/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
- Copyright (C) 1986-2015 Free Software Foundation, Inc.
+ Copyright (C) 1986-2018 Free Software Foundation, Inc.
This file is part of GDB.
#ifndef COMMON_EXCEPTIONS_H
#define COMMON_EXCEPTIONS_H
-#include "gdb_setjmp.h"
+#include <setjmp.h>
+#include <new>
/* Reasons for calling throw_exceptions(). NOTE: all reason values
- must be less than zero. enum value 0 is reserved for internal use
- as the return value from an initial setjmp(). The function
- catch_exceptions() reserves values >= 0 as legal results from its
- wrapped function. */
+ must be different from zero. enum value 0 is reserved for internal
+ use as the return value from an initial setjmp(). */
enum return_reason
{
means the register was not saved in the frame. */
OPTIMIZED_OUT_ERROR,
- /* DW_OP_GNU_entry_value resolving failed. */
+ /* DW_OP_entry_value resolving failed. */
NO_ENTRY_VALUE_ERROR,
/* Target throwing an error has been closed. Current command should be
const char *message;
};
-/* Functions to drive the exceptions state machine. Though declared
- here by necessity, these functions should be considered internal to
- the exceptions subsystem and not used other than via the TRY_CATCH
- macro defined below. */
+/* The different exception mechanisms that TRY/CATCH can map to. */
-extern SIGJMP_BUF *exceptions_state_mc_init (volatile struct
- gdb_exception *exception,
- return_mask mask);
+/* Make GDB exceptions use setjmp/longjmp behind the scenes. */
+#define GDB_XCPT_SJMP 1
+
+/* Make GDB exceptions use try/catch behind the scenes. */
+#define GDB_XCPT_TRY 2
+
+/* Specify this mode to build with TRY/CATCH mapped directly to raw
+ try/catch. GDB won't work correctly, but building that way catches
+ code tryin to break/continue out of the try block, along with
+ spurious code between the TRY and the CATCH block. */
+#define GDB_XCPT_RAW_TRY 3
+
+#define GDB_XCPT GDB_XCPT_TRY
+
+/* Functions to drive the sjlj-based exceptions state machine. Though
+ declared here by necessity, these functions should be considered
+ internal to the exceptions subsystem and not used other than via
+ the TRY/CATCH (or TRY_SJLJ/CATCH_SJLJ) macros defined below. */
+
+extern jmp_buf *exceptions_state_mc_init (void);
extern int exceptions_state_mc_action_iter (void);
extern int exceptions_state_mc_action_iter_1 (void);
+extern int exceptions_state_mc_catch (struct gdb_exception *, int);
+
+/* Same, but for the C++ try/catch-based TRY/CATCH mechanism. */
+
+#if GDB_XCPT != GDB_XCPT_SJMP
+extern void *exception_try_scope_entry (void);
+extern void exception_try_scope_exit (void *saved_state);
+extern void exception_rethrow (void);
+#endif
/* Macro to wrap up standard try/catch behavior.
*INDENT-OFF*
- volatile struct gdb_exception e;
- TRY_CATCH (e, RETURN_MASK_ERROR)
+ TRY
{
}
- switch (e.reason)
+ CATCH (e, RETURN_MASK_ERROR)
{
- case RETURN_ERROR: ...
+ switch (e.reason)
+ {
+ case RETURN_ERROR: ...
+ }
}
+ END_CATCH
- */
+ Note that the SJLJ version of the macros are actually named
+ TRY_SJLJ/CATCH_SJLJ in order to make it possible to call them even
+ when TRY/CATCH are mapped to C++ try/catch. The SJLJ variants are
+ needed in some cases where gdb exceptions need to cross third-party
+ library code compiled without exceptions support (e.g.,
+ readline). */
-#define TRY_CATCH(EXCEPTION,MASK) \
+#define TRY_SJLJ \
{ \
- SIGJMP_BUF *buf = \
- exceptions_state_mc_init (&(EXCEPTION), (MASK)); \
- SIGSETJMP (*buf); \
+ jmp_buf *buf = \
+ exceptions_state_mc_init (); \
+ setjmp (*buf); \
} \
while (exceptions_state_mc_action_iter ()) \
while (exceptions_state_mc_action_iter_1 ())
-/* *INDENT-ON* */
+#define CATCH_SJLJ(EXCEPTION, MASK) \
+ { \
+ struct gdb_exception EXCEPTION; \
+ if (exceptions_state_mc_catch (&(EXCEPTION), MASK))
+
+#define END_CATCH_SJLJ \
+ }
+
+#if GDB_XCPT == GDB_XCPT_SJMP
+
+/* If using SJLJ-based exceptions for all exceptions, then provide
+ standard aliases. */
+
+#define TRY TRY_SJLJ
+#define CATCH CATCH_SJLJ
+#define END_CATCH END_CATCH_SJLJ
+
+#endif /* GDB_XCPT_SJMP */
+
+#if GDB_XCPT == GDB_XCPT_TRY || GDB_XCPT == GDB_XCPT_RAW_TRY
+
+/* Prevent error/quit during TRY from calling cleanups established
+ prior to here. This pops out the scope in either case of normal
+ exit or exception exit. */
+struct exception_try_scope
+{
+ exception_try_scope ()
+ {
+ saved_state = exception_try_scope_entry ();
+ }
+ ~exception_try_scope ()
+ {
+ exception_try_scope_exit (saved_state);
+ }
+
+ void *saved_state;
+};
+
+#if GDB_XCPT == GDB_XCPT_TRY
+
+/* We still need to wrap TRY/CATCH in C++ so that cleanups and C++
+ exceptions can coexist.
+
+ The TRY blocked is wrapped in a do/while(0) so that break/continue
+ within the block works the same as in C.
+
+ END_CATCH makes sure that even if the CATCH block doesn't want to
+ catch the exception, we stop at every frame in the unwind chain to
+ run its cleanups, which may e.g., have pointers to stack variables
+ that are going to be destroyed.
+
+ There's an outer scope around the whole TRY/END_CATCH in order to
+ cause a compilation error if you forget to add the END_CATCH at the
+ end a TRY/CATCH construct. */
-/* Hook to allow client-specific actions to be performed prior to
- throwing an exception. This function must be provided by the
- client, and will be called before any cleanups are run. */
+#define TRY \
+ { \
+ try \
+ { \
+ exception_try_scope exception_try_scope_instance; \
+ do \
+ {
-extern void prepare_to_throw_exception (void);
+#define CATCH(EXCEPTION, MASK) \
+ } while (0); \
+ } \
+ catch (struct gdb_exception ## _ ## MASK &EXCEPTION)
-/* Throw an exception (as described by "struct gdb_exception"). Will
- execute a LONG JUMP to the inner most containing exception handler
- established using catch_exceptions() (or similar).
+#define END_CATCH \
+ catch (...) \
+ { \
+ exception_rethrow (); \
+ } \
+ }
- Code normally throws an exception using error() et.al. For various
- reaons, GDB also contains code that throws an exception directly.
- For instance, the remote*.c targets contain CNTRL-C signal handlers
- that propogate the QUIT event up the exception chain. ``This could
- be a good thing or a dangerous thing.'' -- the Existential
- Wombat. */
+#else
+#define TRY try
+#define CATCH(EXCEPTION, MASK) \
+ catch (struct gdb_exception ## _ ## MASK &EXCEPTION)
+#define END_CATCH
+
+#endif
+
+/* The exception types client code may catch. They're just shims
+ around gdb_exception that add nothing but type info. Which is used
+ is selected depending on the MASK argument passed to CATCH. */
+
+struct gdb_exception_RETURN_MASK_ALL : public gdb_exception
+{
+};
+
+struct gdb_exception_RETURN_MASK_ERROR : public gdb_exception_RETURN_MASK_ALL
+{
+};
+
+struct gdb_exception_RETURN_MASK_QUIT : public gdb_exception_RETURN_MASK_ALL
+{
+};
+
+#endif /* GDB_XCPT_TRY || GDB_XCPT_RAW_TRY */
+
+/* An exception type that inherits from both std::bad_alloc and a gdb
+ exception. This is necessary because operator new can only throw
+ std::bad_alloc, and OTOH, we want exceptions thrown due to memory
+ allocation error to be caught by all the CATCH/RETURN_MASK_ALL
+ spread around the codebase. */
+
+struct gdb_quit_bad_alloc
+ : public gdb_exception_RETURN_MASK_QUIT,
+ public std::bad_alloc
+{
+ explicit gdb_quit_bad_alloc (gdb_exception ex)
+ : std::bad_alloc ()
+ {
+ gdb_exception *self = this;
+
+ *self = ex;
+ }
+};
+
+/* *INDENT-ON* */
+
+/* Throw an exception (as described by "struct gdb_exception"),
+ landing in the inner most containing exception handler established
+ using TRY/CATCH. */
extern void throw_exception (struct gdb_exception exception)
ATTRIBUTE_NORETURN;
+
+/* Throw an exception by executing a LONG JUMP to the inner most
+ containing exception handler established using TRY_SJLJ. Necessary
+ in some cases where we need to throw GDB exceptions across
+ third-party library code (e.g., readline). */
+extern void throw_exception_sjlj (struct gdb_exception exception)
+ ATTRIBUTE_NORETURN;
+
+/* Convenience wrappers around throw_exception that throw GDB
+ errors. */
extern void throw_verror (enum errors, const char *fmt, va_list ap)
ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
extern void throw_vquit (const char *fmt, va_list ap)
extern void throw_quit (const char *fmt, ...)
ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2);
+/* A pre-defined non-exception. */
+extern const struct gdb_exception exception_none;
+
#endif /* COMMON_EXCEPTIONS_H */
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