gdb/common/common-exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2015 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef COMMON_EXCEPTIONS_H
  21 #define COMMON_EXCEPTIONS_H
  22
  23 #include "gdb_setjmp.h"
  24
  25 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  26    must be less than zero.  enum value 0 is reserved for internal use
  27    as the return value from an initial setjmp().  The function
  28    catch_exceptions() reserves values >= 0 as legal results from its
  29    wrapped function.  */
  30
  31 enum return_reason
  32   {
  33     /* User interrupt.  */
  34     RETURN_QUIT = -2,
  35     /* Any other error.  */
  36     RETURN_ERROR
  37   };
  38
  39 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  40
  41 typedef enum
  42 {
  43   RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT),
  44   RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR),
  45   RETURN_MASK_ALL = (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  46 } 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   /* Value not available.  E.g., a register was not collected in a
  82      traceframe.  */
  83   NOT_AVAILABLE_ERROR,
  84
  85   /* Value was optimized out.  Note: if the value was a register, this
  86      means the register was not saved in the frame.  */
  87   OPTIMIZED_OUT_ERROR,
  88
  89   /* DW_OP_GNU_entry_value resolving failed.  */
  90   NO_ENTRY_VALUE_ERROR,
  91
  92   /* Target throwing an error has been closed.  Current command should be
  93      aborted as the inferior state is no longer valid.  */
  94   TARGET_CLOSE_ERROR,
  95
  96   /* An undefined command was executed.  */
  97   UNDEFINED_COMMAND_ERROR,
  98
  99   /* Requested feature, method, mechanism, etc. is not supported.  */
 100   NOT_SUPPORTED_ERROR,
 101
 102   /* Add more errors here.  */
 103   NR_ERRORS
 104 };
 105
 106 struct gdb_exception
 107 {
 108   enum return_reason reason;
 109   enum errors error;
 110   const char *message;
 111 };
 112
 113 /* Functions to drive the exceptions state machine.  Though declared
 114    here by necessity, these functions should be considered internal to
 115    the exceptions subsystem and not used other than via the TRY_CATCH
 116    macro defined below.  */
 117
 118 extern SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 119                                              gdb_exception *exception,
 120                                              return_mask mask);
 121 extern int exceptions_state_mc_action_iter (void);
 122 extern int exceptions_state_mc_action_iter_1 (void);
 123
 124 /* Macro to wrap up standard try/catch behavior.
 125
 126    The double loop lets us correctly handle code "break"ing out of the
 127    try catch block.  (It works as the "break" only exits the inner
 128    "while" loop, the outer for loop detects this handling it
 129    correctly.)  Of course "return" and "goto" are not so lucky.
 130
 131    For instance:
 132
 133    *INDENT-OFF*
 134
 135    volatile struct gdb_exception e;
 136    TRY_CATCH (e, RETURN_MASK_ERROR)
 137      {
 138      }
 139    switch (e.reason)
 140      {
 141      case RETURN_ERROR: ...
 142      }
 143
 144   */
 145
 146 #define TRY_CATCH(EXCEPTION,MASK) \
 147      { \
 148        SIGJMP_BUF *buf = \
 149          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 150        SIGSETJMP (*buf); \
 151      } \
 152      while (exceptions_state_mc_action_iter ()) \
 153        while (exceptions_state_mc_action_iter_1 ())
 154
 155 /* *INDENT-ON* */
 156
 157 /* Hook to allow client-specific actions to be performed prior to
 158    throwing an exception.  This function must be provided by the
 159    client, and will be called before any cleanups are run.  */
 160
 161 extern void prepare_to_throw_exception (void);
 162
 163 /* Throw an exception (as described by "struct gdb_exception").  Will
 164    execute a LONG JUMP to the inner most containing exception handler
 165    established using catch_exceptions() (or similar).
 166
 167    Code normally throws an exception using error() et.al.  For various
 168    reaons, GDB also contains code that throws an exception directly.
 169    For instance, the remote*.c targets contain CNTRL-C signal handlers
 170    that propogate the QUIT event up the exception chain.  ``This could
 171    be a good thing or a dangerous thing.'' -- the Existential
 172    Wombat.  */
 173
 174 extern void throw_exception (struct gdb_exception exception)
 175      ATTRIBUTE_NORETURN;
 176 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 177      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 178 extern void throw_vquit (const char *fmt, va_list ap)
 179      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 180 extern void throw_error (enum errors error, const char *fmt, ...)
 181      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 182 extern void throw_quit (const char *fmt, ...)
 183      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2);
 184
 185 #endif /* COMMON_EXCEPTIONS_H */