freebsd-dev/usr.bin/truss/i386-fbsd.c

/*
 * Copyright 1997 Sean Eric Fagan
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by Sean Eric Fagan
 * 4. Neither the name of the author may be used to endorse or promote
 *    products derived from this software without specific prior written
 *    permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static const char rcsid[] =
  "$FreeBSD$";
#endif /* not lint */

/*
 * FreeBSD/i386-specific system call handling.  This is probably the most
 * complex part of the entire truss program, although I've got lots of
 * it handled relatively cleanly now.  The system call names are generated
 * automatically, thanks to /usr/src/sys/kern/syscalls.master.  The
 * names used for the various structures are confusing, I sadly admit.
 */

#include <sys/types.h>
#include <sys/syscall.h>
#include <sys/ptrace.h>

#include <machine/reg.h>
#include <machine/psl.h>

#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <unistd.h>

#include "truss.h"
#include "syscall.h"
#include "extern.h"

static int cpid = -1;

#include "syscalls.h"

static int nsyscalls = sizeof(syscallnames) / sizeof(syscallnames[0]);

/*
 * This is what this particular file uses to keep track of a system call.
 * It is probably not quite sufficient -- I can probably use the same
 * structure for the various syscall personalities, and I also probably
 * need to nest system calls (for signal handlers).
 *
 * 'struct syscall' describes the system call; it may be NULL, however,
 * if we don't know about this particular system call yet.
 */
static struct freebsd_syscall {
	struct syscall *sc;
	const char *name;
	int number;
	unsigned long *args;
	int nargs;	/* number of arguments -- *not* number of words! */
	char **s_args;	/* the printable arguments */
} fsc;

/* Clear up and free parts of the fsc structure. */
static __inline void
clear_fsc(void) {
  if (fsc.args) {
    free(fsc.args);
  }
  if (fsc.s_args) {
    int i;
    for (i = 0; i < fsc.nargs; i++)
      if (fsc.s_args[i])
	free(fsc.s_args[i]);
    free(fsc.s_args);
  }
  memset(&fsc, 0, sizeof(fsc));
}

/*
 * Called when a process has entered a system call.  nargs is the
 * number of words, not number of arguments (a necessary distinction
 * in some cases).  Note that if the STOPEVENT() code in i386/i386/trap.c
 * is ever changed these functions need to keep up.
 */

void
i386_syscall_entry(struct trussinfo *trussinfo, int nargs) {
  struct reg regs;
  int syscall_num;
  int i;
  unsigned int parm_offset;
  struct syscall *sc = NULL;
  struct ptrace_io_desc iorequest;
  cpid = trussinfo->curthread->tid;

  clear_fsc();
  
  if (ptrace(PT_GETREGS, cpid, (caddr_t)&regs, 0) < 0)
  {
    fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
    return;
  }
  parm_offset = regs.r_esp + sizeof(int);

  /*
   * FreeBSD has two special kinds of system call redirctions --
   * SYS_syscall, and SYS___syscall.  The former is the old syscall()
   * routine, basically; the latter is for quad-aligned arguments.
   */
  syscall_num = regs.r_eax;
  switch (syscall_num) {
  case SYS_syscall:
    syscall_num = ptrace(PT_READ_D, cpid, (caddr_t)parm_offset, 0);
    parm_offset += sizeof(int);
    break;
  case SYS___syscall:
    syscall_num = ptrace(PT_READ_D, cpid, (caddr_t)parm_offset, 0);
    parm_offset += sizeof(quad_t);
    break;
  }

  fsc.number = syscall_num;
  fsc.name =
    (syscall_num < 0 || syscall_num >= nsyscalls) ? NULL : syscallnames[syscall_num];
  if (!fsc.name) {
    fprintf(trussinfo->outfile, "-- UNKNOWN SYSCALL %d --\n", syscall_num);
  }

  if (fsc.name && (trussinfo->flags & FOLLOWFORKS)
   && ((!strcmp(fsc.name, "fork")
    || !strcmp(fsc.name, "rfork")
    || !strcmp(fsc.name, "vfork"))))
  {
    trussinfo->curthread->in_fork = 1;
  }

  if (nargs == 0)
    return;

  fsc.args = malloc((1+nargs) * sizeof(unsigned long));
  iorequest.piod_op = PIOD_READ_D;
  iorequest.piod_offs = (void *)parm_offset;
  iorequest.piod_addr = fsc.args;
  iorequest.piod_len = (1+nargs) * sizeof(unsigned long);
  ptrace(PT_IO, cpid, (caddr_t)&iorequest, 0);
  if (iorequest.piod_len == 0)
    return;

  if (fsc.name)
  	sc = get_syscall(fsc.name);
  if (sc) {
    fsc.nargs = sc->nargs;
  } else {
#if DEBUG
    fprintf(trussinfo->outfile, "unknown syscall %s -- setting args to %d\n",
	   fsc.name, nargs);
#endif
    fsc.nargs = nargs;
  }

  fsc.s_args = calloc(1, (1+fsc.nargs) * sizeof(char*));
  fsc.sc = sc;

  /*
   * At this point, we set up the system call arguments.
   * We ignore any OUT ones, however -- those are arguments that
   * are set by the system call, and so are probably meaningless
   * now.  This doesn't currently support arguments that are
   * passed in *and* out, however.
   */

  if (fsc.name) {

#if DEBUG
    fprintf(stderr, "syscall %s(", fsc.name);
#endif
    for (i = 0; i < fsc.nargs; i++) {
#if DEBUG
      fprintf(stderr, "0x%x%s",
	      sc
	      ? fsc.args[sc->args[i].offset]
	      : fsc.args[i],
	      i < (fsc.nargs - 1) ? "," : "");
#endif
      if (sc && !(sc->args[i].type & OUT)) {
	fsc.s_args[i] = print_arg(&sc->args[i], fsc.args, 0, trussinfo);
      }
    }
#if DEBUG
    fprintf(stderr, ")\n");
#endif
  }

#if DEBUG
  fprintf(trussinfo->outfile, "\n");
#endif

  if (fsc.name != NULL &&
      (!strcmp(fsc.name, "execve") || !strcmp(fsc.name, "exit"))) {

    /* XXX
     * This could be done in a more general
     * manner but it still wouldn't be very pretty.
     */
    if (!strcmp(fsc.name, "execve")) {
        if ((trussinfo->flags & EXECVEARGS) == 0)
          if (fsc.s_args[1]) {
            free(fsc.s_args[1]);
            fsc.s_args[1] = NULL;
          }
        if ((trussinfo->flags & EXECVEENVS) == 0)
          if (fsc.s_args[2]) {
            free(fsc.s_args[2]);
            fsc.s_args[2] = NULL;
          }
    }

  }

  return;
}

/*
 * And when the system call is done, we handle it here.
 * Currently, no attempt is made to ensure that the system calls
 * match -- this needs to be fixed (and is, in fact, why S_SCX includes
 * the system call number instead of, say, an error status).
 */

long
i386_syscall_exit(struct trussinfo *trussinfo, int syscall_num __unused)
{
  struct reg regs;
  long retval;
  int i;
  int errorp;
  struct syscall *sc;

  if (fsc.name == NULL)
    return (-1);
  cpid = trussinfo->curthread->tid;

  if (ptrace(PT_GETREGS, cpid, (caddr_t)&regs, 0) < 0)
  {
    fprintf(trussinfo->outfile, "-- CANNOT READ REGISTERS --\n");
    return (-1);
  }
  
  retval = regs.r_eax;
  errorp = !!(regs.r_eflags & PSL_C);

  /*
   * This code, while simpler than the initial versions I used, could
   * stand some significant cleaning.
   */

  sc = fsc.sc;
  if (!sc) {
    for (i = 0; i < fsc.nargs; i++)
      asprintf(&fsc.s_args[i], "0x%lx", fsc.args[i]);
  } else {
    /*
     * Here, we only look for arguments that have OUT masked in --
     * otherwise, they were handled in the syscall_entry function.
     */
    for (i = 0; i < sc->nargs; i++) {
      char *temp;
      if (sc->args[i].type & OUT) {
	/*
	 * If an error occurred, then don't bother getting the data;
	 * it may not be valid.
	 */
	if (errorp)
	  asprintf(&temp, "0x%lx", fsc.args[sc->args[i].offset]);
	else
	  temp = print_arg(&sc->args[i], fsc.args, retval, trussinfo);
	fsc.s_args[i] = temp;
      }
    }
  }

  if (fsc.name != NULL &&
      (!strcmp(fsc.name, "execve") || !strcmp(fsc.name, "exit"))) {
	trussinfo->curthread->in_syscall = 1;
  }

  /*
   * It would probably be a good idea to merge the error handling,
   * but that complicates things considerably.
   */

  print_syscall_ret(trussinfo, fsc.name, fsc.nargs, fsc.s_args, errorp,
		    retval, fsc.sc);
  clear_fsc();

  return (retval);
}