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, 2008,
   5    2009, 2010, 2011 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 3 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, see <http://www.gnu.org/licenses/>.  */
  21
  22 #ifndef EXCEPTIONS_H
  23 #define EXCEPTIONS_H
  24
  25 #include "ui-out.h"
  26 #include <setjmp.h>
  27
  28 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  29    must be less than zero.  enum value 0 is reserved for internal use
  30    as the return value from an initial setjmp().  The function
  31    catch_exceptions() reserves values >= 0 as legal results from its
  32    wrapped function.  */
  33
  34 enum return_reason
  35   {
  36     /* User interrupt.  */
  37     RETURN_QUIT = -2,
  38     /* Any other error.  */
  39     RETURN_ERROR
  40   };
  41
  42 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  43 #define RETURN_MASK_QUIT        RETURN_MASK (RETURN_QUIT)
  44 #define RETURN_MASK_ERROR       RETURN_MASK (RETURN_ERROR)
  45 #define RETURN_MASK_ALL         (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  46 typedef int return_mask;
  47
  48 /* Describe all exceptions.  */
  49
  50 enum errors {
  51   GDB_NO_ERROR,
  52
  53   /* Any generic error, the corresponding text is in
  54      exception.message.  */
  55   GENERIC_ERROR,
  56
  57   /* Something requested was not found.  */
  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   /* Problem parsing an XML document.  */
  76   XML_PARSE_ERROR,
  77
  78   /* Error accessing memory.  */
  79   MEMORY_ERROR,
  80
  81   /* Feature is not supported in this copy of GDB.  */
  82   UNSUPPORTED_ERROR,
  83
  84   /* Value not available.  E.g., a register was not collected in a
  85      traceframe.  */
  86   NOT_AVAILABLE_ERROR,
  87
  88   /* DW_OP_GNU_entry_value resolving failed.  */
  89   NO_ENTRY_VALUE_ERROR,
  90
  91   /* Add more errors here.  */
  92   NR_ERRORS
  93 };
  94
  95 struct gdb_exception
  96 {
  97   enum return_reason reason;
  98   enum errors error;
  99   const char *message;
 100 };
 101
 102 /* A pre-defined non-exception.  */
 103 extern const struct gdb_exception exception_none;
 104
 105 /* Wrap set/long jmp so that it's more portable (internal to
 106    exceptions).  */
 107
 108 #if defined(HAVE_SIGSETJMP)
 109 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 110 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 111 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 112 #else
 113 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 114 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 115 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 116 #endif
 117
 118 /* Functions to drive the exceptions state m/c (internal to
 119    exceptions).  */
 120 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 121                                                  gdb_exception *exception,
 122                                                  return_mask mask);
 123 int exceptions_state_mc_action_iter (void);
 124 int exceptions_state_mc_action_iter_1 (void);
 125
 126 /* Macro to wrap up standard try/catch behavior.
 127
 128    The double loop lets us correctly handle code "break"ing out of the
 129    try catch block.  (It works as the "break" only exits the inner
 130    "while" loop, the outer for loop detects this handling it
 131    correctly.)  Of course "return" and "goto" are not so lucky.
 132
 133    For instance:
 134
 135    *INDENT-OFF*
 136
 137    volatile struct gdb_exception e;
 138    TRY_CATCH (e, RETURN_MASK_ERROR)
 139      {
 140      }
 141    switch (e.reason)
 142      {
 143      case RETURN_ERROR: ...
 144      }
 145
 146   */
 147
 148 #define TRY_CATCH(EXCEPTION,MASK) \
 149      { \
 150        EXCEPTIONS_SIGJMP_BUF *buf = \
 151          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 152        EXCEPTIONS_SIGSETJMP (*buf); \
 153      } \
 154      while (exceptions_state_mc_action_iter ()) \
 155        while (exceptions_state_mc_action_iter_1 ())
 156
 157 /* *INDENT-ON* */
 158
 159
 160 /* If E is an exception, print it's error message on the specified
 161    stream.  For _fprintf, prefix the message with PREFIX...  */
 162 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 163 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 164                                const char *prefix,
 165                                ...) ATTRIBUTE_PRINTF (3, 4);
 166
 167 /* Throw an exception (as described by "struct gdb_exception").  Will
 168    execute a LONG JUMP to the inner most containing exception handler
 169    established using catch_exceptions() (or similar).
 170
 171    Code normally throws an exception using error() et.al.  For various
 172    reaons, GDB also contains code that throws an exception directly.
 173    For instance, the remote*.c targets contain CNTRL-C signal handlers
 174    that propogate the QUIT event up the exception chain.  ``This could
 175    be a good thing or a dangerous thing.'' -- the Existential
 176    Wombat.  */
 177
 178 extern void throw_exception (struct gdb_exception exception)
 179      ATTRIBUTE_NORETURN;
 180 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 181      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 182 extern void throw_vfatal (const char *fmt, va_list ap)
 183      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 184 extern void throw_error (enum errors error, const char *fmt, ...)
 185      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 186
 187 /* Instead of deprecated_throw_reason, code should use
 188    throw_exception.  */
 189 extern void deprecated_throw_reason (enum return_reason reason)
 190      ATTRIBUTE_NORETURN;
 191
 192 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 193    handler.  If an exception (enum return_reason) is thrown using
 194    throw_exception() than all cleanups installed since
 195    catch_exceptions() was entered are invoked, the (-ve) exception
 196    value is then returned by catch_exceptions.  If FUNC() returns
 197    normally (with a positive or zero return value) then that value is
 198    returned by catch_exceptions().  It is an internal_error() for
 199    FUNC() to return a negative value.
 200
 201    For the period of the FUNC() call: UIOUT is installed as the output
 202    builder; ERRSTRING is installed as the error/quit message; and a
 203    new cleanup_chain is established.  The old values are restored
 204    before catch_exceptions() returns.
 205
 206    The variant catch_exceptions_with_msg() is the same as
 207    catch_exceptions() but adds the ability to return an allocated
 208    copy of the gdb error message.  This is used when a silent error is
 209    issued and the caller wants to manually issue the error message.
 210
 211    MASK specifies what to catch; it is normally set to
 212    RETURN_MASK_ALL, if for no other reason than that the code which
 213    calls catch_errors might not be set up to deal with a quit which
 214    isn't caught.  But if the code can deal with it, it generally
 215    should be RETURN_MASK_ERROR, unless for some reason it is more
 216    useful to abort only the portion of the operation inside the
 217    catch_errors.  Note that quit should return to the command line
 218    fairly quickly, even if some further processing is being done.
 219
 220    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 221    builder variable should just go away.
 222
 223    This function supersedes catch_errors().
 224
 225    This function uses SETJMP() and LONGJUMP().  */
 226
 227 struct ui_out;
 228 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 229 extern int catch_exceptions (struct ui_out *uiout,
 230                              catch_exceptions_ftype *func, void *func_args,
 231                              return_mask mask);
 232 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 233 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 234                                       catch_exceptions_ftype *func,
 235                                       void *func_args,
 236                                       char **gdberrmsg,
 237                                       return_mask mask);
 238
 239 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 240    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 241    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 242    value.  It's unfortunate that, catch_errors() does not return an
 243    indication of the exact exception that it caught - quit_flag might
 244    help.
 245
 246    This function is superseded by catch_exceptions().  */
 247
 248 typedef int (catch_errors_ftype) (void *);
 249 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 250
 251 /* Template to catch_errors() that wraps calls to command
 252    functions.  */
 253
 254 typedef void (catch_command_errors_ftype) (char *, int);
 255 extern int catch_command_errors (catch_command_errors_ftype *func,
 256                                  char *command, int from_tty, return_mask);
 257
 258 #endif