2 * Server-side ptrace support
4 * Copyright (C) 1999 Alexandre Julliard
6 * This library is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU Lesser General Public
8 * License as published by the Free Software Foundation; either
9 * version 2.1 of the License, or (at your option) any later version.
11 * This library is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 * Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public
17 * License along with this library; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
28 #include <sys/types.h>
29 #ifdef HAVE_SYS_PTRACE_H
30 # include <sys/ptrace.h>
32 #ifdef HAVE_SYS_WAIT_H
33 # include <sys/wait.h>
38 #define WIN32_NO_STATUS
46 #define PTRACE_CONT PT_CONTINUE
48 #ifndef PTRACE_SINGLESTEP
49 #define PTRACE_SINGLESTEP PT_STEP
52 #define PTRACE_ATTACH PT_ATTACH
55 #define PTRACE_DETACH PT_DETACH
57 #ifndef PTRACE_PEEKDATA
58 #define PTRACE_PEEKDATA PT_READ_D
60 #ifndef PTRACE_POKEDATA
61 #define PTRACE_POKEDATA PT_WRITE_D
64 #ifndef HAVE_SYS_PTRACE_H
71 inline static int ptrace(int req, ...) { errno = EPERM; return -1; /*FAIL*/ }
72 #endif /* HAVE_SYS_PTRACE_H */
74 static const int use_ptrace = 1; /* set to 0 to disable ptrace */
76 /* handle a status returned by wait4 */
77 static int handle_child_status( struct thread *thread, int pid, int status, int want_sig )
79 if (WIFSTOPPED(status))
81 int sig = WSTOPSIG(status);
82 if (debug_level && thread)
83 fprintf( stderr, "%04x: *signal* signal=%d\n", thread->id, sig );
86 /* ignore other signals for now */
87 ptrace( PTRACE_CONT, pid, (caddr_t)1, sig );
91 if (thread && (WIFSIGNALED(status) || WIFEXITED(status)))
93 thread->unix_pid = -1;
94 thread->unix_tid = -1;
97 if (WIFSIGNALED(status))
98 fprintf( stderr, "%04x: *exited* signal=%d\n",
99 thread->id, WTERMSIG(status) );
101 fprintf( stderr, "%04x: *exited* status=%d\n",
102 thread->id, WEXITSTATUS(status) );
108 /* wait4 wrapper to handle missing __WALL flag in older kernels */
109 static inline pid_t wait4_wrapper( pid_t pid, int *status, int options, struct rusage *usage )
112 static int wall_flag = __WALL;
116 pid_t ret = wait4( pid, status, options | wall_flag, usage );
117 if (ret != -1 || !wall_flag || errno != EINVAL) return ret;
121 return wait4( pid, status, options, usage );
125 /* handle a SIGCHLD signal */
126 void sigchld_callback(void)
132 if (!(pid = wait4_wrapper( -1, &status, WUNTRACED | WNOHANG, NULL ))) break;
133 if (pid != -1) handle_child_status( get_thread_from_pid(pid), pid, status, -1 );
138 /* wait for a ptraced child to get a certain signal */
139 static int wait4_thread( struct thread *thread, int signal )
146 if ((res = wait4_wrapper( get_ptrace_pid(thread), &status, WUNTRACED, NULL )) == -1)
150 if (!watchdog_triggered()) continue;
151 if (debug_level) fprintf( stderr, "%04x: *watchdog* wait4 aborted\n", thread->id );
153 else if (errno == ECHILD) /* must have died */
155 thread->unix_pid = -1;
156 thread->unix_tid = -1;
158 else perror( "wait4" );
162 res = handle_child_status( thread, res, status, signal );
163 if (!res || res == signal) break;
166 return (thread->unix_pid != -1);
169 /* return the Unix pid to use in ptrace calls for a given thread */
170 int get_ptrace_pid( struct thread *thread )
172 if (thread->unix_tid != -1) return thread->unix_tid;
173 return thread->unix_pid;
176 /* send a Unix signal to a specific thread */
177 int send_thread_signal( struct thread *thread, int sig )
181 if (thread->unix_pid != -1)
183 if (thread->unix_tid != -1)
185 ret = tkill( thread->unix_pid, thread->unix_tid, sig );
186 if (ret == -1 && errno == ENOSYS) ret = kill( thread->unix_pid, sig );
188 else ret = kill( thread->unix_pid, sig );
190 if (ret == -1 && errno == ESRCH) /* thread got killed */
192 thread->unix_pid = -1;
193 thread->unix_tid = -1;
199 /* suspend a thread to allow using ptrace on it */
200 /* you must do a resume_after_ptrace when finished with the thread */
201 int suspend_for_ptrace( struct thread *thread )
203 /* can't stop a thread while initialisation is in progress */
204 if (thread->unix_pid == -1 || !is_process_init_done(thread->process)) goto error;
206 /* this may fail if the client is already being debugged */
207 if (ptrace( PTRACE_ATTACH, get_ptrace_pid(thread), 0, 0 ) == -1)
209 if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1; /* thread got killed */
212 if (wait4_thread( thread, SIGSTOP )) return 1;
213 resume_after_ptrace( thread );
215 set_error( STATUS_ACCESS_DENIED );
219 /* resume a thread after we have used ptrace on it */
220 void resume_after_ptrace( struct thread *thread )
222 if (thread->unix_pid == -1) return;
223 if (ptrace( PTRACE_DETACH, get_ptrace_pid(thread), (caddr_t)1, 0 ) == -1)
225 if (errno == ESRCH) thread->unix_pid = thread->unix_tid = -1; /* thread got killed */
229 /* read an int from a thread address space */
230 static int read_thread_int( struct thread *thread, const int *addr, int *data )
233 *data = ptrace( PTRACE_PEEKDATA, get_ptrace_pid(thread), (caddr_t)addr, 0 );
234 if ( *data == -1 && errno)
242 /* write an int to a thread address space */
243 static int write_thread_int( struct thread *thread, int *addr, int data, unsigned int mask )
248 if (read_thread_int( thread, addr, &res ) == -1) return -1;
249 data = (data & mask) | (res & ~mask);
251 if ((res = ptrace( PTRACE_POKEDATA, get_ptrace_pid(thread), (caddr_t)addr, data )) == -1)
256 /* read data from a process memory space */
257 int read_process_memory( struct process *process, const void *ptr, size_t size, char *dest )
259 struct thread *thread = get_process_first_thread( process );
260 unsigned int first_offset, last_offset, len;
263 if (!thread) /* process is dead */
265 set_error( STATUS_ACCESS_DENIED );
269 first_offset = (unsigned long)ptr % sizeof(int);
270 last_offset = (size + first_offset) % sizeof(int);
271 if (!last_offset) last_offset = sizeof(int);
273 addr = (int *)((char *)ptr - first_offset);
274 len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
276 if (suspend_for_ptrace( thread ))
280 if (read_thread_int( thread, addr++, &data ) == -1) goto done;
281 memcpy( dest, (char *)&data + first_offset, sizeof(int) - first_offset );
282 dest += sizeof(int) - first_offset;
289 if (read_thread_int( thread, addr++, &data ) == -1) goto done;
290 memcpy( dest, &data, sizeof(int) );
295 if (read_thread_int( thread, addr++, &data ) == -1) goto done;
296 memcpy( dest, (char *)&data + first_offset, last_offset - first_offset );
300 resume_after_ptrace( thread );
305 /* make sure we can write to the whole address range */
306 /* len is the total size (in ints) */
307 static int check_process_write_access( struct thread *thread, int *addr, size_t len )
309 int page = get_page_size() / sizeof(int);
313 if (write_thread_int( thread, addr, 0, 0 ) == -1) return 0;
314 if (len <= page) break;
318 return (write_thread_int( thread, addr + len - 1, 0, 0 ) != -1);
321 /* write data to a process memory space */
322 int write_process_memory( struct process *process, void *ptr, size_t size, const char *src )
324 struct thread *thread = get_process_first_thread( process );
325 int ret = 0, data = 0;
328 unsigned int first_mask, first_offset, last_mask, last_offset;
330 if (!thread) /* process is dead */
332 set_error( STATUS_ACCESS_DENIED );
336 /* compute the mask for the first int */
338 first_offset = (unsigned long)ptr % sizeof(int);
339 memset( &first_mask, 0, first_offset );
341 /* compute the mask for the last int */
342 last_offset = (size + first_offset) % sizeof(int);
343 if (!last_offset) last_offset = sizeof(int);
345 memset( &last_mask, 0xff, last_offset );
347 addr = (int *)((char *)ptr - first_offset);
348 len = (size + first_offset + sizeof(int) - 1) / sizeof(int);
350 if (suspend_for_ptrace( thread ))
352 if (!check_process_write_access( thread, addr, len ))
354 set_error( STATUS_ACCESS_DENIED );
357 /* first word is special */
360 memcpy( (char *)&data + first_offset, src, sizeof(int) - first_offset );
361 src += sizeof(int) - first_offset;
362 if (write_thread_int( thread, addr++, data, first_mask ) == -1) goto done;
366 else last_mask &= first_mask;
370 memcpy( &data, src, sizeof(int) );
372 if (write_thread_int( thread, addr++, data, ~0 ) == -1) goto done;
376 /* last word is special too */
377 memcpy( (char *)&data + first_offset, src, last_offset - first_offset );
378 if (write_thread_int( thread, addr, data, last_mask ) == -1) goto done;
382 resume_after_ptrace( thread );
387 /* retrieve an LDT selector entry */
388 void get_selector_entry( struct thread *thread, int entry, unsigned int *base,
389 unsigned int *limit, unsigned char *flags )
391 if (!thread->process->ldt_copy)
393 set_error( STATUS_ACCESS_DENIED );
398 set_error( STATUS_INVALID_PARAMETER ); /* FIXME */
401 if (suspend_for_ptrace( thread ))
403 unsigned char flags_buf[4];
404 int *addr = (int *)thread->process->ldt_copy + entry;
405 if (read_thread_int( thread, addr, (int *)base ) == -1) goto done;
406 if (read_thread_int( thread, addr + 8192, (int *)limit ) == -1) goto done;
407 addr = (int *)thread->process->ldt_copy + 2*8192 + (entry >> 2);
408 if (read_thread_int( thread, addr, (int *)flags_buf ) == -1) goto done;
409 *flags = flags_buf[entry & 3];
411 resume_after_ptrace( thread );