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 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   /* Feature is not supported in this copy of GDB.  */
  79   UNSUPPORTED_ERROR,
  80
  81   /* Add more errors here.  */
  82   NR_ERRORS
  83 };
  84
  85 struct gdb_exception
  86 {
  87   enum return_reason reason;
  88   enum errors error;
  89   const char *message;
  90 };
  91
  92 /* A pre-defined non-exception.  */
  93 extern const struct gdb_exception exception_none;
  94
  95 /* Wrap set/long jmp so that it's more portable (internal to
  96    exceptions).  */
  97
  98 #if defined(HAVE_SIGSETJMP)
  99 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 100 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 101 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 102 #else
 103 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 104 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 105 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 106 #endif
 107
 108 /* Functions to drive the exceptions state m/c (internal to
 109    exceptions).  */
 110 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (struct ui_out *func_uiout,
 111                                                  volatile struct gdb_exception *
 112                                                  exception,
 113                                                  return_mask mask);
 114 int exceptions_state_mc_action_iter (void);
 115 int exceptions_state_mc_action_iter_1 (void);
 116
 117 /* Macro to wrap up standard try/catch behavior.
 118
 119    The double loop lets us correctly handle code "break"ing out of the
 120    try catch block.  (It works as the "break" only exits the inner
 121    "while" loop, the outer for loop detects this handling it
 122    correctly.)  Of course "return" and "goto" are not so lucky.
 123
 124    For instance:
 125
 126    *INDENT-OFF*
 127
 128    volatile struct gdb_exception e;
 129    TRY_CATCH (e, RETURN_MASK_ERROR)
 130      {
 131      }
 132    switch (e.reason)
 133      {
 134      case RETURN_ERROR: ...
 135      }
 136
 137   */
 138
 139 #define TRY_CATCH(EXCEPTION,MASK) \
 140      { \
 141        EXCEPTIONS_SIGJMP_BUF *buf = \
 142          exceptions_state_mc_init (uiout, &(EXCEPTION), (MASK)); \
 143        EXCEPTIONS_SIGSETJMP (*buf); \
 144      } \
 145      while (exceptions_state_mc_action_iter ()) \
 146        while (exceptions_state_mc_action_iter_1 ())
 147
 148 /* *INDENT-ON* */
 149
 150
 151 /* If E is an exception, print it's error message on the specified
 152    stream. for _fprintf, prefix the message with PREFIX...  */
 153 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 154 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 155                                const char *prefix,
 156                                ...) ATTRIBUTE_PRINTF (3, 4);
 157
 158 /* Throw an exception (as described by "struct gdb_exception").  Will
 159    execute a LONG JUMP to the inner most containing exception handler
 160    established using catch_exceptions() (or similar).
 161
 162    Code normally throws an exception using error() et.al.  For various
 163    reaons, GDB also contains code that throws an exception directly.
 164    For instance, the remote*.c targets contain CNTRL-C signal handlers
 165    that propogate the QUIT event up the exception chain.  ``This could
 166    be a good thing or a dangerous thing.'' -- the Existential
 167    Wombat.  */
 168
 169 extern void throw_exception (struct gdb_exception exception) ATTRIBUTE_NORETURN;
 170 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 171      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 172 extern void throw_vfatal (const char *fmt, va_list ap)
 173      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 174 extern void throw_error (enum errors error, const char *fmt, ...)
 175      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 176
 177 /* Instead of deprecated_throw_reason, code should use catch_exception
 178    and throw_exception.  */
 179 extern void deprecated_throw_reason (enum return_reason reason)
 180      ATTRIBUTE_NORETURN;
 181
 182 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 183    handler.  If an exception (enum return_reason) is thrown using
 184    throw_exception() than all cleanups installed since
 185    catch_exceptions() was entered are invoked, the (-ve) exception
 186    value is then returned by catch_exceptions.  If FUNC() returns
 187    normally (with a positive or zero return value) then that value is
 188    returned by catch_exceptions().  It is an internal_error() for
 189    FUNC() to return a negative value.
 190
 191    For the period of the FUNC() call: UIOUT is installed as the output
 192    builder; ERRSTRING is installed as the error/quit message; and a
 193    new cleanup_chain is established.  The old values are restored
 194    before catch_exceptions() returns.
 195
 196    The variant catch_exceptions_with_msg() is the same as
 197    catch_exceptions() but adds the ability to return an allocated
 198    copy of the gdb error message.  This is used when a silent error is
 199    issued and the caller wants to manually issue the error message.
 200
 201    MASK specifies what to catch; it is normally set to
 202    RETURN_MASK_ALL, if for no other reason than that the code which
 203    calls catch_errors might not be set up to deal with a quit which
 204    isn't caught.  But if the code can deal with it, it generally
 205    should be RETURN_MASK_ERROR, unless for some reason it is more
 206    useful to abort only the portion of the operation inside the
 207    catch_errors.  Note that quit should return to the command line
 208    fairly quickly, even if some further processing is being done.
 209
 210    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 211    builder variable should just go away.
 212
 213    This function supersedes catch_errors().
 214
 215    This function uses SETJMP() and LONGJUMP().  */
 216
 217 struct ui_out;
 218 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 219 extern int catch_exceptions (struct ui_out *uiout,
 220                              catch_exceptions_ftype *func, void *func_args,
 221                              return_mask mask);
 222 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 223 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 224                                       catch_exceptions_ftype *func,
 225                                       void *func_args,
 226                                       char **gdberrmsg,
 227                                       return_mask mask);
 228
 229 /* This function, in addition, suppresses the printing of the captured
 230    error message.  It's up to the client to print it.  */
 231
 232 extern struct gdb_exception catch_exception (struct ui_out *uiout,
 233                                              catch_exception_ftype *func,
 234                                              void *func_args,
 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, char *command, int from_tty, return_mask);
 254
 255 #endif