granicus.if.org Git - strace/blob - syscall.c

   1 /*
   2  * Copyright (c) 1991, 1992 Paul Kranenburg <pk@cs.few.eur.nl>
   3  * Copyright (c) 1993 Branko Lankester <branko@hacktic.nl>
   4  * Copyright (c) 1993, 1994, 1995, 1996 Rick Sladkey <jrs@world.std.com>
   5  * Copyright (c) 1996-1999 Wichert Akkerman <wichert@cistron.nl>
   6  * Copyright (c) 1999 IBM Deutschland Entwicklung GmbH, IBM Corporation
   7  *                     Linux for s390 port by D.J. Barrow
   8  *                    <barrow_dj@mail.yahoo.com,djbarrow@de.ibm.com>
   9  * Copyright (c) 1999-2017 The strace developers.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. The name of the author may not be used to endorse or promote products
  21  *    derived from this software without specific prior written permission.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  24  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  25  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  26  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  27  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  28  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  29  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  30  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  31  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  32  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  */
  34
  35 #include "defs.h"
  36 #include "native_defs.h"
  37 #include "nsig.h"
  38 #include "number_set.h"
  39 #include <sys/param.h>
  40
  41 /* for struct iovec */
  42 #include <sys/uio.h>
  43
  44 /* for __X32_SYSCALL_BIT */
  45 #include <asm/unistd.h>
  46
  47 #include "regs.h"
  48 #include "ptrace.h"
  49
  50 #if defined(SPARC64)
  51 # undef PTRACE_GETREGS
  52 # define PTRACE_GETREGS PTRACE_GETREGS64
  53 # undef PTRACE_SETREGS
  54 # define PTRACE_SETREGS PTRACE_SETREGS64
  55 #endif
  56
  57 #ifndef NT_PRSTATUS
  58 # define NT_PRSTATUS 1
  59 #endif
  60
  61 #include "syscall.h"
  62 #include "xstring.h"
  63
  64 /* Define these shorthand notations to simplify the syscallent files. */
  65 #include "sysent_shorthand_defs.h"
  66
  67 #define SEN(syscall_name) SEN_ ## syscall_name, SYS_FUNC_NAME(sys_ ## syscall_name)
  68
  69 const struct_sysent sysent0[] = {
  70 #include "syscallent.h"
  71 };
  72
  73 #if SUPPORTED_PERSONALITIES > 1
  74 # include PERSONALITY1_INCLUDE_FUNCS
  75 static const struct_sysent sysent1[] = {
  76 # include "syscallent1.h"
  77 };
  78 #endif
  79
  80 #if SUPPORTED_PERSONALITIES > 2
  81 # include PERSONALITY2_INCLUDE_FUNCS
  82 static const struct_sysent sysent2[] = {
  83 # include "syscallent2.h"
  84 };
  85 #endif
  86
  87 /* Now undef them since short defines cause wicked namespace pollution. */
  88 #include "sysent_shorthand_undefs.h"
  89
  90 /*
  91  * `ioctlent[012].h' files are automatically generated by the auxiliary
  92  * program `ioctlsort', such that the list is sorted by the `code' field.
  93  * This has the side-effect of resolving the _IO.. macros into
  94  * plain integers, eliminating the need to include here everything
  95  * in "/usr/include".
  96  */
  97
  98 const char *const errnoent0[] = {
  99 #include "errnoent.h"
 100 };
 101 const char *const signalent0[] = {
 102 #include "signalent.h"
 103 };
 104 const struct_ioctlent ioctlent0[] = {
 105 #include "ioctlent0.h"
 106 };
 107
 108 #if SUPPORTED_PERSONALITIES > 1
 109 static const char *const errnoent1[] = {
 110 # include "errnoent1.h"
 111 };
 112 static const char *const signalent1[] = {
 113 # include "signalent1.h"
 114 };
 115 static const struct_ioctlent ioctlent1[] = {
 116 # include "ioctlent1.h"
 117 };
 118 # include PERSONALITY0_INCLUDE_PRINTERS_DECLS
 119 static const struct_printers printers0 = {
 120 # include PERSONALITY0_INCLUDE_PRINTERS_DEFS
 121 };
 122 # include PERSONALITY1_INCLUDE_PRINTERS_DECLS
 123 static const struct_printers printers1 = {
 124 # include PERSONALITY1_INCLUDE_PRINTERS_DEFS
 125 };
 126 #endif
 127
 128 #if SUPPORTED_PERSONALITIES > 2
 129 static const char *const errnoent2[] = {
 130 # include "errnoent2.h"
 131 };
 132 static const char *const signalent2[] = {
 133 # include "signalent2.h"
 134 };
 135 static const struct_ioctlent ioctlent2[] = {
 136 # include "ioctlent2.h"
 137 };
 138 # include PERSONALITY2_INCLUDE_PRINTERS_DECLS
 139 static const struct_printers printers2 = {
 140 # include PERSONALITY2_INCLUDE_PRINTERS_DEFS
 141 };
 142 #endif
 143
 144 enum {
 145         nsyscalls0 = ARRAY_SIZE(sysent0)
 146 #if SUPPORTED_PERSONALITIES > 1
 147         , nsyscalls1 = ARRAY_SIZE(sysent1)
 148 # if SUPPORTED_PERSONALITIES > 2
 149         , nsyscalls2 = ARRAY_SIZE(sysent2)
 150 # endif
 151 #endif
 152 };
 153
 154 enum {
 155         nerrnos0 = ARRAY_SIZE(errnoent0)
 156 #if SUPPORTED_PERSONALITIES > 1
 157         , nerrnos1 = ARRAY_SIZE(errnoent1)
 158 # if SUPPORTED_PERSONALITIES > 2
 159         , nerrnos2 = ARRAY_SIZE(errnoent2)
 160 # endif
 161 #endif
 162 };
 163
 164 enum {
 165         nsignals0 = ARRAY_SIZE(signalent0)
 166 #if SUPPORTED_PERSONALITIES > 1
 167         , nsignals1 = ARRAY_SIZE(signalent1)
 168 # if SUPPORTED_PERSONALITIES > 2
 169         , nsignals2 = ARRAY_SIZE(signalent2)
 170 # endif
 171 #endif
 172 };
 173
 174 enum {
 175         nioctlents0 = ARRAY_SIZE(ioctlent0)
 176 #if SUPPORTED_PERSONALITIES > 1
 177         , nioctlents1 = ARRAY_SIZE(ioctlent1)
 178 # if SUPPORTED_PERSONALITIES > 2
 179         , nioctlents2 = ARRAY_SIZE(ioctlent2)
 180 # endif
 181 #endif
 182 };
 183
 184 #if SUPPORTED_PERSONALITIES > 1
 185 const struct_sysent *sysent = sysent0;
 186 const char *const *errnoent = errnoent0;
 187 const char *const *signalent = signalent0;
 188 const struct_ioctlent *ioctlent = ioctlent0;
 189 const struct_printers *printers = &printers0;
 190 #endif
 191
 192 unsigned nsyscalls = nsyscalls0;
 193 unsigned nerrnos = nerrnos0;
 194 unsigned nsignals = nsignals0;
 195 unsigned nioctlents = nioctlents0;
 196
 197 const unsigned int nsyscall_vec[SUPPORTED_PERSONALITIES] = {
 198         nsyscalls0,
 199 #if SUPPORTED_PERSONALITIES > 1
 200         nsyscalls1,
 201 #endif
 202 #if SUPPORTED_PERSONALITIES > 2
 203         nsyscalls2,
 204 #endif
 205 };
 206 const struct_sysent *const sysent_vec[SUPPORTED_PERSONALITIES] = {
 207         sysent0,
 208 #if SUPPORTED_PERSONALITIES > 1
 209         sysent1,
 210 #endif
 211 #if SUPPORTED_PERSONALITIES > 2
 212         sysent2,
 213 #endif
 214 };
 215
 216 const char *const personality_names[] =
 217 # if defined X86_64
 218         {"64 bit", "32 bit", "x32"}
 219 # elif defined X32
 220         {"x32", "32 bit"}
 221 # elif SUPPORTED_PERSONALITIES == 2
 222         {"64 bit", "32 bit"}
 223 # else
 224         {STRINGIFY_VAL(__WORDSIZE) " bit"}
 225 # endif
 226         ;
 227
 228 #if SUPPORTED_PERSONALITIES > 1
 229
 230 unsigned current_personality;
 231
 232 # ifndef current_wordsize
 233 unsigned current_wordsize;
 234 static const int personality_wordsize[SUPPORTED_PERSONALITIES] = {
 235         PERSONALITY0_WORDSIZE,
 236         PERSONALITY1_WORDSIZE,
 237 # if SUPPORTED_PERSONALITIES > 2
 238         PERSONALITY2_WORDSIZE,
 239 # endif
 240 };
 241 # endif
 242
 243 # ifndef current_klongsize
 244 unsigned current_klongsize;
 245 static const int personality_klongsize[SUPPORTED_PERSONALITIES] = {
 246         PERSONALITY0_KLONGSIZE,
 247         PERSONALITY1_KLONGSIZE,
 248 #  if SUPPORTED_PERSONALITIES > 2
 249         PERSONALITY2_KLONGSIZE,
 250 #  endif
 251 };
 252 # endif
 253
 254 void
 255 set_personality(int personality)
 256 {
 257         nsyscalls = nsyscall_vec[personality];
 258         sysent = sysent_vec[personality];
 259
 260         switch (personality) {
 261         case 0:
 262                 errnoent = errnoent0;
 263                 nerrnos = nerrnos0;
 264                 ioctlent = ioctlent0;
 265                 nioctlents = nioctlents0;
 266                 signalent = signalent0;
 267                 nsignals = nsignals0;
 268                 printers = &printers0;
 269                 break;
 270
 271         case 1:
 272                 errnoent = errnoent1;
 273                 nerrnos = nerrnos1;
 274                 ioctlent = ioctlent1;
 275                 nioctlents = nioctlents1;
 276                 signalent = signalent1;
 277                 nsignals = nsignals1;
 278                 printers = &printers1;
 279                 break;
 280
 281 # if SUPPORTED_PERSONALITIES > 2
 282         case 2:
 283                 errnoent = errnoent2;
 284                 nerrnos = nerrnos2;
 285                 ioctlent = ioctlent2;
 286                 nioctlents = nioctlents2;
 287                 signalent = signalent2;
 288                 nsignals = nsignals2;
 289                 printers = &printers2;
 290                 break;
 291 # endif
 292         }
 293
 294         current_personality = personality;
 295 # ifndef current_wordsize
 296         current_wordsize = personality_wordsize[personality];
 297 # endif
 298 # ifndef current_klongsize
 299         current_klongsize = personality_klongsize[personality];
 300 # endif
 301 }
 302
 303 static void
 304 update_personality(struct tcb *tcp, unsigned int personality)
 305 {
 306         static bool need_mpers_warning[] =
 307                 { false, !HAVE_PERSONALITY_1_MPERS, !HAVE_PERSONALITY_2_MPERS };
 308
 309         if (personality == current_personality)
 310                 return;
 311         set_personality(personality);
 312
 313         if (personality == tcp->currpers)
 314                 return;
 315         tcp->currpers = personality;
 316
 317         if (!qflag) {
 318                 error_msg("[ Process PID=%d runs in %s mode. ]",
 319                           tcp->pid, personality_names[personality]);
 320         }
 321
 322         if (need_mpers_warning[personality]) {
 323                 error_msg("WARNING: Proper structure decoding for this "
 324                           "personality is not supported, please consider "
 325                           "building strace with mpers support enabled.");
 326                 need_mpers_warning[personality] = false;
 327         }
 328 }
 329 #endif
 330
 331 #ifdef SYS_socket_subcall
 332 static void
 333 decode_socket_subcall(struct tcb *tcp)
 334 {
 335         const int call = tcp->u_arg[0];
 336
 337         if (call < 1 || call >= SYS_socket_nsubcalls)
 338                 return;
 339
 340         const kernel_ulong_t scno = SYS_socket_subcall + call;
 341         const unsigned int nargs = sysent[scno].nargs;
 342         uint64_t buf[nargs];
 343
 344         if (umoven(tcp, tcp->u_arg[1], nargs * current_wordsize, buf) < 0)
 345                 return;
 346
 347         tcp->scno = scno;
 348         tcp->qual_flg = qual_flags(scno);
 349         tcp->s_ent = &sysent[scno];
 350
 351         unsigned int i;
 352         for (i = 0; i < nargs; ++i)
 353                 tcp->u_arg[i] = (sizeof(uint32_t) == current_wordsize)
 354                                 ? ((uint32_t *) (void *) buf)[i] : buf[i];
 355 }
 356 #endif /* SYS_socket_subcall */
 357
 358 #ifdef SYS_ipc_subcall
 359 static void
 360 decode_ipc_subcall(struct tcb *tcp)
 361 {
 362         unsigned int call = tcp->u_arg[0];
 363         const unsigned int version = call >> 16;
 364
 365         if (version) {
 366 # if defined S390 || defined S390X
 367                 return;
 368 # else
 369 #  ifdef SPARC64
 370                 if (current_wordsize == 8)
 371                         return;
 372 #  endif
 373                 set_tcb_priv_ulong(tcp, version);
 374                 call &= 0xffff;
 375 # endif
 376         }
 377
 378         switch (call) {
 379                 case  1: case  2: case  3: case  4:
 380                 case 11: case 12: case 13: case 14:
 381                 case 21: case 22: case 23: case 24:
 382                         break;
 383                 default:
 384                         return;
 385         }
 386
 387         tcp->scno = SYS_ipc_subcall + call;
 388         tcp->qual_flg = qual_flags(tcp->scno);
 389         tcp->s_ent = &sysent[tcp->scno];
 390
 391         const unsigned int n = tcp->s_ent->nargs;
 392         unsigned int i;
 393         for (i = 0; i < n; i++)
 394                 tcp->u_arg[i] = tcp->u_arg[i + 1];
 395 }
 396 #endif /* SYS_ipc_subcall */
 397
 398 #ifdef SYS_syscall_subcall
 399 static void
 400 decode_syscall_subcall(struct tcb *tcp)
 401 {
 402         if (!scno_is_valid(tcp->u_arg[0]))
 403                 return;
 404         tcp->scno = tcp->u_arg[0];
 405         tcp->qual_flg = qual_flags(tcp->scno);
 406         tcp->s_ent = &sysent[tcp->scno];
 407         memmove(&tcp->u_arg[0], &tcp->u_arg[1],
 408                 sizeof(tcp->u_arg) - sizeof(tcp->u_arg[0]));
 409 # ifdef LINUX_MIPSO32
 410         /*
 411          * Fetching the last arg of 7-arg syscalls (fadvise64_64
 412          * and sync_file_range) requires additional code,
 413          * see linux/mips/get_syscall_args.c
 414          */
 415         if (tcp->s_ent->nargs == MAX_ARGS) {
 416                 if (umoven(tcp,
 417                            mips_REG_SP + MAX_ARGS * sizeof(tcp->u_arg[0]),
 418                            sizeof(tcp->u_arg[0]),
 419                            &tcp->u_arg[MAX_ARGS - 1]) < 0)
 420                 tcp->u_arg[MAX_ARGS - 1] = 0;
 421         }
 422 # endif /* LINUX_MIPSO32 */
 423 }
 424 #endif /* SYS_syscall_subcall */
 425
 426 static void
 427 dumpio(struct tcb *tcp)
 428 {
 429         if (syserror(tcp))
 430                 return;
 431
 432         int fd = tcp->u_arg[0];
 433         if (fd < 0)
 434                 return;
 435
 436         if (is_number_in_set(fd, read_set)) {
 437                 switch (tcp->s_ent->sen) {
 438                 case SEN_read:
 439                 case SEN_pread:
 440                 case SEN_recv:
 441                 case SEN_recvfrom:
 442                 case SEN_mq_timedreceive:
 443                         dumpstr(tcp, tcp->u_arg[1], tcp->u_rval);
 444                         return;
 445                 case SEN_readv:
 446                 case SEN_preadv:
 447                 case SEN_preadv2:
 448                         dumpiov_upto(tcp, tcp->u_arg[2], tcp->u_arg[1],
 449                                      tcp->u_rval);
 450                         return;
 451                 case SEN_recvmsg:
 452                         dumpiov_in_msghdr(tcp, tcp->u_arg[1], tcp->u_rval);
 453                         return;
 454                 case SEN_recvmmsg:
 455                         dumpiov_in_mmsghdr(tcp, tcp->u_arg[1]);
 456                         return;
 457                 }
 458         }
 459         if (is_number_in_set(fd, write_set)) {
 460                 switch (tcp->s_ent->sen) {
 461                 case SEN_write:
 462                 case SEN_pwrite:
 463                 case SEN_send:
 464                 case SEN_sendto:
 465                 case SEN_mq_timedsend:
 466                         dumpstr(tcp, tcp->u_arg[1], tcp->u_arg[2]);
 467                         break;
 468                 case SEN_writev:
 469                 case SEN_pwritev:
 470                 case SEN_pwritev2:
 471                 case SEN_vmsplice:
 472                         dumpiov_upto(tcp, tcp->u_arg[2], tcp->u_arg[1], -1);
 473                         break;
 474                 case SEN_sendmsg:
 475                         dumpiov_in_msghdr(tcp, tcp->u_arg[1], -1);
 476                         break;
 477                 case SEN_sendmmsg:
 478                         dumpiov_in_mmsghdr(tcp, tcp->u_arg[1]);
 479                         break;
 480                 }
 481         }
 482 }
 483
 484 /*
 485  * Shuffle syscall numbers so that we don't have huge gaps in syscall table.
 486  * The shuffling should be an involution: shuffle_scno(shuffle_scno(n)) == n.
 487  */
 488 static kernel_ulong_t
 489 shuffle_scno(kernel_ulong_t scno)
 490 {
 491 #ifdef ARM_FIRST_SHUFFLED_SYSCALL       /* So far only 32-bit ARM needs this */
 492         if (scno < ARM_FIRST_SHUFFLED_SYSCALL)
 493                 return scno;
 494
 495         /* __ARM_NR_cmpxchg? Swap with LAST_ORDINARY+1 */
 496         if (scno == ARM_FIRST_SHUFFLED_SYSCALL)
 497                 return 0x000ffff0;
 498         if (scno == 0x000ffff0)
 499                 return ARM_FIRST_SHUFFLED_SYSCALL;
 500
 501 # define ARM_SECOND_SHUFFLED_SYSCALL (ARM_FIRST_SHUFFLED_SYSCALL + 1)
 502         /*
 503          * Is it ARM specific syscall?
 504          * Swap [0x000f0000, 0x000f0000 + LAST_SPECIAL] range
 505          * with [SECOND_SHUFFLED, SECOND_SHUFFLED + LAST_SPECIAL] range.
 506          */
 507         if (scno >= 0x000f0000 &&
 508             scno <= 0x000f0000 + ARM_LAST_SPECIAL_SYSCALL) {
 509                 return scno - 0x000f0000 + ARM_SECOND_SHUFFLED_SYSCALL;
 510         }
 511         if (scno <= ARM_SECOND_SHUFFLED_SYSCALL + ARM_LAST_SPECIAL_SYSCALL) {
 512                 return scno + 0x000f0000 - ARM_SECOND_SHUFFLED_SYSCALL;
 513         }
 514 #endif /* ARM_FIRST_SHUFFLED_SYSCALL */
 515
 516         return scno;
 517 }
 518
 519 const char *
 520 err_name(unsigned long err)
 521 {
 522         if ((err < nerrnos) && errnoent[err])
 523                 return errnoent[err];
 524
 525         return NULL;
 526 }
 527
 528 static long get_regs(struct tcb *);
 529 static int get_syscall_args(struct tcb *);
 530 static int get_syscall_result(struct tcb *);
 531 static int arch_get_scno(struct tcb *tcp);
 532 static int arch_set_scno(struct tcb *, kernel_ulong_t);
 533 static void get_error(struct tcb *, const bool);
 534 static int arch_set_error(struct tcb *);
 535 static int arch_set_success(struct tcb *);
 536
 537 struct inject_opts *inject_vec[SUPPORTED_PERSONALITIES];
 538
 539 static struct inject_opts *
 540 tcb_inject_opts(struct tcb *tcp)
 541 {
 542         return (scno_in_range(tcp->scno) && tcp->inject_vec[current_personality])
 543                ? &tcp->inject_vec[current_personality][tcp->scno] : NULL;
 544 }
 545
 546
 547 static long
 548 tamper_with_syscall_entering(struct tcb *tcp, unsigned int *signo)
 549 {
 550         if (!tcp->inject_vec[current_personality]) {
 551                 tcp->inject_vec[current_personality] =
 552                         xcalloc(nsyscalls, sizeof(**inject_vec));
 553                 memcpy(tcp->inject_vec[current_personality],
 554                        inject_vec[current_personality],
 555                        nsyscalls * sizeof(**inject_vec));
 556         }
 557
 558         struct inject_opts *opts = tcb_inject_opts(tcp);
 559
 560         if (!opts || opts->first == 0)
 561                 return 0;
 562
 563         --opts->first;
 564
 565         if (opts->first != 0)
 566                 return 0;
 567
 568         opts->first = opts->step;
 569
 570         if (opts->data.flags & INJECT_F_SIGNAL)
 571                 *signo = opts->data.signo;
 572         if (opts->data.flags & INJECT_F_RETVAL && !arch_set_scno(tcp, -1))
 573                 tcp->flags |= TCB_TAMPERED;
 574
 575         return 0;
 576 }
 577
 578 static long
 579 tamper_with_syscall_exiting(struct tcb *tcp)
 580 {
 581         struct inject_opts *opts = tcb_inject_opts(tcp);
 582
 583         if (!opts)
 584                 return 0;
 585
 586         if (opts->data.rval >= 0) {
 587                 kernel_long_t u_rval = tcp->u_rval;
 588
 589                 tcp->u_rval = opts->data.rval;
 590                 if (arch_set_success(tcp)) {
 591                         tcp->u_rval = u_rval;
 592                 } else {
 593                         tcp->u_error = 0;
 594                 }
 595         } else {
 596                 unsigned long new_error = -opts->data.rval;
 597
 598                 if (new_error != tcp->u_error && new_error <= MAX_ERRNO_VALUE) {
 599                         unsigned long u_error = tcp->u_error;
 600
 601                         tcp->u_error = new_error;
 602                         if (arch_set_error(tcp)) {
 603                                 tcp->u_error = u_error;
 604                         }
 605                 }
 606         }
 607
 608         return 0;
 609 }
 610
 611 /*
 612  * Returns:
 613  * 0: "ignore this ptrace stop", bail out silently.
 614  * 1: ok, decoded; call
 615  *    syscall_entering_finish(tcp, syscall_entering_trace(tcp, ...)).
 616  * other: error; call syscall_entering_finish(tcp, res), where res is the value
 617  *    returned.
 618  */
 619 int
 620 syscall_entering_decode(struct tcb *tcp)
 621 {
 622         int res = get_scno(tcp);
 623         if (res == 0)
 624                 return res;
 625         int scno_good = res;
 626         if (res != 1 || (res = get_syscall_args(tcp)) != 1) {
 627                 printleader(tcp);
 628                 tprintf("%s(", scno_good == 1 ? tcp->s_ent->sys_name : "????");
 629                 /*
 630                  * " <unavailable>" will be added later by the code which
 631                  * detects ptrace errors.
 632                  */
 633                 return res;
 634         }
 635
 636 #if defined SYS_ipc_subcall     \
 637  || defined SYS_socket_subcall  \
 638  || defined SYS_syscall_subcall
 639         for (;;) {
 640                 switch (tcp->s_ent->sen) {
 641 # ifdef SYS_ipc_subcall
 642                 case SEN_ipc:
 643                         decode_ipc_subcall(tcp);
 644                         break;
 645 # endif
 646 # ifdef SYS_socket_subcall
 647                 case SEN_socketcall:
 648                         decode_socket_subcall(tcp);
 649                         break;
 650 # endif
 651 # ifdef SYS_syscall_subcall
 652                 case SEN_syscall:
 653                         decode_syscall_subcall(tcp);
 654                         if (tcp->s_ent->sen != SEN_syscall)
 655                                 continue;
 656                         break;
 657 # endif
 658                 }
 659                 break;
 660         }
 661 #endif
 662
 663         return 1;
 664 }
 665
 666 int
 667 syscall_entering_trace(struct tcb *tcp, unsigned int *sig)
 668 {
 669         /* Restrain from fault injection while the trace executes strace code. */
 670         if (hide_log(tcp)) {
 671                 tcp->qual_flg &= ~QUAL_INJECT;
 672         }
 673
 674         switch (tcp->s_ent->sen) {
 675                 case SEN_execve:
 676                 case SEN_execveat:
 677 #if defined SPARC || defined SPARC64
 678                 case SEN_execv:
 679 #endif
 680                         tcp->flags &= ~TCB_HIDE_LOG;
 681                         break;
 682         }
 683
 684         if (!traced(tcp) || (tracing_paths && !pathtrace_match(tcp))) {
 685                 tcp->flags |= TCB_FILTERED;
 686                 return 0;
 687         }
 688
 689         tcp->flags &= ~TCB_FILTERED;
 690
 691         if (hide_log(tcp)) {
 692                 return 0;
 693         }
 694
 695         if (inject(tcp))
 696                 tamper_with_syscall_entering(tcp, sig);
 697
 698         if (cflag == CFLAG_ONLY_STATS) {
 699                 return 0;
 700         }
 701
 702 #ifdef USE_LIBUNWIND
 703         if (stack_trace_enabled) {
 704                 if (tcp->s_ent->sys_flags & STACKTRACE_CAPTURE_ON_ENTER)
 705                         unwind_capture_stacktrace(tcp);
 706         }
 707 #endif
 708
 709         printleader(tcp);
 710         tprintf("%s(", tcp->s_ent->sys_name);
 711         int res = raw(tcp) ? printargs(tcp) : tcp->s_ent->sys_func(tcp);
 712         fflush(tcp->outf);
 713         return res;
 714 }
 715
 716 void
 717 syscall_entering_finish(struct tcb *tcp, int res)
 718 {
 719         tcp->flags |= TCB_INSYSCALL;
 720         tcp->sys_func_rval = res;
 721         /* Measure the entrance time as late as possible to avoid errors. */
 722         if ((Tflag || cflag) && !filtered(tcp))
 723                 gettimeofday(&tcp->etime, NULL);
 724 }
 725
 726 /* Returns:
 727  * 0: "bail out".
 728  * 1: ok.
 729  * -1: error in one of ptrace ops.
 730  *
 731  * If not 0, call syscall_exiting_trace(tcp, res), where res is the return
 732  *    value. Anyway, call syscall_exiting_finish(tcp) then.
 733  */
 734 int
 735 syscall_exiting_decode(struct tcb *tcp, struct timeval *ptv)
 736 {
 737         /* Measure the exit time as early as possible to avoid errors. */
 738         if ((Tflag || cflag) && !(filtered(tcp) || hide_log(tcp)))
 739                 gettimeofday(ptv, NULL);
 740
 741 #ifdef USE_LIBUNWIND
 742         if (stack_trace_enabled) {
 743                 if (tcp->s_ent->sys_flags & STACKTRACE_INVALIDATE_CACHE)
 744                         unwind_cache_invalidate(tcp);
 745         }
 746 #endif
 747
 748         if (filtered(tcp) || hide_log(tcp))
 749                 return 0;
 750
 751 #if SUPPORTED_PERSONALITIES > 1
 752         update_personality(tcp, tcp->currpers);
 753 #endif
 754
 755         return get_syscall_result(tcp);
 756 }
 757
 758 int
 759 syscall_exiting_trace(struct tcb *tcp, struct timeval tv, int res)
 760 {
 761         if (syserror(tcp) && syscall_tampered(tcp))
 762                 tamper_with_syscall_exiting(tcp);
 763
 764         if (cflag) {
 765                 count_syscall(tcp, &tv);
 766                 if (cflag == CFLAG_ONLY_STATS) {
 767                         return 0;
 768                 }
 769         }
 770
 771         /* If not in -ff mode, and printing_tcp != tcp,
 772          * then the log currently does not end with output
 773          * of _our syscall entry_, but with something else.
 774          * We need to say which syscall's return is this.
 775          *
 776          * Forced reprinting via TCB_REPRINT is used only by
 777          * "strace -ff -oLOG test/threaded_execve" corner case.
 778          * It's the only case when -ff mode needs reprinting.
 779          */
 780         if ((followfork < 2 && printing_tcp != tcp) || (tcp->flags & TCB_REPRINT)) {
 781                 tcp->flags &= ~TCB_REPRINT;
 782                 printleader(tcp);
 783                 tprintf("<... %s resumed> ", tcp->s_ent->sys_name);
 784         }
 785         printing_tcp = tcp;
 786
 787         tcp->s_prev_ent = NULL;
 788         if (res != 1) {
 789                 /* There was error in one of prior ptrace ops */
 790                 tprints(") ");
 791                 tabto();
 792                 tprints("= ? <unavailable>\n");
 793                 line_ended();
 794                 return res;
 795         }
 796         tcp->s_prev_ent = tcp->s_ent;
 797
 798         int sys_res = 0;
 799         if (raw(tcp)) {
 800                 /* sys_res = printargs(tcp); - but it's nop on sysexit */
 801         } else {
 802         /* FIXME: not_failing_only (IOW, option -z) is broken:
 803          * failure of syscall is known only after syscall return.
 804          * Thus we end up with something like this on, say, ENOENT:
 805          *     open("does_not_exist", O_RDONLY <unfinished ...>
 806          *     {next syscall decode}
 807          * whereas the intended result is that open(...) line
 808          * is not shown at all.
 809          */
 810                 if (not_failing_only && tcp->u_error)
 811                         return 0;       /* ignore failed syscalls */
 812                 if (tcp->sys_func_rval & RVAL_DECODED)
 813                         sys_res = tcp->sys_func_rval;
 814                 else
 815                         sys_res = tcp->s_ent->sys_func(tcp);
 816         }
 817
 818         tprints(") ");
 819         tabto();
 820         unsigned long u_error = tcp->u_error;
 821         kernel_long_t u_rval;
 822
 823         if (raw(tcp)) {
 824                 if (u_error) {
 825                         tprintf("= -1 (errno %lu)", u_error);
 826                 } else {
 827                         tprintf("= %#" PRI_klx, tcp->u_rval);
 828                 }
 829                 if (syscall_tampered(tcp))
 830                         tprints(" (INJECTED)");
 831         } else if (!(sys_res & RVAL_NONE) && u_error) {
 832                 const char *u_error_str;
 833
 834                 switch (u_error) {
 835                 /* Blocked signals do not interrupt any syscalls.
 836                  * In this case syscalls don't return ERESTARTfoo codes.
 837                  *
 838                  * Deadly signals set to SIG_DFL interrupt syscalls
 839                  * and kill the process regardless of which of the codes below
 840                  * is returned by the interrupted syscall.
 841                  * In some cases, kernel forces a kernel-generated deadly
 842                  * signal to be unblocked and set to SIG_DFL (and thus cause
 843                  * death) if it is blocked or SIG_IGNed: for example, SIGSEGV
 844                  * or SIGILL. (The alternative is to leave process spinning
 845                  * forever on the faulty instruction - not useful).
 846                  *
 847                  * SIG_IGNed signals and non-deadly signals set to SIG_DFL
 848                  * (for example, SIGCHLD, SIGWINCH) interrupt syscalls,
 849                  * but kernel will always restart them.
 850                  */
 851                 case ERESTARTSYS:
 852                         /* Most common type of signal-interrupted syscall exit code.
 853                          * The system call will be restarted with the same arguments
 854                          * if SA_RESTART is set; otherwise, it will fail with EINTR.
 855                          */
 856                         tprints("= ? ERESTARTSYS (To be restarted if SA_RESTART is set)");
 857                         break;
 858                 case ERESTARTNOINTR:
 859                         /* Rare. For example, fork() returns this if interrupted.
 860                          * SA_RESTART is ignored (assumed set): the restart is unconditional.
 861                          */
 862                         tprints("= ? ERESTARTNOINTR (To be restarted)");
 863                         break;
 864                 case ERESTARTNOHAND:
 865                         /* pause(), rt_sigsuspend() etc use this code.
 866                          * SA_RESTART is ignored (assumed not set):
 867                          * syscall won't restart (will return EINTR instead)
 868                          * even after signal with SA_RESTART set. However,
 869                          * after SIG_IGN or SIG_DFL signal it will restart
 870                          * (thus the name "restart only if has no handler").
 871                          */
 872                         tprints("= ? ERESTARTNOHAND (To be restarted if no handler)");
 873                         break;
 874                 case ERESTART_RESTARTBLOCK:
 875                         /* Syscalls like nanosleep(), poll() which can't be
 876                          * restarted with their original arguments use this
 877                          * code. Kernel will execute restart_syscall() instead,
 878                          * which changes arguments before restarting syscall.
 879                          * SA_RESTART is ignored (assumed not set) similarly
 880                          * to ERESTARTNOHAND. (Kernel can't honor SA_RESTART
 881                          * since restart data is saved in "restart block"
 882                          * in task struct, and if signal handler uses a syscall
 883                          * which in turn saves another such restart block,
 884                          * old data is lost and restart becomes impossible)
 885                          */
 886                         tprints("= ? ERESTART_RESTARTBLOCK (Interrupted by signal)");
 887                         break;
 888                 default:
 889                         u_rval = sys_res & RVAL_PRINT_ERR_VAL ?
 890                                  tcp->u_rval : -1;
 891                         u_error_str = err_name(u_error);
 892                         if (u_error_str)
 893                                 tprintf("= %" PRI_kld " %s (%s)",
 894                                         u_rval, u_error_str, strerror(u_error));
 895                         else
 896                                 tprintf("= %" PRI_kld " %lu (%s)",
 897                                         u_rval, u_error, strerror(u_error));
 898                         break;
 899                 }
 900                 if (syscall_tampered(tcp))
 901                         tprints(" (INJECTED)");
 902                 if ((sys_res & RVAL_STR) && tcp->auxstr)
 903                         tprintf(" (%s)", tcp->auxstr);
 904         } else {
 905                 if (sys_res & RVAL_NONE)
 906                         tprints("= ?");
 907                 else {
 908                         switch (sys_res & RVAL_MASK) {
 909                         case RVAL_HEX:
 910 #if ANY_WORDSIZE_LESS_THAN_KERNEL_LONG
 911                                 if (current_wordsize < sizeof(tcp->u_rval)) {
 912                                         tprintf("= %#x",
 913                                                 (unsigned int) tcp->u_rval);
 914                                 } else
 915 #endif
 916                                 {
 917                                         tprintf("= %#" PRI_klx, tcp->u_rval);
 918                                 }
 919                                 break;
 920                         case RVAL_OCTAL:
 921                                 tprints("= ");
 922                                 print_numeric_long_umask(tcp->u_rval);
 923                                 break;
 924                         case RVAL_UDECIMAL:
 925 #if ANY_WORDSIZE_LESS_THAN_KERNEL_LONG
 926                                 if (current_wordsize < sizeof(tcp->u_rval)) {
 927                                         tprintf("= %u",
 928                                                 (unsigned int) tcp->u_rval);
 929                                 } else
 930 #endif
 931                                 {
 932                                         tprintf("= %" PRI_klu, tcp->u_rval);
 933                                 }
 934                                 break;
 935                         case RVAL_DECIMAL:
 936                                 tprintf("= %" PRI_kld, tcp->u_rval);
 937                                 break;
 938                         case RVAL_FD:
 939                                 if (show_fd_path) {
 940                                         tprints("= ");
 941                                         printfd(tcp, tcp->u_rval);
 942                                 } else
 943                                         tprintf("= %" PRI_kld, tcp->u_rval);
 944                                 break;
 945                         default:
 946                                 error_msg("invalid rval format");
 947                                 break;
 948                         }
 949                 }
 950                 if ((sys_res & RVAL_STR) && tcp->auxstr)
 951                         tprintf(" (%s)", tcp->auxstr);
 952                 if (syscall_tampered(tcp))
 953                         tprints(" (INJECTED)");
 954         }
 955         if (Tflag) {
 956                 tv_sub(&tv, &tv, &tcp->etime);
 957                 tprintf(" <%ld.%06ld>",
 958                         (long) tv.tv_sec, (long) tv.tv_usec);
 959         }
 960         tprints("\n");
 961         dumpio(tcp);
 962         line_ended();
 963
 964 #ifdef USE_LIBUNWIND
 965         if (stack_trace_enabled)
 966                 unwind_print_stacktrace(tcp);
 967 #endif
 968         return 0;
 969 }
 970
 971 void
 972 syscall_exiting_finish(struct tcb *tcp)
 973 {
 974         tcp->flags &= ~(TCB_INSYSCALL | TCB_TAMPERED);
 975         tcp->sys_func_rval = 0;
 976         free_tcb_priv_data(tcp);
 977 }
 978
 979 bool
 980 is_erestart(struct tcb *tcp)
 981 {
 982         switch (tcp->u_error) {
 983                 case ERESTARTSYS:
 984                 case ERESTARTNOINTR:
 985                 case ERESTARTNOHAND:
 986                 case ERESTART_RESTARTBLOCK:
 987                         return true;
 988                 default:
 989                         return false;
 990         }
 991 }
 992
 993 static unsigned long saved_u_error;
 994
 995 void
 996 temporarily_clear_syserror(struct tcb *tcp)
 997 {
 998         saved_u_error = tcp->u_error;
 999         tcp->u_error = 0;
1000 }
1001
1002 void
1003 restore_cleared_syserror(struct tcb *tcp)
1004 {
1005         tcp->u_error = saved_u_error;
1006 }
1007
1008 #include "arch_regs.c"
1009
1010 #ifdef HAVE_GETRVAL2
1011 # include "arch_getrval2.c"
1012 #endif
1013
1014 void
1015 print_pc(struct tcb *tcp)
1016 {
1017 #if defined ARCH_PC_REG
1018 # define ARCH_GET_PC 0
1019 #elif defined ARCH_PC_PEEK_ADDR
1020         kernel_ulong_t pc;
1021 # define ARCH_PC_REG pc
1022 # define ARCH_GET_PC upeek(tcp, ARCH_PC_PEEK_ADDR, &pc)
1023 #else
1024 # error Neither ARCH_PC_REG nor ARCH_PC_PEEK_ADDR is defined
1025 #endif
1026         if (get_regs(tcp) < 0 || ARCH_GET_PC)
1027                 tprints(current_wordsize == 4 ? "[????????] "
1028                                               : "[????????????????] ");
1029         else
1030                 tprintf(current_wordsize == 4
1031                         ? "[%08" PRI_klx "] " : "[%016" PRI_klx "] ",
1032                         (kernel_ulong_t) ARCH_PC_REG);
1033 }
1034
1035 #include "getregs_old.h"
1036
1037 #undef ptrace_getregset_or_getregs
1038 #undef ptrace_setregset_or_setregs
1039 #ifdef ARCH_REGS_FOR_GETREGSET
1040
1041 # define ptrace_getregset_or_getregs ptrace_getregset
1042 static long
1043 ptrace_getregset(pid_t pid)
1044 {
1045 # ifdef ARCH_IOVEC_FOR_GETREGSET
1046         /* variable iovec */
1047         ARCH_IOVEC_FOR_GETREGSET.iov_len = sizeof(ARCH_REGS_FOR_GETREGSET);
1048         return ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS,
1049                       &ARCH_IOVEC_FOR_GETREGSET);
1050 # else
1051         /* constant iovec */
1052         static struct iovec io = {
1053                 .iov_base = &ARCH_REGS_FOR_GETREGSET,
1054                 .iov_len = sizeof(ARCH_REGS_FOR_GETREGSET)
1055         };
1056         return ptrace(PTRACE_GETREGSET, pid, NT_PRSTATUS, &io);
1057
1058 # endif
1059 }
1060
1061 # ifndef HAVE_GETREGS_OLD
1062 #  define ptrace_setregset_or_setregs ptrace_setregset
1063 static int
1064 ptrace_setregset(pid_t pid)
1065 {
1066 #  ifdef ARCH_IOVEC_FOR_GETREGSET
1067         /* variable iovec */
1068         return ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS,
1069                       &ARCH_IOVEC_FOR_GETREGSET);
1070 #  else
1071         /* constant iovec */
1072         static struct iovec io = {
1073                 .iov_base = &ARCH_REGS_FOR_GETREGSET,
1074                 .iov_len = sizeof(ARCH_REGS_FOR_GETREGSET)
1075         };
1076         return ptrace(PTRACE_SETREGSET, pid, NT_PRSTATUS, &io);
1077 #  endif
1078 }
1079 # endif /* !HAVE_GETREGS_OLD */
1080
1081 #elif defined ARCH_REGS_FOR_GETREGS
1082
1083 # define ptrace_getregset_or_getregs ptrace_getregs
1084 static long
1085 ptrace_getregs(pid_t pid)
1086 {
1087 # if defined SPARC || defined SPARC64
1088         /* SPARC systems have the meaning of data and addr reversed */
1089         return ptrace(PTRACE_GETREGS, pid, (void *) &ARCH_REGS_FOR_GETREGS, 0);
1090 # else
1091         return ptrace(PTRACE_GETREGS, pid, NULL, &ARCH_REGS_FOR_GETREGS);
1092 # endif
1093 }
1094
1095 # ifndef HAVE_GETREGS_OLD
1096 #  define ptrace_setregset_or_setregs ptrace_setregs
1097 static int
1098 ptrace_setregs(pid_t pid)
1099 {
1100 #  if defined SPARC || defined SPARC64
1101         /* SPARC systems have the meaning of data and addr reversed */
1102         return ptrace(PTRACE_SETREGS, pid, (void *) &ARCH_REGS_FOR_GETREGS, 0);
1103 #  else
1104         return ptrace(PTRACE_SETREGS, pid, NULL, &ARCH_REGS_FOR_GETREGS);
1105 #  endif
1106 }
1107 # endif /* !HAVE_GETREGS_OLD */
1108
1109 #endif /* ARCH_REGS_FOR_GETREGSET || ARCH_REGS_FOR_GETREGS */
1110
1111 #ifdef ptrace_getregset_or_getregs
1112 static long get_regs_error;
1113 #endif
1114
1115 void
1116 clear_regs(struct tcb *tcp)
1117 {
1118 #ifdef ptrace_getregset_or_getregs
1119         get_regs_error = -1;
1120 #endif
1121 }
1122
1123 static long
1124 get_regs(struct tcb *const tcp)
1125 {
1126 #ifdef ptrace_getregset_or_getregs
1127
1128         if (get_regs_error != -1)
1129                 return get_regs_error;
1130
1131 # ifdef HAVE_GETREGS_OLD
1132         /*
1133          * Try PTRACE_GETREGSET/PTRACE_GETREGS first,
1134          * fallback to getregs_old.
1135          */
1136         static int use_getregs_old;
1137         if (use_getregs_old < 0) {
1138                 return get_regs_error = ptrace_getregset_or_getregs(tcp->pid);
1139         } else if (use_getregs_old == 0) {
1140                 get_regs_error = ptrace_getregset_or_getregs(tcp->pid);
1141                 if (get_regs_error >= 0) {
1142                         use_getregs_old = -1;
1143                         return get_regs_error;
1144                 }
1145                 if (errno == EPERM || errno == ESRCH)
1146                         return get_regs_error;
1147                 use_getregs_old = 1;
1148         }
1149         return get_regs_error = getregs_old(tcp);
1150 # else /* !HAVE_GETREGS_OLD */
1151         /* Assume that PTRACE_GETREGSET/PTRACE_GETREGS works. */
1152         return get_regs_error = ptrace_getregset_or_getregs(tcp->pid);
1153 # endif /* !HAVE_GETREGS_OLD */
1154
1155 #else /* !ptrace_getregset_or_getregs */
1156
1157 # warning get_regs is not implemented for this architecture yet
1158         return 0;
1159
1160 #endif /* !ptrace_getregset_or_getregs */
1161 }
1162
1163 #ifdef ptrace_setregset_or_setregs
1164 static int
1165 set_regs(pid_t pid)
1166 {
1167         return ptrace_setregset_or_setregs(pid);
1168 }
1169 #endif /* ptrace_setregset_or_setregs */
1170
1171 struct sysent_buf {
1172         struct tcb *tcp;
1173         struct_sysent ent;
1174         char buf[sizeof("syscall_%lu") + sizeof(kernel_ulong_t) * 3];
1175 };
1176
1177 static void
1178 free_sysent_buf(void *ptr)
1179 {
1180         struct sysent_buf *s = ptr;
1181         s->tcp->s_prev_ent = s->tcp->s_ent = NULL;
1182         free(ptr);
1183 }
1184
1185 /*
1186  * Returns:
1187  * 0: "ignore this ptrace stop", syscall_entering_decode() should return a "bail
1188  *    out silently" code.
1189  * 1: ok, continue in syscall_entering_decode().
1190  * other: error, syscall_entering_decode() should print error indicator
1191  *    ("????" etc) and return an appropriate code.
1192  */
1193 int
1194 get_scno(struct tcb *tcp)
1195 {
1196         if (get_regs(tcp) < 0)
1197                 return -1;
1198
1199         int rc = arch_get_scno(tcp);
1200         if (rc != 1)
1201                 return rc;
1202
1203         if (scno_is_valid(tcp->scno)) {
1204                 tcp->s_ent = &sysent[tcp->scno];
1205                 tcp->qual_flg = qual_flags(tcp->scno);
1206         } else {
1207                 struct sysent_buf *s = xcalloc(1, sizeof(*s));
1208
1209                 s->tcp = tcp;
1210                 s->ent.nargs = MAX_ARGS;
1211                 s->ent.sen = SEN_printargs;
1212                 s->ent.sys_func = printargs;
1213                 s->ent.sys_name = s->buf;
1214                 xsprintf(s->buf, "syscall_%" PRI_klu, shuffle_scno(tcp->scno));
1215
1216                 tcp->s_ent = &s->ent;
1217                 tcp->qual_flg = QUAL_RAW | DEFAULT_QUAL_FLAGS;
1218
1219                 set_tcb_priv_data(tcp, s, free_sysent_buf);
1220
1221                 debug_msg("pid %d invalid syscall %" PRI_kld,
1222                           tcp->pid, tcp->scno);
1223         }
1224         return 1;
1225 }
1226
1227 #ifdef ptrace_getregset_or_getregs
1228 # define get_syscall_result_regs get_regs
1229 #else
1230 static int get_syscall_result_regs(struct tcb *);
1231 #endif
1232
1233 /* Returns:
1234  * 1: ok, continue in syscall_exiting_trace().
1235  * -1: error, syscall_exiting_trace() should print error indicator
1236  *    ("????" etc) and bail out.
1237  */
1238 static int
1239 get_syscall_result(struct tcb *tcp)
1240 {
1241         if (get_syscall_result_regs(tcp) < 0)
1242                 return -1;
1243         tcp->u_error = 0;
1244         get_error(tcp, !(tcp->s_ent->sys_flags & SYSCALL_NEVER_FAILS));
1245
1246         return 1;
1247 }
1248
1249 #include "get_scno.c"
1250 #include "set_scno.c"
1251 #include "get_syscall_args.c"
1252 #ifndef ptrace_getregset_or_getregs
1253 # include "get_syscall_result.c"
1254 #endif
1255 #include "get_error.c"
1256 #include "set_error.c"
1257 #ifdef HAVE_GETREGS_OLD
1258 # include "getregs_old.c"
1259 #endif
1260
1261 const char *
1262 syscall_name(kernel_ulong_t scno)
1263 {
1264 #if defined X32_PERSONALITY_NUMBER && defined __X32_SYSCALL_BIT
1265         if (current_personality == X32_PERSONALITY_NUMBER)
1266                 scno &= ~__X32_SYSCALL_BIT;
1267 #endif
1268         return scno_is_valid(scno) ? sysent[scno].sys_name : NULL;
1269 }