/* Low-level child interface to ptrace.
Copyright 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1998, 1999, 2000, 2001, 2002, 2004, 2005
Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA. */
#include "defs.h"
#include "command.h"
#include "inferior.h"
#include "inflow.h"
#include "gdbcore.h"
#include "observer.h"
#include "regcache.h"
#include "gdb_assert.h"
#include "gdb_string.h"
#include "gdb_ptrace.h"
#include "gdb_wait.h"
#include <signal.h>
#include "inf-child.h"
/* HACK: Save the ptrace ops returned by inf_ptrace_target. */
static struct target_ops *ptrace_ops_hack;
static void
inf_ptrace_kill_inferior (void)
{
int status;
int pid = PIDGET (inferior_ptid);
if (pid == 0)
return;
/* This once used to call "kill" to kill the inferior just in case
the inferior was still running. As others have noted in the past
(kingdon) there shouldn't be any way to get here if the inferior
is still running -- else there's a major problem elsewere in GDB
and it needs to be fixed.
The kill call causes problems under HP-UX 10, so it's been
removed; if this causes problems we'll deal with them as they
arise. */
ptrace (PT_KILL, pid, (PTRACE_TYPE_ARG3) 0, 0);
wait (&status);
target_mourn_inferior ();
}
/* Resume execution of the inferior process. If STEP is nonzero,
single-step it. If SIGNAL is nonzero, give it that signal. */
static void
inf_ptrace_resume (ptid_t ptid, int step, enum target_signal signal)
{
int request = PT_CONTINUE;
int pid = PIDGET (ptid);
if (pid == -1)
/* Resume all threads. */
/* I think this only gets used in the non-threaded case, where
"resume all threads" and "resume inferior_ptid" are the
same. */
pid = PIDGET (inferior_ptid);
if (step)
{
/* If this system does not support PT_STEP, a higher level
function will have called single_step() to transmute the step
request into a continue request (by setting breakpoints on
all possible successor instructions), so we don't have to
worry about that here. */
request = PT_STEP;
}
/* An address of (PTRACE_TYPE_ARG3)1 tells ptrace to continue from
where it was. If GDB wanted it to start some other way, we have
already written a new PC value to the child. */
errno = 0;
ptrace (request, pid, (PTRACE_TYPE_ARG3) 1, target_signal_to_host (signal));
if (errno != 0)
perror_with_name (("ptrace"));
}
/* Wait for child to do something. Return pid of child, or -1 in case
of error; store status through argument pointer OURSTATUS. */
static ptid_t
inf_ptrace_wait (ptid_t ptid, struct target_waitstatus *ourstatus)
{
int save_errno;
int status;
char *execd_pathname = NULL;
int exit_status;
int related_pid;
int syscall_id;
enum target_waitkind kind;
int pid;
do
{
set_sigint_trap (); /* Causes SIGINT to be passed on to the
attached process. */
set_sigio_trap ();
pid = wait (&status);
save_errno = errno;
clear_sigio_trap ();
clear_sigint_trap ();
if (pid == -1)
{
if (save_errno == EINTR)
continue;
fprintf_unfiltered (gdb_stderr,
"Child process unexpectedly missing: %s.\n",
safe_strerror (save_errno));
/* Claim it exited with unknown signal. */
ourstatus->kind = TARGET_WAITKIND_SIGNALLED;
ourstatus->value.sig = TARGET_SIGNAL_UNKNOWN;
return pid_to_ptid (-1);
}
/* Did it exit? */
if (target_has_exited (pid, status, &exit_status))
{
/* ??rehrauer: For now, ignore this. */
continue;
}
if (!target_thread_alive (pid_to_ptid (pid)))
{
ourstatus->kind = TARGET_WAITKIND_SPURIOUS;
return pid_to_ptid (pid);
}
}
while (pid != PIDGET (inferior_ptid)); /* Some other child died or
stopped. */
store_waitstatus (ourstatus, status);
return pid_to_ptid (pid);
}
/* Check to see if the given thread is alive.
FIXME: Is kill() ever the right way to do this? I doubt it, but
for now we're going to try and be compatable with the old thread
code. */
static int
inf_ptrace_thread_alive (ptid_t ptid)
{
pid_t pid = PIDGET (ptid);
return (kill (pid, 0) != -1);
}
/* Attach to process PID, then initialize for debugging it. */
static void
inf_ptrace_attach (char *args, int from_tty)
{
char *exec_file;
int pid;
char *dummy;
if (!args)
error_no_arg (_("process-id to attach"));
dummy = args;
pid = strtol (args, &dummy, 0);
/* Some targets don't set errno on errors, grrr! */
if (pid == 0 && args == dummy)
error (_("Illegal process-id: %s."), args);
if (pid == getpid ()) /* Trying to masturbate? */
error (_("I refuse to debug myself!"));
if (from_tty)
{
exec_file = (char *) get_exec_file (0);
if (exec_file)
printf_unfiltered (_("Attaching to program: %s, %s\n"), exec_file,
target_pid_to_str (pid_to_ptid (pid)));
else
printf_unfiltered (_("Attaching to %s\n"),
target_pid_to_str (pid_to_ptid (pid)));
gdb_flush (gdb_stdout);
}
#ifdef PT_ATTACH
errno = 0;
ptrace (PT_ATTACH, pid, (PTRACE_TYPE_ARG3) 0, 0);
if (errno != 0)
perror_with_name (("ptrace"));
attach_flag = 1;
#else
error (_("This system does not support attaching to a process"));
#endif
inferior_ptid = pid_to_ptid (pid);
push_target (ptrace_ops_hack);
/* Do this first, before anything has had a chance to query the
inferior's symbol table or similar. */
observer_notify_inferior_created (¤t_target, from_tty);
}
static void
inf_ptrace_post_attach (int pid)
{
/* This version of Unix doesn't require a meaningful "post attach"
operation by a debugger. */
}
/* Take a program previously attached to and detaches it. The program
resumes execution and will no longer stop on signals, etc. We'd
better not have left any breakpoints in the program or it'll die
when it hits one. For this to work, it may be necessary for the
process to have been previously attached. It *might* work if the
program was started via the normal ptrace (PTRACE_TRACEME). */
static void
inf_ptrace_detach (char *args, int from_tty)
{
int sig = 0;
int pid = PIDGET (inferior_ptid);
if (from_tty)
{
char *exec_file = get_exec_file (0);
if (exec_file == 0)
exec_file = "";
printf_unfiltered (_("Detaching from program: %s, %s\n"), exec_file,
target_pid_to_str (pid_to_ptid (pid)));
gdb_flush (gdb_stdout);
}
if (args)
sig = atoi (args);
#ifdef PT_DETACH
errno = 0;
ptrace (PT_DETACH, pid, (PTRACE_TYPE_ARG3) 1, sig);
if (errno != 0)
perror_with_name (("ptrace"));
attach_flag = 0;
#else
error (_("This system does not support detaching from a process"));
#endif
inferior_ptid = null_ptid;
unpush_target (ptrace_ops_hack);
}
/* Print status information about what we're accessing. */
static void
inf_ptrace_files_info (struct target_ops *ignore)
{
printf_unfiltered (_("\tUsing the running image of %s %s.\n"),
attach_flag ? "attached" : "child",
target_pid_to_str (inferior_ptid));
}
static void
inf_ptrace_open (char *arg, int from_tty)
{
error (_("Use the \"run\" command to start a Unix child process."));
}
/* Stub function which causes the inferior that runs it, to be ptrace-able
by its parent process. */
static void
inf_ptrace_me (void)
{
/* "Trace me, Dr. Memory!" */
ptrace (0, 0, (PTRACE_TYPE_ARG3) 0, 0);
}
/* Stub function which causes the GDB that runs it, to start ptrace-ing
the child process. */
static void
inf_ptrace_him (int pid)
{
push_target (ptrace_ops_hack);
/* On some targets, there must be some explicit synchronization
between the parent and child processes after the debugger
forks, and before the child execs the debuggee program. This
call basically gives permission for the child to exec. */
target_acknowledge_created_inferior (pid);
/* START_INFERIOR_TRAPS_EXPECTED is defined in inferior.h, and will
be 1 or 2 depending on whether we're starting without or with a
shell. */
startup_inferior (START_INFERIOR_TRAPS_EXPECTED);
/* On some targets, there must be some explicit actions taken after
the inferior has been started up. */
target_post_startup_inferior (pid_to_ptid (pid));
}
/* Start an inferior Unix child process and sets inferior_ptid to its
pid. EXEC_FILE is the file to run. ALLARGS is a string containing
the arguments to the program. ENV is the environment vector to
pass. Errors reported with error(). */
static void
inf_ptrace_create_inferior (char *exec_file, char *allargs, char **env,
int from_tty)
{
fork_inferior (exec_file, allargs, env, inf_ptrace_me, inf_ptrace_him,
NULL, NULL);
/* We are at the first instruction we care about. */
observer_notify_inferior_created (¤t_target, from_tty);
/* Pedal to the metal... */
proceed ((CORE_ADDR) -1, TARGET_SIGNAL_0, 0);
}
static int
inf_ptrace_reported_exec_events_per_exec_call (void)
{
/* Typically, we get a single SIGTRAP per exec. */
return 1;
}
static int
inf_ptrace_has_exited (int pid, int wait_status, int *exit_status)
{
if (WIFEXITED (wait_status))
{
*exit_status = WEXITSTATUS (wait_status);
return 1;
}
if (WIFSIGNALED (wait_status))
{
*exit_status = 0; /* ?? Don't know what else to say here. */
return 1;
}
/* ??? Do we really need to consult the event state, too?
Assume the wait_state alone suffices. */
return 0;
}
static void
inf_ptrace_mourn_inferior (void)
{
unpush_target (ptrace_ops_hack);
generic_mourn_inferior ();
}
static int
inf_ptrace_can_run (void)
{
return 1;
}
/* Send a SIGINT to the process group. This acts just like the user
typed a ^C on the controlling terminal.
FIXME: This may not be correct for all systems. Some may want to
use killpg() instead of kill (-pgrp). */
static void
inf_ptrace_stop (void)
{
kill (-inferior_process_group, SIGINT);
}
/* Perform a partial transfer to/from the specified object. For
memory transfers, fall back to the old memory xfer functions. */
static LONGEST
inf_ptrace_xfer_partial (struct target_ops *ops, enum target_object object,
const char *annex, void *readbuf,
const void *writebuf, ULONGEST offset, LONGEST len)
{
switch (object)
{
case TARGET_OBJECT_MEMORY:
#ifdef PT_IO
/* OpenBSD 3.1, NetBSD 1.6 and FreeBSD 5.0 have a new PT_IO
request that promises to be much more efficient in reading
and writing data in the traced process's address space. */
{
struct ptrace_io_desc piod;
/* NOTE: We assume that there are no distinct address spaces
for instruction and data. */
piod.piod_op = writebuf ? PIOD_WRITE_D : PIOD_READ_D;
piod.piod_addr = writebuf ? (void *) writebuf : readbuf;
piod.piod_offs = (void *) (long) offset;
piod.piod_len = len;
errno = 0;
if (ptrace (PT_IO, PIDGET (inferior_ptid), (caddr_t) &piod, 0) == 0)
/* Return the actual number of bytes read or written. */
return piod.piod_len;
/* If the PT_IO request is somehow not supported, fallback on
using PT_WRITE_D/PT_READ_D. Otherwise we will return zero
to indicate failure. */
if (errno != EINVAL)
return 0;
}
#endif
{
union
{
PTRACE_TYPE_RET word;
unsigned char byte[sizeof (PTRACE_TYPE_RET)];
} buffer;
ULONGEST rounded_offset;
LONGEST partial_len;
/* Round the start offset down to the next long word
boundary. */
rounded_offset = offset & -(ULONGEST) sizeof (PTRACE_TYPE_RET);
/* Since ptrace will transfer a single word starting at that
rounded_offset the partial_len needs to be adjusted down to
that (remember this function only does a single transfer).
Should the required length be even less, adjust it down
again. */
partial_len = (rounded_offset + sizeof (PTRACE_TYPE_RET)) - offset;
if (partial_len > len)
partial_len = len;
if (writebuf)
{
/* If OFFSET:PARTIAL_LEN is smaller than
ROUNDED_OFFSET:WORDSIZE then a read/modify write will
be needed. Read in the entire word. */
if (rounded_offset < offset
|| (offset + partial_len
< rounded_offset + sizeof (PTRACE_TYPE_RET)))
/* Need part of initial word -- fetch it. */
buffer.word = ptrace (PT_READ_I, PIDGET (inferior_ptid),
(PTRACE_TYPE_ARG3) (long) rounded_offset,
0);
/* Copy data to be written over corresponding part of
buffer. */
memcpy (buffer.byte + (offset - rounded_offset),
writebuf, partial_len);
errno = 0;
ptrace (PT_WRITE_D, PIDGET (inferior_ptid),
(PTRACE_TYPE_ARG3) (long) rounded_offset,
buffer.word);
if (errno)
{
/* Using the appropriate one (I or D) is necessary for
Gould NP1, at least. */
errno = 0;
ptrace (PT_WRITE_I, PIDGET (inferior_ptid),
(PTRACE_TYPE_ARG3) (long) rounded_offset,
buffer.word);
if (errno)
return 0;
}
}
if (readbuf)
{
errno = 0;
buffer.word = ptrace (PT_READ_I, PIDGET (inferior_ptid),
(PTRACE_TYPE_ARG3) (long) rounded_offset, 0);
if (errno)
return 0;
/* Copy appropriate bytes out of the buffer. */
memcpy (readbuf, buffer.byte + (offset - rounded_offset),
partial_len);
}
return partial_len;
}
case TARGET_OBJECT_UNWIND_TABLE:
return -1;
case TARGET_OBJECT_AUXV:
return -1;
case TARGET_OBJECT_WCOOKIE:
return -1;
default:
return -1;
}
}
static char *
inf_ptrace_pid_to_str (ptid_t ptid)
{
return normal_pid_to_str (ptid);
}
/* Create a prototype ptrace target. The client can override it with
local methods. */
struct target_ops *
inf_ptrace_target (void)
{
struct target_ops *t = inf_child_target ();
t->to_open = inf_ptrace_open;
t->to_attach = inf_ptrace_attach;
t->to_post_attach = inf_ptrace_post_attach;
t->to_detach = inf_ptrace_detach;
t->to_resume = inf_ptrace_resume;
t->to_wait = inf_ptrace_wait;
t->to_xfer_partial = inf_ptrace_xfer_partial;
t->to_files_info = inf_ptrace_files_info;
t->to_kill = inf_ptrace_kill_inferior;
t->to_create_inferior = inf_ptrace_create_inferior;
t->to_reported_exec_events_per_exec_call =
inf_ptrace_reported_exec_events_per_exec_call;
t->to_has_exited = inf_ptrace_has_exited;
t->to_mourn_inferior = inf_ptrace_mourn_inferior;
t->to_can_run = inf_ptrace_can_run;
t->to_thread_alive = inf_ptrace_thread_alive;
t->to_pid_to_str = inf_ptrace_pid_to_str;
t->to_stop = inf_ptrace_stop;
t->to_stratum = process_stratum;
t->to_has_all_memory = 1;
t->to_has_memory = 1;
t->to_has_stack = 1;
t->to_has_registers = 1;
t->to_has_execution = 1;
t->to_magic = OPS_MAGIC;
ptrace_ops_hack = t;
return t;
}
/* Pointer to a function that returns the oggset within the user area
where a particular register is stored. */
static CORE_ADDR (*inf_ptrace_register_u_offset)(int);
/* Fetch register REGNUM from the inferior. */
static void
inf_ptrace_fetch_register (int regnum)
{
CORE_ADDR addr;
size_t size;
PTRACE_TYPE_RET *buf;
int pid, i;
/* Cater for systems like GNU/Linux, that implement threads as
seperate processes. */
pid = ptid_get_lwp (inferior_ptid);
if (pid == 0)
pid = ptid_get_pid (inferior_ptid);
/* This isn't really an address, but ptrace thinks of it as one. */
addr = inf_ptrace_register_u_offset (regnum);
size = register_size (current_gdbarch, regnum);
gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
buf = alloca (size);
/* Read the register contents from the inferior a chuck at the time. */
for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
{
errno = 0;
buf[i] = ptrace (PT_READ_U, pid, (PTRACE_TYPE_ARG3) addr, 0);
if (errno != 0)
error (_("Couldn't read register %s (#%d): %s."), REGISTER_NAME (regnum),
regnum, safe_strerror (errno));
addr += sizeof (PTRACE_TYPE_RET);
}
regcache_raw_supply (current_regcache, regnum, buf);
}
/* Fetch register REGNUM from the inferior. If REGNUM is -1, do this
for all registers. */
static void
inf_ptrace_fetch_registers (int regnum)
{
if (regnum == -1)
for (regnum = 0; regnum < NUM_REGS; regnum++)
inf_ptrace_fetch_register (regnum);
else
inf_ptrace_fetch_register (regnum);
}
/* Store register REGNUM into the inferior. */
static void
inf_ptrace_store_register (int regnum)
{
CORE_ADDR addr;
size_t size;
PTRACE_TYPE_RET *buf;
int pid, i;
/* Cater for systems like GNU/Linux, that implement threads as
seperate processes. */
pid = ptid_get_lwp (inferior_ptid);
if (pid == 0)
pid = ptid_get_pid (inferior_ptid);
/* This isn't really an address, but ptrace thinks of it as one. */
addr = inf_ptrace_register_u_offset (regnum);
size = register_size (current_gdbarch, regnum);
gdb_assert ((size % sizeof (PTRACE_TYPE_RET)) == 0);
buf = alloca (size);
/* Write the register contents into the inferior a chunk at the time. */
regcache_raw_collect (current_regcache, regnum, buf);
for (i = 0; i < size / sizeof (PTRACE_TYPE_RET); i++)
{
errno = 0;
ptrace (PT_WRITE_U, pid, (PTRACE_TYPE_ARG3) addr, buf[i]);
if (errno != 0)
error (_("Couldn't write register %s (#%d): %s."), REGISTER_NAME (regnum),
regnum, safe_strerror (errno));
addr += sizeof (PTRACE_TYPE_RET);
}
}
/* Store register REGNUM back into the inferior. If REGNUM is -1, do
this for all registers. */
void
inf_ptrace_store_registers (int regnum)
{
if (regnum == -1)
for (regnum = 0; regnum < NUM_REGS; regnum++)
inf_ptrace_store_register (regnum);
else
inf_ptrace_store_register (regnum);
}
/* Create a "traditional" ptrace target. REGISTER_U_OFFSET should be
a function returning the offset within the user area where a
particular register is stored. */
struct target_ops *
inf_ptrace_trad_target (CORE_ADDR (*register_u_offset)(int))
{
struct target_ops *t = inf_ptrace_target();
gdb_assert (register_u_offset);
inf_ptrace_register_u_offset = register_u_offset;
t->to_fetch_registers = inf_ptrace_fetch_registers;
t->to_store_registers = inf_ptrace_store_registers;
return t;
}