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 struct ui_out;
  28
  29 #include <setjmp.h>
  30
  31 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  32    must be less than zero.  enum value 0 is reserved for internal use
  33    as the return value from an initial setjmp().  The function
  34    catch_exceptions() reserves values >= 0 as legal results from its
  35    wrapped function.  */
  36
  37 enum return_reason
  38   {
  39     /* User interrupt.  */
  40     RETURN_QUIT = -2,
  41     /* Any other error.  */
  42     RETURN_ERROR
  43   };
  44
  45 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  46 #define RETURN_MASK_QUIT        RETURN_MASK (RETURN_QUIT)
  47 #define RETURN_MASK_ERROR       RETURN_MASK (RETURN_ERROR)
  48 #define RETURN_MASK_ALL         (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  49 typedef int return_mask;
  50
  51 /* Describe all exceptions.  */
  52
  53 enum errors {
  54   NO_ERROR,
  55   /* Any generic error, the corresponding text is in
  56      exception.message.  */
  57   GENERIC_ERROR,
  58   NOT_FOUND_ERROR,
  59   /* Add more errors here.  */
  60   NR_ERRORS
  61 };
  62
  63 struct exception
  64 {
  65   enum return_reason reason;
  66   enum errors error;
  67   const char *message;
  68 };
  69
  70 /* A pre-defined non-exception.  */
  71 extern const struct exception exception_none;
  72
  73 /* Wrap set/long jmp so that it's more portable (internal to
  74    exceptions).  */
  75
  76 #if defined(HAVE_SIGSETJMP)
  77 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
  78 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
  79 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
  80 #else
  81 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
  82 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
  83 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
  84 #endif
  85
  86 /* Functions to drive the exceptions state m/c (internal to
  87    exceptions).  */
  88 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (struct ui_out *func_uiout,
  89                                                  volatile struct exception *
  90                                                  exception,
  91                                                  return_mask mask);
  92 int exceptions_state_mc_action_iter (void);
  93 int exceptions_state_mc_action_iter_1 (void);
  94
  95 /* Macro to wrap up standard try/catch behavior.
  96
  97    The double loop lets us correctly handle code "break"ing out of the
  98    try catch block.  (It works as the "break" only exits the inner
  99    "while" loop, the outer for loop detects this handling it
 100    correctly.)  Of course "return" and "goto" are not so lucky.
 101
 102    For instance:
 103
 104    *INDENT-OFF*
 105
 106    volatile struct exception e;
 107    TRY_CATCH (e, RETURN_MASK_ERROR)
 108      {
 109      }
 110    switch (e.reason)
 111      {
 112      case RETURN_ERROR: ...
 113      }
 114
 115   */
 116
 117 #define TRY_CATCH(EXCEPTION,MASK) \
 118     for (EXCEPTIONS_SIGSETJMP \
 119            (*exceptions_state_mc_init (uiout, &(EXCEPTION), (MASK))); \
 120          exceptions_state_mc_action_iter (); ) \
 121       while (exceptions_state_mc_action_iter_1 ())
 122
 123 /* *INDENT-ON* */
 124
 125
 126 /* If E is an exception, print it's error message on the specified
 127    stream. for _fprintf, prefix the message with PREFIX...  */
 128 extern void exception_print (struct ui_file *file, struct exception e);
 129 extern void exception_fprintf (struct ui_file *file, struct exception e,
 130                                const char *prefix,
 131                                ...) ATTR_FORMAT (printf, 3, 4);
 132
 133 /* Throw an exception (as described by "struct exception").  Will
 134    execute a LONG JUMP to the inner most containing exception handler
 135    established using catch_exceptions() (or similar).
 136
 137    Code normally throws an exception using error() et.al.  For various
 138    reaons, GDB also contains code that throws an exception directly.
 139    For instance, the remote*.c targets contain CNTRL-C signal handlers
 140    that propogate the QUIT event up the exception chain.  ``This could
 141    be a good thing or a dangerous thing.'' -- the Existential
 142    Wombat.  */
 143
 144 extern NORETURN void throw_exception (struct exception exception) ATTR_NORETURN;
 145 extern NORETURN void throw_verror (enum errors, const char *fmt,
 146                                    va_list ap) ATTR_NORETURN;
 147 extern NORETURN void throw_vfatal (const char *fmt, va_list ap) ATTR_NORETURN;
 148 extern NORETURN void throw_error (enum errors error, const char *fmt,
 149                                   ...) ATTR_NORETURN ATTR_FORMAT (printf, 2, 3);
 150
 151 /* Instead of deprecated_throw_reason, code should use catch_exception
 152    and throw_exception.  */
 153 extern NORETURN void deprecated_throw_reason (enum return_reason reason) ATTR_NORETURN;
 154
 155 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 156    handler.  If an exception (enum return_reason) is thrown using
 157    throw_exception() than all cleanups installed since
 158    catch_exceptions() was entered are invoked, the (-ve) exception
 159    value is then returned by catch_exceptions.  If FUNC() returns
 160    normally (with a postive or zero return value) then that value is
 161    returned by catch_exceptions().  It is an internal_error() for
 162    FUNC() to return a negative value.
 163
 164    For the period of the FUNC() call: UIOUT is installed as the output
 165    builder; ERRSTRING is installed as the error/quit message; and a
 166    new cleanup_chain is established.  The old values are restored
 167    before catch_exceptions() returns.
 168
 169    The variant catch_exceptions_with_msg() is the same as
 170    catch_exceptions() but adds the ability to return an allocated
 171    copy of the gdb error message.  This is used when a silent error is
 172    issued and the caller wants to manually issue the error message.
 173
 174    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 175    builder variable should just go away.
 176
 177    This function superseeds catch_errors().
 178
 179    This function uses SETJMP() and LONGJUMP().  */
 180
 181 struct ui_out;
 182 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 183 extern int catch_exceptions (struct ui_out *uiout,
 184                              catch_exceptions_ftype *func, void *func_args,
 185                              return_mask mask);
 186 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 187 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 188                                       catch_exceptions_ftype *func,
 189                                       void *func_args,
 190                                       char **gdberrmsg,
 191                                       return_mask mask);
 192
 193 /* This function, in addition, suppresses the printing of the captured
 194    error message.  It's up to the client to print it.  */
 195
 196 extern struct exception catch_exception (struct ui_out *uiout,
 197                                          catch_exception_ftype *func,
 198                                          void *func_args,
 199                                          return_mask mask);
 200
 201 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 202    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
 203    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 204    value. It's unfortunate that, catch_errors() does not return an
 205    indication of the exact exception that it caught - quit_flag might
 206    help.
 207
 208    This function is superseeded by catch_exceptions().  */
 209
 210 typedef int (catch_errors_ftype) (void *);
 211 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 212
 213 /* Template to catch_errors() that wraps calls to command
 214    functions. */
 215
 216 typedef void (catch_command_errors_ftype) (char *, int);
 217 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 218
 219 #endif