Share fork_inferior et al with gdbserver

This is the most important (and the biggest, sorry) patch of the
series.  It moves fork_inferior from gdb/fork-child.c to
nat/fork-inferior.c and makes all the necessary adjustments to both
GDB and gdbserver to make sure everything works OK.

There is no "most important change" with this patch; all changes are
made in a progressive way, making sure that gdbserver had the
necessary features while not breaking GDB at the same time.

I decided to go ahead and implement a partial support for starting the
inferior with a shell on gdbserver, although the full feature comes in
the next patch.  The user won't have the option to disable the
startup-with-shell, and also won't be able to change which shell
gdbserver will use (other than setting the $SHELL environment
variable, that is).

Everything is working as expected, and no regressions were present
during the tests.

gdb/ChangeLog:
2017-06-07  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Pedro Alves  <palves@redhat.com>

	* Makefile.in (HFILES_NO_SRCDIR): Add "common/common-inferior.h"
	and "nat/fork-inferior.h".
	* common/common-inferior.h: New file, with contents from
	"gdb/inferior.h".
	* commom/common-utils.c: Include "common-utils.h".
	(stringify_argv): New function.
	* common/common-utils.h (stringify_argv): New prototype.
	* configure.nat: Add "fork-inferior.o" as a dependency for
	"*linux*", "fbsd*" and "nbsd*" hosts.
	* corefile.c (get_exec_file): Update comment.
	* darwin-nat.c (darwin_ptrace_him): Call "gdb_startup_inferior"
	instead of "startup_inferior".
	(darwin_create_inferior): Call "add_thread_silent" after
	"fork_inferior".
	* fork-child.c: Cleanup unnecessary includes.
	(SHELL_FILE): Move to "common/common-fork-child.c".
	(environ): Likewise.
	(exec_wrapper): Initialize.
	(get_exec_wrapper): New function.
	(breakup_args): Move to "common/common-fork-child.c"; rename to
	"breakup_args_for_exec".
	(escape_bang_in_quoted_argument): Move to
	"common/common-fork-child.c".
	(saved_ui): New variable.
	(prefork_hook): New function.
	(postfork_hook): Likewise.
	(postfork_child_hook): Likewise.
	(gdb_startup_inferior): Likewise.
	(fork_inferior): Move to "common/common-fork-child.c".  Update
	function to support gdbserver.
	(startup_inferior): Likewise.
	* gdbcore.h (get_exec_file): Remove declaration.
	* gnu-nat.c (gnu_create_inferior): Call "gdb_startup_inferior"
	instead of "startup_inferior".  Call "add_thread_silent" after
	"fork_inferior".
	* inf-ptrace.c: Include "nat/fork-inferior.h" and "utils.h".
	(inf_ptrace_create_inferior): Call "gdb_startup_inferior"
	instead of "startup_inferior".  Call "add_thread_silent" after
	"fork_inferior".
	* inferior.h: Include "common-inferior.h".
	(trace_start_error): Move to "common/common-utils.h".
	(trace_start_error_with_name): Likewise.
	(fork_inferior): Move prototype to "nat/fork-inferior.h".
	(startup_inferior): Likewise.
	(gdb_startup_inferior): New prototype.
	* nat/fork-inferior.c: New file, with contents from "fork-child.c".
	* nat/fork-inferior.h: New file.
	* procfs.c (procfs_init_inferior): Call "gdb_startup_inferior"
	instead of "startup_inferior".  Call "add_thread_silent" after
	"fork_inferior".
	* target.h (target_terminal_init): Move prototype to
	"target/target.h".
	(target_terminal_inferior): Likewise.
	(target_terminal_ours): Likewise.
	* target/target.h (target_terminal_init): New prototype, moved
	from "target.h".
	(target_terminal_inferior): Likewise.
	(target_terminal_ours): Likewise.
	* utils.c (gdb_flush_out_err): New function.

gdb/gdbserver/ChangeLog:
2017-06-07  Sergio Durigan Junior  <sergiodj@redhat.com>
	    Pedro Alves  <palves@redhat.com>

	* Makefile.in (SFILES): Add "nat/fork-inferior.o".
	* configure: Regenerate.
	* configure.srv (srv_linux_obj): Add "fork-child.o" and
	"fork-inferior.o".
	(i[34567]86-*-lynxos*): Likewise.
	(spu*-*-*): Likewise.
	* fork-child.c: New file.
	* linux-low.c: Include "common-inferior.h", "nat/fork-inferior.h"
	and "environ.h".
	(linux_ptrace_fun): New function.
	(linux_create_inferior): Adjust function prototype to reflect
	change on "target.h".  Adjust function code to use
	"fork_inferior".
	(linux_request_interrupt): Delete "signal_pid".
	* lynx-low.c: Include "common-inferior.h" and "nat/fork-inferior.h".
	(lynx_ptrace_fun): New function.
	(lynx_create_inferior): Adjust function prototype to reflect
	change on "target.h".  Adjust function code to use
	"fork_inferior".
	* nto-low.c (nto_create_inferior): Adjust function prototype and
	code to reflect change on "target.h".  Update comments.
	* server.c: Include "common-inferior.h", "nat/fork-inferior.h",
	"common-terminal.h" and "environ.h".
	(terminal_fd): Moved to fork-child.c.
	(old_foreground_pgrp): Likewise.
	(restore_old_foreground_pgrp): Likewise.
	(last_status): Make it global.
	(last_ptid): Likewise.
	(our_environ): New variable.
	(startup_with_shell): Likewise.
	(program_name): Likewise.
	(program_argv): Rename to...
	(program_args): ...this.
	(wrapper_argv): New variable.
	(start_inferior): Delete function.
	(get_exec_wrapper): New function.
	(get_exec_file): Likewise.
	(get_environ): Likewise.
	(prefork_hook): Likewise.
	(post_fork_inferior): Likewise.
	(postfork_hook): Likewise.
	(postfork_child_hook): Likewise.
	(handle_v_run): Update code to deal with arguments coming from the
	remote host.  Update calls from "start_inferior" to
	"create_inferior".
	(captured_main): Likewise.  Initialize environment variable.  Call
	"have_job_control".
	* server.h (post_fork_inferior): New prototype.
	(get_environ): Likewise.
	(last_status): Declare.
	(last_ptid): Likewise.
	(signal_pid): Likewise.
	* spu-low.c: Include "common-inferior.h" and "nat/fork-inferior.h".
	(spu_ptrace_fun): New function.
	(spu_create_inferior): Adjust function prototype to reflect change
	on "target.h".  Adjust function code to use "fork_inferior".
	* target.c (target_terminal_init): New function.
	(target_terminal_inferior): Likewise.
	(target_terminal_ours): Likewise.
	* target.h: Include <vector>.
	(struct target_ops) <create_inferior>: Update prototype.
	(create_inferior): Update macro.
	* utils.c (gdb_flush_out_err): New function.
	* win32-low.c (win32_create_inferior): Adjust function prototype
	and code to reflect change on "target.h".

gdb/testsuite/ChangeLog:
2017-06-07  Sergio Durigan Junior  <sergiodj@redhat.com>

	* gdb.server/non-existing-program.exp: Update regex in order to
	reflect the fact that gdbserver is now using fork_inferior (with a
	shell) to startup the inferior.

1 files changed, 30 insertions, 21 deletions

diff --git a/gdb/gdbserver/lynx-low.c b/gdb/gdbserver/lynx-low.c
index d300aae..35160d6 100644
--- a/gdb/gdbserver/lynx-low.c
+++ b/gdb/gdbserver/lynx-low.c
@@ -28,6 +28,8 @@
 #include "gdb_wait.h"
 #include <signal.h>
 #include "filestuff.h"
+#include "common-inferior.h"
+#include "nat/fork-inferior.h"
 
 int using_threads = 1;
 
@@ -224,36 +226,43 @@ lynx_add_process (int pid, int attached)
   return proc;
 }
 
+/* Callback used by fork_inferior to start tracing the inferior.  */
+
+static void
+lynx_ptrace_fun ()
+{
+  int pgrp;
+
+  /* Switch child to its own process group so that signals won't
+     directly affect GDBserver. */
+  pgrp = getpid();
+  if (pgrp < 0)
+    trace_start_error_with_name ("pgrp");
+  if (setpgid (0, pgrp) < 0)
+    trace_start_error_with_name ("setpgid");
+  if (ioctl (0, TIOCSPGRP, &pgrp) < 0)
+    trace_start_error_with_name ("ioctl");
+  if (lynx_ptrace (PTRACE_TRACEME, null_ptid, 0, 0, 0) < 0)
+    trace_start_error_with_name ("lynx_ptrace");
+}
+
 /* Implement the create_inferior method of the target_ops vector.  */
 
 static int
-lynx_create_inferior (char *program, char **allargs)
+lynx_create_inferior (const char *program,
+		      const std::vector<char *> &program_args)
 {
   int pid;
+  std::string str_program_args = stringify_argv (program_args);
 
   lynx_debug ("lynx_create_inferior ()");
 
-  pid = fork ();
-  if (pid < 0)
-    perror_with_name ("fork");
+  pid = fork_inferior (program,
+		       str_program_args.c_str (),
+		       environ_vector (get_environ ()), lynx_ptrace_fun,
+		       NULL, NULL, NULL, NULL);
 
-  if (pid == 0)
-    {
-      int pgrp;
-
-      close_most_fds ();
-
-      /* Switch child to its own process group so that signals won't
-         directly affect gdbserver. */
-      pgrp = getpid();
-      setpgid (0, pgrp);
-      ioctl (0, TIOCSPGRP, &pgrp);
-      lynx_ptrace (PTRACE_TRACEME, null_ptid, 0, 0, 0);
-      execv (program, allargs);
-      fprintf (stderr, "Cannot exec %s: %s.\n", program, strerror (errno));
-      fflush (stderr);
-      _exit (0177);
-    }
+  post_fork_inferior (pid, program);
 
   lynx_add_process (pid, 0);
   /* Do not add the process thread just yet, as we do not know its tid.