[v7,3/4] Share fork_inferior et al with gdbserver

  So here's the patch showing what I meant in:
 https://sourceware.org/ml/gdb-patches/2017-06/msg00169.html

I'll be happy with the resulting patch once if you fold this in.
Could you do that, retest and repost?

I think we could get rid of the new common-inferior.h
header too, but I'll leave that as is, for now at least.

From 1d66adbd79ab97415d519f18906257e99ce49706 Mon Sep 17 00:00:00 2001
From: Pedro Alves <palves@redhat.com>
Date: Wed, 7 Jun 2017 13:18:14 +0100
Subject: [PATCH] Fixes

---
 gdb/common/common-utils.c   |  24 ----------
 gdb/common/common-utils.h   |  16 -------
 gdb/fork-child.c            |   9 ++++
 gdb/gdbserver/configure     |   4 +-
 gdb/gdbserver/configure.ac  |   4 +-
 gdb/gdbserver/configure.srv |   6 +--
 gdb/gdbserver/fork-child.c  | 113 ++++++++++++++++++++++++++++++++++++++++++++
 gdb/gdbserver/linux-low.c   |   4 +-
 gdb/gdbserver/lynx-low.c    |   2 +-
 gdb/gdbserver/server.c      | 100 ++-------------------------------------
 gdb/gdbserver/server.h      |  18 ++++---
 gdb/gdbserver/spu-low.c     |   3 +-
 gdb/gdbserver/utils.c       |   9 ----
 gdb/inf-ptrace.c            |   2 +-
 gdb/inferior.h              |   1 -
 gdb/nat/fork-inferior.c     |  26 ++++++++++
 gdb/nat/fork-inferior.h     |  16 +++++++
 gdb/utils.c                 |   9 ----
 18 files changed, 185 insertions(+), 181 deletions(-)
 create mode 100644 gdb/gdbserver/fork-child.c
  

On Wednesday, June 07 2017, Pedro Alves wrote:

> So here's the patch showing what I meant in:
>  https://sourceware.org/ml/gdb-patches/2017-06/msg00169.html
>
> I'll be happy with the resulting patch once if you fold this in.
> Could you do that, retest and repost?

Thanks for the patch, it makes sense to me in light of the discussions
we had.  I'll apply it and resubmit this specific patch of the series
(instead of resubmitting everything), if that's OK with you.

> I think we could get rid of the new common-inferior.h
> header too, but I'll leave that as is, for now at least.

And move get_exec_{wrapper,file} to fork-inferior.h and fork-child.c,
you mean?

> From 1d66adbd79ab97415d519f18906257e99ce49706 Mon Sep 17 00:00:00 2001
> From: Pedro Alves <palves@redhat.com>
> Date: Wed, 7 Jun 2017 13:18:14 +0100
> Subject: [PATCH] Fixes
>
> ---
>  gdb/common/common-utils.c   |  24 ----------
>  gdb/common/common-utils.h   |  16 -------
>  gdb/fork-child.c            |   9 ++++
>  gdb/gdbserver/configure     |   4 +-
>  gdb/gdbserver/configure.ac  |   4 +-
>  gdb/gdbserver/configure.srv |   6 +--
>  gdb/gdbserver/fork-child.c  | 113 ++++++++++++++++++++++++++++++++++++++++++++
>  gdb/gdbserver/linux-low.c   |   4 +-
>  gdb/gdbserver/lynx-low.c    |   2 +-
>  gdb/gdbserver/server.c      | 100 ++-------------------------------------
>  gdb/gdbserver/server.h      |  18 ++++---
>  gdb/gdbserver/spu-low.c     |   3 +-
>  gdb/gdbserver/utils.c       |   9 ----
>  gdb/inf-ptrace.c            |   2 +-
>  gdb/inferior.h              |   1 -
>  gdb/nat/fork-inferior.c     |  26 ++++++++++
>  gdb/nat/fork-inferior.h     |  16 +++++++
>  gdb/utils.c                 |   9 ----
>  18 files changed, 185 insertions(+), 181 deletions(-)
>  create mode 100644 gdb/gdbserver/fork-child.c
>
> diff --git a/gdb/common/common-utils.c b/gdb/common/common-utils.c
> index fbec0da..793ab3b 100644
> --- a/gdb/common/common-utils.c
> +++ b/gdb/common/common-utils.c
> @@ -352,27 +352,3 @@ stringify_argv (const std::vector<char *> &args)
>  
>    return ret;
>  }
> -
> -/* See common/common-inferior.h.  */
> -
> -void
> -trace_start_error (const char *fmt, ...)
> -{
> -  va_list ap;
> -
> -  va_start (ap, fmt);
> -  warning ("Could not trace the inferior process.\nError: ");
> -  vwarning (fmt, ap);
> -  va_end (ap);
> -
> -  gdb_flush_out_err ();
> -  _exit (0177);
> -}
> -
> -/* See common/common-inferior.h.  */
> -
> -void
> -trace_start_error_with_name (const char *string)
> -{
> -  trace_start_error ("%s: %s", string, safe_strerror (errno));
> -}
> diff --git a/gdb/common/common-utils.h b/gdb/common/common-utils.h
> index 38505e0..787bac9 100644
> --- a/gdb/common/common-utils.h
> +++ b/gdb/common/common-utils.h
> @@ -112,20 +112,4 @@ extern void free_vector_argv (std::vector<char *> &v);
>     joining all the arguments with a whitespace separating them.  */
>  extern std::string stringify_argv (const std::vector<char *> &argv);
>  
> -/* Flush both stdout and stderr.  This function needs to be
> -   implemented differently on GDB and GDBserver.  */
> -extern void gdb_flush_out_err ();
> -
> -/* Report an error that happened when starting to trace the inferior
> -   (i.e., when the "traceme_fun" callback is called on fork_inferior)
> -   and bail out.  This function does not return.  */
> -extern void trace_start_error (const char *fmt, ...)
> -  ATTRIBUTE_NORETURN;
> -
> -/* Like "trace_start_error", but the error message is constructed by
> -   combining STRING with the system error message for errno.  This
> -   function does not return.  */
> -extern void trace_start_error_with_name (const char *string)
> -  ATTRIBUTE_NORETURN;
> -
>  #endif
> diff --git a/gdb/fork-child.c b/gdb/fork-child.c
> index 39e49b5..60985d8 100644
> --- a/gdb/fork-child.c
> +++ b/gdb/fork-child.c
> @@ -43,6 +43,15 @@ get_exec_wrapper ()
>    return exec_wrapper;
>  }
>  
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +gdb_flush_out_err ()
> +{
> +  gdb_flush (main_ui->m_gdb_stdout);
> +  gdb_flush (main_ui->m_gdb_stderr);
> +}
> +
>  /* The ui structure that will be saved on 'prefork_hook' and
>     restored on 'postfork_hook'.  */
>  static struct ui *saved_ui = NULL;
> diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
> index 96befef..b314c41 100755
> --- a/gdb/gdbserver/configure
> +++ b/gdb/gdbserver/configure
> @@ -8422,9 +8422,7 @@ fi
>  
>  if $want_ipa ; then
>     if $have_ipa ; then
> -     # Needed because safe_strerror's definition is host-dependent
> -     strerror_obj="`echo $srv_host_obs | sed 's/\(.*-strerror\)\.o/\1-ipa.o/'`"
> -     IPA_DEPFILES="$ipa_obj $strerror_obj"
> +     IPA_DEPFILES="$ipa_obj"
>       extra_libraries="$extra_libraries libinproctrace.so"
>     else
>       as_fn_error "inprocess agent not supported for this target" "$LINENO" 5
> diff --git a/gdb/gdbserver/configure.ac b/gdb/gdbserver/configure.ac
> index 8aa85db..4ea7913 100644
> --- a/gdb/gdbserver/configure.ac
> +++ b/gdb/gdbserver/configure.ac
> @@ -462,9 +462,7 @@ esac],
>  
>  if $want_ipa ; then
>     if $have_ipa ; then
> -     # Needed because safe_strerror's definition is host-dependent
> -     strerror_obj="`echo $srv_host_obs | sed 's/\(.*-strerror\)\.o/\1-ipa.o/'`"
> -     IPA_DEPFILES="$ipa_obj $strerror_obj"
> +     IPA_DEPFILES="$ipa_obj"
>       extra_libraries="$extra_libraries libinproctrace.so"
>     else
>       AC_MSG_ERROR([inprocess agent not supported for this target])
> diff --git a/gdb/gdbserver/configure.srv b/gdb/gdbserver/configure.srv
> index 056ac27..43f90c9 100644
> --- a/gdb/gdbserver/configure.srv
> +++ b/gdb/gdbserver/configure.srv
> @@ -43,7 +43,7 @@ srv_amd64_linux_xmlfiles="i386/amd64-linux.xml i386/amd64-avx-linux.xml i386/amd
>  
>  # Linux object files.  This is so we don't have to repeat
>  # these files over and over again.
> -srv_linux_obj="linux-low.o linux-osdata.o linux-procfs.o linux-ptrace.o linux-waitpid.o linux-personality.o linux-namespaces.o fork-inferior.o"
> +srv_linux_obj="linux-low.o linux-osdata.o linux-procfs.o linux-ptrace.o linux-waitpid.o linux-personality.o linux-namespaces.o fork-child.o fork-inferior.o"
>  
>  # Input is taken from the "${target}" variable.
>  
> @@ -131,7 +131,7 @@ case "${target}" in
>  			ipa_obj="${ipa_i386_linux_regobj} linux-i386-ipa.o"
>  			;;
>    i[34567]86-*-lynxos*)	srv_regobj="i386.o"
> -			srv_tgtobj="lynx-low.o lynx-i386-low.o fork-inferior.o"
> +			srv_tgtobj="lynx-low.o lynx-i386-low.o fork-child.o fork-inferior.o"
>  			srv_xmlfiles="i386/i386.xml"
>  			srv_xmlfiles="${srv_xmlfiles} i386/32bit-core.xml"
>  			srv_xmlfiles="${srv_xmlfiles} i386/32bit-sse.xml"
> @@ -338,7 +338,7 @@ case "${target}" in
>  			srv_linux_thread_db=yes
>  			;;
>    spu*-*-*)		srv_regobj=reg-spu.o
> -			srv_tgtobj="spu-low.o fork-inferior.o"
> +			srv_tgtobj="spu-low.o fork-child.o fork-inferior.o"
>  			;;
>    tic6x-*-uclinux)	srv_regobj="tic6x-c64xp-linux.o"
>  			srv_regobj="${srv_regobj} tic6x-c64x-linux.o"
> diff --git a/gdb/gdbserver/fork-child.c b/gdb/gdbserver/fork-child.c
> new file mode 100644
> index 0000000..a1a8ff1
> --- /dev/null
> +++ b/gdb/gdbserver/fork-child.c
> @@ -0,0 +1,113 @@
> +/* Fork a Unix child process, and set up to debug it, for GDBserver.
> +   Copyright (C) 1989-2017 Free Software Foundation, Inc.
> +
> +   This file is part of GDB.
> +
> +   This program is free software; you can redistribute it and/or modify
> +   it under the terms of the GNU General Public License as published by
> +   the Free Software Foundation; either version 3 of the License, or
> +   (at your option) any later version.
> +
> +   This program is distributed in the hope that it will be useful,
> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> +   GNU General Public License for more details.
> +
> +   You should have received a copy of the GNU General Public License
> +   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
> +
> +#include "server.h"
> +#include "job-control.h"
> +#include "nat/fork-inferior.h"
> +
> +#ifdef SIGTTOU
> +/* A file descriptor for the controlling terminal.  */
> +static int terminal_fd;
> +
> +/* TERMINAL_FD's original foreground group.  */
> +static pid_t old_foreground_pgrp;
> +
> +/* Hand back terminal ownership to the original foreground group.  */
> +
> +static void
> +restore_old_foreground_pgrp (void)
> +{
> +  tcsetpgrp (terminal_fd, old_foreground_pgrp);
> +}
> +#endif
> +
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +prefork_hook (const char *args)
> +{
> +  if (debug_threads)
> +    {
> +      debug_printf ("args: %s\n", args);
> +      debug_flush ();
> +    }
> +
> +#ifdef SIGTTOU
> +  signal (SIGTTOU, SIG_DFL);
> +  signal (SIGTTIN, SIG_DFL);
> +#endif
> +
> +  /* Clear this so the backend doesn't get confused, thinking
> +     CONT_THREAD died, and it needs to resume all threads.  */
> +  cont_thread = null_ptid;
> +}
> +
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +postfork_hook (pid_t pid)
> +{
> +}
> +
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +postfork_child_hook ()
> +{
> +  /* 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;
> +
> +  debug_setpgrp = gdb_setpgid ();
> +  if (debug_setpgrp == -1)
> +    perror (_("setpgrp failed in child"));
> +}
> +
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +gdb_flush_out_err ()
> +{
> +  fflush (stdout);
> +  fflush (stderr);
> +}
> +
> +/* See server.h.  */
> +
> +void
> +post_fork_inferior (int pid, const char *program)
> +{
> +#ifdef SIGTTOU
> +  signal (SIGTTOU, SIG_IGN);
> +  signal (SIGTTIN, SIG_IGN);
> +  terminal_fd = fileno (stderr);
> +  old_foreground_pgrp = tcgetpgrp (terminal_fd);
> +  tcsetpgrp (terminal_fd, pid);
> +  atexit (restore_old_foreground_pgrp);
> +#endif
> +
> +  startup_inferior (pid, START_INFERIOR_TRAPS_EXPECTED,
> +		    &last_status, &last_ptid);
> +  current_thread->last_resume_kind = resume_stop;
> +  current_thread->last_status = last_status;
> +  signal_pid = pid;
> +  target_post_create_inferior ();
> +  fprintf (stderr, "Process %s created; pid = %d\n", program, pid);
> +  fflush (stderr);
> +}
> diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
> index ab6670b..7fbf744 100644
> --- a/gdb/gdbserver/linux-low.c
> +++ b/gdb/gdbserver/linux-low.c
> @@ -1009,7 +1009,7 @@ linux_create_inferior (const char *program,
>    new_lwp = add_lwp (ptid);
>    new_lwp->must_set_ptrace_flags = 1;
>  
> -  post_fork_inferior (pid, program, startup_inferior);
> +  post_fork_inferior (pid, program);
>  
>    return pid;
>  }
> @@ -6058,8 +6058,6 @@ linux_look_up_symbols (void)
>  static void
>  linux_request_interrupt (void)
>  {
> -  extern unsigned long signal_pid;
> -
>    /* Send a SIGINT to the process group.  This acts just like the user
>       typed a ^C on the controlling terminal.  */
>    kill (-signal_pid, SIGINT);
> diff --git a/gdb/gdbserver/lynx-low.c b/gdb/gdbserver/lynx-low.c
> index 382d71c..35160d6 100644
> --- a/gdb/gdbserver/lynx-low.c
> +++ b/gdb/gdbserver/lynx-low.c
> @@ -262,7 +262,7 @@ lynx_create_inferior (const char *program,
>  		       environ_vector (get_environ ()), lynx_ptrace_fun,
>  		       NULL, NULL, NULL, NULL);
>  
> -  post_fork_inferior (pid, program, startup_inferior);
> +  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.
> diff --git a/gdb/gdbserver/server.c b/gdb/gdbserver/server.c
> index 5a76927..3ab042d 100644
> --- a/gdb/gdbserver/server.c
> +++ b/gdb/gdbserver/server.c
> @@ -37,7 +37,6 @@
>  #include "hostio.h"
>  #include <vector>
>  #include "common-inferior.h"
> -#include "nat/fork-inferior.h"
>  #include "job-control.h"
>  #include "environ.h"
>  
> @@ -108,22 +107,6 @@ int program_signals_p;
>  
>  unsigned long signal_pid;
>  
> -#ifdef SIGTTOU
> -/* A file descriptor for the controlling terminal.  */
> -int terminal_fd;
> -
> -/* TERMINAL_FD's original foreground group.  */
> -pid_t old_foreground_pgrp;
> -
> -/* Hand back terminal ownership to the original foreground group.  */
> -
> -static void
> -restore_old_foreground_pgrp (void)
> -{
> -  tcsetpgrp (terminal_fd, old_foreground_pgrp);
> -}
> -#endif
> -
>  /* Set if you want to disable optional thread related packets support
>     in gdbserver, for the sake of testing GDB against stubs that don't
>     support them.  */
> @@ -133,8 +116,8 @@ int disable_packet_qC;
>  int disable_packet_qfThreadInfo;
>  
>  /* Last status reported to GDB.  */
> -static struct target_waitstatus last_status;
> -static ptid_t last_ptid;
> +struct target_waitstatus last_status;
> +ptid_t last_ptid;
>  
>  char *own_buf;
>  static unsigned char *mem_buf;
> @@ -258,7 +241,7 @@ target_running (void)
>  const char *
>  get_exec_wrapper ()
>  {
> -  return wrapper_argv.size () > 0 ? wrapper_argv.c_str () : NULL;
> +  return !wrapper_argv.empty () ? wrapper_argv.c_str () : NULL;
>  }
>  
>  /* See common/common-inferior.h.  */
> @@ -280,81 +263,6 @@ get_environ ()
>    return our_environ;
>  }
>  
> -/* See nat/fork-inferior.h.  */
> -
> -void
> -prefork_hook (const char *args)
> -{
> -  if (debug_threads)
> -    {
> -      debug_printf ("args: %s\n", args);
> -      debug_flush ();
> -    }
> -
> -#ifdef SIGTTOU
> -  signal (SIGTTOU, SIG_DFL);
> -  signal (SIGTTIN, SIG_DFL);
> -#endif
> -
> -  /* Clear this so the backend doesn't get confused, thinking
> -     CONT_THREAD died, and it needs to resume all threads.  */
> -  cont_thread = null_ptid;
> -}
> -
> -/* See server.h.  */
> -
> -void
> -post_fork_inferior (int pid, const char *program,
> -		    ptid_t (*my_startup_inferior) (pid_t pid, int ntraps,
> -						   struct target_waitstatus
> -						   *mystatus,
> -						   ptid_t *myptid))
> -
> -{
> -  /* Number of traps to be expected by startup_inferior.  We always
> -     expect at least one trap for the main executable.  */
> -  int num_traps = START_INFERIOR_TRAPS_EXPECTED;
> -
> -#ifdef SIGTTOU
> -  signal (SIGTTOU, SIG_IGN);
> -  signal (SIGTTIN, SIG_IGN);
> -  terminal_fd = fileno (stderr);
> -  old_foreground_pgrp = tcgetpgrp (terminal_fd);
> -  tcsetpgrp (terminal_fd, pid);
> -  atexit (restore_old_foreground_pgrp);
> -#endif
> -
> -  my_startup_inferior (pid, num_traps, &last_status, &last_ptid);
> -  current_thread->last_resume_kind = resume_stop;
> -  current_thread->last_status = last_status;
> -  signal_pid = pid;
> -  target_post_create_inferior ();
> -  fprintf (stderr, "Process %s created; pid = %d\n", program, pid);
> -  fflush (stderr);
> -}
> -
> -/* See nat/fork-inferior.h.  */
> -
> -void
> -postfork_hook (pid_t pid)
> -{
> -}
> -
> -/* See nat/fork-inferior.h.  */
> -
> -void
> -postfork_child_hook ()
> -{
> -  /* 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;
> -
> -  debug_setpgrp = gdb_setpgid ();
> -  if (debug_setpgrp == -1)
> -    perror (_("setpgrp failed in child"));
> -}
> -
>  static int
>  attach_inferior (int pid)
>  {
> @@ -3612,7 +3520,7 @@ captured_main (int argc, char *argv[])
>  	      next_arg++;
>  	    }
>  
> -	  if (wrapper_argv.size () > 0)
> +	  if (!wrapper_argv.empty ())
>  	    {
>  	      /* Erase the last whitespace.  */
>  	      wrapper_argv.erase (wrapper_argv.end () - 1);
> diff --git a/gdb/gdbserver/server.h b/gdb/gdbserver/server.h
> index 96566fe..4de4244 100644
> --- a/gdb/gdbserver/server.h
> +++ b/gdb/gdbserver/server.h
> @@ -149,19 +149,17 @@ extern int in_queued_stop_replies (ptid_t ptid);
>  #define ANY_SYSCALL (-2)
>  
>  /* After fork_inferior has been called, we need to adjust a few
> -   signals and call startup_inferior.  This is done here.  PID is the
> -   pid of the new inferior, PROGRAM is its name, and
> -   MY_STARTUP_INFERIOR is the function that should be called to start
> -   the inferior and consume its first events.  In most cases, this
> -   function should be "startup_inferior" itself.  */
> -extern void post_fork_inferior (int pid, const char *program,
> -				ptid_t (*my_startup_inferior)
> -				(pid_t pid, int ntraps,
> -				 struct target_waitstatus *mystatus,
> -				 ptid_t *myptid));
> +   signals and call startup_inferior to start the inferior and consume
> +   its first events.  This is done here.  PID is the pid of the new
> +   inferior and PROGRAM is its name.  */
> +extern void post_fork_inferior (int pid, const char *program);
>  
>  /* Get the 'struct gdb_environ *' being used in the current
>     session.  */
>  extern struct gdb_environ *get_environ ();
>  
> +extern target_waitstatus last_status;
> +extern ptid_t last_ptid;
> +extern unsigned long signal_pid;
> +
>  #endif /* SERVER_H */
> diff --git a/gdb/gdbserver/spu-low.c b/gdb/gdbserver/spu-low.c
> index c71e8ba..0f770a0 100644
> --- a/gdb/gdbserver/spu-low.c
> +++ b/gdb/gdbserver/spu-low.c
> @@ -27,7 +27,6 @@
>  #include <sys/syscall.h>
>  #include "filestuff.h"
>  #include "hostio.h"
> -#include "common-inferior.h"
>  #include "nat/fork-inferior.h"
>  
>  /* Some older glibc versions do not define this.  */
> @@ -293,7 +292,7 @@ spu_create_inferior (const char *program,
>  		       environ_vector (get_environ ()), spu_ptrace_fun,
>  		       NULL, NULL, NULL, NULL);
>  
> -  post_fork_inferior (pid, program, startup_inferior);
> +  post_fork_inferior (pid, program);
>  
>    proc = add_process (pid, 0);
>    proc->tdesc = tdesc_spu;
> diff --git a/gdb/gdbserver/utils.c b/gdb/gdbserver/utils.c
> index 3f96a6c..307d15a 100644
> --- a/gdb/gdbserver/utils.c
> +++ b/gdb/gdbserver/utils.c
> @@ -137,12 +137,3 @@ pfildes (gdb_fildes_t fd)
>    return plongest (fd);
>  #endif
>  }
> -
> -/* See common/common-utils.h.  */
> -
> -void
> -gdb_flush_out_err ()
> -{
> -  fflush (stdout);
> -  fflush (stderr);
> -}
> diff --git a/gdb/inf-ptrace.c b/gdb/inf-ptrace.c
> index 2a01dd2..af181f0 100644
> --- a/gdb/inf-ptrace.c
> +++ b/gdb/inf-ptrace.c
> @@ -96,7 +96,7 @@ inf_ptrace_create_inferior (struct target_ops *ops,
>  			    char **env, int from_tty)
>  {
>    pid_t pid;
> -  ptid_t ptid;  
> +  ptid_t ptid;
>  
>    /* Do not change either targets above or the same target if already present.
>       The reason is the target stack is shared across multiple inferiors.  */
> diff --git a/gdb/inferior.h b/gdb/inferior.h
> index cdaeb11..6376952 100644
> --- a/gdb/inferior.h
> +++ b/gdb/inferior.h
> @@ -45,7 +45,6 @@ struct inferior;
>  
>  #include "progspace.h"
>  #include "registry.h"
> -#include "common-inferior.h"
>  
>  #include "symfile-add-flags.h"
>  #include "common/refcounted-object.h"
> diff --git a/gdb/nat/fork-inferior.c b/gdb/nat/fork-inferior.c
> index 7fd93ef..0913409 100644
> --- a/gdb/nat/fork-inferior.c
> +++ b/gdb/nat/fork-inferior.c
> @@ -358,9 +358,11 @@ fork_inferior (const char *exec_file_arg, const std::string &allargs,
>       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 !(defined(__UCLIBC__) && defined(HAS_NOMMU))
>    if (pre_trace_fun || debug_fork)
>      pid = fork ();
>    else
> +#endif
>      pid = vfork ();
>  
>    if (pid < 0)
> @@ -567,3 +569,27 @@ startup_inferior (pid_t pid, int ntraps,
>  
>    return resume_ptid;
>  }
> +
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +trace_start_error (const char *fmt, ...)
> +{
> +  va_list ap;
> +
> +  va_start (ap, fmt);
> +  warning ("Could not trace the inferior process.\nError: ");
> +  vwarning (fmt, ap);
> +  va_end (ap);
> +
> +  gdb_flush_out_err ();
> +  _exit (0177);
> +}
> +
> +/* See nat/fork-inferior.h.  */
> +
> +void
> +trace_start_error_with_name (const char *string)
> +{
> +  trace_start_error ("%s: %s", string, safe_strerror (errno));
> +}
> diff --git a/gdb/nat/fork-inferior.h b/gdb/nat/fork-inferior.h
> index 39bdd8d..10e3832 100644
> --- a/gdb/nat/fork-inferior.h
> +++ b/gdb/nat/fork-inferior.h
> @@ -87,4 +87,20 @@ extern void postfork_hook (pid_t pid);
>     place.  This function is mainly used by fork_inferior.  */
>  extern void postfork_child_hook ();
>  
> +/* Flush both stdout and stderr.  This function needs to be
> +   implemented differently on GDB and GDBserver.  */
> +extern void gdb_flush_out_err ();
> +
> +/* Report an error that happened when starting to trace the inferior
> +   (i.e., when the "traceme_fun" callback is called on fork_inferior)
> +   and bail out.  This function does not return.  */
> +extern void trace_start_error (const char *fmt, ...)
> +  ATTRIBUTE_NORETURN;
> +
> +/* Like "trace_start_error", but the error message is constructed by
> +   combining STRING with the system error message for errno.  This
> +   function does not return.  */
> +extern void trace_start_error_with_name (const char *string)
> +  ATTRIBUTE_NORETURN;
> +
>  #endif /* ! FORK_INFERIOR_H */
> diff --git a/gdb/utils.c b/gdb/utils.c
> index bd0a0d8..c61557e 100644
> --- a/gdb/utils.c
> +++ b/gdb/utils.c
> @@ -3391,15 +3391,6 @@ strip_leading_path_elements (const char *path, int n)
>    return p;
>  }
>  
> -/* See common/common-utils.h.  */
> -
> -void
> -gdb_flush_out_err ()
> -{
> -  gdb_flush (main_ui->m_gdb_stdout);
> -  gdb_flush (main_ui->m_gdb_stderr);
> -}
> -
>  /* Provide a prototype to silence -Wmissing-prototypes.  */
>  extern initialize_file_ftype _initialize_utils;
>  
> -- 
> 2.5.5
  

On Wednesday, June 07 2017, I wrote:

> On Wednesday, June 07 2017, Pedro Alves wrote:
>> I think we could get rid of the new common-inferior.h
>> header too, but I'll leave that as is, for now at least.
>
> And move get_exec_{wrapper,file} to fork-inferior.h and fork-child.c,
> you mean?

Probably not, because get_exec_file is used by Windows targets as well.
I'll wait for your reply before submitting the next patch.
  

On 06/07/2017 10:41 PM, Sergio Durigan Junior wrote:
> On Wednesday, June 07 2017, I wrote:
> 
>> On Wednesday, June 07 2017, Pedro Alves wrote:
>>> I think we could get rid of the new common-inferior.h
>>> header too, but I'll leave that as is, for now at least.
>>
>> And move get_exec_{wrapper,file} to fork-inferior.h and fork-child.c,
>> you mean?
> 
> Probably not, because get_exec_file is used by Windows targets as well.
> I'll wait for your reply before submitting the next patch.
> 

Considering exec_file for instance:  fork_inferior calls
get_exec_file if exec_file is NULL.  But, we could just
pass down the right exec_file to fork_inferior in the first
place.  We could do that by e.g., adding fork_child
wrapper functions to both gdb and gdbserver's fork-child.c that
would call the shared fork_inferior function, and then adjust
targets to call that instead.  For the exec wrapper, we could
add a new "const char *exec_wrapper" parameter to fork_inferior.

Since it's arguable which approach is better in this case,
I'm totally fine with leaving things as is.

I notice now that get_exec_file is still declared
in gdbcore.h, however.

Thanks,
Pedro Alves
  

On Wednesday, June 07 2017, Pedro Alves wrote:

> On 06/07/2017 10:41 PM, Sergio Durigan Junior wrote:
>> On Wednesday, June 07 2017, I wrote:
>> 
>>> On Wednesday, June 07 2017, Pedro Alves wrote:
>>>> I think we could get rid of the new common-inferior.h
>>>> header too, but I'll leave that as is, for now at least.
>>>
>>> And move get_exec_{wrapper,file} to fork-inferior.h and fork-child.c,
>>> you mean?
>> 
>> Probably not, because get_exec_file is used by Windows targets as well.
>> I'll wait for your reply before submitting the next patch.
>> 
>
> Considering exec_file for instance:  fork_inferior calls
> get_exec_file if exec_file is NULL.  But, we could just
> pass down the right exec_file to fork_inferior in the first
> place.  We could do that by e.g., adding fork_child
> wrapper functions to both gdb and gdbserver's fork-child.c that
> would call the shared fork_inferior function, and then adjust
> targets to call that instead.  For the exec wrapper, we could
> add a new "const char *exec_wrapper" parameter to fork_inferior.
>
> Since it's arguable which approach is better in this case,
> I'm totally fine with leaving things as is.
>
> I notice now that get_exec_file is still declared
> in gdbcore.h, however.

OK, I'll leave things as is then, and will tackle this problem at a
later date.

Thanks,
  

On 06/07/2017 11:08 PM, Sergio Durigan Junior wrote:
> On Wednesday, June 07 2017, Pedro Alves wrote:

>> I notice now that get_exec_file is still declared
>> in gdbcore.h, however.
> 
> OK, I'll leave things as is then, and will tackle this problem at a
> later date.

TBC, please remove the redundant declaration in gdbcore.h
(and add back the common-inferior.h inclusion from inferior.h,
I guess).

Thanks,
Pedro Alves