sim/common/syscall.c

   1 /* Remote target system call support.
   2    Copyright 1997-2021 Free Software Foundation, Inc.
   3    Contributed by Cygnus Solutions.
   4
   5    This file is part of GDB.
   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
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 /* This interface isn't intended to be specific to any particular kind
  21    of remote (hardware, simulator, whatever).  As such, support for it
  22    (e.g. sim/common/callback.c) should *not* live in the simulator source
  23    tree, nor should it live in the gdb source tree.  K&R C must be
  24    supported.  */
  25
  26 /* This must come before any other includes.  */
  27 #include "defs.h"
  28
  29 #include <errno.h>
  30 #include <fcntl.h>
  31 #include <stdarg.h>
  32 #include <stdio.h>
  33 #include <stdlib.h>
  34 #include <string.h>
  35 #include <time.h>
  36 #ifdef HAVE_UNISTD_H
  37 #include <unistd.h>
  38 #endif
  39 #include <sys/stat.h>
  40 #include <sys/types.h>
  41
  42 #include "ansidecl.h"
  43 #include "libiberty.h"
  44
  45 #include "sim/callback.h"
  46
  47 #ifndef ENOSYS
  48 #define ENOSYS EINVAL
  49 #endif
  50 #ifndef ENAMETOOLONG
  51 #define ENAMETOOLONG EINVAL
  52 #endif
  53
  54 /* Maximum length of a path name.  */
  55 #ifndef MAX_PATH_LEN
  56 #define MAX_PATH_LEN 1024
  57 #endif
  58
  59 /* When doing file read/writes, do this many bytes at a time.  */
  60 #define FILE_XFR_SIZE 4096
  61
  62 /* FIXME: for now, need to consider target word size.  */
  63 #define TWORD long
  64 #define TADDR unsigned long
  65
  66 /* Path to be prepended to syscalls with absolute paths, and to be
  67    chdir:ed at startup, if not empty.  */
  68 char *simulator_sysroot = "";
  69
  70 /* Utility of cb_syscall to fetch a path name or other string from the target.
  71    The result is 0 for success or a host errno value.  */
  72
  73 int
  74 cb_get_string (host_callback *cb, CB_SYSCALL *sc, char *buf, int buflen,
  75                TADDR addr)
  76 {
  77   char *p, *pend;
  78
  79   for (p = buf, pend = buf + buflen; p < pend; ++p, ++addr)
  80     {
  81       /* No, it isn't expected that this would cause one transaction with
  82          the remote target for each byte.  The target could send the
  83          path name along with the syscall request, and cache the file
  84          name somewhere (or otherwise tweak this as desired).  */
  85       unsigned int count = (*sc->read_mem) (cb, sc, addr, p, 1);
  86
  87       if (count != 1)
  88         return EINVAL;
  89       if (*p == 0)
  90         break;
  91     }
  92   if (p == pend)
  93     return ENAMETOOLONG;
  94   return 0;
  95 }
  96
  97 /* Utility of cb_syscall to fetch a path name.
  98    The buffer is malloc'd and the address is stored in BUFP.
  99    The result is that of get_string, but prepended with
 100    simulator_sysroot if the string starts with '/'.
 101    If an error occurs, no buffer is left malloc'd.  */
 102
 103 static int
 104 get_path (host_callback *cb, CB_SYSCALL *sc, TADDR addr, char **bufp)
 105 {
 106   char *buf = xmalloc (MAX_PATH_LEN);
 107   int result;
 108   int sysroot_len = strlen (simulator_sysroot);
 109
 110   result = cb_get_string (cb, sc, buf, MAX_PATH_LEN - sysroot_len, addr);
 111   if (result == 0)
 112     {
 113       /* Prepend absolute paths with simulator_sysroot.  Relative paths
 114          are supposed to be relative to a chdir within that path, but at
 115          this point unknown where.  */
 116       if (simulator_sysroot[0] != '\0' && *buf == '/')
 117         {
 118           /* Considering expected rareness of syscalls with absolute
 119              file paths (compared to relative file paths and insn
 120              execution), it does not seem worthwhile to rearrange things
 121              to get rid of the string moves here; we'd need at least an
 122              extra call to check the initial '/' in the path.  */
 123           memmove (buf + sysroot_len, buf, sysroot_len);
 124           memcpy (buf, simulator_sysroot, sysroot_len);
 125         }
 126
 127       *bufp = buf;
 128     }
 129   else
 130     free (buf);
 131   return result;
 132 }
 133
 134 /* Perform a system call on behalf of the target.  */
 135
 136 CB_RC
 137 cb_syscall (host_callback *cb, CB_SYSCALL *sc)
 138 {
 139   TWORD result = 0, errcode = 0;
 140
 141   if (sc->magic != CB_SYSCALL_MAGIC)
 142     abort ();
 143
 144   switch (cb_target_to_host_syscall (cb, sc->func))
 145     {
 146     case CB_SYS_argc:
 147       result = countargv (cb->argv);
 148       break;
 149
 150     case CB_SYS_argnlen:
 151       {
 152         if (sc->arg1 >= 0 && sc->arg1 < countargv (cb->argv))
 153           result = strlen (cb->argv[sc->arg1]);
 154         else
 155           {
 156             result = -1;
 157             errcode = EINVAL;
 158           }
 159       }
 160       break;
 161
 162     case CB_SYS_argn:
 163       {
 164         if (sc->arg1 >= 0 && sc->arg1 < countargv (cb->argv))
 165           {
 166             const char *argn = cb->argv[sc->arg1];
 167             int len = strlen (argn);
 168             int written = sc->write_mem (cb, sc, sc->arg2, argn, len + 1);
 169
 170             if (written == len + 1)
 171               result = sc->arg2;
 172             else
 173               {
 174                 result = -1;
 175                 errcode = EINVAL;
 176               }
 177           }
 178         else
 179           {
 180             result = -1;
 181             errcode = EINVAL;
 182           }
 183       }
 184       break;
 185
 186     case CB_SYS_argvlen :
 187       {
 188         /* Compute how much space is required to store the argv,envp
 189            strings so that the program can allocate the space and then
 190            call SYS_argv to fetch the values.  */
 191         int argc, envc, arglen, envlen;
 192         char **argv = cb->argv;
 193         char **envp = cb->envp;
 194
 195         argc = arglen = 0;
 196         if (argv)
 197           {
 198             for ( ; argv[argc]; ++argc)
 199               arglen += strlen (argv[argc]) + 1;
 200           }
 201         envc = envlen = 0;
 202         if (envp)
 203           {
 204             for ( ; envp[envc]; ++envc)
 205               envlen += strlen (envp[envc]) + 1;
 206           }
 207         result = arglen + 1 + envlen + 1;
 208         break;
 209       }
 210
 211     case CB_SYS_argv :
 212       {
 213         /* Pointer to target's buffer.  */
 214         TADDR tbuf = sc->arg1;
 215         /* Buffer size.  */
 216         int bufsize = sc->arg2;
 217         int written = 0;
 218         /* Q is the target address of where all the strings go.  */
 219         TADDR q;
 220         int i, argc, envc, len, ret;
 221         char **argv = cb->argv;
 222         char **envp = cb->envp;
 223
 224         result = -1;
 225
 226         argc = 0;
 227         if (argv)
 228           {
 229             for ( ; argv[argc]; ++argc)
 230               {
 231                 len = strlen (argv[argc]) + 1;
 232                 if (written + len > bufsize)
 233                   goto efault;
 234
 235                 ret = (*sc->write_mem) (cb, sc, tbuf + written, argv[argc],
 236                                         len);
 237                 if (ret != len)
 238                   goto einval;
 239
 240                 written += ret;
 241               }
 242           }
 243         /* Double NUL bytes indicates end of strings.  */
 244         if (written >= bufsize)
 245           goto efault;
 246         if ((*sc->write_mem) (cb, sc, tbuf + written, "", 1) != 1)
 247           goto einval;
 248         ++written;
 249
 250         envc = 0;
 251         if (envp)
 252           {
 253             for ( ; envp[envc]; ++envc)
 254               {
 255                 len = strlen (envp[envc]) + 1;
 256                 if (written + len > bufsize)
 257                   goto efault;
 258
 259                 ret = (*sc->write_mem) (cb, sc, tbuf + written, envp[envc],
 260                                         len);
 261                 if (ret != len)
 262                   goto einval;
 263                 written += ret;
 264               }
 265           }
 266         /* Double NUL bytes indicates end of strings.  */
 267         if (written >= bufsize)
 268           goto efault;
 269         if ((*sc->write_mem) (cb, sc, tbuf + written, "", 1) != 1)
 270           goto einval;
 271
 272         result = argc;
 273         sc->result2 = envc;
 274         break;
 275
 276  efault:
 277         errcode = EFAULT;
 278         goto FinishSyscall;
 279
 280  einval:
 281         errcode = EINVAL;
 282         goto FinishSyscall;
 283       }
 284
 285     case CB_SYS_exit :
 286       /* Caller must catch and handle; see sim_syscall as an example.  */
 287       break;
 288
 289     case CB_SYS_open :
 290       {
 291         char *path;
 292
 293         errcode = get_path (cb, sc, sc->arg1, &path);
 294         if (errcode != 0)
 295           {
 296             result = -1;
 297             goto FinishSyscall;
 298           }
 299         result = (*cb->open) (cb, path, sc->arg2 /*, sc->arg3*/);
 300         free (path);
 301         if (result < 0)
 302           goto ErrorFinish;
 303       }
 304       break;
 305
 306     case CB_SYS_close :
 307       result = (*cb->close) (cb, sc->arg1);
 308       if (result < 0)
 309         goto ErrorFinish;
 310       break;
 311
 312     case CB_SYS_read :
 313       {
 314         /* ??? Perfect handling of error conditions may require only one
 315            call to cb->read.  One can't assume all the data is
 316            contiguously stored in host memory so that would require
 317            malloc'ing/free'ing the space.  Maybe later.  */
 318         char buf[FILE_XFR_SIZE];
 319         int fd = sc->arg1;
 320         TADDR addr = sc->arg2;
 321         size_t count = sc->arg3;
 322         size_t bytes_read = 0;
 323         int bytes_written;
 324
 325         while (count > 0)
 326           {
 327             if (cb_is_stdin (cb, fd))
 328               result = (int) (*cb->read_stdin) (cb, buf,
 329                                                 (count < FILE_XFR_SIZE
 330                                                  ? count : FILE_XFR_SIZE));
 331             else
 332               result = (int) (*cb->read) (cb, fd, buf,
 333                                           (count < FILE_XFR_SIZE
 334                                            ? count : FILE_XFR_SIZE));
 335             if (result == -1)
 336               goto ErrorFinish;
 337             if (result == 0)    /* EOF */
 338               break;
 339             bytes_written = (*sc->write_mem) (cb, sc, addr, buf, result);
 340             if (bytes_written != result)
 341               {
 342                 result = -1;
 343                 errcode = EINVAL;
 344                 goto FinishSyscall;
 345               }
 346             bytes_read += result;
 347             count -= result;
 348             addr += result;
 349             /* If this is a short read, don't go back for more */
 350             if (result != FILE_XFR_SIZE)
 351               break;
 352           }
 353         result = bytes_read;
 354       }
 355       break;
 356
 357     case CB_SYS_write :
 358       {
 359         /* ??? Perfect handling of error conditions may require only one
 360            call to cb->write.  One can't assume all the data is
 361            contiguously stored in host memory so that would require
 362            malloc'ing/free'ing the space.  Maybe later.  */
 363         char buf[FILE_XFR_SIZE];
 364         int fd = sc->arg1;
 365         TADDR addr = sc->arg2;
 366         size_t count = sc->arg3;
 367         int bytes_read;
 368         size_t bytes_written = 0;
 369
 370         while (count > 0)
 371           {
 372             int bytes_to_read = count < FILE_XFR_SIZE ? count : FILE_XFR_SIZE;
 373             bytes_read = (*sc->read_mem) (cb, sc, addr, buf, bytes_to_read);
 374             if (bytes_read != bytes_to_read)
 375               {
 376                 result = -1;
 377                 errcode = EINVAL;
 378                 goto FinishSyscall;
 379               }
 380             if (cb_is_stdout (cb, fd))
 381               {
 382                 result = (int) (*cb->write_stdout) (cb, buf, bytes_read);
 383                 (*cb->flush_stdout) (cb);
 384               }
 385             else if (cb_is_stderr (cb, fd))
 386               {
 387                 result = (int) (*cb->write_stderr) (cb, buf, bytes_read);
 388                 (*cb->flush_stderr) (cb);
 389               }
 390             else
 391               result = (int) (*cb->write) (cb, fd, buf, bytes_read);
 392             if (result == -1)
 393               goto ErrorFinish;
 394             bytes_written += result;
 395             count -= result;
 396             addr += result;
 397           }
 398         result = bytes_written;
 399       }
 400       break;
 401
 402     case CB_SYS_lseek :
 403       {
 404         int fd = sc->arg1;
 405         unsigned long offset = sc->arg2;
 406         int whence = sc->arg3;
 407
 408         result = (*cb->lseek) (cb, fd, offset, whence);
 409         if (result < 0)
 410           goto ErrorFinish;
 411       }
 412       break;
 413
 414     case CB_SYS_unlink :
 415       {
 416         char *path;
 417
 418         errcode = get_path (cb, sc, sc->arg1, &path);
 419         if (errcode != 0)
 420           {
 421             result = -1;
 422             goto FinishSyscall;
 423           }
 424         result = (*cb->unlink) (cb, path);
 425         free (path);
 426         if (result < 0)
 427           goto ErrorFinish;
 428       }
 429       break;
 430
 431     case CB_SYS_truncate :
 432       {
 433         char *path;
 434         long len = sc->arg2;
 435
 436         errcode = get_path (cb, sc, sc->arg1, &path);
 437         if (errcode != 0)
 438           {
 439             result = -1;
 440             errcode = EFAULT;
 441             goto FinishSyscall;
 442           }
 443         result = (*cb->truncate) (cb, path, len);
 444         free (path);
 445         if (result < 0)
 446           goto ErrorFinish;
 447       }
 448       break;
 449
 450     case CB_SYS_ftruncate :
 451       {
 452         int fd = sc->arg1;
 453         long len = sc->arg2;
 454
 455         result = (*cb->ftruncate) (cb, fd, len);
 456         if (result < 0)
 457           goto ErrorFinish;
 458       }
 459       break;
 460
 461     case CB_SYS_rename :
 462       {
 463         char *path1, *path2;
 464
 465         errcode = get_path (cb, sc, sc->arg1, &path1);
 466         if (errcode != 0)
 467           {
 468             result = -1;
 469             errcode = EFAULT;
 470             goto FinishSyscall;
 471           }
 472         errcode = get_path (cb, sc, sc->arg2, &path2);
 473         if (errcode != 0)
 474           {
 475             result = -1;
 476             errcode = EFAULT;
 477             free (path1);
 478             goto FinishSyscall;
 479           }
 480         result = (*cb->rename) (cb, path1, path2);
 481         free (path1);
 482         free (path2);
 483         if (result < 0)
 484           goto ErrorFinish;
 485       }
 486       break;
 487
 488     case CB_SYS_stat :
 489       {
 490         char *path,*buf;
 491         int buflen;
 492         struct stat statbuf;
 493         TADDR addr = sc->arg2;
 494
 495         errcode = get_path (cb, sc, sc->arg1, &path);
 496         if (errcode != 0)
 497           {
 498             result = -1;
 499             goto FinishSyscall;
 500           }
 501         result = (*cb->to_stat) (cb, path, &statbuf);
 502         free (path);
 503         if (result < 0)
 504           goto ErrorFinish;
 505         buflen = cb_host_to_target_stat (cb, NULL, NULL);
 506         buf = xmalloc (buflen);
 507         if (cb_host_to_target_stat (cb, &statbuf, buf) != buflen)
 508           {
 509             /* The translation failed.  This is due to an internal
 510                host program error, not the target's fault.  */
 511             free (buf);
 512             errcode = ENOSYS;
 513             result = -1;
 514             goto FinishSyscall;
 515           }
 516         if ((*sc->write_mem) (cb, sc, addr, buf, buflen) != buflen)
 517           {
 518             free (buf);
 519             errcode = EINVAL;
 520             result = -1;
 521             goto FinishSyscall;
 522           }
 523         free (buf);
 524       }
 525       break;
 526
 527     case CB_SYS_fstat :
 528       {
 529         char *buf;
 530         int buflen;
 531         struct stat statbuf;
 532         TADDR addr = sc->arg2;
 533
 534         result = (*cb->to_fstat) (cb, sc->arg1, &statbuf);
 535         if (result < 0)
 536           goto ErrorFinish;
 537         buflen = cb_host_to_target_stat (cb, NULL, NULL);
 538         buf = xmalloc (buflen);
 539         if (cb_host_to_target_stat (cb, &statbuf, buf) != buflen)
 540           {
 541             /* The translation failed.  This is due to an internal
 542                host program error, not the target's fault.  */
 543             free (buf);
 544             errcode = ENOSYS;
 545             result = -1;
 546             goto FinishSyscall;
 547           }
 548         if ((*sc->write_mem) (cb, sc, addr, buf, buflen) != buflen)
 549           {
 550             free (buf);
 551             errcode = EINVAL;
 552             result = -1;
 553             goto FinishSyscall;
 554           }
 555         free (buf);
 556       }
 557       break;
 558
 559     case CB_SYS_lstat :
 560       {
 561         char *path, *buf;
 562         int buflen;
 563         struct stat statbuf;
 564         TADDR addr = sc->arg2;
 565
 566         errcode = get_path (cb, sc, sc->arg1, &path);
 567         if (errcode != 0)
 568           {
 569             result = -1;
 570             goto FinishSyscall;
 571           }
 572         result = (*cb->to_lstat) (cb, path, &statbuf);
 573         free (path);
 574         if (result < 0)
 575           goto ErrorFinish;
 576
 577         buflen = cb_host_to_target_stat (cb, NULL, NULL);
 578         buf = xmalloc (buflen);
 579         if (cb_host_to_target_stat (cb, &statbuf, buf) != buflen)
 580           {
 581             /* The translation failed.  This is due to an internal
 582                host program error, not the target's fault.
 583                Unfortunately, it's hard to test this case, so there's no
 584                test-case for this execution path.  */
 585             free (buf);
 586             errcode = ENOSYS;
 587             result = -1;
 588             goto FinishSyscall;
 589           }
 590
 591         if ((*sc->write_mem) (cb, sc, addr, buf, buflen) != buflen)
 592           {
 593             free (buf);
 594             errcode = EINVAL;
 595             result = -1;
 596             goto FinishSyscall;
 597           }
 598
 599         free (buf);
 600       }
 601       break;
 602
 603     case CB_SYS_pipe :
 604       {
 605         int p[2];
 606         char *target_p = xcalloc (1, cb->target_sizeof_int * 2);
 607
 608         result = (*cb->pipe) (cb, p);
 609         if (result != 0)
 610           goto ErrorFinish;
 611
 612         cb_store_target_endian (cb, target_p, cb->target_sizeof_int, p[0]);
 613         cb_store_target_endian (cb, target_p + cb->target_sizeof_int,
 614                                 cb->target_sizeof_int, p[1]);
 615         if ((*sc->write_mem) (cb, sc, sc->arg1, target_p,
 616                               cb->target_sizeof_int * 2)
 617             != cb->target_sizeof_int * 2)
 618           {
 619             /* Close the pipe fd:s.  */
 620             (*cb->close) (cb, p[0]);
 621             (*cb->close) (cb, p[1]);
 622             errcode = EFAULT;
 623             result = -1;
 624           }
 625
 626         free (target_p);
 627       }
 628       break;
 629
 630     case CB_SYS_getpid:
 631       /* POSIX says getpid always succeeds.  */
 632       result = (*cb->getpid) (cb);
 633       break;
 634
 635     case CB_SYS_kill:
 636       /* If killing self, leave it to the caller to process so it can send the
 637          signal to the engine.  */
 638       if (sc->arg1 == (*cb->getpid) (cb))
 639         {
 640           result = -1;
 641           errcode = ENOSYS;
 642         }
 643       else
 644         {
 645           int signum = cb_target_to_host_signal (cb, sc->arg2);
 646
 647           result = (*cb->kill) (cb, sc->arg1, signum);
 648           cb->last_errno = errno;
 649           goto ErrorFinish;
 650         }
 651       break;
 652
 653     case CB_SYS_time :
 654       {
 655         /* FIXME: May wish to change CB_SYS_time to something else.
 656            We might also want gettimeofday or times, but if system calls
 657            can be built on others, we can keep the number we have to support
 658            here down.  */
 659         time_t t = (*cb->time) (cb);
 660         result = t;
 661         /* It is up to target code to process the argument to time().  */
 662       }
 663       break;
 664
 665     case CB_SYS_chdir :
 666     case CB_SYS_chmod :
 667     case CB_SYS_utime :
 668       /* fall through for now */
 669
 670     default :
 671       result = -1;
 672       errcode = ENOSYS;
 673       break;
 674     }
 675
 676  FinishSyscall:
 677   sc->result = result;
 678   if (errcode == 0)
 679     sc->errcode = 0;
 680   else
 681     sc->errcode = cb_host_to_target_errno (cb, errcode);
 682   return CB_RC_OK;
 683
 684  ErrorFinish:
 685   sc->result = result;
 686   sc->errcode = (*cb->get_errno) (cb);
 687   return CB_RC_OK;
 688 }