X-Git-Url: http://git.efficios.com/?a=blobdiff_plain;f=gdb%2Ffork-child.c;h=41d5e2a0a47b53baf12799e16880d146a10098f3;hb=refs%2Fheads%2Fconcurrent-displaced-stepping-2020-04-01;hp=2b085ffe6aef8b9ed275c54ad1044f0b21b00d72;hpb=bb9bcb69cdddee8069bf24321f9a0e91ffd22f32;p=deliverable%2Fbinutils-gdb.git

diff --git a/gdb/fork-child.c b/gdb/fork-child.c
index 2b085ffe6a..41d5e2a0a4 100644
--- a/gdb/fork-child.c
+++ b/gdb/fork-child.c
@@ -1,8 +1,6 @@
 /* Fork a Unix child process, and set up to debug it, for GDB.
 
-   Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2000,
-   2001, 2004, 2005, 2006, 2007, 2008, 2009, 2010
-   Free Software Foundation, Inc.
+   Copyright (C) 1990-2020 Free Software Foundation, Inc.
 
    Contributed by Cygnus Support.
 
@@ -22,537 +20,146 @@
    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include "defs.h"
-#include "gdb_string.h"
 #include "inferior.h"
-#include "terminal.h"
-#include "target.h"
-#include "gdb_wait.h"
-#include "gdb_vfork.h"
-#include "gdbcore.h"
+#include "gdbcmd.h"
 #include "terminal.h"
 #include "gdbthread.h"
-#include "command.h" /* for dont_repeat () */
-#include "gdbcmd.h"
-#include "solib.h"
-
-#include <signal.h>
+#include "top.h"
+#include "gdbsupport/job-control.h"
+#include "gdbsupport/filestuff.h"
+#include "nat/fork-inferior.h"
+#include "gdbsupport/common-inferior.h"
 
-/* This just gets used as a default if we can't find SHELL.  */
-#define SHELL_FILE "/bin/sh"
+/* The exec-wrapper, if any, that will be used when starting the
+   inferior.  */
 
-extern char **environ;
+static char *exec_wrapper = NULL;
 
-static char *exec_wrapper;
+/* See gdbsupport/common-inferior.h.  */
 
-/* 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)
+const char *
+get_exec_wrapper ()
 {
-  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';
-    }
-
-  /* Null-terminate the vector.  */
-  *argv = NULL;
+  return exec_wrapper;
 }
 
-/* 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.  */
+/* See nat/fork-inferior.h.  */
 
-static int
-escape_bang_in_quoted_argument (const char *shell_file)
+void
+gdb_flush_out_err ()
 {
-  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;
+  gdb_flush (main_ui->m_gdb_stdout);
+  gdb_flush (main_ui->m_gdb_stderr);
 }
 
-/* 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.  */
+/* The ui structure that will be saved on 'prefork_hook' and
+   restored on 'postfork_hook'.  */
+static struct ui *saved_ui = NULL;
 
-/* This function is NOT reentrant.  Some of the variables have been
-   made static to ensure that they survive the vfork call.  */
+/* See nat/fork-inferior.h.  */
 
-int
-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)
+void
+prefork_hook (const char *args)
 {
-  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;
-  static char *shell_file;
-  static char *exec_file;
-  char **save_our_env;
-  int shell = 0;
-  static char **argv;
   const char *inferior_io_terminal = get_inferior_io_terminal ();
-  struct inferior *inf;
-
-  /* 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,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.  */
-      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 (exec_wrapper)
-    len += strlen (exec_wrapper) + 1;
-
-  shell_command = (char *) alloca (len);
-  shell_command[0] = '\0';
-
-  if (!shell)
-    {
-      /* 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.  */
-
-      char *p;
-      int need_to_quote;
-      const int escape_bang = escape_bang_in_quoted_argument (shell_file);
-
-      strcat (shell_command, "exec ");
-
-      /* Add any exec wrapper.  That may be a program name with arguments, so
-	 the user must handle quoting.  */
-      if (exec_wrapper)
-	{
-	  strcat (shell_command, exec_wrapper);
-	  strcat (shell_command, " ");
-	}
-
-      /* Now add exec_file, quoting as necessary.  */
-
-      /* 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 ' ':
-	    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 if (*p == '!' && escape_bang)
-		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);
-    }
-
-  /* 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
-     restore it.  */
-  save_our_env = environ;
+  gdb_assert (saved_ui == NULL);
+  /* Retain a copy of our UI, since the child will replace this value
+     and if we're vforked, we have to restore it.  */
+  saved_ui = current_ui;
 
   /* 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) ();
-
-  /* Create the child process.  Since the child process is going to
-     exec(3) shortly 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 (pid < 0)
-    perror_with_name (("vfork"));
-
-  if (pid == 0)
-    {
-      if (debug_fork)
-	sleep (debug_fork);
-
-      /* Create a new session for the inferior process, if necessary.
-         It will also place the inferior in a separate process group.  */
-      if (create_tty_session () <= 0)
-	{
-	  /* No session was created, but we still want to run the 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>".  */
-      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");
-#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);
-	}
-    }
-
-  /* Restore our environment in case a vforked child clob'd it.  */
-  environ = save_our_env;
-
-  if (!have_inferiors ())
-    init_thread_list ();
+/* See nat/fork-inferior.h.  */
 
-  inf = current_inferior ();
+void
+postfork_hook (pid_t pid)
+{
+  inferior *inf = current_inferior ();
 
   inferior_appeared (inf, pid);
 
-  /* Needed for wait_for_inferior stuff below.  */
-  inferior_ptid = pid_to_ptid (pid);
+  /* Needed for wait_for_inferior stuff.  */
+  inferior_ptid = ptid_t (pid);
 
-  new_tty_postfork ();
+  gdb_assert (saved_ui != NULL);
+  current_ui = saved_ui;
+  saved_ui = NULL;
 
-  /* We have something that executes now.  We'll be running through
-     the shell at this point, but the pid shouldn't change.  Targets
-     supporting MT should fill this task's ptid with more data as soon
-     as they can.  */
-  add_thread_silent (inferior_ptid);
-
-  /* Now that we have a child process, make it our target, and
-     initialize anything target-vector-specific that needs
-     initializing.  */
-  if (init_trace_fun)
-    (*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.  */
-  return pid;
+  new_tty_postfork ();
 }
 
-/* Accept NTRAPS traps from the inferior.  */
+/* See nat/fork-inferior.h.  */
 
 void
-startup_inferior (int ntraps)
+postfork_child_hook ()
 {
-  int pending_execs = ntraps;
-  int terminal_initted = 0;
-  ptid_t resume_ptid;
-
-  if (target_supports_multi_process ())
-    resume_ptid = pid_to_ptid (ptid_get_pid (inferior_ptid));
-  else
-    resume_ptid = minus_one_ptid;
-
-  /* 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.  */
+  /* 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;
 
-  if (exec_wrapper)
-    pending_execs++;
+  /* Make sure we switch to main_ui here in order to be able to
+     use the fprintf_unfiltered/warning/error functions.  */
+  current_ui = main_ui;
 
-  while (1)
+  /* Create a new session for the inferior process, if necessary.
+     It will also place the inferior in a separate process group.  */
+  if (create_tty_session () <= 0)
     {
-      int resume_signal = TARGET_SIGNAL_0;
-      ptid_t event_ptid;
-
-      struct target_waitstatus ws;
-      memset (&ws, 0, sizeof (ws));
-      event_ptid = target_wait (resume_ptid, &ws, 0);
-
-      if (ws.kind == TARGET_WAITKIND_IGNORE)
-	/* The inferior didn't really stop, keep waiting.  */
-	continue;
-
-      switch (ws.kind)
-	{
-	  case TARGET_WAITKIND_SPURIOUS:
-	  case TARGET_WAITKIND_LOADED:
-	  case TARGET_WAITKIND_FORKED:
-	  case TARGET_WAITKIND_VFORKED:
-	  case TARGET_WAITKIND_SYSCALL_ENTRY:
-	  case TARGET_WAITKIND_SYSCALL_RETURN:
-	    /* Ignore gracefully during startup of the inferior.  */
-	    switch_to_thread (event_ptid);
-	    break;
-
-	  case TARGET_WAITKIND_SIGNALLED:
-	    target_terminal_ours ();
-	    target_mourn_inferior ();
-	    error (_("During startup program terminated with signal %s, %s."),
-		   target_signal_to_name (ws.value.sig),
-		   target_signal_to_string (ws.value.sig));
-	    return;
-
-	  case TARGET_WAITKIND_EXITED:
-	    target_terminal_ours ();
-	    target_mourn_inferior ();
-	    if (ws.value.integer)
-	      error (_("During startup program exited with code %d."),
-		     ws.value.integer);
-	    else
-	      error (_("During startup program exited normally."));
-	    return;
-
-	  case TARGET_WAITKIND_EXECD:
-	    /* Handle EXEC signals as if they were SIGTRAP signals.  */
-	    xfree (ws.value.execd_pathname);
-	    resume_signal = TARGET_SIGNAL_TRAP;
-	    switch_to_thread (event_ptid);
-	    break;
-
-	  case TARGET_WAITKIND_STOPPED:
-	    resume_signal = ws.value.sig;
-	    switch_to_thread (event_ptid);
-	    break;
-	}
-
-      if (resume_signal != TARGET_SIGNAL_TRAP)
-	{
-	  /* Let shell child handle its own signals in its own way.  */
-	  target_resume (resume_ptid, 0, resume_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;
-	    }
-
-	  if (--pending_execs == 0)
-	    break;
-
-	  /* Just make it go on.  */
-	  target_resume (resume_ptid, 0, TARGET_SIGNAL_0);
-	}
+      /* No session was created, but we still want to run the 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 ();
+}
+
+/* See inferior.h.  */
+
+ptid_t
+gdb_startup_inferior (pid_t pid, int num_traps)
+{
+  inferior *inf = current_inferior ();
+  process_stratum_target *proc_target = inf->process_target ();
+
+  ptid_t ptid = startup_inferior (proc_target, pid, num_traps, NULL, NULL);
+
   /* Mark all threads non-executing.  */
-  set_executing (resume_ptid, 0);
+  set_executing (proc_target, ptid, false);
+
+  return ptid;
 }
 
 /* Implement the "unset exec-wrapper" command.  */
 
 static void
-unset_exec_wrapper_command (char *args, int from_tty)
+unset_exec_wrapper_command (const char *args, int from_tty)
 {
   xfree (exec_wrapper);
   exec_wrapper = NULL;
 }
 
-/* Provide a prototype to silence -Wmissing-prototypes.  */
-extern initialize_file_ftype _initialize_fork_child;
+static void
+show_startup_with_shell (struct ui_file *file, int from_tty,
+			 struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file,
+		    _("Use of shell to start subprocesses is %s.\n"),
+		    value);
+}
 
+void _initialize_fork_child ();
 void
-_initialize_fork_child (void)
+_initialize_fork_child ()
 {
   add_setshow_filename_cmd ("exec-wrapper", class_run, &exec_wrapper, _("\
 Set a wrapper for running programs.\n\
@@ -565,4 +172,12 @@ Show the wrapper for running programs."), NULL,
   add_cmd ("exec-wrapper", class_run, unset_exec_wrapper_command,
            _("Disable use of an execution wrapper."),
            &unsetlist);
+
+  add_setshow_boolean_cmd ("startup-with-shell", class_support,
+			   &startup_with_shell, _("\
+Set use of shell to start subprocesses.  The default is on."), _("\
+Show use of shell to start subprocesses."), NULL,
+			   NULL,
+			   show_startup_with_shell,
+			   &setlist, &showlist);
 }