342 lines
9.9 KiB
C++
342 lines
9.9 KiB
C++
/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
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Copyright (C) 1986-2019 Free Software Foundation, Inc.
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#ifndef COMMON_EXCEPTIONS_H
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#define COMMON_EXCEPTIONS_H
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#include <setjmp.h>
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#include <new>
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/* Reasons for calling throw_exceptions(). NOTE: all reason values
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must be different from zero. enum value 0 is reserved for internal
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use as the return value from an initial setjmp(). */
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enum return_reason
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{
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/* User interrupt. */
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RETURN_QUIT = -2,
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/* Any other error. */
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RETURN_ERROR
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};
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#define RETURN_MASK(reason) (1 << (int)(-reason))
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typedef enum
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{
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RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT),
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RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR),
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RETURN_MASK_ALL = (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
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} return_mask;
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/* Describe all exceptions. */
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enum errors {
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GDB_NO_ERROR,
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/* Any generic error, the corresponding text is in
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exception.message. */
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GENERIC_ERROR,
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/* Something requested was not found. */
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NOT_FOUND_ERROR,
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/* Thread library lacks support necessary for finding thread local
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storage. */
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TLS_NO_LIBRARY_SUPPORT_ERROR,
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/* Load module not found while attempting to find thread local storage. */
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TLS_LOAD_MODULE_NOT_FOUND_ERROR,
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/* Thread local storage has not been allocated yet. */
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TLS_NOT_ALLOCATED_YET_ERROR,
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/* Something else went wrong while attempting to find thread local
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storage. The ``struct gdb_exception'' message field provides
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more detail. */
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TLS_GENERIC_ERROR,
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/* Problem parsing an XML document. */
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XML_PARSE_ERROR,
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/* Error accessing memory. */
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MEMORY_ERROR,
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/* Value not available. E.g., a register was not collected in a
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traceframe. */
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NOT_AVAILABLE_ERROR,
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/* Value was optimized out. Note: if the value was a register, this
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means the register was not saved in the frame. */
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OPTIMIZED_OUT_ERROR,
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/* DW_OP_entry_value resolving failed. */
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NO_ENTRY_VALUE_ERROR,
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/* Target throwing an error has been closed. Current command should be
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aborted as the inferior state is no longer valid. */
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TARGET_CLOSE_ERROR,
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/* An undefined command was executed. */
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UNDEFINED_COMMAND_ERROR,
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/* Requested feature, method, mechanism, etc. is not supported. */
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NOT_SUPPORTED_ERROR,
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/* The number of candidates generated during line completion has
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reached the user's specified limit. This isn't an error, this exception
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is used to halt searching for more completions, but for consistency
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"_ERROR" is appended to the name. */
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MAX_COMPLETIONS_REACHED_ERROR,
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/* Add more errors here. */
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NR_ERRORS
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};
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struct gdb_exception
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{
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enum return_reason reason;
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enum errors error;
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const char *message;
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};
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/* The different exception mechanisms that TRY/CATCH can map to. */
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/* Make GDB exceptions use setjmp/longjmp behind the scenes. */
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#define GDB_XCPT_SJMP 1
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/* Make GDB exceptions use try/catch behind the scenes. */
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#define GDB_XCPT_TRY 2
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/* Specify this mode to build with TRY/CATCH mapped directly to raw
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try/catch. GDB won't work correctly, but building that way catches
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code tryin to break/continue out of the try block, along with
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spurious code between the TRY and the CATCH block. */
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#define GDB_XCPT_RAW_TRY 3
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#define GDB_XCPT GDB_XCPT_TRY
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/* Functions to drive the sjlj-based exceptions state machine. Though
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declared here by necessity, these functions should be considered
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internal to the exceptions subsystem and not used other than via
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the TRY/CATCH (or TRY_SJLJ/CATCH_SJLJ) macros defined below. */
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extern jmp_buf *exceptions_state_mc_init (void);
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extern int exceptions_state_mc_action_iter (void);
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extern int exceptions_state_mc_action_iter_1 (void);
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extern int exceptions_state_mc_catch (struct gdb_exception *, int);
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/* Same, but for the C++ try/catch-based TRY/CATCH mechanism. */
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#if GDB_XCPT != GDB_XCPT_SJMP
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extern void *exception_try_scope_entry (void);
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extern void exception_try_scope_exit (void *saved_state);
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extern void exception_rethrow (void) ATTRIBUTE_NORETURN;
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#endif
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/* Macro to wrap up standard try/catch behavior.
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The double loop lets us correctly handle code "break"ing out of the
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try catch block. (It works as the "break" only exits the inner
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"while" loop, the outer for loop detects this handling it
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correctly.) Of course "return" and "goto" are not so lucky.
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For instance:
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*INDENT-OFF*
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TRY
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{
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}
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CATCH (e, RETURN_MASK_ERROR)
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{
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switch (e.reason)
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{
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case RETURN_ERROR: ...
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}
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}
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END_CATCH
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Note that the SJLJ version of the macros are actually named
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TRY_SJLJ/CATCH_SJLJ in order to make it possible to call them even
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when TRY/CATCH are mapped to C++ try/catch. The SJLJ variants are
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needed in some cases where gdb exceptions need to cross third-party
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library code compiled without exceptions support (e.g.,
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readline). */
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#define TRY_SJLJ \
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{ \
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jmp_buf *buf = \
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exceptions_state_mc_init (); \
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setjmp (*buf); \
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} \
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while (exceptions_state_mc_action_iter ()) \
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while (exceptions_state_mc_action_iter_1 ())
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#define CATCH_SJLJ(EXCEPTION, MASK) \
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{ \
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struct gdb_exception EXCEPTION; \
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if (exceptions_state_mc_catch (&(EXCEPTION), MASK))
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#define END_CATCH_SJLJ \
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}
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#if GDB_XCPT == GDB_XCPT_SJMP
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/* If using SJLJ-based exceptions for all exceptions, then provide
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standard aliases. */
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#define TRY TRY_SJLJ
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#define CATCH CATCH_SJLJ
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#define END_CATCH END_CATCH_SJLJ
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#endif /* GDB_XCPT_SJMP */
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#if GDB_XCPT == GDB_XCPT_TRY || GDB_XCPT == GDB_XCPT_RAW_TRY
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/* Prevent error/quit during TRY from calling cleanups established
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prior to here. This pops out the scope in either case of normal
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exit or exception exit. */
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struct exception_try_scope
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{
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exception_try_scope ()
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{
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saved_state = exception_try_scope_entry ();
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}
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~exception_try_scope ()
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{
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exception_try_scope_exit (saved_state);
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}
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void *saved_state;
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};
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#if GDB_XCPT == GDB_XCPT_TRY
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/* We still need to wrap TRY/CATCH in C++ so that cleanups and C++
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exceptions can coexist.
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The TRY blocked is wrapped in a do/while(0) so that break/continue
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within the block works the same as in C.
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END_CATCH makes sure that even if the CATCH block doesn't want to
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catch the exception, we stop at every frame in the unwind chain to
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run its cleanups, which may e.g., have pointers to stack variables
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that are going to be destroyed.
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There's an outer scope around the whole TRY/END_CATCH in order to
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cause a compilation error if you forget to add the END_CATCH at the
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end a TRY/CATCH construct. */
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#define TRY \
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{ \
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try \
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{ \
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exception_try_scope exception_try_scope_instance; \
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do \
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{
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#define CATCH(EXCEPTION, MASK) \
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} while (0); \
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} \
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catch (struct gdb_exception ## _ ## MASK &EXCEPTION)
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#define END_CATCH \
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catch (...) \
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{ \
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exception_rethrow (); \
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} \
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}
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#else
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#define TRY try
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#define CATCH(EXCEPTION, MASK) \
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catch (struct gdb_exception ## _ ## MASK &EXCEPTION)
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#define END_CATCH
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#endif
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/* The exception types client code may catch. They're just shims
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around gdb_exception that add nothing but type info. Which is used
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is selected depending on the MASK argument passed to CATCH. */
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struct gdb_exception_RETURN_MASK_ALL : public gdb_exception
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{
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};
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struct gdb_exception_RETURN_MASK_ERROR : public gdb_exception_RETURN_MASK_ALL
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{
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};
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struct gdb_exception_RETURN_MASK_QUIT : public gdb_exception_RETURN_MASK_ALL
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{
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};
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#endif /* GDB_XCPT_TRY || GDB_XCPT_RAW_TRY */
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/* An exception type that inherits from both std::bad_alloc and a gdb
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exception. This is necessary because operator new can only throw
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std::bad_alloc, and OTOH, we want exceptions thrown due to memory
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allocation error to be caught by all the CATCH/RETURN_MASK_ALL
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spread around the codebase. */
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struct gdb_quit_bad_alloc
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: public gdb_exception_RETURN_MASK_QUIT,
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public std::bad_alloc
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{
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explicit gdb_quit_bad_alloc (gdb_exception ex)
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: std::bad_alloc ()
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{
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gdb_exception *self = this;
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*self = ex;
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}
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};
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/* *INDENT-ON* */
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/* Throw an exception (as described by "struct gdb_exception"),
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landing in the inner most containing exception handler established
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using TRY/CATCH. */
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extern void throw_exception (struct gdb_exception exception)
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ATTRIBUTE_NORETURN;
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/* Throw an exception by executing a LONG JUMP to the inner most
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containing exception handler established using TRY_SJLJ. Necessary
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in some cases where we need to throw GDB exceptions across
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third-party library code (e.g., readline). */
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extern void throw_exception_sjlj (struct gdb_exception exception)
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ATTRIBUTE_NORETURN;
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/* Convenience wrappers around throw_exception that throw GDB
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errors. */
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extern void throw_verror (enum errors, const char *fmt, va_list ap)
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ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
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extern void throw_vquit (const char *fmt, va_list ap)
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ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
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extern void throw_error (enum errors error, const char *fmt, ...)
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ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
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extern void throw_quit (const char *fmt, ...)
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ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2);
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/* A pre-defined non-exception. */
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extern const struct gdb_exception exception_none;
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#endif /* COMMON_EXCEPTIONS_H */
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