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