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   /* The number of candidates generated during line completion has
 103      reached the user's specified limit.  This isn't an error, this exception
 104      is used to halt searching for more completions, but for consistency
 105      "_ERROR" is appended to the name.  */
 106   MAX_COMPLETIONS_REACHED_ERROR,
 107
 108   /* Add more errors here.  */
 109   NR_ERRORS
 110 };
 111
 112 struct gdb_exception
 113 {
 114   enum return_reason reason;
 115   enum errors error;
 116   const char *message;
 117 };
 118
 119 /* Functions to drive the exceptions state machine.  Though declared
 120    here by necessity, these functions should be considered internal to
 121    the exceptions subsystem and not used other than via the TRY_CATCH
 122    macro defined below.  */
 123
 124 extern SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 125                                              gdb_exception *exception,
 126                                              return_mask mask);
 127 extern int exceptions_state_mc_action_iter (void);
 128 extern int exceptions_state_mc_action_iter_1 (void);
 129
 130 /* Macro to wrap up standard try/catch behavior.
 131
 132    The double loop lets us correctly handle code "break"ing out of the
 133    try catch block.  (It works as the "break" only exits the inner
 134    "while" loop, the outer for loop detects this handling it
 135    correctly.)  Of course "return" and "goto" are not so lucky.
 136
 137    For instance:
 138
 139    *INDENT-OFF*
 140
 141    volatile struct gdb_exception e;
 142    TRY_CATCH (e, RETURN_MASK_ERROR)
 143      {
 144      }
 145    switch (e.reason)
 146      {
 147      case RETURN_ERROR: ...
 148      }
 149
 150   */
 151
 152 #define TRY_CATCH(EXCEPTION,MASK) \
 153      { \
 154        SIGJMP_BUF *buf = \
 155          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 156        SIGSETJMP (*buf); \
 157      } \
 158      while (exceptions_state_mc_action_iter ()) \
 159        while (exceptions_state_mc_action_iter_1 ())
 160
 161 /* *INDENT-ON* */
 162
 163 /* Hook to allow client-specific actions to be performed prior to
 164    throwing an exception.  This function must be provided by the
 165    client, and will be called before any cleanups are run.  */
 166
 167 extern void prepare_to_throw_exception (void);
 168
 169 /* Throw an exception (as described by "struct gdb_exception").  Will
 170    execute a LONG JUMP to the inner most containing exception handler
 171    established using catch_exceptions() (or similar).
 172
 173    Code normally throws an exception using error() et.al.  For various
 174    reaons, GDB also contains code that throws an exception directly.
 175    For instance, the remote*.c targets contain CNTRL-C signal handlers
 176    that propogate the QUIT event up the exception chain.  ``This could
 177    be a good thing or a dangerous thing.'' -- the Existential
 178    Wombat.  */
 179
 180 extern void throw_exception (struct gdb_exception exception)
 181      ATTRIBUTE_NORETURN;
 182 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 183      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 184 extern void throw_vquit (const char *fmt, va_list ap)
 185      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 186 extern void throw_error (enum errors error, const char *fmt, ...)
 187      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 188 extern void throw_quit (const char *fmt, ...)
 189      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2);
 190
 191 #endif /* COMMON_EXCEPTIONS_H */