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