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
  60   /* Thread library lacks support necessary for finding thread local
  61      storage.  */
  62   TLS_NO_LIBRARY_SUPPORT_ERROR,
  63
  64   /* Load module not found while attempting to find thread local storage.  */
  65   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  66
  67   /* Thread local storage has not been allocated yet.  */
  68   TLS_NOT_ALLOCATED_YET_ERROR,
  69
  70   /* Something else went wrong while attempting to find thread local
  71      storage.  The ``struct gdb_exception'' message field provides
  72      more detail.  */
  73   TLS_GENERIC_ERROR,
  74
  75   /* Add more errors here.  */
  76   NR_ERRORS
  77 };
  78
  79 struct gdb_exception
  80 {
  81   enum return_reason reason;
  82   enum errors error;
  83   const char *message;
  84 };
  85
  86 /* A pre-defined non-exception.  */
  87 extern const struct gdb_exception exception_none;
  88
  89 /* Wrap set/long jmp so that it's more portable (internal to
  90    exceptions).  */
  91
  92 #if defined(HAVE_SIGSETJMP)
  93 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
  94 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
  95 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
  96 #else
  97 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
  98 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
  99 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 100 #endif
 101
 102 /* Functions to drive the exceptions state m/c (internal to
 103    exceptions).  */
 104 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (struct ui_out *func_uiout,
 105                                                  volatile struct gdb_exception *
 106                                                  exception,
 107                                                  return_mask mask);
 108 int exceptions_state_mc_action_iter (void);
 109 int exceptions_state_mc_action_iter_1 (void);
 110
 111 /* Macro to wrap up standard try/catch behavior.
 112
 113    The double loop lets us correctly handle code "break"ing out of the
 114    try catch block.  (It works as the "break" only exits the inner
 115    "while" loop, the outer for loop detects this handling it
 116    correctly.)  Of course "return" and "goto" are not so lucky.
 117
 118    For instance:
 119
 120    *INDENT-OFF*
 121
 122    volatile struct gdb_exception e;
 123    TRY_CATCH (e, RETURN_MASK_ERROR)
 124      {
 125      }
 126    switch (e.reason)
 127      {
 128      case RETURN_ERROR: ...
 129      }
 130
 131   */
 132
 133 #define TRY_CATCH(EXCEPTION,MASK) \
 134      { \
 135        EXCEPTIONS_SIGJMP_BUF *buf = \
 136          exceptions_state_mc_init (uiout, &(EXCEPTION), (MASK)); \
 137        EXCEPTIONS_SIGSETJMP (*buf); \
 138      } \
 139      while (exceptions_state_mc_action_iter ()) \
 140        while (exceptions_state_mc_action_iter_1 ())
 141
 142 /* *INDENT-ON* */
 143
 144
 145 /* If E is an exception, print it's error message on the specified
 146    stream. for _fprintf, prefix the message with PREFIX...  */
 147 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 148 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 149                                const char *prefix,
 150                                ...) ATTR_FORMAT (printf, 3, 4);
 151
 152 /* Throw an exception (as described by "struct gdb_exception").  Will
 153    execute a LONG JUMP to the inner most containing exception handler
 154    established using catch_exceptions() (or similar).
 155
 156    Code normally throws an exception using error() et.al.  For various
 157    reaons, GDB also contains code that throws an exception directly.
 158    For instance, the remote*.c targets contain CNTRL-C signal handlers
 159    that propogate the QUIT event up the exception chain.  ``This could
 160    be a good thing or a dangerous thing.'' -- the Existential
 161    Wombat.  */
 162
 163 extern NORETURN void throw_exception (struct gdb_exception exception) ATTR_NORETURN;
 164 extern NORETURN void throw_verror (enum errors, const char *fmt,
 165                                    va_list ap) ATTR_NORETURN;
 166 extern NORETURN void throw_vfatal (const char *fmt, va_list ap) ATTR_NORETURN;
 167 extern NORETURN void throw_error (enum errors error, const char *fmt,
 168                                   ...) ATTR_NORETURN ATTR_FORMAT (printf, 2, 3);
 169
 170 /* Instead of deprecated_throw_reason, code should use catch_exception
 171    and throw_exception.  */
 172 extern NORETURN void deprecated_throw_reason (enum return_reason reason) ATTR_NORETURN;
 173
 174 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 175    handler.  If an exception (enum return_reason) is thrown using
 176    throw_exception() than all cleanups installed since
 177    catch_exceptions() was entered are invoked, the (-ve) exception
 178    value is then returned by catch_exceptions.  If FUNC() returns
 179    normally (with a postive or zero return value) then that value is
 180    returned by catch_exceptions().  It is an internal_error() for
 181    FUNC() to return a negative value.
 182
 183    For the period of the FUNC() call: UIOUT is installed as the output
 184    builder; ERRSTRING is installed as the error/quit message; and a
 185    new cleanup_chain is established.  The old values are restored
 186    before catch_exceptions() returns.
 187
 188    The variant catch_exceptions_with_msg() is the same as
 189    catch_exceptions() but adds the ability to return an allocated
 190    copy of the gdb error message.  This is used when a silent error is
 191    issued and the caller wants to manually issue the error message.
 192
 193    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 194    builder variable should just go away.
 195
 196    This function superseeds catch_errors().
 197
 198    This function uses SETJMP() and LONGJUMP().  */
 199
 200 struct ui_out;
 201 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 202 extern int catch_exceptions (struct ui_out *uiout,
 203                              catch_exceptions_ftype *func, void *func_args,
 204                              return_mask mask);
 205 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 206 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 207                                       catch_exceptions_ftype *func,
 208                                       void *func_args,
 209                                       char **gdberrmsg,
 210                                       return_mask mask);
 211
 212 /* This function, in addition, suppresses the printing of the captured
 213    error message.  It's up to the client to print it.  */
 214
 215 extern struct gdb_exception catch_exception (struct ui_out *uiout,
 216                                              catch_exception_ftype *func,
 217                                              void *func_args,
 218                                              return_mask mask);
 219
 220 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 221    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
 222    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 223    value. It's unfortunate that, catch_errors() does not return an
 224    indication of the exact exception that it caught - quit_flag might
 225    help.
 226
 227    This function is superseeded by catch_exceptions().  */
 228
 229 typedef int (catch_errors_ftype) (void *);
 230 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 231
 232 /* Template to catch_errors() that wraps calls to command
 233    functions. */
 234
 235 typedef void (catch_command_errors_ftype) (char *, int);
 236 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 237
 238 #endif