35   struct fd_list *next;
  36 };
  37
  38 static struct fd_list *open_fds;
  39
  40 static int
  41 safe_fromhex (char a, int *nibble)
  42 {
  43   if (a >= '0' && a <= '9')
  44     *nibble = a - '0';
  45   else if (a >= 'a' && a <= 'f')
  46     *nibble = a - 'a' + 10;
  47   else if (a >= 'A' && a <= 'F')
  48     *nibble = a - 'A' + 10;
  49   else
  50     return -1;
  51
  52   return 0;
  53 }
  54
  55 /* Filenames are hex encoded, so the maximum we can handle is half the
  56    packet buffer size.  Cap to PATH_MAX, if it is shorter.  */
  57 #if !defined (PATH_MAX) || (PATH_MAX > (PBUFSIZ / 2 + 1))
  58 #  define HOSTIO_PATH_MAX (PBUFSIZ / 2 + 1)
  59 #else
  60 #  define HOSTIO_PATH_MAX PATH_MAX
  61 #endif
  62
  63 static int
  64 require_filename (char **pp, char *filename)
  65 {
  66   int count;
  67   char *p;
  68
  69   p = *pp;
  70   count = 0;
  71
  72   while (*p && *p != ',')
  73     {
  74       int nib1, nib2;
  75
  76       /* Don't allow overflow.  */
  77       if (count >= HOSTIO_PATH_MAX - 1)
  78         return -1;
  79
  80       if (safe_fromhex (p[0], &nib1)
  81           || safe_fromhex (p[1], &nib2))
  82         return -1;
  83
  84       filename[count++] = nib1 * 16 + nib2;
  85       p += 2;
  86     }
  87
  88   filename[count] = '\0';
  89   *pp = p;
  90   return 0;
  91 }
  92
  93 static int
  94 require_int (char **pp, int *value)
  95 {
  96   char *p;
  97   int count, firstdigit;
  98
  99   p = *pp;
 100   *value = 0;
 101   count = 0;
 102   firstdigit = -1;
 103
 104   while (*p && *p != ',')
 105     {
 106       int nib;
 107
 108       if (safe_fromhex (p[0], &nib))
 109         return -1;
 110
 111       if (firstdigit == -1)
 112         firstdigit = nib;
 113
 114       /* Don't allow overflow.  */
 115       if (count >= 8 || (count == 7 && firstdigit >= 0x8))
 116         return -1;
 117
 118       *value = *value * 16 + nib;
 119       p++;
 120       count++;
 121     }
 122
 123   *pp = p;
 124   return 0;
 125 }
 126
 127 static int
 128 require_data (char *p, int p_len, char **data, int *data_len)
 129 {
 130   int input_index, output_index, escaped;
 131
 132   *data = (char *) xmalloc (p_len);
 133
 134   output_index = 0;
 135   escaped = 0;
 136   for (input_index = 0; input_index < p_len; input_index++)
 137     {
 138       char b = p[input_index];
 139
 140       if (escaped)
 141         {
 142           (*data)[output_index++] = b ^ 0x20;
 143           escaped = 0;
 144         }
 145       else if (b == '}')
 146         escaped = 1;
 147       else
 148         (*data)[output_index++] = b;
 149     }
 150
 151   if (escaped)
 152     {
 153       free (*data);
 154       return -1;
 155     }
 156
 157   *data_len = output_index;
 158   return 0;
 159 }
 160
 161 static int
 162 require_comma (char **pp)
 163 {
 164   if (**pp == ',')
 165     {
 166       (*pp)++;
 167       return 0;
 168     }
 169   else
 170     return -1;
 171 }
 172
 173 static int
 174 require_end (char *p)
 175 {
 176   if (*p == '\0')
 177     return 0;
 178   else
 179     return -1;
 180 }
 181
 182 static int
 183 require_valid_fd (int fd)
 184 {
 185   struct fd_list *fd_ptr;
 186
 187   for (fd_ptr = open_fds; fd_ptr != NULL; fd_ptr = fd_ptr->next)
 188     if (fd_ptr->fd == fd)
 189       return 0;
 190
 191   return -1;
 192 }
 193
 194 /* Fill in own_buf with the last hostio error packet, however it
 195    suitable for the target.  */
 196 static void
 197 hostio_error (char *own_buf)
 198 {
 199   the_target->pt->hostio_last_error (own_buf);
 200 }
 201
 202 static void
 203 hostio_packet_error (char *own_buf)
 204 {
 205   sprintf (own_buf, "F-1,%x", FILEIO_EINVAL);
 206 }
 207
 208 static void
 209 hostio_reply (char *own_buf, int result)
 210 {
 211   sprintf (own_buf, "F%x", result);
 212 }
 213
 214 static int
 215 hostio_reply_with_data (char *own_buf, char *buffer, int len,
 216                         int *new_packet_len)
 217 {
 218   int input_index, output_index, out_maxlen;
 219
 220   sprintf (own_buf, "F%x;", len);
 221   output_index = strlen (own_buf);
 222
 223   out_maxlen = PBUFSIZ;
 224
 225   for (input_index = 0; input_index < len; input_index++)
 226     {
 227       char b = buffer[input_index];
 228
 229       if (b == '$' || b == '#' || b == '}' || b == '*')
 230         {
 231           /* These must be escaped.  */
 232           if (output_index + 2 > out_maxlen)
 233             break;
 234           own_buf[output_index++] = '}';
 235           own_buf[output_index++] = b ^ 0x20;
 236         }
 237       else
 238         {
 239           if (output_index + 1 > out_maxlen)
 240             break;
 241           own_buf[output_index++] = b;
 242         }
 243     }
 244
 245   *new_packet_len = output_index;
 246   return input_index;
 247 }
 248
 249 /* Process ID of inferior whose filesystem hostio functions
 250    that take FILENAME arguments will use.  Zero means to use
 251    our own filesystem.  */
 252
 253 static int hostio_fs_pid;
 254
 255 /* See hostio.h.  */
 256
 257 void
 258 hostio_handle_new_gdb_connection (void)
 259 {
 260   hostio_fs_pid = 0;
 261 }
 262
 263 /* Handle a "vFile:setfs:" packet.  */
 264
 265 static void
 266 handle_setfs (char *own_buf)
 267 {
 268   char *p;
 269   int pid;
 270
 271   /* If the target doesn't have any of the in-filesystem-of methods
 272      then there's no point in GDB sending "vFile:setfs:" packets.  We
 273      reply with an empty packet (i.e. we pretend we don't understand
 274      "vFile:setfs:") and that should stop GDB sending any more.  */
 275   if (the_target->multifs_open == NULL
 276       && the_target->multifs_unlink == NULL
 277       && the_target->multifs_readlink == NULL)
 278     {
 279       own_buf[0] = '\0';
 280       return;
 281     }
 282
 283   p = own_buf + strlen ("vFile:setfs:");
 284
 285   if (require_int (&p, &pid)
 286       || pid < 0
 287       || require_end (p))
 288     {
 289       hostio_packet_error (own_buf);
 290       return;
 291     }
 292
 293   hostio_fs_pid = pid;
 294
 295   hostio_reply (own_buf, 0);
 296 }
 297
 298 static void
 299 handle_open (char *own_buf)
 300 {
 301   char filename[HOSTIO_PATH_MAX];
 302   char *p;
 303   int fileio_flags, fileio_mode, flags, fd;
 304   mode_t mode;
 305   struct fd_list *new_fd;
 306
 307   p = own_buf + strlen ("vFile:open:");
 308
 309   if (require_filename (&p, filename)
 310       || require_comma (&p)
 311       || require_int (&p, &fileio_flags)
 312       || require_comma (&p)
 313       || require_int (&p, &fileio_mode)
 314       || require_end (p)
 315       || fileio_to_host_openflags (fileio_flags, &flags)
 316       || fileio_to_host_mode (fileio_mode, &mode))
 317     {
 318       hostio_packet_error (own_buf);
 319       return;
 320     }
 321
 322   /* We do not need to convert MODE, since the fileio protocol
 323      uses the standard values.  */
 324   if (hostio_fs_pid != 0 && the_target->multifs_open != NULL)
 325     fd = the_target->multifs_open (hostio_fs_pid, filename,
 326                                    flags, mode);
 327   else
 328     fd = open (filename, flags, mode);
 329
 330   if (fd == -1)
 331     {
 332       hostio_error (own_buf);
 333       return;
 334     }
 335
 336   /* Record the new file descriptor.  */
 337   new_fd = XNEW (struct fd_list);
 338   new_fd->fd = fd;
 339   new_fd->next = open_fds;
 340   open_fds = new_fd;
 341
 342   hostio_reply (own_buf, fd);
 343 }
 344
 345 static void
 346 handle_pread (char *own_buf, int *new_packet_len)
 347 {
 348   int fd, ret, len, offset, bytes_sent;
 349   char *p, *data;
 350   static int max_reply_size = -1;
 351
 352   p = own_buf + strlen ("vFile:pread:");
 353
 354   if (require_int (&p, &fd)
 355       || require_comma (&p)
 356       || require_valid_fd (fd)
 357       || require_int (&p, &len)
 358       || require_comma (&p)
 359       || require_int (&p, &offset)
 360       || require_end (p))
 361     {
 362       hostio_packet_error (own_buf);
 363       return;
 364     }
 365
 366   /* Do not attempt to read more than the maximum number of bytes
 367      hostio_reply_with_data can fit in a packet.  We may still read
 368      too much because of escaping, but this is handled below.  */
 369   if (max_reply_size == -1)
 370     {
 371       sprintf (own_buf, "F%x;", PBUFSIZ);
 372       max_reply_size = PBUFSIZ - strlen (own_buf);
 373     }
 374   if (len > max_reply_size)
 375     len = max_reply_size;
 376
 377   data = (char *) xmalloc (len);
 378 #ifdef HAVE_PREAD
 379   ret = pread (fd, data, len, offset);
 380 #else
 381   ret = -1;
 382 #endif
 383   /* If we have no pread or it failed for this file, use lseek/read.  */
 384   if (ret == -1)
 385     {
 386       ret = lseek (fd, offset, SEEK_SET);
 387       if (ret != -1)
 388         ret = read (fd, data, len);
 389     }
 390
 391   if (ret == -1)
 392     {
 393       hostio_error (own_buf);
 394       free (data);
 395       return;
 396     }
 397
 398   bytes_sent = hostio_reply_with_data (own_buf, data, ret, new_packet_len);
 399
 400   /* If we were using read, and the data did not all fit in the reply,
 401      we would have to back up using lseek here.  With pread it does
 402      not matter.  But we still have a problem; the return value in the
 403      packet might be wrong, so we must fix it.  This time it will
 404      definitely fit.  */
 405   if (bytes_sent < ret)
 406     bytes_sent = hostio_reply_with_data (own_buf, data, bytes_sent,
 407                                          new_packet_len);
 408
 409   free (data);
 410 }
 411
 412 static void
 413 handle_pwrite (char *own_buf, int packet_len)
 414 {
 415   int fd, ret, len, offset;
 416   char *p, *data;
 417
 418   p = own_buf + strlen ("vFile:pwrite:");
 419
 420   if (require_int (&p, &fd)
 421       || require_comma (&p)
 422       || require_valid_fd (fd)
 423       || require_int (&p, &offset)
 424       || require_comma (&p)
 425       || require_data (p, packet_len - (p - own_buf), &data, &len))
 426     {
 427       hostio_packet_error (own_buf);
 428       return;
 429     }
 430
 431 #ifdef HAVE_PWRITE
 432   ret = pwrite (fd, data, len, offset);
 433 #else
 434   ret = -1;
 435 #endif
 436   /* If we have no pwrite or it failed for this file, use lseek/write.  */
 437   if (ret == -1)
 438     {
 439       ret = lseek (fd, offset, SEEK_SET);
 440       if (ret != -1)
 441         ret = write (fd, data, len);
 442     }
 443
 444   if (ret == -1)
 445     {
 446       hostio_error (own_buf);
 447       free (data);
 448       return;
 449     }
 450
 451   hostio_reply (own_buf, ret);
 452   free (data);
 453 }
 454
 455 static void
 456 handle_fstat (char *own_buf, int *new_packet_len)
 457 {
 458   int fd, bytes_sent;
 459   char *p;
 460   struct stat st;
 461   struct fio_stat fst;
 462
 463   p = own_buf + strlen ("vFile:fstat:");
 464
 465   if (require_int (&p, &fd)
 466       || require_valid_fd (fd)
 467       || require_end (p))
 468     {
 469       hostio_packet_error (own_buf);
 470       return;
 471     }
 472
 473   if (fstat (fd, &st) == -1)
 474     {
 475       hostio_error (own_buf);
 476       return;
 477     }
 478
 479   host_to_fileio_stat (&st, &fst);
 480
 481   bytes_sent = hostio_reply_with_data (own_buf,
 482                                        (char *) &fst, sizeof (fst),
 483                                        new_packet_len);
 484
 485   /* If the response does not fit into a single packet, do not attempt
 486      to return a partial response, but simply fail.  */
 487   if (bytes_sent < sizeof (fst))
 488     write_enn (own_buf);
 489 }
 490
 491 static void
 492 handle_close (char *own_buf)
 493 {
 494   int fd, ret;
 495   char *p;
 496   struct fd_list **open_fd_p, *old_fd;
 497
 498   p = own_buf + strlen ("vFile:close:");
 499
 500   if (require_int (&p, &fd)
 501       || require_valid_fd (fd)
 502       || require_end (p))
 503     {
 504       hostio_packet_error (own_buf);
 505       return;
 506     }
 507
 508   ret = close (fd);
 509
 510   if (ret == -1)
 511     {
 512       hostio_error (own_buf);
 513       return;
 514     }
 515
 516   open_fd_p = &open_fds;
 517   /* We know that fd is in the list, thanks to require_valid_fd.  */
 518   while ((*open_fd_p)->fd != fd)
 519     open_fd_p = &(*open_fd_p)->next;
 520
 521   old_fd = *open_fd_p;
 522   *open_fd_p = (*open_fd_p)->next;
 523   free (old_fd);
 524
 525   hostio_reply (own_buf, ret);
 526 }
 527
 528 static void
 529 handle_unlink (char *own_buf)
 530 {
 531   char filename[HOSTIO_PATH_MAX];
 532   char *p;
 533   int ret;
 534
 535   p = own_buf + strlen ("vFile:unlink:");
 536
 537   if (require_filename (&p, filename)
 538       || require_end (p))
 539     {
 540       hostio_packet_error (own_buf);
 541       return;
 542     }
 543
 544   if (hostio_fs_pid != 0 && the_target->multifs_unlink != NULL)
 545     ret = the_target->multifs_unlink (hostio_fs_pid, filename);
 546   else
 547     ret = unlink (filename);
 548
 549   if (ret == -1)
 550     {
 551       hostio_error (own_buf);
 552       return;
 553     }
 554
 555   hostio_reply (own_buf, ret);
 556 }
 557
 558 static void
 559 handle_readlink (char *own_buf, int *new_packet_len)
 560 {
 561   char filename[HOSTIO_PATH_MAX], linkname[HOSTIO_PATH_MAX];
 562   char *p;
 563   int ret, bytes_sent;
 564
 565   p = own_buf + strlen ("vFile:readlink:");
 566
 567   if (require_filename (&p, filename)
 568       || require_end (p))
 569     {
 570       hostio_packet_error (own_buf);
 571       return;
 572     }
 573
 574   if (hostio_fs_pid != 0 && the_target->multifs_readlink != NULL)
 575     ret = the_target->multifs_readlink (hostio_fs_pid, filename,
 576                                         linkname,
 577                                         sizeof (linkname) - 1);
 578   else
 579     ret = readlink (filename, linkname, sizeof (linkname) - 1);
 580
 581   if (ret == -1)
 582     {
 583       hostio_error (own_buf);
 584       return;
 585     }
 586
 587   bytes_sent = hostio_reply_with_data (own_buf, linkname, ret, new_packet_len);
 588
 589   /* If the response does not fit into a single packet, do not attempt
 590      to return a partial response, but simply fail.  */
 591   if (bytes_sent < ret)
 592     sprintf (own_buf, "F-1,%x", FILEIO_ENAMETOOLONG);
 593 }
 594
 595 /* Handle all the 'F' file transfer packets.  */
 596
 597 int
 598 handle_vFile (char *own_buf, int packet_len, int *new_packet_len)
 599 {
 600   if (startswith (own_buf, "vFile:open:"))
 601     handle_open (own_buf);
 602   else if (startswith (own_buf, "vFile:pread:"))
 603     handle_pread (own_buf, new_packet_len);
 604   else if (startswith (own_buf, "vFile:pwrite:"))
 605     handle_pwrite (own_buf, packet_len);
 606   else if (startswith (own_buf, "vFile:fstat:"))
 607     handle_fstat (own_buf, new_packet_len);
 608   else if (startswith (own_buf, "vFile:close:"))
 609     handle_close (own_buf);
 610   else if (startswith (own_buf, "vFile:unlink:"))
 611     handle_unlink (own_buf);
 612   else if (startswith (own_buf, "vFile:readlink:"))
 613     handle_readlink (own_buf, new_packet_len);
 614   else if (startswith (own_buf, "vFile:setfs:"))
 615     handle_setfs (own_buf);
 616   else
 617     return 0;
 618
 619   return 1;
 620 }