/* Copyright (C) 1986-2024 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/>. */
#include "extract-store-integer.h"
#include "gdbtypes.h"
#include "gdbarch.h"
#include "gdbsupport/selftest.h"
template<typename T, typename>
T
extract_integer (gdb::array_view<const gdb_byte> buf, enum bfd_endian byte_order)
{
typename std::make_unsigned<T>::type retval = 0;
/* It is ok if BUF is wider than T, but only if the value is
representable. */
bool bad_repr = false;
if (buf.size () > (int) sizeof (T))
{
const size_t end = buf.size () - sizeof (T);
if (byte_order == BFD_ENDIAN_BIG)
{
for (size_t i = 0; i < end; ++i)
{
/* High bytes == 0 are always ok, and high bytes == 0xff
are ok when the type is signed. */
if ((buf[i] == 0
|| (std::is_signed<T>::value && buf[i] == 0xff))
/* All the high bytes must be the same, no
alternating 0 and 0xff. */
&& (i == 0 || buf[i - 1] == buf[i]))
{
/* Ok. */
}
else
{
bad_repr = true;
break;
}
}
buf = buf.slice (end);
}
else
{
size_t bufsz = buf.size () - 1;
for (size_t i = bufsz; i >= end; --i)
{
/* High bytes == 0 are always ok, and high bytes == 0xff
are ok when the type is signed. */
if ((buf[i] == 0
|| (std::is_signed<T>::value && buf[i] == 0xff))
/* All the high bytes must be the same, no
alternating 0 and 0xff. */
&& (i == bufsz || buf[i] == buf[i + 1]))
{
/* Ok. */
}
else
{
bad_repr = true;
break;
}
}
buf = buf.slice (0, end);
}
}
if (bad_repr)
error (_("Value cannot be represented as integer of %d bytes."),
(int) sizeof (T));
/* Start at the most significant end of the integer, and work towards
the least significant. */
if (byte_order == BFD_ENDIAN_BIG)
{
size_t i = 0;
if (std::is_signed<T>::value)
{
/* Do the sign extension once at the start. */
retval = ((LONGEST) buf[i] ^ 0x80) - 0x80;
++i;
}
for (; i < buf.size (); ++i)
retval = (retval << 8) | buf[i];
}
else
{
ssize_t i = buf.size () - 1;
if (std::is_signed<T>::value)
{
/* Do the sign extension once at the start. */
retval = ((LONGEST) buf[i] ^ 0x80) - 0x80;
--i;
}
for (; i >= 0; --i)
retval = (retval << 8) | buf[i];
}
return retval;
}
/* Explicit instantiations. */
template LONGEST extract_integer<LONGEST> (gdb::array_view<const gdb_byte> buf,
enum bfd_endian byte_order);
template ULONGEST extract_integer<ULONGEST>
(gdb::array_view<const gdb_byte> buf, enum bfd_endian byte_order);
/* Treat the bytes at BUF as a pointer of type TYPE, and return the
address it represents. */
CORE_ADDR
extract_typed_address (const gdb_byte *buf, struct type *type)
{
gdb_assert (type->is_pointer_or_reference ());
return gdbarch_pointer_to_address (type->arch (), type, buf);
}
/* All 'store' functions accept a host-format integer and store a
target-format integer at ADDR which is LEN bytes long. */
template<typename T, typename>
void
store_integer (gdb::array_view<gdb_byte> dst, enum bfd_endian byte_order,
T val)
{
gdb_byte *p;
gdb_byte *startaddr = dst.data ();
gdb_byte *endaddr = startaddr + dst.size ();
/* Start at the least significant end of the integer, and work towards
the most significant. */
if (byte_order == BFD_ENDIAN_BIG)
{
for (p = endaddr - 1; p >= startaddr; --p)
{
*p = val & 0xff;
val >>= 8;
}
}
else
{
for (p = startaddr; p < endaddr; ++p)
{
*p = val & 0xff;
val >>= 8;
}
}
}
/* Explicit instantiations. */
template void store_integer (gdb::array_view<gdb_byte> dst,
bfd_endian byte_order, LONGEST val);
template void store_integer (gdb::array_view<gdb_byte> dst,
bfd_endian byte_order, ULONGEST val);
/* Store the address ADDR as a pointer of type TYPE at BUF, in target
form. */
void
store_typed_address (gdb_byte *buf, struct type *type, CORE_ADDR addr)
{
gdb_assert (type->is_pointer_or_reference ());
gdbarch_address_to_pointer (type->arch (), type, buf, addr);
}
/* Copy a value from SOURCE of size SOURCE_SIZE bytes to DEST of size DEST_SIZE
bytes. If SOURCE_SIZE is greater than DEST_SIZE, then truncate the most
significant bytes. If SOURCE_SIZE is less than DEST_SIZE then either sign
or zero extended according to IS_SIGNED. Values are stored in memory with
endianness BYTE_ORDER. */
void
copy_integer_to_size (gdb_byte *dest, int dest_size, const gdb_byte *source,
int source_size, bool is_signed,
enum bfd_endian byte_order)
{
signed int size_diff = dest_size - source_size;
/* Copy across everything from SOURCE that can fit into DEST. */
if (byte_order == BFD_ENDIAN_BIG && size_diff > 0)
memcpy (dest + size_diff, source, source_size);
else if (byte_order == BFD_ENDIAN_BIG && size_diff < 0)
memcpy (dest, source - size_diff, dest_size);
else
memcpy (dest, source, std::min (source_size, dest_size));
/* Fill the remaining space in DEST by either zero extending or sign
extending. */
if (size_diff > 0)
{
gdb_byte extension = 0;
if (is_signed
&& ((byte_order != BFD_ENDIAN_BIG && source[source_size - 1] & 0x80)
|| (byte_order == BFD_ENDIAN_BIG && source[0] & 0x80)))
extension = 0xff;
/* Extend into MSBs of SOURCE. */
if (byte_order == BFD_ENDIAN_BIG)
memset (dest, extension, size_diff);
else
memset (dest + source_size, extension, size_diff);
}
}
#if GDB_SELF_TEST
namespace selftests {
/* Function to test copy_integer_to_size. Store SOURCE_VAL with size
SOURCE_SIZE to a buffer, making sure no sign extending happens at this
stage. Copy buffer to a new buffer using copy_integer_to_size. Extract
copied value and compare to DEST_VALU. Copy again with a signed
copy_integer_to_size and compare to DEST_VALS. Do everything for both
LITTLE and BIG target endians. Use unsigned values throughout to make
sure there are no implicit sign extensions. */
static void
do_cint_test (ULONGEST dest_valu, ULONGEST dest_vals, int dest_size,
ULONGEST src_val, int src_size)
{
for (int i = 0; i < 2 ; i++)
{
gdb_byte srcbuf[sizeof (ULONGEST)] = {};
gdb_byte destbuf[sizeof (ULONGEST)] = {};
enum bfd_endian byte_order = i ? BFD_ENDIAN_BIG : BFD_ENDIAN_LITTLE;
/* Fill the src buffer (and later the dest buffer) with non-zero junk,
to ensure zero extensions aren't hidden. */
memset (srcbuf, 0xaa, sizeof (srcbuf));
/* Store (and later extract) using unsigned to ensure there are no sign
extensions. */
store_unsigned_integer (srcbuf, src_size, byte_order, src_val);
/* Test unsigned. */
memset (destbuf, 0xaa, sizeof (destbuf));
copy_integer_to_size (destbuf, dest_size, srcbuf, src_size, false,
byte_order);
SELF_CHECK (dest_valu == extract_unsigned_integer (destbuf, dest_size,
byte_order));
/* Test signed. */
memset (destbuf, 0xaa, sizeof (destbuf));
copy_integer_to_size (destbuf, dest_size, srcbuf, src_size, true,
byte_order);
SELF_CHECK (dest_vals == extract_unsigned_integer (destbuf, dest_size,
byte_order));
}
}
static void
copy_integer_to_size_test ()
{
/* Destination is bigger than the source, which has the signed bit unset. */
do_cint_test (0x12345678, 0x12345678, 8, 0x12345678, 4);
do_cint_test (0x345678, 0x345678, 8, 0x12345678, 3);
/* Destination is bigger than the source, which has the signed bit set. */
do_cint_test (0xdeadbeef, 0xffffffffdeadbeef, 8, 0xdeadbeef, 4);
do_cint_test (0xadbeef, 0xffffffffffadbeef, 8, 0xdeadbeef, 3);
/* Destination is smaller than the source. */
do_cint_test (0x5678, 0x5678, 2, 0x12345678, 3);
do_cint_test (0xbeef, 0xbeef, 2, 0xdeadbeef, 3);
/* Destination and source are the same size. */
do_cint_test (0x8765432112345678, 0x8765432112345678, 8, 0x8765432112345678,
8);
do_cint_test (0x432112345678, 0x432112345678, 6, 0x8765432112345678, 6);
do_cint_test (0xfeedbeaddeadbeef, 0xfeedbeaddeadbeef, 8, 0xfeedbeaddeadbeef,
8);
do_cint_test (0xbeaddeadbeef, 0xbeaddeadbeef, 6, 0xfeedbeaddeadbeef, 6);
/* Destination is bigger than the source. Source is bigger than 32bits. */
do_cint_test (0x3412345678, 0x3412345678, 8, 0x3412345678, 6);
do_cint_test (0xff12345678, 0xff12345678, 8, 0xff12345678, 6);
do_cint_test (0x432112345678, 0x432112345678, 8, 0x8765432112345678, 6);
do_cint_test (0xff2112345678, 0xffffff2112345678, 8, 0xffffff2112345678, 6);
}
template<typename T>
void
do_extract_test (gdb_byte byte1, gdb_byte byte2, enum bfd_endian endian,
std::optional<T> expected)
{
std::optional<T> result;
try
{
const gdb_byte val[2] = { byte1, byte2 };
result = extract_integer<T> (gdb::make_array_view (val, 2), endian);
}
catch (const gdb_exception_error &)
{
}
SELF_CHECK (result == expected);
}
template<typename T>
void
do_extract_tests (gdb_byte low, gdb_byte high, std::optional<T> expected)
{
do_extract_test (low, high, BFD_ENDIAN_LITTLE, expected);
do_extract_test (high, low, BFD_ENDIAN_BIG, expected);
}
static void
extract_integer_test ()
{
do_extract_tests<uint8_t> (0x00, 0xff, {});
do_extract_tests<uint8_t> (0x7f, 0x23, {});
do_extract_tests<uint8_t> (0x80, 0xff, {});
do_extract_tests<uint8_t> (0x00, 0x00, 0x00);
do_extract_tests<int8_t> (0xff, 0x00, 0xff);
do_extract_tests<int8_t> (0x7f, 0x23, {});
do_extract_tests<int8_t> (0x80, 0xff, 0x80);
do_extract_tests<int8_t> (0x00, 0x00, 0x00);
}
} /* namespace selftests */
#endif
void _initialize_extract_store_integer ();
void
_initialize_extract_store_integer ()
{
#if GDB_SELF_TEST
selftests::register_test ("copy_integer_to_size",
selftests::copy_integer_to_size_test);
selftests::register_test ("extract_integer",
selftests::extract_integer_test);
#endif
}