gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986, 1988-2012 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 EXCEPTIONS_H
  21 #define EXCEPTIONS_H
  22
  23 #include "ui-out.h"
  24 #include <setjmp.h>
  25
  26 /* Reasons for calling throw_exceptions().  NOTE: all reason values
  27    must be less than zero.  enum value 0 is reserved for internal use
  28    as the return value from an initial setjmp().  The function
  29    catch_exceptions() reserves values >= 0 as legal results from its
  30    wrapped function.  */
  31
  32 enum return_reason
  33   {
  34     /* User interrupt.  */
  35     RETURN_QUIT = -2,
  36     /* Any other error.  */
  37     RETURN_ERROR
  38   };
  39
  40 #define RETURN_MASK(reason)     (1 << (int)(-reason))
  41 #define RETURN_MASK_QUIT        RETURN_MASK (RETURN_QUIT)
  42 #define RETURN_MASK_ERROR       RETURN_MASK (RETURN_ERROR)
  43 #define RETURN_MASK_ALL         (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  44 typedef int return_mask;
  45
  46 /* Describe all exceptions.  */
  47
  48 enum errors {
  49   GDB_NO_ERROR,
  50
  51   /* Any generic error, the corresponding text is in
  52      exception.message.  */
  53   GENERIC_ERROR,
  54
  55   /* Something requested was not found.  */
  56   NOT_FOUND_ERROR,
  57
  58   /* Thread library lacks support necessary for finding thread local
  59      storage.  */
  60   TLS_NO_LIBRARY_SUPPORT_ERROR,
  61
  62   /* Load module not found while attempting to find thread local storage.  */
  63   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  64
  65   /* Thread local storage has not been allocated yet.  */
  66   TLS_NOT_ALLOCATED_YET_ERROR,
  67
  68   /* Something else went wrong while attempting to find thread local
  69      storage.  The ``struct gdb_exception'' message field provides
  70      more detail.  */
  71   TLS_GENERIC_ERROR,
  72
  73   /* Problem parsing an XML document.  */
  74   XML_PARSE_ERROR,
  75
  76   /* Error accessing memory.  */
  77   MEMORY_ERROR,
  78
  79   /* Feature is not supported in this copy of GDB.  */
  80   UNSUPPORTED_ERROR,
  81
  82   /* Value not available.  E.g., a register was not collected in a
  83      traceframe.  */
  84   NOT_AVAILABLE_ERROR,
  85
  86   /* DW_OP_GNU_entry_value resolving failed.  */
  87   NO_ENTRY_VALUE_ERROR,
  88
  89   /* Add more errors here.  */
  90   NR_ERRORS
  91 };
  92
  93 struct gdb_exception
  94 {
  95   enum return_reason reason;
  96   enum errors error;
  97   const char *message;
  98 };
  99
 100 /* A pre-defined non-exception.  */
 101 extern const struct gdb_exception exception_none;
 102
 103 /* Wrap set/long jmp so that it's more portable (internal to
 104    exceptions).  */
 105
 106 #if defined(HAVE_SIGSETJMP)
 107 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 108 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 109 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 110 #else
 111 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 112 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 113 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 114 #endif
 115
 116 /* Functions to drive the exceptions state m/c (internal to
 117    exceptions).  */
 118 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 119                                                  gdb_exception *exception,
 120                                                  return_mask mask);
 121 int exceptions_state_mc_action_iter (void);
 122 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        EXCEPTIONS_SIGJMP_BUF *buf = \
 149          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 150        EXCEPTIONS_SIGSETJMP (*buf); \
 151      } \
 152      while (exceptions_state_mc_action_iter ()) \
 153        while (exceptions_state_mc_action_iter_1 ())
 154
 155 /* *INDENT-ON* */
 156
 157
 158 /* If E is an exception, print it's error message on the specified
 159    stream.  For _fprintf, prefix the message with PREFIX...  */
 160 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 161 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 162                                const char *prefix,
 163                                ...) ATTRIBUTE_PRINTF (3, 4);
 164
 165 /* Throw an exception (as described by "struct gdb_exception").  Will
 166    execute a LONG JUMP to the inner most containing exception handler
 167    established using catch_exceptions() (or similar).
 168
 169    Code normally throws an exception using error() et.al.  For various
 170    reaons, GDB also contains code that throws an exception directly.
 171    For instance, the remote*.c targets contain CNTRL-C signal handlers
 172    that propogate the QUIT event up the exception chain.  ``This could
 173    be a good thing or a dangerous thing.'' -- the Existential
 174    Wombat.  */
 175
 176 extern void throw_exception (struct gdb_exception exception)
 177      ATTRIBUTE_NORETURN;
 178 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 179      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 180 extern void throw_vfatal (const char *fmt, va_list ap)
 181      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 182 extern void throw_error (enum errors error, const char *fmt, ...)
 183      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 184
 185 /* Instead of deprecated_throw_reason, code should use
 186    throw_exception.  */
 187 extern void deprecated_throw_reason (enum return_reason reason)
 188      ATTRIBUTE_NORETURN;
 189
 190 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 191    handler.  If an exception (enum return_reason) is thrown using
 192    throw_exception() than all cleanups installed since
 193    catch_exceptions() was entered are invoked, the (-ve) exception
 194    value is then returned by catch_exceptions.  If FUNC() returns
 195    normally (with a positive or zero return value) then that value is
 196    returned by catch_exceptions().  It is an internal_error() for
 197    FUNC() to return a negative value.
 198
 199    For the period of the FUNC() call: UIOUT is installed as the output
 200    builder; ERRSTRING is installed as the error/quit message; and a
 201    new cleanup_chain is established.  The old values are restored
 202    before catch_exceptions() returns.
 203
 204    The variant catch_exceptions_with_msg() is the same as
 205    catch_exceptions() but adds the ability to return an allocated
 206    copy of the gdb error message.  This is used when a silent error is
 207    issued and the caller wants to manually issue the error message.
 208
 209    MASK specifies what to catch; it is normally set to
 210    RETURN_MASK_ALL, if for no other reason than that the code which
 211    calls catch_errors might not be set up to deal with a quit which
 212    isn't caught.  But if the code can deal with it, it generally
 213    should be RETURN_MASK_ERROR, unless for some reason it is more
 214    useful to abort only the portion of the operation inside the
 215    catch_errors.  Note that quit should return to the command line
 216    fairly quickly, even if some further processing is being done.
 217
 218    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 219    builder variable should just go away.
 220
 221    This function supersedes catch_errors().
 222
 223    This function uses SETJMP() and LONGJUMP().  */
 224
 225 struct ui_out;
 226 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 227 extern int catch_exceptions (struct ui_out *uiout,
 228                              catch_exceptions_ftype *func, void *func_args,
 229                              return_mask mask);
 230 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 231 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 232                                       catch_exceptions_ftype *func,
 233                                       void *func_args,
 234                                       char **gdberrmsg,
 235                                       return_mask mask);
 236
 237 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 238    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 239    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 240    value.  It's unfortunate that, catch_errors() does not return an
 241    indication of the exact exception that it caught - quit_flag might
 242    help.
 243
 244    This function is superseded by catch_exceptions().  */
 245
 246 typedef int (catch_errors_ftype) (void *);
 247 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 248
 249 /* Template to catch_errors() that wraps calls to command
 250    functions.  */
 251
 252 typedef void (catch_command_errors_ftype) (char *, int);
 253 extern int catch_command_errors (catch_command_errors_ftype *func,
 254                                  char *command, int from_tty, return_mask);
 255
 256 #endif