gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995,
   4    1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004 Free Software
   5    Foundation, Inc.
   6
   7    This file is part of GDB.
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 59 Temple Place - Suite 330,
  22    Boston, MA 02111-1307, USA.  */
  23
  24 #ifndef EXCEPTIONS_H
  25 #define EXCEPTIONS_H
  26
  27 /* Reasons for calling throw_exception().  NOTE: all reason values
  28    must be less than zero.  enum value 0 is reserved for internal use
  29    as the return value from an initial setjmp().  The function
  30    catch_exceptions() reserves values >= 0 as legal results from its
  31    wrapped function.  */
  32
  33 enum return_reason
  34   {
  35     /* User interrupt.  */
  36     RETURN_QUIT = -2,
  37     /* Any other error.  */
  38     RETURN_ERROR
  39   };
  40
  41 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  42 #define RETURN_MASK_QUIT        RETURN_MASK (RETURN_QUIT)
  43 #define RETURN_MASK_ERROR       RETURN_MASK (RETURN_ERROR)
  44 #define RETURN_MASK_ALL         (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  45 typedef int return_mask;
  46
  47 /* Throw an exception of type RETURN_REASON.  Will execute a LONG JUMP
  48    to the inner most containing exception handler established using
  49    catch_exceptions() (or the legacy catch_errors()).
  50
  51    Code normally throws an exception using error() et.al.  For various
  52    reaons, GDB also contains code that throws an exception directly.
  53    For instance, the remote*.c targets contain CNTRL-C signal handlers
  54    that propogate the QUIT event up the exception chain.  ``This could
  55    be a good thing or a dangerous thing.'' -- the Existential Wombat.  */
  56
  57 extern NORETURN void throw_exception (enum return_reason) ATTR_NORETURN;
  58
  59 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
  60    handler.  If an exception (enum return_reason) is thrown using
  61    throw_exception() than all cleanups installed since
  62    catch_exceptions() was entered are invoked, the (-ve) exception
  63    value is then returned by catch_exceptions.  If FUNC() returns
  64    normally (with a postive or zero return value) then that value is
  65    returned by catch_exceptions().  It is an internal_error() for
  66    FUNC() to return a negative value.
  67
  68    For the period of the FUNC() call: UIOUT is installed as the output
  69    builder; ERRSTRING is installed as the error/quit message; and a
  70    new cleanup_chain is established.  The old values are restored
  71    before catch_exceptions() returns.
  72
  73    The variant catch_exceptions_with_msg() is the same as
  74    catch_exceptions() but adds the ability to return an allocated
  75    copy of the gdb error message.  This is used when a silent error is
  76    issued and the caller wants to manually issue the error message.
  77
  78    FIXME; cagney/2001-08-13: The need to override the global UIOUT
  79    builder variable should just go away.
  80
  81    This function superseeds catch_errors().
  82
  83    This function uses SETJMP() and LONGJUMP().  */
  84
  85 struct ui_out;
  86 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
  87 extern int catch_exceptions (struct ui_out *uiout,
  88                              catch_exceptions_ftype *func, void *func_args,
  89                              char *errstring, return_mask mask);
  90 extern int catch_exceptions_with_msg (struct ui_out *uiout,
  91                                       catch_exceptions_ftype *func,
  92                                       void *func_args,
  93                                       char *errstring, char **gdberrmsg,
  94                                       return_mask mask);
  95
  96 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
  97    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
  98    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
  99    value. It's unfortunate that, catch_errors() does not return an
 100    indication of the exact exception that it caught - quit_flag might
 101    help.
 102
 103    This function is superseeded by catch_exceptions().  */
 104
 105 typedef int (catch_errors_ftype) (void *);
 106 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 107
 108 /* Template to catch_errors() that wraps calls to command
 109    functions. */
 110
 111 typedef void (catch_command_errors_ftype) (char *, int);
 112 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 113
 114 #endif