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
  42 typedef enum
  43 {
  44   RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT),
  45   RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR),
  46   RETURN_MASK_ALL = (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
  47 } return_mask;
  48
  49 /* Describe all exceptions.  */
  50
  51 enum errors {
  52   GDB_NO_ERROR,
  53
  54   /* Any generic error, the corresponding text is in
  55      exception.message.  */
  56   GENERIC_ERROR,
  57
  58   /* Something requested was not found.  */
  59   NOT_FOUND_ERROR,
  60
  61   /* Thread library lacks support necessary for finding thread local
  62      storage.  */
  63   TLS_NO_LIBRARY_SUPPORT_ERROR,
  64
  65   /* Load module not found while attempting to find thread local storage.  */
  66   TLS_LOAD_MODULE_NOT_FOUND_ERROR,
  67
  68   /* Thread local storage has not been allocated yet.  */
  69   TLS_NOT_ALLOCATED_YET_ERROR,
  70
  71   /* Something else went wrong while attempting to find thread local
  72      storage.  The ``struct gdb_exception'' message field provides
  73      more detail.  */
  74   TLS_GENERIC_ERROR,
  75
  76   /* Problem parsing an XML document.  */
  77   XML_PARSE_ERROR,
  78
  79   /* Error accessing memory.  */
  80   MEMORY_ERROR,
  81
  82   /* Feature is not supported in this copy of GDB.  */
  83   UNSUPPORTED_ERROR,
  84
  85   /* Value not available.  E.g., a register was not collected in a
  86      traceframe.  */
  87   NOT_AVAILABLE_ERROR,
  88
  89   /* DW_OP_GNU_entry_value resolving failed.  */
  90   NO_ENTRY_VALUE_ERROR,
  91
  92   /* Target throwing an error has been closed.  Current command should be
  93      aborted as the inferior state is no longer valid.  */
  94   TARGET_CLOSE_ERROR,
  95
  96   /* Add more errors here.  */
  97   NR_ERRORS
  98 };
  99
 100 struct gdb_exception
 101 {
 102   enum return_reason reason;
 103   enum errors error;
 104   const char *message;
 105 };
 106
 107 /* A pre-defined non-exception.  */
 108 extern const struct gdb_exception exception_none;
 109
 110 /* Wrap set/long jmp so that it's more portable (internal to
 111    exceptions).  */
 112
 113 #if defined(HAVE_SIGSETJMP)
 114 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 115 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 116 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 117 #else
 118 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 119 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 120 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 121 #endif
 122
 123 /* Functions to drive the exceptions state m/c (internal to
 124    exceptions).  */
 125 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 126                                                  gdb_exception *exception,
 127                                                  return_mask mask);
 128 int exceptions_state_mc_action_iter (void);
 129 int exceptions_state_mc_action_iter_1 (void);
 130
 131 /* Macro to wrap up standard try/catch behavior.
 132
 133    The double loop lets us correctly handle code "break"ing out of the
 134    try catch block.  (It works as the "break" only exits the inner
 135    "while" loop, the outer for loop detects this handling it
 136    correctly.)  Of course "return" and "goto" are not so lucky.
 137
 138    For instance:
 139
 140    *INDENT-OFF*
 141
 142    volatile struct gdb_exception e;
 143    TRY_CATCH (e, RETURN_MASK_ERROR)
 144      {
 145      }
 146    switch (e.reason)
 147      {
 148      case RETURN_ERROR: ...
 149      }
 150
 151   */
 152
 153 #define TRY_CATCH(EXCEPTION,MASK) \
 154      { \
 155        EXCEPTIONS_SIGJMP_BUF *buf = \
 156          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 157        EXCEPTIONS_SIGSETJMP (*buf); \
 158      } \
 159      while (exceptions_state_mc_action_iter ()) \
 160        while (exceptions_state_mc_action_iter_1 ())
 161
 162 /* *INDENT-ON* */
 163
 164
 165 /* If E is an exception, print it's error message on the specified
 166    stream.  For _fprintf, prefix the message with PREFIX...  */
 167 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 168 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 169                                const char *prefix,
 170                                ...) ATTRIBUTE_PRINTF (3, 4);
 171
 172 /* Throw an exception (as described by "struct gdb_exception").  Will
 173    execute a LONG JUMP to the inner most containing exception handler
 174    established using catch_exceptions() (or similar).
 175
 176    Code normally throws an exception using error() et.al.  For various
 177    reaons, GDB also contains code that throws an exception directly.
 178    For instance, the remote*.c targets contain CNTRL-C signal handlers
 179    that propogate the QUIT event up the exception chain.  ``This could
 180    be a good thing or a dangerous thing.'' -- the Existential
 181    Wombat.  */
 182
 183 extern void throw_exception (struct gdb_exception exception)
 184      ATTRIBUTE_NORETURN;
 185 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 186      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 187 extern void throw_vfatal (const char *fmt, va_list ap)
 188      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 189 extern void throw_error (enum errors error, const char *fmt, ...)
 190      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 191
 192 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 193    handler.  If an exception (enum return_reason) is thrown using
 194    throw_exception() than all cleanups installed since
 195    catch_exceptions() was entered are invoked, the (-ve) exception
 196    value is then returned by catch_exceptions.  If FUNC() returns
 197    normally (with a positive or zero return value) then that value is
 198    returned by catch_exceptions().  It is an internal_error() for
 199    FUNC() to return a negative value.
 200
 201    For the period of the FUNC() call: UIOUT is installed as the output
 202    builder; ERRSTRING is installed as the error/quit message; and a
 203    new cleanup_chain is established.  The old values are restored
 204    before catch_exceptions() returns.
 205
 206    The variant catch_exceptions_with_msg() is the same as
 207    catch_exceptions() but adds the ability to return an allocated
 208    copy of the gdb error message.  This is used when a silent error is
 209    issued and the caller wants to manually issue the error message.
 210
 211    MASK specifies what to catch; it is normally set to
 212    RETURN_MASK_ALL, if for no other reason than that the code which
 213    calls catch_errors might not be set up to deal with a quit which
 214    isn't caught.  But if the code can deal with it, it generally
 215    should be RETURN_MASK_ERROR, unless for some reason it is more
 216    useful to abort only the portion of the operation inside the
 217    catch_errors.  Note that quit should return to the command line
 218    fairly quickly, even if some further processing is being done.
 219
 220    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 221    builder variable should just go away.
 222
 223    This function supersedes catch_errors().
 224
 225    This function uses SETJMP() and LONGJUMP().  */
 226
 227 struct ui_out;
 228 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 229 extern int catch_exceptions (struct ui_out *uiout,
 230                              catch_exceptions_ftype *func, void *func_args,
 231                              return_mask mask);
 232 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 233 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 234                                       catch_exceptions_ftype *func,
 235                                       void *func_args,
 236                                       char **gdberrmsg,
 237                                       return_mask mask);
 238
 239 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 240    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 241    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 242    value.  It's unfortunate that, catch_errors() does not return an
 243    indication of the exact exception that it caught - quit_flag might
 244    help.
 245
 246    This function is superseded by catch_exceptions().  */
 247
 248 typedef int (catch_errors_ftype) (void *);
 249 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 250
 251 /* Template to catch_errors() that wraps calls to command
 252    functions.  */
 253
 254 typedef void (catch_command_errors_ftype) (char *, int);
 255 extern int catch_command_errors (catch_command_errors_ftype *func,
 256                                  char *arg, int from_tty, return_mask);
 257
 258 /* Like catch_command_errors, but works with const command and args.  */
 259
 260 typedef void (catch_command_errors_const_ftype) (const char *, int);
 261 extern int catch_command_errors_const (catch_command_errors_const_ftype *func,
 262                                        const char *arg, int from_tty, return_mask);
 263
 264 #endif