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// Exception handling and frame unwind runtime interface routines.
// Copyright (C) 2011-2021 Free Software Foundation, Inc.
// GCC 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, or (at your option) any later
// version.
// GCC 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.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
// extern(C) interface for the GNU/GCC pointer encoding library.
// This corresponds to unwind-pe.h
module gcc.unwind.pe;
import gcc.unwind;
import gcc.builtins;
@nogc:
// Pointer encodings, from dwarf2.h.
enum
{
DW_EH_PE_absptr = 0x00,
DW_EH_PE_omit = 0xff,
DW_EH_PE_uleb128 = 0x01,
DW_EH_PE_udata2 = 0x02,
DW_EH_PE_udata4 = 0x03,
DW_EH_PE_udata8 = 0x04,
DW_EH_PE_sleb128 = 0x09,
DW_EH_PE_sdata2 = 0x0A,
DW_EH_PE_sdata4 = 0x0B,
DW_EH_PE_sdata8 = 0x0C,
DW_EH_PE_signed = 0x08,
DW_EH_PE_pcrel = 0x10,
DW_EH_PE_textrel = 0x20,
DW_EH_PE_datarel = 0x30,
DW_EH_PE_funcrel = 0x40,
DW_EH_PE_aligned = 0x50,
DW_EH_PE_indirect = 0x80
}
// 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.
uint size_of_encoded_value(ubyte encoding)
{
if (encoding == DW_EH_PE_omit)
return 0;
final switch (encoding & 0x07)
{
case DW_EH_PE_absptr:
return (void*).sizeof;
case DW_EH_PE_udata2:
return 2;
case DW_EH_PE_udata4:
return 4;
case DW_EH_PE_udata8:
return 8;
}
assert(0);
}
// 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.
_Unwind_Ptr base_of_encoded_value(ubyte encoding, _Unwind_Context* context)
{
if (encoding == DW_EH_PE_omit)
return cast(_Unwind_Ptr) 0;
final switch (encoding & 0x70)
{
case DW_EH_PE_absptr:
case DW_EH_PE_pcrel:
case DW_EH_PE_aligned:
return cast(_Unwind_Ptr) 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);
}
assert(0);
}
// Read an unsigned leb128 value from P, *P is 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.
_uleb128_t read_uleb128(const(ubyte)** p)
{
auto q = *p;
_uleb128_t result = 0;
uint shift = 0;
while (1)
{
ubyte b = *q++;
result |= cast(_uleb128_t)(b & 0x7F) << shift;
if ((b & 0x80) == 0)
break;
shift += 7;
}
*p = q;
return result;
}
// Similar, but read a signed leb128 value.
_sleb128_t read_sleb128(const(ubyte)** p)
{
auto q = *p;
_sleb128_t result = 0;
uint shift = 0;
ubyte b = void;
while (1)
{
b = *q++;
result |= cast(_sleb128_t)(b & 0x7F) << shift;
shift += 7;
if ((b & 0x80) == 0)
break;
}
// Sign-extend a negative value.
if (shift < result.sizeof * 8 && (b & 0x40))
result |= -(cast(_sleb128_t)1 << shift);
*p = q;
return result;
}
// 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.
_Unwind_Ptr read_encoded_value_with_base(ubyte encoding, _Unwind_Ptr base,
const(ubyte)** p)
{
auto q = *p;
_Unwind_Internal_Ptr result;
if (encoding == DW_EH_PE_aligned)
{
_Unwind_Internal_Ptr a = cast(_Unwind_Internal_Ptr)q;
a = cast(_Unwind_Internal_Ptr)((a + (void*).sizeof - 1) & - (void*).sizeof);
result = *cast(_Unwind_Internal_Ptr*)a;
q = cast(ubyte*) cast(_Unwind_Internal_Ptr)(a + (void*).sizeof);
}
else
{
switch (encoding & 0x0f)
{
case DW_EH_PE_uleb128:
result = cast(_Unwind_Internal_Ptr)read_uleb128(&q);
break;
case DW_EH_PE_sleb128:
result = cast(_Unwind_Internal_Ptr)read_sleb128(&q);
break;
case DW_EH_PE_udata2:
result = cast(_Unwind_Internal_Ptr) *cast(ushort*)q;
q += 2;
break;
case DW_EH_PE_udata4:
result = cast(_Unwind_Internal_Ptr) *cast(uint*)q;
q += 4;
break;
case DW_EH_PE_udata8:
result = cast(_Unwind_Internal_Ptr) *cast(ulong*)q;
q += 8;
break;
case DW_EH_PE_sdata2:
result = cast(_Unwind_Internal_Ptr) *cast(short*)q;
q += 2;
break;
case DW_EH_PE_sdata4:
result = cast(_Unwind_Internal_Ptr) *cast(int*)q;
q += 4;
break;
case DW_EH_PE_sdata8:
result = cast(_Unwind_Internal_Ptr) *cast(long*)q;
q += 8;
break;
case DW_EH_PE_absptr:
if (size_t.sizeof == 8)
goto case DW_EH_PE_udata8;
else
goto case DW_EH_PE_udata4;
default:
__builtin_abort();
}
if (result != 0)
{
result += ((encoding & 0x70) == DW_EH_PE_pcrel
? cast(_Unwind_Internal_Ptr)*p : base);
if (encoding & DW_EH_PE_indirect)
result = *cast(_Unwind_Internal_Ptr*)result;
}
}
*p = q;
return result;
}
// Like read_encoded_value_with_base, but get the base from the context
// rather than providing it directly.
_Unwind_Ptr read_encoded_value(_Unwind_Context* context, ubyte encoding,
const(ubyte)** p)
{
auto base = base_of_encoded_value(encoding, context);
return read_encoded_value_with_base(encoding, base, p);
}
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