gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986, 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
   4    1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
   5    Free 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., 51 Franklin Street, Fifth Floor,
  22    Boston, MA 02110-1301, USA.  */
  23
  24 #ifndef EXCEPTIONS_H
  25 #define EXCEPTIONS_H
  26
  27 #include "ui-out.h"
  28 #include <setjmp.h>
  29
  30 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  31    must be less than zero.  enum value 0 is reserved for internal use
  32    as the return value from an initial setjmp().  The function
  33    catch_exceptions() reserves values >= 0 as legal results from its
  34    wrapped function.  */
  35
  36 enum return_reason
  37   {
  38     /* User interrupt.  */
  39     RETURN_QUIT = -2,
  40     /* Any other error.  */
  41     RETURN_ERROR
  42   };
  43
  44 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  45 #define RETURN_MASK_QUIT        RETURN_MASK (RETURN_QUIT)
  46 #define RETURN_MASK_ERROR       RETURN_MASK (RETURN_ERROR)
  47 #define RETURN_MASK_ALL         (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  48 typedef int return_mask;
  49
  50 /* Describe all exceptions.  */
  51
  52 enum errors {
  53   GDB_NO_ERROR,
  54   /* Any generic error, the corresponding text is in
  55      exception.message.  */
  56   GENERIC_ERROR,
  57   NOT_FOUND_ERROR,
  58
  59   /* Thread library lacks support necessary for finding thread local
  60      storage.  */
  61   TLS_NO_LIBRARY_SUPPORT_ERROR,
  62
  63   /* Load module not found while attempting to find thread local storage.  */
  64   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  65
  66   /* Thread local storage has not been allocated yet.  */
  67   TLS_NOT_ALLOCATED_YET_ERROR,
  68
  69   /* Something else went wrong while attempting to find thread local
  70      storage.  The ``struct gdb_exception'' message field provides
  71      more detail.  */
  72   TLS_GENERIC_ERROR,
  73
  74   /* Problem parsing an XML document.  */
  75   XML_PARSE_ERROR,
  76
  77   /* Add more errors here.  */
  78   NR_ERRORS
  79 };
  80
  81 struct gdb_exception
  82 {
  83   enum return_reason reason;
  84   enum errors error;
  85   const char *message;
  86 };
  87
  88 /* A pre-defined non-exception.  */
  89 extern const struct gdb_exception exception_none;
  90
  91 /* Wrap set/long jmp so that it's more portable (internal to
  92    exceptions).  */
  93
  94 #if defined(HAVE_SIGSETJMP)
  95 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
  96 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
  97 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
  98 #else
  99 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 100 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 101 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 102 #endif
 103
 104 /* Functions to drive the exceptions state m/c (internal to
 105    exceptions).  */
 106 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (struct ui_out *func_uiout,
 107                                                  volatile struct gdb_exception *
 108                                                  exception,
 109                                                  return_mask mask);
 110 int exceptions_state_mc_action_iter (void);
 111 int exceptions_state_mc_action_iter_1 (void);
 112
 113 /* Macro to wrap up standard try/catch behavior.
 114
 115    The double loop lets us correctly handle code "break"ing out of the
 116    try catch block.  (It works as the "break" only exits the inner
 117    "while" loop, the outer for loop detects this handling it
 118    correctly.)  Of course "return" and "goto" are not so lucky.
 119
 120    For instance:
 121
 122    *INDENT-OFF*
 123
 124    volatile struct gdb_exception e;
 125    TRY_CATCH (e, RETURN_MASK_ERROR)
 126      {
 127      }
 128    switch (e.reason)
 129      {
 130      case RETURN_ERROR: ...
 131      }
 132
 133   */
 134
 135 #define TRY_CATCH(EXCEPTION,MASK) \
 136      { \
 137        EXCEPTIONS_SIGJMP_BUF *buf = \
 138          exceptions_state_mc_init (uiout, &(EXCEPTION), (MASK)); \
 139        EXCEPTIONS_SIGSETJMP (*buf); \
 140      } \
 141      while (exceptions_state_mc_action_iter ()) \
 142        while (exceptions_state_mc_action_iter_1 ())
 143
 144 /* *INDENT-ON* */
 145
 146
 147 /* If E is an exception, print it's error message on the specified
 148    stream. for _fprintf, prefix the message with PREFIX...  */
 149 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 150 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 151                                const char *prefix,
 152                                ...) ATTR_FORMAT (printf, 3, 4);
 153
 154 /* Throw an exception (as described by "struct gdb_exception").  Will
 155    execute a LONG JUMP to the inner most containing exception handler
 156    established using catch_exceptions() (or similar).
 157
 158    Code normally throws an exception using error() et.al.  For various
 159    reaons, GDB also contains code that throws an exception directly.
 160    For instance, the remote*.c targets contain CNTRL-C signal handlers
 161    that propogate the QUIT event up the exception chain.  ``This could
 162    be a good thing or a dangerous thing.'' -- the Existential
 163    Wombat.  */
 164
 165 extern NORETURN void throw_exception (struct gdb_exception exception) ATTR_NORETURN;
 166 extern NORETURN void throw_verror (enum errors, const char *fmt, va_list ap)
 167      ATTR_NORETURN ATTR_FORMAT (printf, 2, 0);
 168 extern NORETURN void throw_vfatal (const char *fmt, va_list ap)
 169      ATTR_NORETURN ATTR_FORMAT (printf, 1, 0);
 170 extern NORETURN void throw_error (enum errors error, const char *fmt,
 171                                   ...) ATTR_NORETURN ATTR_FORMAT (printf, 2, 3);
 172
 173 /* Instead of deprecated_throw_reason, code should use catch_exception
 174    and throw_exception.  */
 175 extern NORETURN void deprecated_throw_reason (enum return_reason reason) ATTR_NORETURN;
 176
 177 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 178    handler.  If an exception (enum return_reason) is thrown using
 179    throw_exception() than all cleanups installed since
 180    catch_exceptions() was entered are invoked, the (-ve) exception
 181    value is then returned by catch_exceptions.  If FUNC() returns
 182    normally (with a postive or zero return value) then that value is
 183    returned by catch_exceptions().  It is an internal_error() for
 184    FUNC() to return a negative value.
 185
 186    For the period of the FUNC() call: UIOUT is installed as the output
 187    builder; ERRSTRING is installed as the error/quit message; and a
 188    new cleanup_chain is established.  The old values are restored
 189    before catch_exceptions() returns.
 190
 191    The variant catch_exceptions_with_msg() is the same as
 192    catch_exceptions() but adds the ability to return an allocated
 193    copy of the gdb error message.  This is used when a silent error is
 194    issued and the caller wants to manually issue the error message.
 195
 196    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 197    builder variable should just go away.
 198
 199    This function superseeds catch_errors().
 200
 201    This function uses SETJMP() and LONGJUMP().  */
 202
 203 struct ui_out;
 204 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 205 extern int catch_exceptions (struct ui_out *uiout,
 206                              catch_exceptions_ftype *func, void *func_args,
 207                              return_mask mask);
 208 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 209 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 210                                       catch_exceptions_ftype *func,
 211                                       void *func_args,
 212                                       char **gdberrmsg,
 213                                       return_mask mask);
 214
 215 /* This function, in addition, suppresses the printing of the captured
 216    error message.  It's up to the client to print it.  */
 217
 218 extern struct gdb_exception catch_exception (struct ui_out *uiout,
 219                                              catch_exception_ftype *func,
 220                                              void *func_args,
 221                                              return_mask mask);
 222
 223 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 224    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
 225    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 226    value. It's unfortunate that, catch_errors() does not return an
 227    indication of the exact exception that it caught - quit_flag might
 228    help.
 229
 230    This function is superseeded by catch_exceptions().  */
 231
 232 typedef int (catch_errors_ftype) (void *);
 233 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 234
 235 /* Template to catch_errors() that wraps calls to command
 236    functions. */
 237
 238 typedef void (catch_command_errors_ftype) (char *, int);
 239 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 240
 241 #endif