Sweden-Number/server/ptrace.c

178 lines
4.9 KiB
C

/*
* Server-side ptrace support
*
* Copyright (C) 1999 Alexandre Julliard
*/
#include "config.h"
#include <assert.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/ptrace.h>
#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_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
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))
ptrace( PTRACE_CONT, pid, 1, sig );
break;
default: /* ignore other signals for now */
ptrace( PTRACE_CONT, pid, 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 || (ptrace( PTRACE_ATTACH, thread->unix_pid, 0, 0 ) == -1)) 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 )
{
if (!thread->unix_pid) return;
kill( thread->unix_pid, SIGTERM );
if (thread->suspend + thread->process->suspend) continue_thread( thread );
if (thread->attached)
{
wait4_thread( thread, SIGTERM );
if (debug_level) fprintf( stderr, "%08x: *detached*\n", (unsigned int)thread );
ptrace( PTRACE_DETACH, thread->unix_pid, 1, SIGTERM );
thread->attached = 0;
}
}
/* 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 */
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( PTRACE_CONT, thread->unix_pid, 1, SIGSTOP );
}
/* read an int from a thread address space */
int read_thread_int( struct thread *thread, const int *addr, int *data )
{
if (((*data = ptrace( PTRACE_PEEKDATA, thread->unix_pid, addr, 0 )) == -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, addr, data )) == -1) file_set_error();
return res;
}