binutils-gdb/gdb/stub-termcap.c
Pedro Alves 7a85168daf Fallback to stub-termcap.c on all hosts
Currently building gdb is impossible without an installed termcap or
curses library.  But, GDB already has a very minimal termcap in the
tree to handle this situation for Windows -- gdb/stub-termcap.c.  This
patch makes that the fallback for all hosts.

Testing this on GNU/Linux (by simply hacking away the termcap/curses
detection in gdb/configure.ac), we trip on:

 ../readline/libreadline.a(terminal.o): In function `_rl_init_terminal_io':
 /home/pedro/gdb/mygit/src/readline/terminal.c:527: undefined reference to `PC'
 /home/pedro/gdb/mygit/src/readline/terminal.c:528: undefined reference to `BC'
 /home/pedro/gdb/mygit/src/readline/terminal.c:529: undefined reference to `UP'
 /home/pedro/gdb/mygit/src/readline/terminal.c:538: undefined reference to `PC'
 /home/pedro/gdb/mygit/src/readline/terminal.c:539: undefined reference to `BC'
 /home/pedro/gdb/mygit/src/readline/terminal.c:540: undefined reference to `UP'

These are globals that are normally defined by termcap (or ncurses'
termcap emulation).

Now, we could just define replacements in stub-termcap.c, but
readline/terminal.c (at least the copy in our tree) has this:

 #if !defined (__linux__) && !defined (NCURSES_VERSION)
 #  if defined (__EMX__) || defined (NEED_EXTERN_PC)
 extern
 #  endif /* __EMX__ || NEED_EXTERN_PC */
 char PC, *BC, *UP;
 #endif /* !__linux__ && !NCURSES_VERSION */

which can result in readline defining the globals too.  That will
usually work out in C, given that "-fcommon" is usually the default
for C compilers, but that won't work for C++, or C with -fno-common
(link fails with "multiple definition" errors)...

Mirroring those #ifdef conditions in the stub termcap screams
"brittle" to me -- I can see them changing in latter readline
versions.

Work around that by simply using __attribute__((weak)).
Windows/PE/COFF's do support weak, but not on gcc 3.4 based toolchains
(4.8.x does work).  Given the file never needed the variables while it
was Windows-only, just continue not defining them there.  All other
supported hosts should support this.

gdb/ChangeLog:
2015-04-06  Pedro Alves  <palves@redhat.com>
	    Bernd Edlinger  <bernd.edlinger@hotmail.de>

	* configure.ac: Remove the mingw32-specific stub-termcap.o
	fallback, and instead fallback to the stub termcap on all hosts.
	* configure: Regenerate.
	* stub-termcap.c [!__MINGW32__] (PC, BC, UP): Define as weak
	symbols.
2015-04-06 12:35:18 +01:00

104 lines
2.6 KiB
C

/* A very minimal do-nothing termcap emulation stub.
Copyright (C) 2005-2015 Free Software Foundation, Inc.
Contributed by CodeSourcery, LLC.
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 "defs.h"
#include <stdlib.h>
#ifdef __cplusplus
extern "C" {
#endif
/* -Wmissing-prototypes */
extern int tgetent (char *buffer, char *termtype);
extern int tgetnum (char *name);
extern int tgetflag (char *name);
extern char* tgetstr (char *name, char **area);
extern int tputs (char *string, int nlines, int (*outfun) (int));
extern char *tgoto (const char *cap, int col, int row);
#ifdef __cplusplus
}
#endif
/* These globals below are global termcap variables that readline
references.
Actually, depending on preprocessor conditions that we don't want
to mirror here (as they may change depending on readline versions),
readline may define these globals as well, relying on the linker
merging them if needed (-fcommon). That doesn't work with
-fno-common or C++, so instead we define the symbols as weak.
Don't do this on Windows though, as MinGW gcc 3.4.2 doesn't support
weak (later versions, e.g., 4.8, do support it). Given this stub
file originally was Windows only, and we only needed this when we
made it work on other hosts, it should be OK. */
#ifndef __MINGW32__
char PC __attribute__((weak));
char *BC __attribute__((weak));
char *UP __attribute__((weak));
#endif
/* Each of the files below is a minimal implementation of the standard
termcap function with the same name, suitable for use in a Windows
console window, or when a real termcap/curses library isn't
available. */
int
tgetent (char *buffer, char *termtype)
{
return -1;
}
int
tgetnum (char *name)
{
return -1;
}
int
tgetflag (char *name)
{
return -1;
}
char *
tgetstr (char *name, char **area)
{
return NULL;
}
int
tputs (char *string, int nlines, int (*outfun) (int))
{
while (*string)
outfun (*string++);
return 0;
}
char *
tgoto (const char *cap, int col, int row)
{
return NULL;
}