X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gdb%2Ffork-child.c;h=718a3d2de2129e84b596ed292c4608efb7ba4284;hb=c1299d67f5e87927ba19ac99524d238905b9c406;hp=1acb28ad4227c270c063b09dc5938d5e7bf03101;hpb=72ec28b8afa357cdde70c612b4e0e9f37a34f8e4;p=deliverable%2Fbinutils-gdb.git diff --git a/gdb/fork-child.c b/gdb/fork-child.c index 1acb28ad42..718a3d2de2 100644 --- a/gdb/fork-child.c +++ b/gdb/fork-child.c @@ -1,5 +1,8 @@ /* 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. + + Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, + 2000, 2001, 2004 Free Software Foundation, Inc. + Contributed by Cygnus Support. This file is part of GDB. @@ -25,6 +28,7 @@ #include "inferior.h" #include "target.h" #include "gdb_wait.h" +#include "gdb_vfork.h" #include "gdbcore.h" #include "terminal.h" #include "gdbthread.h" @@ -32,81 +36,92 @@ #include -/* This just gets used as a default if we can't find SHELL */ +/* 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". - */ +/* Break up SCRATCH into an argument vector suitable for passing to + execvp and store it in ARGV. 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; +breakup_args (char *scratch, char **argv) { char *cp = scratch; for (;;) { - /* Scan past leading separators */ while (*cp == ' ' || *cp == '\t' || *cp == '\n') - { - cp++; - } + cp++; - /* Break if at end of string */ + /* Break if at end of string. */ if (*cp == '\0') break; - /* Take an arg */ + /* Take an arg. */ *argv++ = cp; - /* Scan for next arg separator */ + /* 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 */ + /* No separators => end of string => break. */ if (cp == NULL) break; - /* Replace the separator with a terminator */ + /* Replace the separator with a terminator. */ *cp++ = '\0'; } - /* execv requires a null-terminated arg vector */ + /* Null-terminate the vector. */ *argv = NULL; +} +/* When executing a command under the given shell, return non-zero if + the '!' character should be escaped when embedded in a quoted + command-line argument. */ + +static int +escape_bang_in_quoted_argument (const char *shell_file) +{ + const int shell_file_len = strlen (shell_file); + + /* Bang should be escaped only in C Shells. For now, simply check + that the shell name ends with 'csh', which covers at least csh + and tcsh. This should be good enough for now. */ + + if (shell_file_len < 3) + return 0; + + if (shell_file[shell_file_len - 3] == 'c' + && shell_file[shell_file_len - 2] == 's' + && shell_file[shell_file_len - 1] == 'h') + return 1; + + return 0; } +/* Start an inferior Unix child process and sets inferior_ptid 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. */ -/* 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(). */ +/* This function is NOT reentrant. Some of the variables have been + made static to ensure that they survive the vfork call. */ 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; +fork_inferior (char *exec_file_arg, char *allargs, char **env, + void (*traceme_fun) (void), void (*init_trace_fun) (int), + void (*pre_trace_fun) (void), char *shell_file_arg) { int pid; char *shell_command; @@ -117,22 +132,25 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, /* 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; + static char *shell_file; + static char *exec_file; char **save_our_env; int shell = 0; - char **argv; + static 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 no exec file handed to us, get it from the exec-file command + -- with a good, common error message if none is specified. */ + exec_file = exec_file_arg; 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. - */ + /* STARTUP_WITH_SHELL is defined in inferior.h. If 0,e we'll just + do a fork/exec, no shell, so don't bother figuring out what + shell. */ + shell_file = shell_file_arg; if (STARTUP_WITH_SHELL) { - /* Figure out what shell to start up the user program under. */ + /* Figure out what shell to start up the user program under. */ if (shell_file == NULL) shell_file = getenv ("SHELL"); if (shell_file == NULL) @@ -140,9 +158,9 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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 '. */ + /* 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. */ @@ -156,34 +174,37 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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)); + /* We're going to call execvp. Create argument vector. + Calculate an upper bound on the length of the vector by + assuming that every other character is a separate + argument. */ + int argc = (strlen (allargs) + 1) / 2 + 2; + argv = (char **) xmalloc (argc * sizeof (*argv)); argv[0] = exec_file; breakup_args (allargs, &argv[1]); - } else { - - /* We're going to call a shell */ + /* We're going to call a shell. */ /* Now add exec_file, quoting as necessary. */ char *p; int need_to_quote; + const int escape_bang = escape_bang_in_quoted_argument (shell_file); 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. */ + /* 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 ')': @@ -215,6 +236,8 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, { if (*p == '\'') strcat (shell_command, "'\\''"); + else if (*p == '!' && escape_bang) + strcat (shell_command, "\\!"); else strncat (shell_command, p, 1); } @@ -225,43 +248,47 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, strcat (shell_command, " "); strcat (shell_command, allargs); - } - /* exec is said to fail if the executable is open. */ + /* On some systems an exec will 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 + 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. */ - + 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 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) + /* Create the child process. Since the child process is going to + exec(3) shortlty afterwards, try to reduce the overhead by + calling vfork(2). However, if PRE_TRACE_FUN is non-null, it's + likely that this optimization won't work since there's too much + work to do between the vfork(2) and the exec(3). This is known + to be the case on ttrace(2)-based HP-UX, where some handshaking + between parent and child needs to happen between fork(2) and + exec(2). However, since the parent is suspended in the vforked + state, this doesn't work. Also note that the vfork(2) call might + actually be a call to fork(2) due to the fact that autoconf will + ``#define vfork fork'' on certain platforms. */ + if (pre_trace_fun || debug_fork) pid = fork (); else pid = vfork (); -#endif if (pid < 0) perror_with_name ("vfork"); @@ -276,9 +303,9 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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). */ - + /* 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 @@ -289,14 +316,15 @@ 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! - */ + 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 @@ -305,19 +333,17 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, 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 ". - * "-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 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 + ". "-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 */ + /* 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); @@ -325,13 +351,14 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, } else { - /* Otherwise, we directly exec the target program with execvp. */ + /* 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 */ + /* If we get here, it's an error. */ errstring = safe_strerror (errno); fprintf_unfiltered (gdb_stderr, "Cannot exec %s ", exec_file); @@ -344,9 +371,10 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, i++; } fprintf_unfiltered (gdb_stderr, ".\n"); - /* This extra info seems to be useless - fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); - */ +#if 0 + /* This extra info seems to be useless. */ + fprintf_unfiltered (gdb_stderr, "Got error %s.\n", errstring); +#endif gdb_flush (gdb_stderr); _exit (0177); } @@ -357,20 +385,21 @@ fork_inferior (exec_file, allargs, env, traceme_fun, init_trace_fun, init_thread_list (); - inferior_pid = pid; /* Needed for wait_for_inferior stuff below */ + /* Needed for wait_for_inferior stuff below. */ + inferior_ptid = pid_to_ptid (pid); /* Now that we have a child process, make it our target, and - initialize anything target-vector-specific that needs initializing. */ - + 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. */ + /* Allow target dependent 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 @@ -378,156 +407,22 @@ 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 -startup_inferior (ntraps) - int ntraps; +startup_inferior (int ntraps) { int pending_execs = ntraps; - int terminal_initted; + int terminal_initted = 0; - /* 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. */ + /* 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 @@ -535,17 +430,16 @@ startup_inferior (ntraps) 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 */ + /* Make wait_for_inferior be quiet. */ + stop_soon = STOP_QUIETLY; 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 */ + /* Let shell child handle its own signals in its own way. + FIXME: what if child has exited? Must exit loop + somehow. */ resume (0, stop_signal); } else @@ -553,9 +447,10 @@ startup_inferior (ntraps) /* 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. */ + /* 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. */ @@ -567,13 +462,11 @@ startup_inferior (ntraps) terminal_initted = 1; } - pending_execs = pending_execs - 1; - if (0 == pending_execs) + if (--pending_execs == 0) break; - resume (0, TARGET_SIGNAL_0); /* Just make it go on */ + resume (0, TARGET_SIGNAL_0); /* Just make it go on. */ } } -#endif /* STARTUP_INFERIOR */ - stop_soon_quietly = 0; + stop_soon = NO_STOP_QUIETLY; }