Sweden-Number/server/ptrace.c

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/*
* Server-side ptrace support
*
* Copyright (C) 1999 Alexandre Julliard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "config.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
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#include <sys/types.h>
#ifdef HAVE_SYS_PTRACE_H
# include <sys/ptrace.h>
#endif
#ifdef HAVE_SYS_WAIT_H
# include <sys/wait.h>
#endif
#include <unistd.h>
#include "process.h"
#include "thread.h"
#ifndef PTRACE_CONT
#define PTRACE_CONT PT_CONTINUE
#endif
#ifndef PTRACE_SINGLESTEP
#define PTRACE_SINGLESTEP PT_STEP
#endif
#ifndef PTRACE_ATTACH
#define PTRACE_ATTACH PT_ATTACH
#endif
#ifndef PTRACE_DETACH
#define PTRACE_DETACH PT_DETACH
#endif
#ifndef PTRACE_PEEKDATA
#define PTRACE_PEEKDATA PT_READ_D
#endif
#ifndef PTRACE_POKEDATA
#define PTRACE_POKEDATA PT_WRITE_D
#endif
#ifndef HAVE_SYS_PTRACE_H
#define PT_CONTINUE 0
#define PT_ATTACH 1
#define PT_DETACH 2
#define PT_READ_D 3
#define PT_WRITE_D 4
#define PT_STEP 5
inline static int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
#endif /* HAVE_SYS_PTRACE_H */
static const int use_ptrace = 1; /* set to 0 to disable ptrace */
/* handle a status returned by wait4 */
static int handle_child_status( struct thread *thread, int pid, int status )
{
if (WIFSTOPPED(status))
{
int sig = WSTOPSIG(status);
if (debug_level && thread)
fprintf( stderr, "%08x: *signal* signal=%d\n", (unsigned int)thread, sig );
switch(sig)
{
case SIGSTOP: /* continue at once if not suspended */
if (thread && (thread->process->suspend + thread->suspend)) break;
/* fall through */
default: /* ignore other signals for now */
if (thread && get_thread_single_step( thread ))
ptrace( PTRACE_SINGLESTEP, pid, (caddr_t)1, sig );
else
ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
break;
}
return sig;
}
if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
{
thread->attached = 0;
thread->unix_pid = 0;
if (debug_level)
{
if (WIFSIGNALED(status))
fprintf( stderr, "%08x: *exited* signal=%d\n",
(unsigned int)thread, WTERMSIG(status) );
else
fprintf( stderr, "%08x: *exited* status=%d\n",
(unsigned int)thread, WEXITSTATUS(status) );
}
}
return 0;
}
/* handle a SIGCHLD signal */
void sigchld_handler()
{
int pid, status;
for (;;)
{
if (!(pid = wait4( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
if (pid != -1) handle_child_status( get_thread_from_pid(pid), pid, status );
else break;
}
}
/* wait for a ptraced child to get a certain signal */
void wait4_thread( struct thread *thread, int signal )
{
int res, status;
do
{
if ((res = wait4( thread->unix_pid, &status, WUNTRACED, NULL )) == -1)
{
perror( "wait4" );
return;
}
res = handle_child_status( thread, res, status );
} while (res && res != signal);
}
/* attach to a Unix thread */
static int attach_thread( struct thread *thread )
{
/* this may fail if the client is already being debugged */
if (!use_ptrace) return 0;
if (ptrace( PTRACE_ATTACH, thread->unix_pid, 0, 0 ) == -1)
{
if (errno == ESRCH) thread->unix_pid = 0; /* process got killed */
return 0;
}
if (debug_level) fprintf( stderr, "%08x: *attached*\n", (unsigned int)thread );
thread->attached = 1;
wait4_thread( thread, SIGSTOP );
return 1;
}
/* detach from a Unix thread and kill it */
void detach_thread( struct thread *thread, int sig )
{
if (!thread->unix_pid) return;
if (thread->attached)
{
/* make sure it is stopped */
suspend_thread( thread, 0 );
if (sig) kill( thread->unix_pid, sig );
if (debug_level) fprintf( stderr, "%08x: *detached*\n", (unsigned int)thread );
ptrace( PTRACE_DETACH, thread->unix_pid, (caddr_t)1, sig );
thread->suspend = 0; /* detach makes it continue */
thread->attached = 0;
}
else
{
if (sig) kill( thread->unix_pid, sig );
if (thread->suspend + thread->process->suspend) continue_thread( thread );
}
}
/* stop a thread (at the Unix level) */
void stop_thread( struct thread *thread )
{
/* can't stop a thread while initialisation is in progress */
if (!thread->unix_pid || thread->process->init_event) return;
/* first try to attach to it */
if (!thread->attached)
if (attach_thread( thread )) return; /* this will have stopped it */
/* attached already, or attach failed -> send a signal */
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if (!thread->unix_pid) return;
kill( thread->unix_pid, SIGSTOP );
if (thread->attached) wait4_thread( thread, SIGSTOP );
}
/* make a thread continue (at the Unix level) */
void continue_thread( struct thread *thread )
{
if (!thread->unix_pid) return;
if (!thread->attached) kill( thread->unix_pid, SIGCONT );
else ptrace( get_thread_single_step(thread) ? PTRACE_SINGLESTEP : PTRACE_CONT,
thread->unix_pid, (caddr_t)1, SIGSTOP );
}
/* suspend a thread to allow using ptrace on it */
/* you must do a resume_thread when finished with the thread */
int suspend_for_ptrace( struct thread *thread )
{
if (thread->attached)
{
suspend_thread( thread, 0 );
return 1;
}
/* can't stop a thread while initialisation is in progress */
if (!thread->unix_pid || thread->process->init_event) goto error;
thread->suspend++;
if (attach_thread( thread )) return 1;
thread->suspend--;
error:
set_error( STATUS_ACCESS_DENIED );
return 0;
}
/* read an int from a thread address space */
int read_thread_int( struct thread *thread, const int *addr, int *data )
{
*data = ptrace( PTRACE_PEEKDATA, thread->unix_pid, (caddr_t)addr, 0 );
if ( *data == -1 && errno)
{
file_set_error();
return -1;
}
return 0;
}
/* write an int to a thread address space */
int write_thread_int( struct thread *thread, int *addr, int data, unsigned int mask )
{
int res;
if (mask != ~0)
{
if (read_thread_int( thread, addr, &res ) == -1) return -1;
data = (data & mask) | (res & ~mask);
}
if ((res = ptrace( PTRACE_POKEDATA, thread->unix_pid, (caddr_t)addr, data )) == -1)
file_set_error();
return res;
}