/* Fork a Unix child process, and set up to debug it, for GDB.
- Copyright 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
- 2001 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.
#include <signal.h>
-/* 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 (char *scratch, char **argv)
{
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
+/* 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. */
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. Errors reported with error(). */
+/* 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. */
-/* This function is NOT-REENTRANT. Some of the variables have been
- made static to ensure that they survive the vfork() call. */
+/* This function is NOT reentrant. Some of the variables have been
+ made static to ensure that they survive the vfork call. */
void
fork_inferior (char *exec_file_arg, char *allargs, char **env,
int shell = 0;
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)
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. */
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. */
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)
{
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) ();
- /* Create the child process. Note that the apparent call to vfork()
- below *might* actually be a call to fork() due to the fact that
- autoconf will ``#define vfork fork'' on certain platforms. */
- 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 ();
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
/* "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
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 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 */
+ /* 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);
}
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);
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);
}
init_thread_list ();
- inferior_ptid = pid_to_ptid (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 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. */
+ /* 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
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
while (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
/* 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. */
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. */
}
}
stop_soon = NO_STOP_QUIETLY;
projects / deliverable / binutils-gdb.git / blobdiff