| /* Fork a Unix child process, and set up to debug it, for GDB. |
| Copyright 1990, 91, 92, 93, 94, 1996, 1999 Free Software Foundation, Inc. |
| Contributed by Cygnus Support. |
| |
| This file is part of GDB. |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place - Suite 330, |
| Boston, MA 02111-1307, USA. */ |
| |
| #include "defs.h" |
| #include "gdb_string.h" |
| #include "frame.h" /* required by inferior.h */ |
| #include "inferior.h" |
| #include "target.h" |
| #include "wait.h" |
| #include "gdbcore.h" |
| #include "terminal.h" |
| #include "gdbthread.h" |
| |
| #include <signal.h> |
| |
| /* This just gets used as a default if we can't find SHELL */ |
| #ifndef SHELL_FILE |
| #define SHELL_FILE "/bin/sh" |
| #endif |
| |
| extern char **environ; |
| |
| /* This function breaks up an argument string into an argument |
| * vector suitable for passing to execvp(). |
| * E.g., on "run a b c d" this routine would get as input |
| * the string "a b c d", and as output it would fill in argv with |
| * the four arguments "a", "b", "c", "d". |
| */ |
| static void |
| breakup_args ( |
| scratch, |
| argv) |
| char *scratch; |
| char **argv; |
| { |
| char *cp = scratch; |
| |
| for (;;) |
| { |
| |
| /* Scan past leading separators */ |
| while (*cp == ' ' || *cp == '\t' || *cp == '\n') |
| { |
| cp++; |
| } |
| |
| /* Break if at end of string */ |
| if (*cp == '\0') |
| break; |
| |
| /* Take an arg */ |
| *argv++ = cp; |
| |
| /* Scan for next arg separator */ |
| cp = strchr (cp, ' '); |
| if (cp == NULL) |
| cp = strchr (cp, '\t'); |
| if (cp == NULL) |
| cp = strchr (cp, '\n'); |
| |
| /* No separators => end of string => break */ |
| if (cp == NULL) |
| break; |
| |
| /* Replace the separator with a terminator */ |
| *cp++ = '\0'; |
| } |
| |
| /* execv requires a null-terminated arg vector */ |
| *argv = NULL; |
| |
| } |
| |
| |
| /* Start an inferior Unix child process and sets inferior_pid to its pid. |
| EXEC_FILE is the file to run. |
| ALLARGS is a string containing the arguments to the program. |
| ENV is the environment vector to pass. SHELL_FILE is the shell file, |
| or NULL if we should pick one. Errors reported with error(). */ |
| |
| void |
| fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, |
| pre_trace_fun, shell_file) |
| char *exec_file; |
| char *allargs; |
| char **env; |
| void (*traceme_fun) PARAMS ((void)); |
| void (*init_trace_fun) PARAMS ((int)); |
| void (*pre_trace_fun) PARAMS ((void)); |
| char *shell_file; |
| { |
| int pid; |
| char *shell_command; |
| static char default_shell_file[] = SHELL_FILE; |
| int len; |
| /* Set debug_fork then attach to the child while it sleeps, to debug. */ |
| static int debug_fork = 0; |
| /* This is set to the result of setpgrp, which if vforked, will be visible |
| to you in the parent process. It's only used by humans for debugging. */ |
| static int debug_setpgrp = 657473; |
| char **save_our_env; |
| int shell = 0; |
| char **argv; |
| |
| /* If no exec file handed to us, get it from the exec-file command -- with |
| a good, common error message if none is specified. */ |
| if (exec_file == 0) |
| exec_file = get_exec_file (1); |
| |
| /* STARTUP_WITH_SHELL is defined in inferior.h. |
| * If 0, we'll just do a fork/exec, no shell, so don't |
| * bother figuring out what shell. |
| */ |
| if (STARTUP_WITH_SHELL) |
| { |
| /* Figure out what shell to start up the user program under. */ |
| if (shell_file == NULL) |
| shell_file = getenv ("SHELL"); |
| if (shell_file == NULL) |
| shell_file = default_shell_file; |
| shell = 1; |
| } |
| |
| /* Multiplying the length of exec_file by 4 is to account for the fact |
| that it may expand when quoted; it is a worst-case number based on |
| every character being '. */ |
| len = 5 + 4 * strlen (exec_file) + 1 + strlen (allargs) + 1 + /*slop */ 12; |
| /* If desired, concat something onto the front of ALLARGS. |
| SHELL_COMMAND is the result. */ |
| #ifdef SHELL_COMMAND_CONCAT |
| shell_command = (char *) alloca (strlen (SHELL_COMMAND_CONCAT) + len); |
| strcpy (shell_command, SHELL_COMMAND_CONCAT); |
| #else |
| shell_command = (char *) alloca (len); |
| shell_command[0] = '\0'; |
| #endif |
| |
| if (!shell) |
| { |
| /* We're going to call execvp. Create argv */ |
| /* Largest case: every other character is a separate arg */ |
| argv = (char **) xmalloc (((strlen (allargs) + 1) / (unsigned) 2 + 2) * sizeof (*argv)); |
| argv[0] = exec_file; |
| breakup_args (allargs, &argv[1]); |
| |
| } |
| else |
| { |
| |
| /* We're going to call a shell */ |
| |
| /* Now add exec_file, quoting as necessary. */ |
| |
| char *p; |
| int need_to_quote; |
| |
| strcat (shell_command, "exec "); |
| |
| /* Quoting in this style is said to work with all shells. But csh |
| on IRIX 4.0.1 can't deal with it. So we only quote it if we need |
| to. */ |
| p = exec_file; |
| while (1) |
| { |
| switch (*p) |
| { |
| case '\'': |
| case '"': |
| case '(': |
| case ')': |
| case '$': |
| case '&': |
| case ';': |
| case '<': |
| case '>': |
| case ' ': |
| case '\n': |
| case '\t': |
| need_to_quote = 1; |
| goto end_scan; |
| |
| case '\0': |
| need_to_quote = 0; |
| goto end_scan; |
| |
| default: |
| break; |
| } |
| ++p; |
| } |
| end_scan: |
| if (need_to_quote) |
| { |
| strcat (shell_command, "'"); |
| for (p = exec_file; *p != '\0'; ++p) |
| { |
| if (*p == '\'') |
| strcat (shell_command, "'\\''"); |
| else |
| strncat (shell_command, p, 1); |
| } |
| strcat (shell_command, "'"); |
| } |
| else |
| strcat (shell_command, exec_file); |
| |
| strcat (shell_command, " "); |
| strcat (shell_command, allargs); |
| |
| } |
| |
| /* exec is said to fail if the executable is open. */ |
| close_exec_file (); |
| |
| /* Retain a copy of our environment variables, since the child will |
| replace the value of environ and if we're vforked, we have to |
| restore it. */ |
| save_our_env = environ; |
| |
| /* Tell the terminal handling subsystem what tty we plan to run on; |
| it will just record the information for later. */ |
| |
| new_tty_prefork (inferior_io_terminal); |
| |
| /* It is generally good practice to flush any possible pending stdio |
| output prior to doing a fork, to avoid the possibility of both the |
| parent and child flushing the same data after the fork. */ |
| |
| gdb_flush (gdb_stdout); |
| gdb_flush (gdb_stderr); |
| |
| /* If there's any initialization of the target layers that must happen |
| to prepare to handle the child we're about fork, do it now... |
| */ |
| if (pre_trace_fun != NULL) |
| (*pre_trace_fun) (); |
| |
| #if defined(USG) && !defined(HAVE_VFORK) |
| pid = fork (); |
| #else |
| if (debug_fork) |
| pid = fork (); |
| else |
| pid = vfork (); |
| #endif |
| |
| if (pid < 0) |
| perror_with_name ("vfork"); |
| |
| if (pid == 0) |
| { |
| if (debug_fork) |
| sleep (debug_fork); |
| |
| /* Run inferior in a separate process group. */ |
| debug_setpgrp = gdb_setpgid (); |
| if (debug_setpgrp == -1) |
| perror ("setpgrp failed in child"); |
| |
| /* Ask the tty subsystem to switch to the one we specified earlier |
| (or to share the current terminal, if none was specified). */ |
| |
| new_tty (); |
| |
| /* Changing the signal handlers for the inferior after |
| a vfork can also change them for the superior, so we don't mess |
| with signals here. See comments in |
| initialize_signals for how we get the right signal handlers |
| for the inferior. */ |
| |
| /* "Trace me, Dr. Memory!" */ |
| (*traceme_fun) (); |
| /* The call above set this process (the "child") as debuggable |
| * by the original gdb process (the "parent"). Since processes |
| * (unlike people) can have only one parent, if you are |
| * debugging gdb itself (and your debugger is thus _already_ the |
| * controller/parent for this child), code from here on out |
| * is undebuggable. Indeed, you probably got an error message |
| * saying "not parent". Sorry--you'll have to use print statements! |
| */ |
| |
| /* There is no execlpe call, so we have to set the environment |
| for our child in the global variable. If we've vforked, this |
| clobbers the parent, but environ is restored a few lines down |
| in the parent. By the way, yes we do need to look down the |
| path to find $SHELL. Rich Pixley says so, and I agree. */ |
| environ = env; |
| |
| /* If we decided above to start up with a shell, |
| * we exec the shell, |
| * "-c" says to interpret the next arg as a shell command |
| * to execute, and this command is "exec <target-program> <args>". |
| * "-f" means "fast startup" to the c-shell, which means |
| * don't do .cshrc file. Doing .cshrc may cause fork/exec |
| * events which will confuse debugger start-up code. |
| */ |
| if (shell) |
| { |
| execlp (shell_file, shell_file, "-c", shell_command, (char *) 0); |
| |
| /* If we get here, it's an error */ |
| fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, |
| safe_strerror (errno)); |
| gdb_flush (gdb_stderr); |
| _exit (0177); |
| } |
| else |
| { |
| /* Otherwise, we directly exec the target program with execvp. */ |
| int i; |
| char *errstring; |
| |
| execvp (exec_file, argv); |
| |
| /* If we get here, it's an error */ |
| errstring = safe_strerror (errno); |
| fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); |
| |
| i = 1; |
| while (argv[i] != NULL) |
| { |
| if (i != 1) |
| fprintf_unfiltered (gdb_stderr, " "); |
| fprintf_unfiltered (gdb_stderr, "%s", argv[i]); |
| i++; |
| } |
| fprintf_unfiltered (gdb_stderr, ".\n"); |
| /* This extra info seems to be useless |
| fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); |
| */ |
| gdb_flush (gdb_stderr); |
| _exit (0177); |
| } |
| } |
| |
| /* Restore our environment in case a vforked child clob'd it. */ |
| environ = save_our_env; |
| |
| init_thread_list (); |
| |
| inferior_pid = pid; /* Needed for wait_for_inferior stuff below */ |
| |
| /* Now that we have a child process, make it our target, and |
| initialize anything target-vector-specific that needs initializing. */ |
| |
| (*init_trace_fun) (pid); |
| |
| /* We are now in the child process of interest, having exec'd the |
| correct program, and are poised at the first instruction of the |
| new program. */ |
| |
| /* Allow target dependant code to play with the new process. This might be |
| used to have target-specific code initialize a variable in the new process |
| prior to executing the first instruction. */ |
| TARGET_CREATE_INFERIOR_HOOK (pid); |
| |
| #ifdef SOLIB_CREATE_INFERIOR_HOOK |
| SOLIB_CREATE_INFERIOR_HOOK (pid); |
| #endif |
| } |
| |
| /* An inferior Unix process CHILD_PID has been created by a call to |
| fork() (or variants like vfork). It is presently stopped, and waiting |
| to be resumed. clone_and_follow_inferior will fork the debugger, |
| and that clone will "follow" (attach to) CHILD_PID. The original copy |
| of the debugger will not touch CHILD_PID again. |
| |
| Also, the original debugger will set FOLLOWED_CHILD FALSE, while the |
| clone will set it TRUE. |
| */ |
| void |
| clone_and_follow_inferior (child_pid, followed_child) |
| int child_pid; |
| int *followed_child; |
| { |
| extern int auto_solib_add; |
| |
| int debugger_pid; |
| int status; |
| char pid_spelling[100]; /* Arbitrary but sufficient length. */ |
| |
| /* This semaphore is used to coordinate the two debuggers' handoff |
| of CHILD_PID. The original debugger will detach from CHILD_PID, |
| and then the clone debugger will attach to it. (It must be done |
| this way because on some targets, only one process at a time can |
| trace another. Thus, the original debugger must relinquish its |
| tracing rights before the clone can pick them up.) |
| */ |
| #define SEM_TALK (1) |
| #define SEM_LISTEN (0) |
| int handoff_semaphore[2]; /* Original "talks" to [1], clone "listens" to [0] */ |
| int talk_value = 99; |
| int listen_value; |
| |
| /* Set debug_fork then attach to the child while it sleeps, to debug. */ |
| static int debug_fork = 0; |
| |
| /* It is generally good practice to flush any possible pending stdio |
| output prior to doing a fork, to avoid the possibility of both the |
| parent and child flushing the same data after the fork. */ |
| |
| gdb_flush (gdb_stdout); |
| gdb_flush (gdb_stderr); |
| |
| /* Open the semaphore pipes. |
| */ |
| status = pipe (handoff_semaphore); |
| if (status < 0) |
| error ("error getting pipe for handoff semaphore"); |
| |
| /* Clone the debugger. */ |
| #if defined(USG) && !defined(HAVE_VFORK) |
| debugger_pid = fork (); |
| #else |
| if (debug_fork) |
| debugger_pid = fork (); |
| else |
| debugger_pid = vfork (); |
| #endif |
| |
| if (debugger_pid < 0) |
| perror_with_name ("fork"); |
| |
| /* Are we the original debugger? If so, we must relinquish all claims |
| to CHILD_PID. */ |
| if (debugger_pid != 0) |
| { |
| char signal_spelling[100]; /* Arbitrary but sufficient length */ |
| |
| /* Detach from CHILD_PID. Deliver a "stop" signal when we do, though, |
| so that it remains stopped until the clone debugger can attach |
| to it. |
| */ |
| detach_breakpoints (child_pid); |
| |
| sprintf (signal_spelling, "%d", target_signal_to_host (TARGET_SIGNAL_STOP)); |
| target_require_detach (child_pid, signal_spelling, 1); |
| |
| /* Notify the clone debugger that it should attach to CHILD_PID. */ |
| write (handoff_semaphore[SEM_TALK], &talk_value, sizeof (talk_value)); |
| |
| *followed_child = 0; |
| } |
| |
| /* We're the child. */ |
| else |
| { |
| if (debug_fork) |
| sleep (debug_fork); |
| |
| /* The child (i.e., the cloned debugger) must now attach to |
| CHILD_PID. inferior_pid is presently set to the parent process |
| of the fork, while CHILD_PID should be the child process of the |
| fork. |
| |
| Wait until the original debugger relinquishes control of CHILD_PID, |
| though. |
| */ |
| read (handoff_semaphore[SEM_LISTEN], &listen_value, sizeof (listen_value)); |
| |
| /* Note that we DON'T want to actually detach from inferior_pid, |
| because that would allow it to run free. The original |
| debugger wants to retain control of the process. So, we |
| just reset inferior_pid to CHILD_PID, and then ensure that all |
| breakpoints are really set in CHILD_PID. |
| */ |
| target_mourn_inferior (); |
| |
| /* Ask the tty subsystem to switch to the one we specified earlier |
| (or to share the current terminal, if none was specified). */ |
| |
| new_tty (); |
| |
| dont_repeat (); |
| sprintf (pid_spelling, "%d", child_pid); |
| target_require_attach (pid_spelling, 1); |
| |
| /* Perform any necessary cleanup, after attachment. (This form |
| of attaching can behave differently on some targets than the |
| standard method, where a process formerly not under debugger |
| control was suddenly attached to..) |
| */ |
| target_post_follow_inferior_by_clone (); |
| |
| *followed_child = 1; |
| } |
| |
| /* Discard the handoff sempahore. */ |
| (void) close (handoff_semaphore[SEM_LISTEN]); |
| (void) close (handoff_semaphore[SEM_TALK]); |
| } |
| |
| /* Accept NTRAPS traps from the inferior. */ |
| |
| void |
| startup_inferior (ntraps) |
| int ntraps; |
| { |
| int pending_execs = ntraps; |
| int terminal_initted; |
| |
| /* The process was started by the fork that created it, |
| but it will have stopped one instruction after execing the shell. |
| Here we must get it up to actual execution of the real program. */ |
| |
| clear_proceed_status (); |
| |
| init_wait_for_inferior (); |
| |
| terminal_initted = 0; |
| |
| if (STARTUP_WITH_SHELL) |
| inferior_ignoring_startup_exec_events = ntraps; |
| else |
| inferior_ignoring_startup_exec_events = 0; |
| inferior_ignoring_leading_exec_events = |
| target_reported_exec_events_per_exec_call () - 1; |
| |
| #ifdef STARTUP_INFERIOR |
| STARTUP_INFERIOR (pending_execs); |
| #else |
| while (1) |
| { |
| stop_soon_quietly = 1; /* Make wait_for_inferior be quiet */ |
| wait_for_inferior (); |
| if (stop_signal != TARGET_SIGNAL_TRAP) |
| { |
| /* Let shell child handle its own signals in its own way */ |
| /* FIXME, what if child has exit()ed? Must exit loop somehow */ |
| resume (0, stop_signal); |
| } |
| else |
| { |
| /* We handle SIGTRAP, however; it means child did an exec. */ |
| if (!terminal_initted) |
| { |
| /* Now that the child has exec'd we know it has already set its |
| process group. On POSIX systems, tcsetpgrp will fail with |
| EPERM if we try it before the child's setpgid. */ |
| |
| /* Set up the "saved terminal modes" of the inferior |
| based on what modes we are starting it with. */ |
| target_terminal_init (); |
| |
| /* Install inferior's terminal modes. */ |
| target_terminal_inferior (); |
| |
| terminal_initted = 1; |
| } |
| |
| pending_execs = pending_execs - 1; |
| if (0 == pending_execs) |
| break; |
| |
| resume (0, TARGET_SIGNAL_0); /* Just make it go on */ |
| } |
| } |
| #endif /* STARTUP_INFERIOR */ |
| stop_soon_quietly = 0; |
| } |