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_exceptions().  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 /* Describe all exceptions.  */
  48
  49 enum errors {
  50   NO_ERROR,
  51   /* Any generic error, the corresponding text is in
  52      exception.message.  */
  53   GENERIC_ERROR,
  54   /* Add more errors here.  */
  55   NR_ERRORS
  56 };
  57
  58 struct exception
  59 {
  60   enum return_reason reason;
  61   enum errors error;
  62   char *message;
  63 };
  64
  65 /* A pre-defined non-exception.  */
  66 extern const struct exception exception_none;
  67
  68 /* Throw an exception (as described by "struct exception").  Will
  69    execute a LONG JUMP to the inner most containing exception handler
  70    established using catch_exceptions() (or similar).
  71
  72    Code normally throws an exception using error() et.al.  For various
  73    reaons, GDB also contains code that throws an exception directly.
  74    For instance, the remote*.c targets contain CNTRL-C signal handlers
  75    that propogate the QUIT event up the exception chain.  ``This could
  76    be a good thing or a dangerous thing.'' -- the Existential
  77    Wombat.  */
  78
  79 extern NORETURN void throw_exception (struct exception exception) ATTR_NORETURN;
  80 extern NORETURN void throw_reason (enum return_reason reason) ATTR_NORETURN;
  81
  82
  83 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
  84    handler.  If an exception (enum return_reason) is thrown using
  85    throw_exception() than all cleanups installed since
  86    catch_exceptions() was entered are invoked, the (-ve) exception
  87    value is then returned by catch_exceptions.  If FUNC() returns
  88    normally (with a postive or zero return value) then that value is
  89    returned by catch_exceptions().  It is an internal_error() for
  90    FUNC() to return a negative value.
  91
  92    For the period of the FUNC() call: UIOUT is installed as the output
  93    builder; ERRSTRING is installed as the error/quit message; and a
  94    new cleanup_chain is established.  The old values are restored
  95    before catch_exceptions() returns.
  96
  97    The variant catch_exceptions_with_msg() is the same as
  98    catch_exceptions() but adds the ability to return an allocated
  99    copy of the gdb error message.  This is used when a silent error is
 100    issued and the caller wants to manually issue the error message.
 101
 102    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 103    builder variable should just go away.
 104
 105    This function superseeds catch_errors().
 106
 107    This function uses SETJMP() and LONGJUMP().  */
 108
 109 struct ui_out;
 110 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 111 extern int catch_exceptions (struct ui_out *uiout,
 112                              catch_exceptions_ftype *func, void *func_args,
 113                              char *errstring, return_mask mask);
 114 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 115 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 116                                       catch_exceptions_ftype *func,
 117                                       void *func_args,
 118                                       char *errstring, char **gdberrmsg,
 119                                       return_mask mask);
 120 extern struct exception catch_exception (struct ui_out *uiout,
 121                                          catch_exception_ftype *func,
 122                                          void *func_args,
 123                                          return_mask mask);
 124
 125 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 126    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
 127    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 128    value. It's unfortunate that, catch_errors() does not return an
 129    indication of the exact exception that it caught - quit_flag might
 130    help.
 131
 132    This function is superseeded by catch_exceptions().  */
 133
 134 typedef int (catch_errors_ftype) (void *);
 135 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 136
 137 /* Template to catch_errors() that wraps calls to command
 138    functions. */
 139
 140 typedef void (catch_command_errors_ftype) (char *, int);
 141 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 142
 143 #endif