//This code was stolen from gcc to read exception tables


/* If using C++, references to abort have to be qualified with std::.  */
#if __cplusplus
#define __gxx_abort std::abort
#else
#define __gxx_abort abort
#endif

/* Pointer encodings, from dwarf2.h.  */
#define DW_EH_PE_absptr         0x00
#define DW_EH_PE_omit           0xff

#define DW_EH_PE_uleb128        0x01
#define DW_EH_PE_udata2         0x02
#define DW_EH_PE_udata4         0x03
#define DW_EH_PE_udata8         0x04
#define DW_EH_PE_sleb128        0x09
#define DW_EH_PE_sdata2         0x0A
#define DW_EH_PE_sdata4         0x0B
#define DW_EH_PE_sdata8         0x0C
#define DW_EH_PE_signed         0x08

#define DW_EH_PE_pcrel          0x10
#define DW_EH_PE_textrel        0x20
#define DW_EH_PE_datarel        0x30
#define DW_EH_PE_funcrel        0x40
#define DW_EH_PE_aligned        0x50

#define DW_EH_PE_indirect	0x80


int handler_found = 0;

/* Given an encoding, return the number of bytes the format occupies.
This is only defined for fixed-size encodings, and so does not
include leb128.  */
static unsigned int size_of_encoded_value (unsigned char encoding) __attribute__ ((unused));

static unsigned int size_of_encoded_value (unsigned char encoding)
{
	if (encoding == DW_EH_PE_omit) return 0;

	switch (encoding & 0x07) {
		case DW_EH_PE_absptr: return sizeof (void *);
		case DW_EH_PE_udata2: return 2;
		case DW_EH_PE_udata4: return 4;
		case DW_EH_PE_udata8: return 8;
	}
	__gxx_abort ();
}

/* Given an encoding and an _Unwind_Context, return the base to which
the encoding is relative.  This base may then be passed to
read_encoded_value_with_base for use when the _Unwind_Context is
not available.  */
static _Unwind_Ptr base_of_encoded_value (unsigned char encoding, struct _Unwind_Context *context)
{
	if (encoding == DW_EH_PE_omit) return 0;

	switch (encoding & 0x70) {
		case DW_EH_PE_absptr:
		case DW_EH_PE_pcrel:
		case DW_EH_PE_aligned:
			return 0;
		case DW_EH_PE_textrel:
			return _Unwind_GetTextRelBase (context);
		case DW_EH_PE_datarel:
			return _Unwind_GetDataRelBase (context);
		case DW_EH_PE_funcrel:
			return _Unwind_GetRegionStart (context);
	}
	__gxx_abort ();
}

/* Read an unsigned leb128 value from P, store the value in VAL, return
P incremented past the value.  We assume that a word is large enough to
hold any value so encoded; if it is smaller than a pointer on some target,
pointers should not be leb128 encoded on that target.  */
static const unsigned char * read_uleb128 (const unsigned char *p, _uleb128_t *val)
{
	unsigned int shift = 0;
	unsigned char byte;
	_uleb128_t result;

	result = 0;
	do
	{
		byte = *p++;
		result |= ((_uleb128_t)byte & 0x7f) << shift;
		shift += 7;
	}
	while (byte & 0x80);

	*val = result;
	return p;
}

/* Similar, but read a signed leb128 value.  */
static const unsigned char * read_sleb128 (const unsigned char *p, _sleb128_t *val)
{
	unsigned int shift = 0;
	unsigned char byte;
	_uleb128_t result;

	result = 0;
	do
	{
		byte = *p++;
		result |= ((_uleb128_t)byte & 0x7f) << shift;
		shift += 7;
	}
	while (byte & 0x80);

	/* Sign-extend a negative value.  */
	if (shift < 8 * sizeof(result) && (byte & 0x40) != 0) result |= -(((_uleb128_t)1L) << shift);

	*val = (_sleb128_t) result;
	return p;
}

/* Load an encoded value from memory at P.  The value is returned in VAL;
The function returns P incremented past the value.  BASE is as given
by base_of_encoded_value for this encoding in the appropriate context.  */

static const unsigned char * read_encoded_value_with_base (unsigned char encoding, _Unwind_Ptr base, const unsigned char *p, _Unwind_Ptr *val)
{
	union unaligned
	{
		void *ptr;
		unsigned u2 __attribute__ ((mode (HI)));
		unsigned u4 __attribute__ ((mode (SI)));
		unsigned u8 __attribute__ ((mode (DI)));
		signed s2 __attribute__ ((mode (HI)));
		signed s4 __attribute__ ((mode (SI)));
		signed s8 __attribute__ ((mode (DI)));
	} __attribute__((__packed__));

	const union unaligned *u = (const union unaligned *) p;
	_Unwind_Internal_Ptr result;

	if (encoding == DW_EH_PE_aligned)
	{
		_Unwind_Internal_Ptr a = (_Unwind_Internal_Ptr) p;
		a = (a + sizeof (void *) - 1) & - sizeof(void *);
		result = *(_Unwind_Internal_Ptr *) a;
		p = (const unsigned char *) (_Unwind_Internal_Ptr) (a + sizeof (void *));
	}
	else
	{
		switch (encoding & 0x0f)
		{
			case DW_EH_PE_absptr:
				result = (_Unwind_Internal_Ptr) u->ptr;
				p += sizeof (void *);
				break;
			case DW_EH_PE_uleb128:
			{
				_uleb128_t tmp;
				p = read_uleb128 (p, &tmp);
				result = (_Unwind_Internal_Ptr) tmp;
			}
			break;

			case DW_EH_PE_sleb128:
			{
				_sleb128_t tmp;
				p = read_sleb128 (p, &tmp);
				result = (_Unwind_Internal_Ptr) tmp;
			}
			break;

			case DW_EH_PE_udata2:
				result = u->u2;
				p += 2;
				break;
			case DW_EH_PE_udata4:
				result = u->u4;
				p += 4;
				break;
			case DW_EH_PE_udata8:
				result = u->u8;
				p += 8;
				break;
			case DW_EH_PE_sdata2:
				result = u->s2;
				p += 2;
				break;
			case DW_EH_PE_sdata4:
				result = u->s4;
				p += 4;
				break;
			case DW_EH_PE_sdata8:
				result = u->s8;
				p += 8;
				break;
			default:
				__gxx_abort();
		}

		if (result != 0)
		{
			result += ((encoding & 0x70) == DW_EH_PE_pcrel ? (_Unwind_Internal_Ptr) u : base);
			
			if (encoding & DW_EH_PE_indirect) result = *(_Unwind_Internal_Ptr *) result;
		}
	}

	*val = result;
	return p;
}

/* Like read_encoded_value_with_base, but get the base from the context
rather than providing it directly.  */
static inline const unsigned char * read_encoded_value (struct _Unwind_Context *context, unsigned char encoding, const unsigned char *p, _Unwind_Ptr *val)
{
	return read_encoded_value_with_base (encoding, base_of_encoded_value (encoding, context), p, val);
}

typedef struct
{
	_Unwind_Ptr Start;
	_Unwind_Ptr LPStart;
	_Unwind_Ptr ttype_base;
	const unsigned char *TType;
	const unsigned char *action_table;
	unsigned char ttype_encoding;
	unsigned char call_site_encoding;
} lsda_header_info;

static const unsigned char * parse_lsda_header (struct _Unwind_Context *context, const unsigned char *p, lsda_header_info *info)
{
	_uleb128_t tmp;
	unsigned char lpstart_encoding;

	info->Start = (context ? _Unwind_GetRegionStart (context) : 0);

	/* Find @LPStart, the base to which landing pad offsets are relative.  */
	lpstart_encoding = *p++;
	if (lpstart_encoding != DW_EH_PE_omit) p = read_encoded_value (context, lpstart_encoding, p, &info->LPStart);

	else info->LPStart = info->Start;

	/* Find @TType, the base of the handler and exception spec type data.  */
	info->ttype_encoding = *p++;
	if (info->ttype_encoding != DW_EH_PE_omit)
	{
		p = read_uleb128 (p, &tmp);
		info->TType = p + tmp;
	}
	else info->TType = 0;

	/* The encoding and length of the call-site table; the action table
	immediately follows.  */
	info->call_site_encoding = *p++;
	p = read_uleb128 (p, &tmp);
	info->action_table = p + tmp;

	return p;
}