gdb/exceptions.h

   1 /* Exception (throw catch) mechanism, for GDB, the GNU debugger.
   2
   3    Copyright (C) 1986-2014 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   /* Value not available.  E.g., a register was not collected in a
  83      traceframe.  */
  84   NOT_AVAILABLE_ERROR,
  85
  86   /* Value was optimized out.  Note: if the value was a register, this
  87      means the register was not saved in the frame.  */
  88   OPTIMIZED_OUT_ERROR,
  89
  90   /* DW_OP_GNU_entry_value resolving failed.  */
  91   NO_ENTRY_VALUE_ERROR,
  92
  93   /* Target throwing an error has been closed.  Current command should be
  94      aborted as the inferior state is no longer valid.  */
  95   TARGET_CLOSE_ERROR,
  96
  97   /* An undefined command was executed.  */
  98   UNDEFINED_COMMAND_ERROR,
  99
 100   /* Requested feature, method, mechanism, etc. is not supported.  */
 101   NOT_SUPPORTED_ERROR,
 102
 103   /* Add more errors here.  */
 104   NR_ERRORS
 105 };
 106
 107 struct gdb_exception
 108 {
 109   enum return_reason reason;
 110   enum errors error;
 111   const char *message;
 112 };
 113
 114 /* A pre-defined non-exception.  */
 115 extern const struct gdb_exception exception_none;
 116
 117 /* Wrap set/long jmp so that it's more portable (internal to
 118    exceptions).  */
 119
 120 #if defined(HAVE_SIGSETJMP)
 121 #define EXCEPTIONS_SIGJMP_BUF           sigjmp_buf
 122 #define EXCEPTIONS_SIGSETJMP(buf)       sigsetjmp((buf), 1)
 123 #define EXCEPTIONS_SIGLONGJMP(buf,val)  siglongjmp((buf), (val))
 124 #else
 125 #define EXCEPTIONS_SIGJMP_BUF           jmp_buf
 126 #define EXCEPTIONS_SIGSETJMP(buf)       setjmp(buf)
 127 #define EXCEPTIONS_SIGLONGJMP(buf,val)  longjmp((buf), (val))
 128 #endif
 129
 130 /* Functions to drive the exceptions state m/c (internal to
 131    exceptions).  */
 132 EXCEPTIONS_SIGJMP_BUF *exceptions_state_mc_init (volatile struct
 133                                                  gdb_exception *exception,
 134                                                  return_mask mask);
 135 int exceptions_state_mc_action_iter (void);
 136 int exceptions_state_mc_action_iter_1 (void);
 137
 138 /* Macro to wrap up standard try/catch behavior.
 139
 140    The double loop lets us correctly handle code "break"ing out of the
 141    try catch block.  (It works as the "break" only exits the inner
 142    "while" loop, the outer for loop detects this handling it
 143    correctly.)  Of course "return" and "goto" are not so lucky.
 144
 145    For instance:
 146
 147    *INDENT-OFF*
 148
 149    volatile struct gdb_exception e;
 150    TRY_CATCH (e, RETURN_MASK_ERROR)
 151      {
 152      }
 153    switch (e.reason)
 154      {
 155      case RETURN_ERROR: ...
 156      }
 157
 158   */
 159
 160 #define TRY_CATCH(EXCEPTION,MASK) \
 161      { \
 162        EXCEPTIONS_SIGJMP_BUF *buf = \
 163          exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
 164        EXCEPTIONS_SIGSETJMP (*buf); \
 165      } \
 166      while (exceptions_state_mc_action_iter ()) \
 167        while (exceptions_state_mc_action_iter_1 ())
 168
 169 /* *INDENT-ON* */
 170
 171
 172 /* If E is an exception, print it's error message on the specified
 173    stream.  For _fprintf, prefix the message with PREFIX...  */
 174 extern void exception_print (struct ui_file *file, struct gdb_exception e);
 175 extern void exception_fprintf (struct ui_file *file, struct gdb_exception e,
 176                                const char *prefix,
 177                                ...) ATTRIBUTE_PRINTF (3, 4);
 178
 179 /* Throw an exception (as described by "struct gdb_exception").  Will
 180    execute a LONG JUMP to the inner most containing exception handler
 181    established using catch_exceptions() (or similar).
 182
 183    Code normally throws an exception using error() et.al.  For various
 184    reaons, GDB also contains code that throws an exception directly.
 185    For instance, the remote*.c targets contain CNTRL-C signal handlers
 186    that propogate the QUIT event up the exception chain.  ``This could
 187    be a good thing or a dangerous thing.'' -- the Existential
 188    Wombat.  */
 189
 190 extern void throw_exception (struct gdb_exception exception)
 191      ATTRIBUTE_NORETURN;
 192 extern void throw_verror (enum errors, const char *fmt, va_list ap)
 193      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
 194 extern void throw_vfatal (const char *fmt, va_list ap)
 195      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
 196 extern void throw_error (enum errors error, const char *fmt, ...)
 197      ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
 198
 199 /* Call FUNC(UIOUT, FUNC_ARGS) but wrapped within an exception
 200    handler.  If an exception (enum return_reason) is thrown using
 201    throw_exception() than all cleanups installed since
 202    catch_exceptions() was entered are invoked, the (-ve) exception
 203    value is then returned by catch_exceptions.  If FUNC() returns
 204    normally (with a positive or zero return value) then that value is
 205    returned by catch_exceptions().  It is an internal_error() for
 206    FUNC() to return a negative value.
 207
 208    For the period of the FUNC() call: UIOUT is installed as the output
 209    builder; ERRSTRING is installed as the error/quit message; and a
 210    new cleanup_chain is established.  The old values are restored
 211    before catch_exceptions() returns.
 212
 213    The variant catch_exceptions_with_msg() is the same as
 214    catch_exceptions() but adds the ability to return an allocated
 215    copy of the gdb error message.  This is used when a silent error is
 216    issued and the caller wants to manually issue the error message.
 217
 218    MASK specifies what to catch; it is normally set to
 219    RETURN_MASK_ALL, if for no other reason than that the code which
 220    calls catch_errors might not be set up to deal with a quit which
 221    isn't caught.  But if the code can deal with it, it generally
 222    should be RETURN_MASK_ERROR, unless for some reason it is more
 223    useful to abort only the portion of the operation inside the
 224    catch_errors.  Note that quit should return to the command line
 225    fairly quickly, even if some further processing is being done.
 226
 227    FIXME; cagney/2001-08-13: The need to override the global UIOUT
 228    builder variable should just go away.
 229
 230    This function supersedes catch_errors().
 231
 232    This function uses SETJMP() and LONGJUMP().  */
 233
 234 struct ui_out;
 235 typedef int (catch_exceptions_ftype) (struct ui_out *ui_out, void *args);
 236 extern int catch_exceptions (struct ui_out *uiout,
 237                              catch_exceptions_ftype *func, void *func_args,
 238                              return_mask mask);
 239 typedef void (catch_exception_ftype) (struct ui_out *ui_out, void *args);
 240 extern int catch_exceptions_with_msg (struct ui_out *uiout,
 241                                       catch_exceptions_ftype *func,
 242                                       void *func_args,
 243                                       char **gdberrmsg,
 244                                       return_mask mask);
 245
 246 /* If CATCH_ERRORS_FTYPE throws an error, catch_errors() returns zero
 247    otherwize the result from CATCH_ERRORS_FTYPE is returned.  It is
 248    probably useful for CATCH_ERRORS_FTYPE to always return a non-zero
 249    value.  It's unfortunate that, catch_errors() does not return an
 250    indication of the exact exception that it caught - quit_flag might
 251    help.
 252
 253    This function is superseded by catch_exceptions().  */
 254
 255 typedef int (catch_errors_ftype) (void *);
 256 extern int catch_errors (catch_errors_ftype *, void *, char *, return_mask);
 257
 258 /* Template to catch_errors() that wraps calls to command
 259    functions.  */
 260
 261 typedef void (catch_command_errors_ftype) (char *, int);
 262 extern int catch_command_errors (catch_command_errors_ftype *func,
 263                                  char *arg, int from_tty, return_mask);
 264
 265 /* Like catch_command_errors, but works with const command and args.  */
 266
 267 typedef void (catch_command_errors_const_ftype) (const char *, int);
 268 extern int catch_command_errors_const (catch_command_errors_const_ftype *func,
 269                                        const char *arg, int from_tty, return_mask);
 270
 271 #endif