[deliverable/binutils-gdb.git] / gdb / common / common-exceptions.h

/* Exception (throw catch) mechanism, for GDB, the GNU debugger.

   Copyright (C) 1986-2017 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#ifndef COMMON_EXCEPTIONS_H
#define COMMON_EXCEPTIONS_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.  */

enum return_reason
  {
    /* User interrupt.  */
    RETURN_QUIT = -2,
    /* Any other error.  */
    RETURN_ERROR
  };

#define RETURN_MASK(reason)	(1 << (int)(-reason))

typedef enum
{
  RETURN_MASK_QUIT = RETURN_MASK (RETURN_QUIT),
  RETURN_MASK_ERROR = RETURN_MASK (RETURN_ERROR),
  RETURN_MASK_ALL = (RETURN_MASK_QUIT | RETURN_MASK_ERROR)
} return_mask;

/* Describe all exceptions.  */

enum errors {
  GDB_NO_ERROR,

  /* Any generic error, the corresponding text is in
     exception.message.  */
  GENERIC_ERROR,

  /* Something requested was not found.  */
  NOT_FOUND_ERROR,

  /* Thread library lacks support necessary for finding thread local
     storage.  */
  TLS_NO_LIBRARY_SUPPORT_ERROR,

  /* Load module not found while attempting to find thread local storage.  */
  TLS_LOAD_MODULE_NOT_FOUND_ERROR,

  /* Thread local storage has not been allocated yet.  */
  TLS_NOT_ALLOCATED_YET_ERROR,

  /* Something else went wrong while attempting to find thread local
     storage.  The ``struct gdb_exception'' message field provides
     more detail.  */
  TLS_GENERIC_ERROR,

  /* Problem parsing an XML document.  */
  XML_PARSE_ERROR,

  /* Error accessing memory.  */
  MEMORY_ERROR,

  /* Value not available.  E.g., a register was not collected in a
     traceframe.  */
  NOT_AVAILABLE_ERROR,

  /* Value was optimized out.  Note: if the value was a register, this
     means the register was not saved in the frame.  */
  OPTIMIZED_OUT_ERROR,

  /* DW_OP_entry_value resolving failed.  */
  NO_ENTRY_VALUE_ERROR,

  /* Target throwing an error has been closed.  Current command should be
     aborted as the inferior state is no longer valid.  */
  TARGET_CLOSE_ERROR,

  /* An undefined command was executed.  */
  UNDEFINED_COMMAND_ERROR,

  /* Requested feature, method, mechanism, etc. is not supported.  */
  NOT_SUPPORTED_ERROR,

  /* The number of candidates generated during line completion has
     reached the user's specified limit.  This isn't an error, this exception
     is used to halt searching for more completions, but for consistency
     "_ERROR" is appended to the name.  */
  MAX_COMPLETIONS_REACHED_ERROR,

  /* Add more errors here.  */
  NR_ERRORS
};

struct gdb_exception
{
  enum return_reason reason;
  enum errors error;
  const char *message;
};

/* The different exception mechanisms that TRY/CATCH can map to.  */

/* 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.

   The double loop lets us correctly handle code "break"ing out of the
   try catch block.  (It works as the "break" only exits the inner
   "while" loop, the outer for loop detects this handling it
   correctly.)  Of course "return" and "goto" are not so lucky.

   For instance:

   *INDENT-OFF*

   TRY
     {
     }
   CATCH (e, RETURN_MASK_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_SJLJ \
     { \
       jmp_buf *buf = \
	 exceptions_state_mc_init (); \
       setjmp (*buf); \
     } \
     while (exceptions_state_mc_action_iter ()) \
       while (exceptions_state_mc_action_iter_1 ())

#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.  */
#define TRY								\
  try									\
    {									\
      exception_try_scope exception_try_scope_instance;			\
      do								\
	{

#define CATCH(EXCEPTION, MASK)						\
	} while (0);							\
    }								        \
  catch (struct gdb_exception ## _ ## MASK &EXCEPTION)

#define END_CATCH				\
  catch (...)					\
  {						\
    exception_rethrow ();			\
  }

#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)
     ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
extern void throw_error (enum errors error, const char *fmt, ...)
     ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
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 */
Commit	Line	Data
ff55e1b5 GB	1	/* Exception (throw catch) mechanism, for GDB, the GNU debugger.
ff55e1b5 GB	2
61baf725	3	Copyright (C) 1986-2017 Free Software Foundation, Inc.
ff55e1b5 GB	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 COMMON_EXCEPTIONS_H
	21	#define COMMON_EXCEPTIONS_H
	22
173981bc	23	#include <setjmp.h>
503b1c39	24	#include <new>
ff55e1b5 GB	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
216f72a1	90	/* DW_OP_entry_value resolving failed. */
ff55e1b5 GB	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
ef0b411a GB	103	/* The number of candidates generated during line completion has
	104	reached the user's specified limit. This isn't an error, this exception
	105	is used to halt searching for more completions, but for consistency
	106	"_ERROR" is appended to the name. */
	107	MAX_COMPLETIONS_REACHED_ERROR,
	108
ff55e1b5 GB	109	/* Add more errors here. */
	110	NR_ERRORS
	111	};
	112
	113	struct gdb_exception
	114	{
	115	enum return_reason reason;
	116	enum errors error;
	117	const char *message;
	118	};
	119
eec461d0 PA	120	/* The different exception mechanisms that TRY/CATCH can map to. */
eec461d0 PA	121
ddb6d633	122	/* Make GDB exceptions use setjmp/longjmp behind the scenes. */
eec461d0 PA	123	#define GDB_XCPT_SJMP 1
eec461d0 PA	124
6290672f	125	/* Make GDB exceptions use try/catch behind the scenes. */
eec461d0 PA	126	#define GDB_XCPT_TRY 2
	127
	128	/* Specify this mode to build with TRY/CATCH mapped directly to raw
	129	try/catch. GDB won't work correctly, but building that way catches
	130	code tryin to break/continue out of the try block, along with
	131	spurious code between the TRY and the CATCH block. */
	132	#define GDB_XCPT_RAW_TRY 3
	133
ddb6d633	134	#define GDB_XCPT GDB_XCPT_TRY
eec461d0	135
89525768 PA	136	/* Functions to drive the sjlj-based exceptions state machine. Though
	137	declared here by necessity, these functions should be considered
	138	internal to the exceptions subsystem and not used other than via
	139	the TRY/CATCH (or TRY_SJLJ/CATCH_SJLJ) macros defined below. */
ff55e1b5	140
173981bc	141	extern jmp_buf *exceptions_state_mc_init (void);
ff55e1b5 GB	142	extern int exceptions_state_mc_action_iter (void);
ff55e1b5 GB	143	extern int exceptions_state_mc_action_iter_1 (void);
492d29ea	144	extern int exceptions_state_mc_catch (struct gdb_exception *, int);
89525768 PA	145
	146	/* Same, but for the C++ try/catch-based TRY/CATCH mechanism. */
	147
	148	#if GDB_XCPT != GDB_XCPT_SJMP
72df25b2 PA	149	extern void *exception_try_scope_entry (void);
	150	extern void exception_try_scope_exit (void *saved_state);
	151	extern void exception_rethrow (void);
	152	#endif
ff55e1b5 GB	153
	154	/* Macro to wrap up standard try/catch behavior.
	155
	156	The double loop lets us correctly handle code "break"ing out of the
	157	try catch block. (It works as the "break" only exits the inner
	158	"while" loop, the outer for loop detects this handling it
	159	correctly.) Of course "return" and "goto" are not so lucky.
	160
	161	For instance:
	162
	163	INDENT-OFF
	164
492d29ea	165	TRY
ff55e1b5 GB	166	{
ff55e1b5 GB	167	}
492d29ea	168	CATCH (e, RETURN_MASK_ERROR)
ff55e1b5	169	{
492d29ea PA	170	switch (e.reason)
	171	{
	172	case RETURN_ERROR: ...
	173	}
ff55e1b5	174	}
492d29ea	175	END_CATCH
ff55e1b5	176
89525768 PA	177	Note that the SJLJ version of the macros are actually named
	178	TRY_SJLJ/CATCH_SJLJ in order to make it possible to call them even
	179	when TRY/CATCH are mapped to C++ try/catch. The SJLJ variants are
	180	needed in some cases where gdb exceptions need to cross third-party
	181	library code compiled without exceptions support (e.g.,
	182	readline). */
ff55e1b5	183
89525768	184	#define TRY_SJLJ \
ff55e1b5	185	{ \
173981bc	186	jmp_buf *buf = \
492d29ea	187	exceptions_state_mc_init (); \
173981bc	188	setjmp (*buf); \
ff55e1b5 GB	189	} \
	190	while (exceptions_state_mc_action_iter ()) \
	191	while (exceptions_state_mc_action_iter_1 ())
	192
89525768	193	#define CATCH_SJLJ(EXCEPTION, MASK) \
492d29ea PA	194	{ \
	195	struct gdb_exception EXCEPTION; \
	196	if (exceptions_state_mc_catch (&(EXCEPTION), MASK))
	197
89525768	198	#define END_CATCH_SJLJ \
492d29ea PA	199	}
492d29ea PA	200
89525768 PA	201	#if GDB_XCPT == GDB_XCPT_SJMP
	202
	203	/* If using SJLJ-based exceptions for all exceptions, then provide
	204	standard aliases. */
	205
	206	#define TRY TRY_SJLJ
	207	#define CATCH CATCH_SJLJ
	208	#define END_CATCH END_CATCH_SJLJ
	209
eec461d0 PA	210	#endif /* GDB_XCPT_SJMP */
	211
	212	#if GDB_XCPT == GDB_XCPT_TRY \|\| GDB_XCPT == GDB_XCPT_RAW_TRY
72df25b2 PA	213
	214	/* Prevent error/quit during TRY from calling cleanups established
	215	prior to here. This pops out the scope in either case of normal
	216	exit or exception exit. */
	217	struct exception_try_scope
	218	{
	219	exception_try_scope ()
	220	{
	221	saved_state = exception_try_scope_entry ();
	222	}
	223	~exception_try_scope ()
	224	{
	225	exception_try_scope_exit (saved_state);
	226	}
	227
	228	void *saved_state;
	229	};
	230
eec461d0	231	#if GDB_XCPT == GDB_XCPT_TRY
9c6595ab	232
72df25b2 PA	233	/* We still need to wrap TRY/CATCH in C++ so that cleanups and C++
	234	exceptions can coexist. The TRY blocked is wrapped in a
	235	do/while(0) so that break/continue within the block works the same
	236	as in C. */
	237	#define TRY \
	238	try \
	239	{ \
	240	exception_try_scope exception_try_scope_instance; \
	241	do \
	242	{
	243
	244	#define CATCH(EXCEPTION, MASK) \
	245	} while (0); \
	246	} \
	247	catch (struct gdb_exception ## _ ## MASK &EXCEPTION)
	248
	249	#define END_CATCH \
	250	catch (...) \
	251	{ \
	252	exception_rethrow (); \
	253	}
eec461d0	254
9c6595ab PA	255	#else
	256
	257	#define TRY try
	258	#define CATCH(EXCEPTION, MASK) \
	259	catch (struct gdb_exception ## _ ## MASK &EXCEPTION)
	260	#define END_CATCH
	261
	262	#endif
72df25b2 PA	263
	264	/* The exception types client code may catch. They're just shims
	265	around gdb_exception that add nothing but type info. Which is used
	266	is selected depending on the MASK argument passed to CATCH. */
	267
	268	struct gdb_exception_RETURN_MASK_ALL : public gdb_exception
	269	{
	270	};
	271
	272	struct gdb_exception_RETURN_MASK_ERROR : public gdb_exception_RETURN_MASK_ALL
	273	{
	274	};
	275
	276	struct gdb_exception_RETURN_MASK_QUIT : public gdb_exception_RETURN_MASK_ALL
	277	{
	278	};
	279
eec461d0	280	#endif /* GDB_XCPT_TRY \|\| GDB_XCPT_RAW_TRY */
72df25b2	281
503b1c39 PA	282	/* An exception type that inherits from both std::bad_alloc and a gdb
	283	exception. This is necessary because operator new can only throw
	284	std::bad_alloc, and OTOH, we want exceptions thrown due to memory
	285	allocation error to be caught by all the CATCH/RETURN_MASK_ALL
	286	spread around the codebase. */
	287
	288	struct gdb_quit_bad_alloc
	289	: public gdb_exception_RETURN_MASK_QUIT,
	290	public std::bad_alloc
	291	{
	292	explicit gdb_quit_bad_alloc (gdb_exception ex)
	293	: std::bad_alloc ()
	294	{
	295	gdb_exception *self = this;
	296
	297	*self = ex;
	298	}
	299	};
	300
ff55e1b5 GB	301	/* INDENT-ON */
ff55e1b5 GB	302
ddb6d633 PA	303	/* Throw an exception (as described by "struct gdb_exception"),
	304	landing in the inner most containing exception handler established
	305	using TRY/CATCH. */
ff55e1b5 GB	306	extern void throw_exception (struct gdb_exception exception)
ff55e1b5 GB	307	ATTRIBUTE_NORETURN;
89525768 PA	308
89525768 PA	309	/* Throw an exception by executing a LONG JUMP to the inner most
ddb6d633 PA	310	containing exception handler established using TRY_SJLJ. Necessary
	311	in some cases where we need to throw GDB exceptions across
	312	third-party library code (e.g., readline). */
89525768 PA	313	extern void throw_exception_sjlj (struct gdb_exception exception)
	314	ATTRIBUTE_NORETURN;
	315
	316	/* Convenience wrappers around throw_exception that throw GDB
	317	errors. */
ff55e1b5 GB	318	extern void throw_verror (enum errors, const char *fmt, va_list ap)
	319	ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 0);
	320	extern void throw_vquit (const char *fmt, va_list ap)
	321	ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 0);
	322	extern void throw_error (enum errors error, const char *fmt, ...)
	323	ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (2, 3);
	324	extern void throw_quit (const char *fmt, ...)
	325	ATTRIBUTE_NORETURN ATTRIBUTE_PRINTF (1, 2);
	326
ad6aff7d PA	327	/* A pre-defined non-exception. */
	328	extern const struct gdb_exception exception_none;
	329
ff55e1b5	330	#endif /* COMMON_EXCEPTIONS_H */