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 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   /* Any generic error, the corresponding text is in
  53      exception.message.  */
  54   GENERIC_ERROR,
  55   NOT_FOUND_ERROR,
  56
  57   /* Thread library lacks support necessary for finding thread local
  58      storage.  */
  59   TLS_NO_LIBRARY_SUPPORT_ERROR,
  60
  61   /* Load module not found while attempting to find thread local storage.  */
  62   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  63
  64   /* Thread local storage has not been allocated yet.  */
  65   TLS_NOT_ALLOCATED_YET_ERROR,
  66
  67   /* Something else went wrong while attempting to find thread local
  68      storage.  The ``struct gdb_exception'' message field provides
  69      more detail.  */
  70   TLS_GENERIC_ERROR,
  71
  72   /* Problem parsing an XML document.  */
  73   XML_PARSE_ERROR,
  74
  75   /* Error accessing memory.  */
  76   MEMORY_ERROR,
  77
  78   /* Add more errors here.  */
  79   NR_ERRORS
  80 };
  81
  82 struct gdb_exception
  83 {
  84   enum return_reason reason;
  85   enum errors error;
  86   const char *message;
  87 };
  88
  89 /* A pre-defined non-exception.  */
  90 extern const struct gdb_exception exception_none;
  91
  92 /* Wrap set/long jmp so that it's more portable (internal to
  93    exceptions).  */
  94
  95 #if defined(HAVE_SIGSETJMP)
  96 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
  97 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
  98 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
  99 #else
 100 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 101 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 102 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 103 #endif
 104
 105 /* Functions to drive the exceptions state m/c (internal to
 106    exceptions).  */
 107 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (struct ui_out *func_uiout,
 108                                                  volatile struct gdb_exception *
 109                                                  exception,
 110                                                  return_mask mask);
 111 int exceptions_state_mc_action_iter (void);
 112 int exceptions_state_mc_action_iter_1 (void);
 113
 114 /* Macro to wrap up standard try/catch behavior.
 115
 116    The double loop lets us correctly handle code "break"ing out of the
 117    try catch block.  (It works as the "break" only exits the inner
 118    "while" loop, the outer for loop detects this handling it
 119    correctly.)  Of course "return" and "goto" are not so lucky.
 120
 121    For instance:
 122
 123    *INDENT-OFF*
 124
 125    volatile struct gdb_exception e;
 126    TRY_CATCH (e, RETURN_MASK_ERROR)
 127      {
 128      }
 129    switch (e.reason)
 130      {
 131      case RETURN_ERROR: ...
 132      }
 133
 134   */
 135
 136 #define TRY_CATCH(EXCEPTION,MASK) \
 137      { \
 138        EXCEPTIONS_SIGJMP_BUF *buf = \
 139          exceptions_state_mc_init (uiout, &(EXCEPTION), (MASK)); \
 140        EXCEPTIONS_SIGSETJMP (*buf); \
 141      } \
 142      while (exceptions_state_mc_action_iter ()) \
 143        while (exceptions_state_mc_action_iter_1 ())
 144
 145 /* *INDENT-ON* */
 146
 147
 148 /* If E is an exception, print it's error message on the specified
 149    stream. for _fprintf, prefix the message with PREFIX...  */
 150 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 151 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 152                                const char *prefix,
 153                                ...) ATTR_FORMAT (printf, 3, 4);
 154
 155 /* Throw an exception (as described by "struct gdb_exception").  Will
 156    execute a LONG JUMP to the inner most containing exception handler
 157    established using catch_exceptions() (or similar).
 158
 159    Code normally throws an exception using error() et.al.  For various
 160    reaons, GDB also contains code that throws an exception directly.
 161    For instance, the remote*.c targets contain CNTRL-C signal handlers
 162    that propogate the QUIT event up the exception chain.  ``This could
 163    be a good thing or a dangerous thing.'' -- the Existential
 164    Wombat.  */
 165
 166 extern NORETURN void throw_exception (struct gdb_exception exception) ATTR_NORETURN;
 167 extern NORETURN void throw_verror (enum errors, const char *fmt, va_list ap)
 168      ATTR_NORETURN ATTR_FORMAT (printf, 2, 0);
 169 extern NORETURN void throw_vfatal (const char *fmt, va_list ap)
 170      ATTR_NORETURN ATTR_FORMAT (printf, 1, 0);
 171 extern NORETURN void throw_error (enum errors error, const char *fmt,
 172                                   ...) ATTR_NORETURN ATTR_FORMAT (printf, 2, 3);
 173
 174 /* Instead of deprecated_throw_reason, code should use catch_exception
 175    and throw_exception.  */
 176 extern NORETURN void deprecated_throw_reason (enum return_reason reason) ATTR_NORETURN;
 177
 178 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 179    handler.  If an exception (enum return_reason) is thrown using
 180    throw_exception() than all cleanups installed since
 181    catch_exceptions() was entered are invoked, the (-ve) exception
 182    value is then returned by catch_exceptions.  If FUNC() returns
 183    normally (with a positive or zero return value) then that value is
 184    returned by catch_exceptions().  It is an internal_error() for
 185    FUNC() to return a negative value.
 186
 187    For the period of the FUNC() call: UIOUT is installed as the output
 188    builder; ERRSTRING is installed as the error/quit message; and a
 189    new cleanup_chain is established.  The old values are restored
 190    before catch_exceptions() returns.
 191
 192    The variant catch_exceptions_with_msg() is the same as
 193    catch_exceptions() but adds the ability to return an allocated
 194    copy of the gdb error message.  This is used when a silent error is
 195    issued and the caller wants to manually issue the error message.
 196
 197    MASK specifies what to catch; it is normally set to
 198    RETURN_MASK_ALL, if for no other reason than that the code which
 199    calls catch_errors might not be set up to deal with a quit which
 200    isn't caught.  But if the code can deal with it, it generally
 201    should be RETURN_MASK_ERROR, unless for some reason it is more
 202    useful to abort only the portion of the operation inside the
 203    catch_errors.  Note that quit should return to the command line
 204    fairly quickly, even if some further processing is being done.
 205
 206    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 207    builder variable should just go away.
 208
 209    This function supersedes catch_errors().
 210
 211    This function uses SETJMP() and LONGJUMP().  */
 212
 213 struct ui_out;
 214 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 215 extern int catch_exceptions (struct ui_out *uiout,
 216                              catch_exceptions_ftype *func, void *func_args,
 217                              return_mask mask);
 218 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 219 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 220                                       catch_exceptions_ftype *func,
 221                                       void *func_args,
 222                                       char **gdberrmsg,
 223                                       return_mask mask);
 224
 225 /* This function, in addition, suppresses the printing of the captured
 226    error message.  It's up to the client to print it.  */
 227
 228 extern struct gdb_exception catch_exception (struct ui_out *uiout,
 229                                              catch_exception_ftype *func,
 230                                              void *func_args,
 231                                              return_mask mask);
 232
 233 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 234    otherwize the result from CATCH_ERRORS_FTYPE is returned. It is
 235    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 236    value. It's unfortunate that, catch_errors() does not return an
 237    indication of the exact exception that it caught - quit_flag might
 238    help.
 239
 240    This function is superseded by catch_exceptions().  */
 241
 242 typedef int (catch_errors_ftype) (void *);
 243 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 244
 245 /* Template to catch_errors() that wraps calls to command
 246    functions. */
 247
 248 typedef void (catch_command_errors_ftype) (char *, int);
 249 extern int catch_command_errors (catch_command_errors_ftype *func, char *command, int from_tty, return_mask);
 250
 251 #endif