File: | src/gnu/usr.bin/binutils/gdb/fork-child.c |
Warning: | line 354, column 4 Value stored to 'errstring' is never read |
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1 | /* Fork a Unix child process, and set up to debug it, for GDB. |
2 | |
3 | Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, |
4 | 2000, 2001, 2004 Free Software Foundation, Inc. |
5 | |
6 | Contributed by Cygnus Support. |
7 | |
8 | This file is part of GDB. |
9 | |
10 | This program is free software; you can redistribute it and/or modify |
11 | it under the terms of the GNU General Public License as published by |
12 | the Free Software Foundation; either version 2 of the License, or |
13 | (at your option) any later version. |
14 | |
15 | This program is distributed in the hope that it will be useful, |
16 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
18 | GNU General Public License for more details. |
19 | |
20 | You should have received a copy of the GNU General Public License |
21 | along with this program; if not, write to the Free Software |
22 | Foundation, Inc., 59 Temple Place - Suite 330, |
23 | Boston, MA 02111-1307, USA. */ |
24 | |
25 | #include "defs.h" |
26 | #include "gdb_string.h" |
27 | #include "frame.h" /* required by inferior.h */ |
28 | #include "inferior.h" |
29 | #include "target.h" |
30 | #include "gdb_wait.h" |
31 | #include "gdb_vfork.h" |
32 | #include "gdbcore.h" |
33 | #include "terminal.h" |
34 | #include "gdbthread.h" |
35 | #include "command.h" /* for dont_repeat () */ |
36 | |
37 | #include <signal.h> |
38 | |
39 | /* This just gets used as a default if we can't find SHELL. */ |
40 | #ifndef SHELL_FILE"/bin/sh" |
41 | #define SHELL_FILE"/bin/sh" "/bin/sh" |
42 | #endif |
43 | |
44 | extern char **environ; |
45 | |
46 | /* Break up SCRATCH into an argument vector suitable for passing to |
47 | execvp and store it in ARGV. E.g., on "run a b c d" this routine |
48 | would get as input the string "a b c d", and as output it would |
49 | fill in ARGV with the four arguments "a", "b", "c", "d". */ |
50 | |
51 | static void |
52 | breakup_args (char *scratch, char **argv) |
53 | { |
54 | char *cp = scratch; |
55 | |
56 | for (;;) |
57 | { |
58 | /* Scan past leading separators */ |
59 | while (*cp == ' ' || *cp == '\t' || *cp == '\n') |
60 | cp++; |
61 | |
62 | /* Break if at end of string. */ |
63 | if (*cp == '\0') |
64 | break; |
65 | |
66 | /* Take an arg. */ |
67 | *argv++ = cp; |
68 | |
69 | /* Scan for next arg separator. */ |
70 | cp = strchr (cp, ' '); |
71 | if (cp == NULL((void*)0)) |
72 | cp = strchr (cp, '\t'); |
73 | if (cp == NULL((void*)0)) |
74 | cp = strchr (cp, '\n'); |
75 | |
76 | /* No separators => end of string => break. */ |
77 | if (cp == NULL((void*)0)) |
78 | break; |
79 | |
80 | /* Replace the separator with a terminator. */ |
81 | *cp++ = '\0'; |
82 | } |
83 | |
84 | /* Null-terminate the vector. */ |
85 | *argv = NULL((void*)0); |
86 | } |
87 | |
88 | /* When executing a command under the given shell, return non-zero if |
89 | the '!' character should be escaped when embedded in a quoted |
90 | command-line argument. */ |
91 | |
92 | static int |
93 | escape_bang_in_quoted_argument (const char *shell_file) |
94 | { |
95 | const int shell_file_len = strlen (shell_file); |
96 | |
97 | /* Bang should be escaped only in C Shells. For now, simply check |
98 | that the shell name ends with 'csh', which covers at least csh |
99 | and tcsh. This should be good enough for now. */ |
100 | |
101 | if (shell_file_len < 3) |
102 | return 0; |
103 | |
104 | if (shell_file[shell_file_len - 3] == 'c' |
105 | && shell_file[shell_file_len - 2] == 's' |
106 | && shell_file[shell_file_len - 1] == 'h') |
107 | return 1; |
108 | |
109 | return 0; |
110 | } |
111 | |
112 | /* Start an inferior Unix child process and sets inferior_ptid to its |
113 | pid. EXEC_FILE is the file to run. ALLARGS is a string containing |
114 | the arguments to the program. ENV is the environment vector to |
115 | pass. SHELL_FILE is the shell file, or NULL if we should pick |
116 | one. */ |
117 | |
118 | /* This function is NOT reentrant. Some of the variables have been |
119 | made static to ensure that they survive the vfork call. */ |
120 | |
121 | void |
122 | fork_inferior (char *exec_file_arg, char *allargs, char **env, |
123 | void (*traceme_fun) (void), void (*init_trace_fun) (int), |
124 | void (*pre_trace_fun) (void), char *shell_file_arg) |
125 | { |
126 | int pid; |
127 | char *shell_command; |
128 | static char default_shell_file[] = SHELL_FILE"/bin/sh"; |
129 | int len; |
130 | /* Set debug_fork then attach to the child while it sleeps, to debug. */ |
131 | static int debug_fork = 0; |
132 | /* This is set to the result of setpgrp, which if vforked, will be visible |
133 | to you in the parent process. It's only used by humans for debugging. */ |
134 | static int debug_setpgrp = 657473; |
135 | static char *shell_file; |
136 | static char *exec_file; |
137 | char **save_our_env; |
138 | int shell = 0; |
139 | static char **argv; |
140 | |
141 | /* If no exec file handed to us, get it from the exec-file command |
142 | -- with a good, common error message if none is specified. */ |
143 | exec_file = exec_file_arg; |
144 | if (exec_file == 0) |
145 | exec_file = get_exec_file (1); |
146 | |
147 | /* STARTUP_WITH_SHELL is defined in inferior.h. If 0,e we'll just |
148 | do a fork/exec, no shell, so don't bother figuring out what |
149 | shell. */ |
150 | shell_file = shell_file_arg; |
151 | if (STARTUP_WITH_SHELL1) |
152 | { |
153 | /* Figure out what shell to start up the user program under. */ |
154 | if (shell_file == NULL((void*)0)) |
155 | shell_file = getenv ("SHELL"); |
156 | if (shell_file == NULL((void*)0)) |
157 | shell_file = default_shell_file; |
158 | shell = 1; |
159 | } |
160 | |
161 | /* Multiplying the length of exec_file by 4 is to account for the |
162 | fact that it may expand when quoted; it is a worst-case number |
163 | based on every character being '. */ |
164 | len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop */ 12; |
165 | /* If desired, concat something onto the front of ALLARGS. |
166 | SHELL_COMMAND is the result. */ |
167 | #ifdef SHELL_COMMAND_CONCAT |
168 | shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len)__builtin_alloca(strlen (SHELL_COMMAND_CONCAT) + len); |
169 | strcpy (shell_command, SHELL_COMMAND_CONCAT); |
170 | #else |
171 | shell_command = (char *) alloca (len)__builtin_alloca(len); |
172 | shell_command[0] = '\0'; |
173 | #endif |
174 | |
175 | if (!shell) |
176 | { |
177 | /* We're going to call execvp. Create argument vector. |
178 | Calculate an upper bound on the length of the vector by |
179 | assuming that every other character is a separate |
180 | argument. */ |
181 | int argc = (strlen (allargs) + 1) / 2 + 2; |
182 | argv = (char **) xmalloc (argc * sizeof (*argv)); |
183 | argv[0] = exec_file; |
184 | breakup_args (allargs, &argv[1]); |
185 | } |
186 | else |
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 | const int escape_bang = escape_bang_in_quoted_argument (shell_file); |
195 | |
196 | strcat (shell_command, "exec "); |
197 | |
198 | /* Quoting in this style is said to work with all shells. But |
199 | csh on IRIX 4.0.1 can't deal with it. So we only quote it if |
200 | we need to. */ |
201 | p = exec_file; |
202 | while (1) |
203 | { |
204 | switch (*p) |
205 | { |
206 | case '\'': |
207 | case '!': |
208 | case '"': |
209 | case '(': |
210 | case ')': |
211 | case '$': |
212 | case '&': |
213 | case ';': |
214 | case '<': |
215 | case '>': |
216 | case ' ': |
217 | case '\n': |
218 | case '\t': |
219 | need_to_quote = 1; |
220 | goto end_scan; |
221 | |
222 | case '\0': |
223 | need_to_quote = 0; |
224 | goto end_scan; |
225 | |
226 | default: |
227 | break; |
228 | } |
229 | ++p; |
230 | } |
231 | end_scan: |
232 | if (need_to_quote) |
233 | { |
234 | strcat (shell_command, "'"); |
235 | for (p = exec_file; *p != '\0'; ++p) |
236 | { |
237 | if (*p == '\'') |
238 | strcat (shell_command, "'\\''"); |
239 | else if (*p == '!' && escape_bang) |
240 | strcat (shell_command, "\\!"); |
241 | else |
242 | strncat (shell_command, p, 1); |
243 | } |
244 | strcat (shell_command, "'"); |
245 | } |
246 | else |
247 | strcat (shell_command, exec_file); |
248 | |
249 | strcat (shell_command, " "); |
250 | strcat (shell_command, allargs); |
251 | } |
252 | |
253 | /* On some systems an exec will fail if the executable is open. */ |
254 | close_exec_file (); |
255 | |
256 | /* Retain a copy of our environment variables, since the child will |
257 | replace the value of environ and if we're vforked, we have to |
258 | restore it. */ |
259 | save_our_env = environ; |
260 | |
261 | /* Tell the terminal handling subsystem what tty we plan to run on; |
262 | it will just record the information for later. */ |
263 | new_tty_prefork (inferior_io_terminal); |
264 | |
265 | /* It is generally good practice to flush any possible pending stdio |
266 | output prior to doing a fork, to avoid the possibility of both |
267 | the parent and child flushing the same data after the fork. */ |
268 | gdb_flush (gdb_stdout); |
269 | gdb_flush (gdb_stderr); |
270 | |
271 | /* If there's any initialization of the target layers that must |
272 | happen to prepare to handle the child we're about fork, do it |
273 | now... */ |
274 | if (pre_trace_fun != NULL((void*)0)) |
275 | (*pre_trace_fun) (); |
276 | |
277 | /* Create the child process. Note that the apparent call to vfork() |
278 | below *might* actually be a call to fork() due to the fact that |
279 | autoconf will ``#define vfork fork'' on certain platforms. */ |
280 | if (debug_fork) |
281 | pid = fork (); |
282 | else |
283 | pid = vfork (); |
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 |
299 | earlier (or to share the current terminal, if none was |
300 | specified). */ |
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 | |
312 | /* The call above set this process (the "child") as debuggable |
313 | by the original gdb process (the "parent"). Since processes |
314 | (unlike people) can have only one parent, if you are debugging |
315 | gdb itself (and your debugger is thus _already_ the |
316 | controller/parent for this child), code from here on out is |
317 | undebuggable. Indeed, you probably got an error message |
318 | saying "not parent". Sorry; you'll have to use print |
319 | statements! */ |
320 | |
321 | /* There is no execlpe call, so we have to set the environment |
322 | for our child in the global variable. If we've vforked, this |
323 | clobbers the parent, but environ is restored a few lines down |
324 | in the parent. By the way, yes we do need to look down the |
325 | path to find $SHELL. Rich Pixley says so, and I agree. */ |
326 | environ = env; |
327 | |
328 | /* If we decided above to start up with a shell, we exec the |
329 | shell, "-c" says to interpret the next arg as a shell command |
330 | to execute, and this command is "exec <target-program> |
331 | <args>". "-f" means "fast startup" to the c-shell, which |
332 | means don't do .cshrc file. Doing .cshrc may cause fork/exec |
333 | events which will confuse debugger start-up code. */ |
334 | if (shell) |
335 | { |
336 | execlp (shell_file, shell_file, "-c", shell_command, (char *) 0); |
337 | |
338 | /* If we get here, it's an error. */ |
339 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, |
340 | safe_strerror (errno(*__errno()))); |
341 | gdb_flush (gdb_stderr); |
342 | _exit (0177); |
343 | } |
344 | else |
345 | { |
346 | /* Otherwise, we directly exec the target program with |
347 | execvp. */ |
348 | int i; |
349 | char *errstring; |
350 | |
351 | execvp (exec_file, argv); |
352 | |
353 | /* If we get here, it's an error. */ |
354 | errstring = safe_strerror (errno(*__errno())); |
Value stored to 'errstring' is never read | |
355 | fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); |
356 | |
357 | i = 1; |
358 | while (argv[i] != NULL((void*)0)) |
359 | { |
360 | if (i != 1) |
361 | fprintf_unfiltered (gdb_stderr, " "); |
362 | fprintf_unfiltered (gdb_stderr, "%s", argv[i]); |
363 | i++; |
364 | } |
365 | fprintf_unfiltered (gdb_stderr, ".\n"); |
366 | #if 0 |
367 | /* This extra info seems to be useless. */ |
368 | fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); |
369 | #endif |
370 | gdb_flush (gdb_stderr); |
371 | _exit (0177); |
372 | } |
373 | } |
374 | |
375 | /* Restore our environment in case a vforked child clob'd it. */ |
376 | environ = save_our_env; |
377 | |
378 | init_thread_list (); |
379 | |
380 | /* Needed for wait_for_inferior stuff below. */ |
381 | inferior_ptid = pid_to_ptid (pid); |
382 | |
383 | /* Now that we have a child process, make it our target, and |
384 | initialize anything target-vector-specific that needs |
385 | initializing. */ |
386 | (*init_trace_fun) (pid); |
387 | |
388 | /* We are now in the child process of interest, having exec'd the |
389 | correct program, and are poised at the first instruction of the |
390 | new program. */ |
391 | |
392 | /* Allow target dependent code to play with the new process. This |
393 | might be used to have target-specific code initialize a variable |
394 | in the new process prior to executing the first instruction. */ |
395 | TARGET_CREATE_INFERIOR_HOOK (pid); |
396 | |
397 | #ifdef SOLIB_CREATE_INFERIOR_HOOK |
398 | SOLIB_CREATE_INFERIOR_HOOK (pid)solib_create_inferior_hook(); |
399 | #endif |
400 | } |
401 | |
402 | /* Accept NTRAPS traps from the inferior. */ |
403 | |
404 | void |
405 | startup_inferior (int ntraps) |
406 | { |
407 | int pending_execs = ntraps; |
408 | int terminal_initted = 0; |
409 | |
410 | /* The process was started by the fork that created it, but it will |
411 | have stopped one instruction after execing the shell. Here we |
412 | must get it up to actual execution of the real program. */ |
413 | |
414 | clear_proceed_status (); |
415 | |
416 | init_wait_for_inferior (); |
417 | |
418 | if (STARTUP_WITH_SHELL1) |
419 | inferior_ignoring_startup_exec_events = ntraps; |
420 | else |
421 | inferior_ignoring_startup_exec_events = 0; |
422 | inferior_ignoring_leading_exec_events = |
423 | target_reported_exec_events_per_exec_call ()(*current_target.to_reported_exec_events_per_exec_call) () - 1; |
424 | |
425 | while (1) |
426 | { |
427 | /* Make wait_for_inferior be quiet. */ |
428 | stop_soon = STOP_QUIETLY; |
429 | wait_for_inferior (); |
430 | if (stop_signal != TARGET_SIGNAL_TRAP) |
431 | { |
432 | /* Let shell child handle its own signals in its own way. |
433 | FIXME: what if child has exited? Must exit loop |
434 | somehow. */ |
435 | resume (0, stop_signal); |
436 | } |
437 | else |
438 | { |
439 | /* We handle SIGTRAP, however; it means child did an exec. */ |
440 | if (!terminal_initted) |
441 | { |
442 | /* Now that the child has exec'd we know it has already |
443 | set its process group. On POSIX systems, tcsetpgrp |
444 | will fail with EPERM if we try it before the child's |
445 | setpgid. */ |
446 | |
447 | /* Set up the "saved terminal modes" of the inferior |
448 | based on what modes we are starting it with. */ |
449 | target_terminal_init ()(*current_target.to_terminal_init) (); |
450 | |
451 | /* Install inferior's terminal modes. */ |
452 | target_terminal_inferior ()(*current_target.to_terminal_inferior) (); |
453 | |
454 | terminal_initted = 1; |
455 | } |
456 | |
457 | if (--pending_execs == 0) |
458 | break; |
459 | |
460 | resume (0, TARGET_SIGNAL_0); /* Just make it go on. */ |
461 | } |
462 | } |
463 | stop_soon = NO_STOP_QUIETLY; |
464 | } |