diff options
Diffstat (limited to 'gdb/fork-child.c')
| -rw-r--r-- | gdb/fork-child.c | 355 |
1 files changed, 324 insertions, 31 deletions
diff --git a/gdb/fork-child.c b/gdb/fork-child.c index 243bed4..e262f89 100644 --- a/gdb/fork-child.c +++ b/gdb/fork-child.c @@ -33,12 +33,67 @@ Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ #include <unistd.h> #endif -extern char **environ; +#define DEBUGGING 0 +/* 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; + +#if DEBUGGING + printf("breakup_args: input = %s\n", scratch); +#endif + 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. @@ -47,12 +102,13 @@ extern char **environ; void fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, - shell_file) + pre_trace_fun, shell_file) char *exec_file; char *allargs; char **env; void (*traceme_fun) PARAMS ((void)); - int (*init_trace_fun) PARAMS ((int)); + void (*init_trace_fun) PARAMS ((int)); + void (*pre_trace_fun) PARAMS ((void)); char *shell_file; { int pid; @@ -65,22 +121,31 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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; + char *tryname; /* 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); - /* The user might want tilde-expansion, and in general probably wants - the program to behave the same way as if run from - his/her favorite shell. So we let the shell run it for us. - FIXME-maybe, we might want a "set shell" command so the user can change - the shell from within GDB (if so, change callers which pass in a non-NULL - shell_file too). */ - if (shell_file == NULL) - shell_file = getenv ("SHELL"); - if (shell_file == NULL) - shell_file = default_shell_file; + /* 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; + } + +#if DEBUGGING + printf("shell is %s\n", shell_file); +#endif /* 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 @@ -95,20 +160,40 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, shell_command = (char *) alloca (len); shell_command[0] = '\0'; #endif - strcat (shell_command, "exec "); - /* Now add exec_file, quoting as necessary. */ - { + if (!shell) { + /* We're going to call execvp. Create argv */ + /* Largest case: every other character is a separate arg */ +#if DEBUGGING + printf("allocating argv, length = %d\n", + ( + (strlen (allargs) + 1) / (unsigned) 2 + + 2 + ) * sizeof (*argv) + ); +#endif + 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) + switch (*p) { case '\'': case '"': @@ -137,8 +222,8 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, end_scan: if (need_to_quote) { - strcat (shell_command, "'"); - for (p = exec_file; *p != '\0'; ++p) + strcat (shell_command, "'"); + for (p = exec_file; *p != '\0'; ++p) { if (*p == '\'') strcat (shell_command, "'\\''"); @@ -149,10 +234,11 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, } else strcat (shell_command, exec_file); - } + + strcat (shell_command, " "); + strcat (shell_command, allargs); - strcat (shell_command, " "); - strcat (shell_command, allargs); + } /* exec is said to fail if the executable is open. */ close_exec_file (); @@ -174,6 +260,12 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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 @@ -209,6 +301,14 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, /* "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 @@ -216,12 +316,65 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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; - execlp (shell_file, shell_file, "-c", shell_command, (char *)0); - fprintf_unfiltered (gdb_stderr, "Cannot exec %s: %s.\n", shell_file, - safe_strerror (errno)); - gdb_flush (gdb_stderr); - _exit (0177); + /* 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) { +#if 0 + + /* HP change is problematic. The -f option has different meanings + for different shells. It is particularly inappropriate for + bourne shells. */ + execlp (shell_file, shell_file, "-f", "-c", shell_command, (char *)0); +#else + execlp (shell_file, shell_file, "-c", shell_command, (char *)0); +#endif + + + /* 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; +#if DEBUGGING + printf("about to exec target, exec_file = %s\n", exec_file); + i = 0; + while (argv[i] != NULL) { + printf("strlen(argv[%d]) is %d\n", i, strlen(argv[i])); + printf("argv[%d] is %s\n", i, argv[i]); + i++; + } +#endif + 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. */ @@ -234,8 +387,7 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, /* Now that we have a child process, make it our target, and initialize anything target-vector-specific that needs initializing. */ - /* Note that pid may be modified by this function. */ - inferior_pid = pid = (*init_trace_fun)(pid); + (*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 @@ -251,6 +403,137 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, #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 @@ -270,6 +553,13 @@ startup_inferior (ntraps) 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 @@ -301,9 +591,12 @@ startup_inferior (ntraps) terminal_initted = 1; } - if (0 == --pending_execs) + + pending_execs = pending_execs - 1; + if (0 == pending_execs) break; - resume (0, TARGET_SIGNAL_0); /* Just make it go on */ + + resume (0, TARGET_SIGNAL_0); /* Just make it go on */ } } #endif /* STARTUP_INFERIOR */ |