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c906108c SS |
1 | /* Fork a Unix child process, and set up to debug it, for GDB. |
2 | Copyright 1990, 1991, 1992, 1993, 1994, 1996 Free Software Foundation, Inc. | |
3 | Contributed by Cygnus Support. | |
4 | ||
5 | This file is part of GDB. | |
6 | ||
7 | This program is free software; you can redistribute it and/or modify | |
8 | it under the terms of the GNU General Public License as published by | |
9 | the Free Software Foundation; either version 2 of the License, or | |
10 | (at your option) any later version. | |
11 | ||
12 | This program is distributed in the hope that it will be useful, | |
13 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | GNU General Public License for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with this program; if not, write to the Free Software | |
19 | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "defs.h" | |
22 | #include "gdb_string.h" | |
23 | #include "frame.h" /* required by inferior.h */ | |
24 | #include "inferior.h" | |
25 | #include "target.h" | |
26 | #include "wait.h" | |
27 | #include "gdbcore.h" | |
28 | #include "terminal.h" | |
29 | #include "gdbthread.h" | |
30 | ||
31 | #include <signal.h> | |
32 | #ifdef HAVE_UNISTD_H | |
33 | #include <unistd.h> | |
34 | #endif | |
35 | ||
36 | #define DEBUGGING 0 | |
37 | ||
38 | /* This just gets used as a default if we can't find SHELL */ | |
39 | #ifndef SHELL_FILE | |
40 | #define SHELL_FILE "/bin/sh" | |
41 | #endif | |
42 | ||
43 | extern char **environ; | |
44 | ||
45 | /* This function breaks up an argument string into an argument | |
46 | * vector suitable for passing to execvp(). | |
47 | * E.g., on "run a b c d" this routine would get as input | |
48 | * the string "a b c d", and as output it would fill in argv with | |
49 | * the four arguments "a", "b", "c", "d". | |
50 | */ | |
51 | static void | |
52 | breakup_args ( | |
53 | scratch, | |
54 | argv) | |
55 | char *scratch; | |
56 | char **argv; | |
57 | { | |
58 | char *cp = scratch; | |
59 | ||
60 | #if DEBUGGING | |
61 | printf ("breakup_args: input = %s\n", scratch); | |
62 | #endif | |
63 | for (;;) | |
64 | { | |
65 | ||
66 | /* Scan past leading separators */ | |
67 | while (*cp == ' ' || *cp == '\t' || *cp == '\n') | |
68 | { | |
69 | cp++; | |
70 | } | |
71 | ||
72 | /* Break if at end of string */ | |
73 | if (*cp == '\0') | |
74 | break; | |
75 | ||
76 | /* Take an arg */ | |
77 | *argv++ = cp; | |
78 | ||
79 | /* Scan for next arg separator */ | |
80 | cp = strchr (cp, ' '); | |
81 | if (cp == NULL) | |
82 | cp = strchr (cp, '\t'); | |
83 | if (cp == NULL) | |
84 | cp = strchr (cp, '\n'); | |
85 | ||
86 | /* No separators => end of string => break */ | |
87 | if (cp == NULL) | |
88 | break; | |
89 | ||
90 | /* Replace the separator with a terminator */ | |
91 | *cp++ = '\0'; | |
92 | } | |
93 | ||
94 | /* execv requires a null-terminated arg vector */ | |
95 | *argv = NULL; | |
96 | ||
97 | } | |
98 | ||
99 | ||
100 | /* Start an inferior Unix child process and sets inferior_pid to its pid. | |
101 | EXEC_FILE is the file to run. | |
102 | ALLARGS is a string containing the arguments to the program. | |
103 | ENV is the environment vector to pass. SHELL_FILE is the shell file, | |
104 | or NULL if we should pick one. Errors reported with error(). */ | |
105 | ||
106 | void | |
107 | fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, | |
108 | pre_trace_fun, shell_file) | |
109 | char *exec_file; | |
110 | char *allargs; | |
111 | char **env; | |
112 | void (*traceme_fun) PARAMS ((void)); | |
113 | void (*init_trace_fun) PARAMS ((int)); | |
114 | void (*pre_trace_fun) PARAMS ((void)); | |
115 | char *shell_file; | |
116 | { | |
117 | int pid; | |
118 | char *shell_command; | |
119 | static char default_shell_file[] = SHELL_FILE; | |
120 | int len; | |
121 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ | |
122 | static int debug_fork = 0; | |
123 | /* This is set to the result of setpgrp, which if vforked, will be visible | |
124 | to you in the parent process. It's only used by humans for debugging. */ | |
125 | static int debug_setpgrp = 657473; | |
126 | char **save_our_env; | |
127 | int shell = 0; | |
128 | char **argv; | |
129 | char *tryname; | |
130 | ||
131 | /* If no exec file handed to us, get it from the exec-file command -- with | |
132 | a good, common error message if none is specified. */ | |
133 | if (exec_file == 0) | |
134 | exec_file = get_exec_file (1); | |
135 | ||
136 | /* STARTUP_WITH_SHELL is defined in inferior.h. | |
137 | * If 0, we'll just do a fork/exec, no shell, so don't | |
138 | * bother figuring out what shell. | |
139 | */ | |
140 | if (STARTUP_WITH_SHELL) | |
141 | { | |
142 | /* Figure out what shell to start up the user program under. */ | |
143 | if (shell_file == NULL) | |
144 | shell_file = getenv ("SHELL"); | |
145 | if (shell_file == NULL) | |
146 | shell_file = default_shell_file; | |
147 | shell = 1; | |
148 | } | |
149 | ||
150 | #if DEBUGGING | |
151 | printf ("shell is %s\n", shell_file); | |
152 | #endif | |
153 | ||
154 | /* Multiplying the length of exec_file by 4 is to account for the fact | |
155 | that it may expand when quoted; it is a worst-case number based on | |
156 | every character being '. */ | |
157 | len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop*/ 12; | |
158 | /* If desired, concat something onto the front of ALLARGS. | |
159 | SHELL_COMMAND is the result. */ | |
160 | #ifdef SHELL_COMMAND_CONCAT | |
161 | shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len); | |
162 | strcpy (shell_command, SHELL_COMMAND_CONCAT); | |
163 | #else | |
164 | shell_command = (char *) alloca (len); | |
165 | shell_command[0] = '\0'; | |
166 | #endif | |
167 | ||
168 | if (!shell) | |
169 | { | |
170 | /* We're going to call execvp. Create argv */ | |
171 | /* Largest case: every other character is a separate arg */ | |
172 | #if DEBUGGING | |
173 | printf ("allocating argv, length = %d\n", | |
174 | ( | |
175 | (strlen (allargs) + 1) / (unsigned) 2 | |
176 | + 2 | |
177 | ) * sizeof (*argv) | |
178 | ); | |
179 | #endif | |
180 | argv = (char **) xmalloc (((strlen (allargs) + 1) / (unsigned) 2 + 2) * sizeof (*argv)); | |
181 | argv[0] = exec_file; | |
182 | breakup_args (allargs, &argv[1]); | |
183 | ||
184 | } | |
185 | else | |
186 | { | |
187 | ||
188 | /* We're going to call a shell */ | |
189 | ||
190 | /* Now add exec_file, quoting as necessary. */ | |
191 | ||
192 | char *p; | |
193 | int need_to_quote; | |
194 | ||
195 | strcat (shell_command, "exec "); | |
196 | ||
197 | /* Quoting in this style is said to work with all shells. But csh | |
198 | on IRIX 4.0.1 can't deal with it. So we only quote it if we need | |
199 | to. */ | |
200 | p = exec_file; | |
201 | while (1) | |
202 | { | |
203 | switch (*p) | |
204 | { | |
205 | case '\'': | |
206 | case '"': | |
207 | case '(': | |
208 | case ')': | |
209 | case '$': | |
210 | case '&': | |
211 | case ';': | |
212 | case '<': | |
213 | case '>': | |
214 | case ' ': | |
215 | case '\n': | |
216 | case '\t': | |
217 | need_to_quote = 1; | |
218 | goto end_scan; | |
219 | ||
220 | case '\0': | |
221 | need_to_quote = 0; | |
222 | goto end_scan; | |
223 | ||
224 | default: | |
225 | break; | |
226 | } | |
227 | ++p; | |
228 | } | |
229 | end_scan: | |
230 | if (need_to_quote) | |
231 | { | |
232 | strcat (shell_command, "'"); | |
233 | for (p = exec_file; *p != '\0'; ++p) | |
234 | { | |
235 | if (*p == '\'') | |
236 | strcat (shell_command, "'\\''"); | |
237 | else | |
238 | strncat (shell_command, p, 1); | |
239 | } | |
240 | strcat (shell_command, "'"); | |
241 | } | |
242 | else | |
243 | strcat (shell_command, exec_file); | |
244 | ||
245 | strcat (shell_command, " "); | |
246 | strcat (shell_command, allargs); | |
247 | ||
248 | } | |
249 | ||
250 | /* exec is said to fail if the executable is open. */ | |
251 | close_exec_file (); | |
252 | ||
253 | /* Retain a copy of our environment variables, since the child will | |
254 | replace the value of environ and if we're vforked, we have to | |
255 | restore it. */ | |
256 | save_our_env = environ; | |
257 | ||
258 | /* Tell the terminal handling subsystem what tty we plan to run on; | |
259 | it will just record the information for later. */ | |
260 | ||
261 | new_tty_prefork (inferior_io_terminal); | |
262 | ||
263 | /* It is generally good practice to flush any possible pending stdio | |
264 | output prior to doing a fork, to avoid the possibility of both the | |
265 | parent and child flushing the same data after the fork. */ | |
266 | ||
267 | gdb_flush (gdb_stdout); | |
268 | gdb_flush (gdb_stderr); | |
269 | ||
270 | /* If there's any initialization of the target layers that must happen | |
271 | to prepare to handle the child we're about fork, do it now... | |
272 | */ | |
273 | if (pre_trace_fun != NULL) | |
274 | (*pre_trace_fun) (); | |
275 | ||
276 | #if defined(USG) && !defined(HAVE_VFORK) | |
277 | pid = fork (); | |
278 | #else | |
279 | if (debug_fork) | |
280 | pid = fork (); | |
281 | else | |
282 | pid = vfork (); | |
283 | #endif | |
284 | ||
285 | if (pid < 0) | |
286 | perror_with_name ("vfork"); | |
287 | ||
288 | if (pid == 0) | |
289 | { | |
290 | if (debug_fork) | |
291 | sleep (debug_fork); | |
292 | ||
293 | /* Run inferior in a separate process group. */ | |
294 | debug_setpgrp = gdb_setpgid (); | |
295 | if (debug_setpgrp == -1) | |
296 | perror ("setpgrp failed in child"); | |
297 | ||
298 | /* Ask the tty subsystem to switch to the one we specified earlier | |
299 | (or to share the current terminal, if none was specified). */ | |
300 | ||
301 | new_tty (); | |
302 | ||
303 | /* Changing the signal handlers for the inferior after | |
304 | a vfork can also change them for the superior, so we don't mess | |
305 | with signals here. See comments in | |
306 | initialize_signals for how we get the right signal handlers | |
307 | for the inferior. */ | |
308 | ||
309 | /* "Trace me, Dr. Memory!" */ | |
310 | (*traceme_fun) (); | |
311 | /* The call above set this process (the "child") as debuggable | |
312 | * by the original gdb process (the "parent"). Since processes | |
313 | * (unlike people) can have only one parent, if you are | |
314 | * debugging gdb itself (and your debugger is thus _already_ the | |
315 | * controller/parent for this child), code from here on out | |
316 | * is undebuggable. Indeed, you probably got an error message | |
317 | * saying "not parent". Sorry--you'll have to use print statements! | |
318 | */ | |
319 | ||
320 | /* There is no execlpe call, so we have to set the environment | |
321 | for our child in the global variable. If we've vforked, this | |
322 | clobbers the parent, but environ is restored a few lines down | |
323 | in the parent. By the way, yes we do need to look down the | |
324 | path to find $SHELL. Rich Pixley says so, and I agree. */ | |
325 | environ = env; | |
326 | ||
327 | /* If we decided above to start up with a shell, | |
328 | * we exec the shell, | |
329 | * "-c" says to interpret the next arg as a shell command | |
330 | * to execute, and this command is "exec <target-program> <args>". | |
331 | * "-f" means "fast startup" to the c-shell, which means | |
332 | * don't do .cshrc file. Doing .cshrc may cause fork/exec | |
333 | * events which will confuse debugger start-up code. | |
334 | */ | |
335 | if (shell) | |
336 | { | |
337 | #if 0 | |
338 | ||
339 | /* HP change is problematic. The -f option has different meanings | |
340 | for different shells. It is particularly inappropriate for | |
341 | bourne shells. */ | |
342 | execlp (shell_file, shell_file, "-f", "-c", shell_command, (char *) 0); | |
343 | #else | |
344 | execlp (shell_file, shell_file, "-c", shell_command, (char *) 0); | |
345 | #endif | |
346 | ||
347 | ||
348 | /* If we get here, it's an error */ | |
349 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, | |
350 | safe_strerror (errno)); | |
351 | gdb_flush (gdb_stderr); | |
352 | _exit (0177); | |
353 | } | |
354 | else | |
355 | { | |
356 | /* Otherwise, we directly exec the target program with execvp. */ | |
357 | int i; | |
358 | char *errstring; | |
359 | #if DEBUGGING | |
360 | printf ("about to exec target, exec_file = %s\n", exec_file); | |
361 | i = 0; | |
362 | while (argv[i] != NULL) | |
363 | { | |
364 | printf ("strlen(argv[%d]) is %d\n", i, strlen (argv[i])); | |
365 | printf ("argv[%d] is %s\n", i, argv[i]); | |
366 | i++; | |
367 | } | |
368 | #endif | |
369 | execvp (exec_file, argv); | |
370 | ||
371 | /* If we get here, it's an error */ | |
372 | errstring = safe_strerror (errno); | |
373 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); | |
374 | ||
375 | i = 1; | |
376 | while (argv[i] != NULL) | |
377 | { | |
378 | if (i != 1) | |
379 | fprintf_unfiltered (gdb_stderr, " "); | |
380 | fprintf_unfiltered (gdb_stderr, "%s", argv[i]); | |
381 | i++; | |
382 | } | |
383 | fprintf_unfiltered (gdb_stderr, ".\n"); | |
384 | /* This extra info seems to be useless | |
385 | fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); | |
386 | */ | |
387 | gdb_flush (gdb_stderr); | |
388 | _exit (0177); | |
389 | } | |
390 | } | |
391 | ||
392 | /* Restore our environment in case a vforked child clob'd it. */ | |
393 | environ = save_our_env; | |
394 | ||
395 | init_thread_list (); | |
396 | ||
397 | inferior_pid = pid; /* Needed for wait_for_inferior stuff below */ | |
398 | ||
399 | /* Now that we have a child process, make it our target, and | |
400 | initialize anything target-vector-specific that needs initializing. */ | |
401 | ||
402 | (*init_trace_fun) (pid); | |
403 | ||
404 | /* We are now in the child process of interest, having exec'd the | |
405 | correct program, and are poised at the first instruction of the | |
406 | new program. */ | |
407 | ||
408 | /* Allow target dependant code to play with the new process. This might be | |
409 | used to have target-specific code initialize a variable in the new process | |
410 | prior to executing the first instruction. */ | |
411 | TARGET_CREATE_INFERIOR_HOOK (pid); | |
412 | ||
413 | #ifdef SOLIB_CREATE_INFERIOR_HOOK | |
414 | SOLIB_CREATE_INFERIOR_HOOK (pid); | |
415 | #endif | |
416 | } | |
417 | ||
418 | /* An inferior Unix process CHILD_PID has been created by a call to | |
419 | fork() (or variants like vfork). It is presently stopped, and waiting | |
420 | to be resumed. clone_and_follow_inferior will fork the debugger, | |
421 | and that clone will "follow" (attach to) CHILD_PID. The original copy | |
422 | of the debugger will not touch CHILD_PID again. | |
423 | ||
424 | Also, the original debugger will set FOLLOWED_CHILD FALSE, while the | |
425 | clone will set it TRUE. | |
426 | */ | |
427 | void | |
428 | clone_and_follow_inferior (child_pid, followed_child) | |
429 | int child_pid; | |
430 | int *followed_child; | |
431 | { | |
432 | extern int auto_solib_add; | |
433 | ||
434 | int debugger_pid; | |
435 | int status; | |
436 | char pid_spelling[100]; /* Arbitrary but sufficient length. */ | |
437 | ||
438 | /* This semaphore is used to coordinate the two debuggers' handoff | |
439 | of CHILD_PID. The original debugger will detach from CHILD_PID, | |
440 | and then the clone debugger will attach to it. (It must be done | |
441 | this way because on some targets, only one process at a time can | |
442 | trace another. Thus, the original debugger must relinquish its | |
443 | tracing rights before the clone can pick them up.) | |
444 | */ | |
445 | #define SEM_TALK (1) | |
446 | #define SEM_LISTEN (0) | |
447 | int handoff_semaphore[2]; /* Original "talks" to [1], clone "listens" to [0] */ | |
448 | int talk_value = 99; | |
449 | int listen_value; | |
450 | ||
451 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ | |
452 | static int debug_fork = 0; | |
453 | ||
454 | /* It is generally good practice to flush any possible pending stdio | |
455 | output prior to doing a fork, to avoid the possibility of both the | |
456 | parent and child flushing the same data after the fork. */ | |
457 | ||
458 | gdb_flush (gdb_stdout); | |
459 | gdb_flush (gdb_stderr); | |
460 | ||
461 | /* Open the semaphore pipes. | |
462 | */ | |
463 | status = pipe (handoff_semaphore); | |
464 | if (status < 0) | |
465 | error ("error getting pipe for handoff semaphore"); | |
466 | ||
467 | /* Clone the debugger. */ | |
468 | #if defined(USG) && !defined(HAVE_VFORK) | |
469 | debugger_pid = fork (); | |
470 | #else | |
471 | if (debug_fork) | |
472 | debugger_pid = fork (); | |
473 | else | |
474 | debugger_pid = vfork (); | |
475 | #endif | |
476 | ||
477 | if (debugger_pid < 0) | |
478 | perror_with_name ("fork"); | |
479 | ||
480 | /* Are we the original debugger? If so, we must relinquish all claims | |
481 | to CHILD_PID. */ | |
482 | if (debugger_pid != 0) | |
483 | { | |
484 | char signal_spelling[100];/* Arbitrary but sufficient length */ | |
485 | ||
486 | /* Detach from CHILD_PID. Deliver a "stop" signal when we do, though, | |
487 | so that it remains stopped until the clone debugger can attach | |
488 | to it. | |
489 | */ | |
490 | detach_breakpoints (child_pid); | |
491 | ||
492 | sprintf (signal_spelling, "%d", target_signal_to_host (TARGET_SIGNAL_STOP)); | |
493 | target_require_detach (child_pid, signal_spelling, 1); | |
494 | ||
495 | /* Notify the clone debugger that it should attach to CHILD_PID. */ | |
496 | write (handoff_semaphore[SEM_TALK], &talk_value, sizeof (talk_value)); | |
497 | ||
498 | *followed_child = 0; | |
499 | } | |
500 | ||
501 | /* We're the child. */ | |
502 | else | |
503 | { | |
504 | if (debug_fork) | |
505 | sleep (debug_fork); | |
506 | ||
507 | /* The child (i.e., the cloned debugger) must now attach to | |
508 | CHILD_PID. inferior_pid is presently set to the parent process | |
509 | of the fork, while CHILD_PID should be the child process of the | |
510 | fork. | |
511 | ||
512 | Wait until the original debugger relinquishes control of CHILD_PID, | |
513 | though. | |
514 | */ | |
515 | read (handoff_semaphore[SEM_LISTEN], &listen_value, sizeof (listen_value)); | |
516 | ||
517 | /* Note that we DON'T want to actually detach from inferior_pid, | |
518 | because that would allow it to run free. The original | |
519 | debugger wants to retain control of the process. So, we | |
520 | just reset inferior_pid to CHILD_PID, and then ensure that all | |
521 | breakpoints are really set in CHILD_PID. | |
522 | */ | |
523 | target_mourn_inferior (); | |
524 | ||
525 | /* Ask the tty subsystem to switch to the one we specified earlier | |
526 | (or to share the current terminal, if none was specified). */ | |
527 | ||
528 | new_tty (); | |
529 | ||
530 | dont_repeat (); | |
531 | sprintf (pid_spelling, "%d", child_pid); | |
532 | target_require_attach (pid_spelling, 1); | |
533 | ||
534 | /* Perform any necessary cleanup, after attachment. (This form | |
535 | of attaching can behave differently on some targets than the | |
536 | standard method, where a process formerly not under debugger | |
537 | control was suddenly attached to..) | |
538 | */ | |
539 | target_post_follow_inferior_by_clone (); | |
540 | ||
541 | *followed_child = 1; | |
542 | } | |
543 | ||
544 | /* Discard the handoff sempahore. */ | |
545 | (void) close (handoff_semaphore[SEM_LISTEN]); | |
546 | (void) close (handoff_semaphore[SEM_TALK]); | |
547 | } | |
548 | ||
549 | /* Accept NTRAPS traps from the inferior. */ | |
550 | ||
551 | void | |
552 | startup_inferior (ntraps) | |
553 | int ntraps; | |
554 | { | |
555 | int pending_execs = ntraps; | |
556 | int terminal_initted; | |
557 | ||
558 | /* The process was started by the fork that created it, | |
559 | but it will have stopped one instruction after execing the shell. | |
560 | Here we must get it up to actual execution of the real program. */ | |
561 | ||
562 | clear_proceed_status (); | |
563 | ||
564 | init_wait_for_inferior (); | |
565 | ||
566 | terminal_initted = 0; | |
567 | ||
568 | if (STARTUP_WITH_SHELL) | |
569 | inferior_ignoring_startup_exec_events = ntraps; | |
570 | else | |
571 | inferior_ignoring_startup_exec_events = 0; | |
572 | inferior_ignoring_leading_exec_events = | |
573 | target_reported_exec_events_per_exec_call () - 1; | |
574 | ||
575 | #ifdef STARTUP_INFERIOR | |
576 | STARTUP_INFERIOR (pending_execs); | |
577 | #else | |
578 | while (1) | |
579 | { | |
580 | stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */ | |
581 | wait_for_inferior (); | |
582 | if (stop_signal != TARGET_SIGNAL_TRAP) | |
583 | { | |
584 | /* Let shell child handle its own signals in its own way */ | |
585 | /* FIXME, what if child has exit()ed? Must exit loop somehow */ | |
586 | resume (0, stop_signal); | |
587 | } | |
588 | else | |
589 | { | |
590 | /* We handle SIGTRAP, however; it means child did an exec. */ | |
591 | if (!terminal_initted) | |
592 | { | |
593 | /* Now that the child has exec'd we know it has already set its | |
594 | process group. On POSIX systems, tcsetpgrp will fail with | |
595 | EPERM if we try it before the child's setpgid. */ | |
596 | ||
597 | /* Set up the "saved terminal modes" of the inferior | |
598 | based on what modes we are starting it with. */ | |
599 | target_terminal_init (); | |
600 | ||
601 | /* Install inferior's terminal modes. */ | |
602 | target_terminal_inferior (); | |
603 | ||
604 | terminal_initted = 1; | |
605 | } | |
606 | ||
607 | pending_execs = pending_execs - 1; | |
608 | if (0 == pending_execs) | |
609 | break; | |
610 | ||
611 | resume (0, TARGET_SIGNAL_0); /* Just make it go on */ | |
612 | } | |
613 | } | |
614 | #endif /* STARTUP_INFERIOR */ | |
615 | stop_soon_quietly = 0; | |
616 | } |