gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2013 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   /* Target throwing an error has been closed.  Current command should be
  90      aborted as the inferior state is no longer valid.  */
  91   TARGET_CLOSE_ERROR,
  92
  93   /* Add more errors here.  */
  94   NR_ERRORS
  95 };
  96
  97 struct gdb_exception
  98 {
  99   enum return_reason reason;
 100   enum errors error;
 101   const char *message;
 102 };
 103
 104 /* A pre-defined non-exception.  */
 105 extern const struct gdb_exception exception_none;
 106
 107 /* Wrap set/long jmp so that it's more portable (internal to
 108    exceptions).  */
 109
 110 #if defined(HAVE_SIGSETJMP)
 111 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 112 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 113 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 114 #else
 115 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 116 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 117 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 118 #endif
 119
 120 /* Functions to drive the exceptions state m/c (internal to
 121    exceptions).  */
 122 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 123                                                  gdb_exception *exception,
 124                                                  return_mask mask);
 125 int exceptions_state_mc_action_iter (void);
 126 int exceptions_state_mc_action_iter_1 (void);
 127
 128 /* Macro to wrap up standard try/catch behavior.
 129
 130    The double loop lets us correctly handle code "break"ing out of the
 131    try catch block.  (It works as the "break" only exits the inner
 132    "while" loop, the outer for loop detects this handling it
 133    correctly.)  Of course "return" and "goto" are not so lucky.
 134
 135    For instance:
 136
 137    *INDENT-OFF*
 138
 139    volatile struct gdb_exception e;
 140    TRY_CATCH (e, RETURN_MASK_ERROR)
 141      {
 142      }
 143    switch (e.reason)
 144      {
 145      case RETURN_ERROR: ...
 146      }
 147
 148   */
 149
 150 #define TRY_CATCH(EXCEPTION,MASK) \
 151      { \
 152        EXCEPTIONS_SIGJMP_BUF *buf = \
 153          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 154        EXCEPTIONS_SIGSETJMP (*buf); \
 155      } \
 156      while (exceptions_state_mc_action_iter ()) \
 157        while (exceptions_state_mc_action_iter_1 ())
 158
 159 /* *INDENT-ON* */
 160
 161
 162 /* If E is an exception, print it's error message on the specified
 163    stream.  For _fprintf, prefix the message with PREFIX...  */
 164 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 165 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 166                                const char *prefix,
 167                                ...) ATTRIBUTE_PRINTF (3, 4);
 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_vfatal (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
 189 /* Instead of deprecated_throw_reason, code should use
 190    throw_exception.  */
 191 extern void deprecated_throw_reason (enum return_reason reason)
 192      ATTRIBUTE_NORETURN;
 193
 194 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 195    handler.  If an exception (enum return_reason) is thrown using
 196    throw_exception() than all cleanups installed since
 197    catch_exceptions() was entered are invoked, the (-ve) exception
 198    value is then returned by catch_exceptions.  If FUNC() returns
 199    normally (with a positive or zero return value) then that value is
 200    returned by catch_exceptions().  It is an internal_error() for
 201    FUNC() to return a negative value.
 202
 203    For the period of the FUNC() call: UIOUT is installed as the output
 204    builder; ERRSTRING is installed as the error/quit message; and a
 205    new cleanup_chain is established.  The old values are restored
 206    before catch_exceptions() returns.
 207
 208    The variant catch_exceptions_with_msg() is the same as
 209    catch_exceptions() but adds the ability to return an allocated
 210    copy of the gdb error message.  This is used when a silent error is
 211    issued and the caller wants to manually issue the error message.
 212
 213    MASK specifies what to catch; it is normally set to
 214    RETURN_MASK_ALL, if for no other reason than that the code which
 215    calls catch_errors might not be set up to deal with a quit which
 216    isn't caught.  But if the code can deal with it, it generally
 217    should be RETURN_MASK_ERROR, unless for some reason it is more
 218    useful to abort only the portion of the operation inside the
 219    catch_errors.  Note that quit should return to the command line
 220    fairly quickly, even if some further processing is being done.
 221
 222    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 223    builder variable should just go away.
 224
 225    This function supersedes catch_errors().
 226
 227    This function uses SETJMP() and LONGJUMP().  */
 228
 229 struct ui_out;
 230 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 231 extern int catch_exceptions (struct ui_out *uiout,
 232                              catch_exceptions_ftype *func, void *func_args,
 233                              return_mask mask);
 234 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 235 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 236                                       catch_exceptions_ftype *func,
 237                                       void *func_args,
 238                                       char **gdberrmsg,
 239                                       return_mask mask);
 240
 241 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 242    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 243    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 244    value.  It's unfortunate that, catch_errors() does not return an
 245    indication of the exact exception that it caught - quit_flag might
 246    help.
 247
 248    This function is superseded by catch_exceptions().  */
 249
 250 typedef int (catch_errors_ftype) (void *);
 251 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 252
 253 /* Template to catch_errors() that wraps calls to command
 254    functions.  */
 255
 256 typedef void (catch_command_errors_ftype) (char *, int);
 257 extern int catch_command_errors (catch_command_errors_ftype *func,
 258                                  char *arg, int from_tty, return_mask);
 259
 260 /* Like catch_command_errors, but works with const command and args.  */
 261
 262 typedef void (catch_command_errors_const_ftype) (const char *, int);
 263 extern int catch_command_errors_const (catch_command_errors_const_ftype *func,
 264                                        const char *arg, int from_tty, return_mask);
 265
 266 #endif