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, 2005 Free
   5    Software 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   NOT_FOUND_ERROR,
  55   /* Add more errors here.  */
  56   NR_ERRORS
  57 };
  58
  59 struct exception
  60 {
  61   enum return_reason reason;
  62   enum errors error;
  63   const char *message;
  64 };
  65
  66 /* A pre-defined non-exception.  */
  67 extern const struct exception exception_none;
  68
  69 /* If E is an exception, print it's error message on the specified
  70    stream. for _fprintf, prefix the message with PREFIX...  */
  71 extern void exception_print (struct ui_file *file, struct exception e);
  72 extern void exception_fprintf (struct ui_file *file, struct exception e,
  73                                const char *prefix,
  74                                ...) ATTR_FORMAT (printf, 3, 4);
  75
  76 /* Throw an exception (as described by "struct exception").  Will
  77    execute a LONG JUMP to the inner most containing exception handler
  78    established using catch_exceptions() (or similar).
  79
  80    Code normally throws an exception using error() et.al.  For various
  81    reaons, GDB also contains code that throws an exception directly.
  82    For instance, the remote*.c targets contain CNTRL-C signal handlers
  83    that propogate the QUIT event up the exception chain.  ``This could
  84    be a good thing or a dangerous thing.'' -- the Existential
  85    Wombat.  */
  86
  87 extern NORETURN void throw_exception (struct exception exception) ATTR_NORETURN;
  88 extern NORETURN void throw_reason (enum return_reason reason) ATTR_NORETURN;
  89 extern NORETURN void throw_verror (enum errors, const char *fmt,
  90                                    va_list ap) ATTR_NORETURN;
  91 extern NORETURN void throw_vfatal (const char *fmt, va_list ap) ATTR_NORETURN;
  92 extern NORETURN void throw_error (enum errors error, const char *fmt,
  93                                   ...) ATTR_NORETURN ATTR_FORMAT (printf, 2, 3);
  94
  95 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
  96    handler.  If an exception (enum return_reason) is thrown using
  97    throw_exception() than all cleanups installed since
  98    catch_exceptions() was entered are invoked, the (-ve) exception
  99    value is then returned by catch_exceptions.  If FUNC() returns
 100    normally (with a postive or zero return value) then that value is
 101    returned by catch_exceptions().  It is an internal_error() for
 102    FUNC() to return a negative value.
 103
 104    For the period of the FUNC() call: UIOUT is installed as the output
 105    builder; ERRSTRING is installed as the error/quit message; and a
 106    new cleanup_chain is established.  The old values are restored
 107    before catch_exceptions() returns.
 108
 109    The variant catch_exceptions_with_msg() is the same as
 110    catch_exceptions() but adds the ability to return an allocated
 111    copy of the gdb error message.  This is used when a silent error is
 112    issued and the caller wants to manually issue the error message.
 113
 114    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 115    builder variable should just go away.
 116
 117    This function superseeds catch_errors().
 118
 119    This function uses SETJMP() and LONGJUMP().  */
 120
 121 struct ui_out;
 122 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 123 extern int catch_exceptions (struct ui_out *uiout,
 124                              catch_exceptions_ftype *func, void *func_args,
 125                              char *errstring, return_mask mask);
 126 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 127 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 128                                       catch_exceptions_ftype *func,
 129                                       void *func_args,
 130                                       char *errstring, char **gdberrmsg,
 131                                       return_mask mask);
 132
 133 /* This function, in addition, suppresses the printing of the captured
 134    error message.  It's up to the client to print it.  */
 135
 136 extern struct exception catch_exception (struct ui_out *uiout,
 137                                          catch_exception_ftype *func,
 138                                          void *func_args,
 139                                          return_mask mask);
 140
 141 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 142    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
 143    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 144    value. It's unfortunate that, catch_errors() does not return an
 145    indication of the exact exception that it caught - quit_flag might
 146    help.
 147
 148    This function is superseeded by catch_exceptions().  */
 149
 150 typedef int (catch_errors_ftype) (void *);
 151 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 152
 153 /* Template to catch_errors() that wraps calls to command
 154    functions. */
 155
 156 typedef void (catch_command_errors_ftype) (char *, int);
 157 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 158
 159 #endif