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   /* An undefined command was executed.  */
  97   UNDEFINED_COMMAND_ERROR,
  98
  99   /* Add more errors here.  */
 100   NR_ERRORS
 101 };
 102
 103 struct gdb_exception
 104 {
 105   enum return_reason reason;
 106   enum errors error;
 107   const char *message;
 108 };
 109
 110 /* A pre-defined non-exception.  */
 111 extern const struct gdb_exception exception_none;
 112
 113 /* Wrap set/long jmp so that it's more portable (internal to
 114    exceptions).  */
 115
 116 #if defined(HAVE_SIGSETJMP)
 117 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 118 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 119 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 120 #else
 121 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 122 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 123 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 124 #endif
 125
 126 /* Functions to drive the exceptions state m/c (internal to
 127    exceptions).  */
 128 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 129                                                  gdb_exception *exception,
 130                                                  return_mask mask);
 131 int exceptions_state_mc_action_iter (void);
 132 int exceptions_state_mc_action_iter_1 (void);
 133
 134 /* Macro to wrap up standard try/catch behavior.
 135
 136    The double loop lets us correctly handle code "break"ing out of the
 137    try catch block.  (It works as the "break" only exits the inner
 138    "while" loop, the outer for loop detects this handling it
 139    correctly.)  Of course "return" and "goto" are not so lucky.
 140
 141    For instance:
 142
 143    *INDENT-OFF*
 144
 145    volatile struct gdb_exception e;
 146    TRY_CATCH (e, RETURN_MASK_ERROR)
 147      {
 148      }
 149    switch (e.reason)
 150      {
 151      case RETURN_ERROR: ...
 152      }
 153
 154   */
 155
 156 #define TRY_CATCH(EXCEPTION,MASK) \
 157      { \
 158        EXCEPTIONS_SIGJMP_BUF *buf = \
 159          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 160        EXCEPTIONS_SIGSETJMP (*buf); \
 161      } \
 162      while (exceptions_state_mc_action_iter ()) \
 163        while (exceptions_state_mc_action_iter_1 ())
 164
 165 /* *INDENT-ON* */
 166
 167
 168 /* If E is an exception, print it's error message on the specified
 169    stream.  For _fprintf, prefix the message with PREFIX...  */
 170 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 171 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 172                                const char *prefix,
 173                                ...) ATTRIBUTE_PRINTF (3, 4);
 174
 175 /* Throw an exception (as described by "struct gdb_exception").  Will
 176    execute a LONG JUMP to the inner most containing exception handler
 177    established using catch_exceptions() (or similar).
 178
 179    Code normally throws an exception using error() et.al.  For various
 180    reaons, GDB also contains code that throws an exception directly.
 181    For instance, the remote*.c targets contain CNTRL-C signal handlers
 182    that propogate the QUIT event up the exception chain.  ``This could
 183    be a good thing or a dangerous thing.'' -- the Existential
 184    Wombat.  */
 185
 186 extern void throw_exception (struct gdb_exception exception)
 187      ATTRIBUTE_NORETURN;
 188 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 189      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 190 extern void throw_vfatal (const char *fmt, va_list ap)
 191      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 192 extern void throw_error (enum errors error, const char *fmt, ...)
 193      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 194
 195 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 196    handler.  If an exception (enum return_reason) is thrown using
 197    throw_exception() than all cleanups installed since
 198    catch_exceptions() was entered are invoked, the (-ve) exception
 199    value is then returned by catch_exceptions.  If FUNC() returns
 200    normally (with a positive or zero return value) then that value is
 201    returned by catch_exceptions().  It is an internal_error() for
 202    FUNC() to return a negative value.
 203
 204    For the period of the FUNC() call: UIOUT is installed as the output
 205    builder; ERRSTRING is installed as the error/quit message; and a
 206    new cleanup_chain is established.  The old values are restored
 207    before catch_exceptions() returns.
 208
 209    The variant catch_exceptions_with_msg() is the same as
 210    catch_exceptions() but adds the ability to return an allocated
 211    copy of the gdb error message.  This is used when a silent error is
 212    issued and the caller wants to manually issue the error message.
 213
 214    MASK specifies what to catch; it is normally set to
 215    RETURN_MASK_ALL, if for no other reason than that the code which
 216    calls catch_errors might not be set up to deal with a quit which
 217    isn't caught.  But if the code can deal with it, it generally
 218    should be RETURN_MASK_ERROR, unless for some reason it is more
 219    useful to abort only the portion of the operation inside the
 220    catch_errors.  Note that quit should return to the command line
 221    fairly quickly, even if some further processing is being done.
 222
 223    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 224    builder variable should just go away.
 225
 226    This function supersedes catch_errors().
 227
 228    This function uses SETJMP() and LONGJUMP().  */
 229
 230 struct ui_out;
 231 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 232 extern int catch_exceptions (struct ui_out *uiout,
 233                              catch_exceptions_ftype *func, void *func_args,
 234                              return_mask mask);
 235 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 236 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 237                                       catch_exceptions_ftype *func,
 238                                       void *func_args,
 239                                       char **gdberrmsg,
 240                                       return_mask mask);
 241
 242 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 243    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 244    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 245    value.  It's unfortunate that, catch_errors() does not return an
 246    indication of the exact exception that it caught - quit_flag might
 247    help.
 248
 249    This function is superseded by catch_exceptions().  */
 250
 251 typedef int (catch_errors_ftype) (void *);
 252 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 253
 254 /* Template to catch_errors() that wraps calls to command
 255    functions.  */
 256
 257 typedef void (catch_command_errors_ftype) (char *, int);
 258 extern int catch_command_errors (catch_command_errors_ftype *func,
 259                                  char *arg, int from_tty, return_mask);
 260
 261 /* Like catch_command_errors, but works with const command and args.  */
 262
 263 typedef void (catch_command_errors_const_ftype) (const char *, int);
 264 extern int catch_command_errors_const (catch_command_errors_const_ftype *func,
 265                                        const char *arg, int from_tty, return_mask);
 266
 267 #endif