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/* SPDX-License-Identifier: Unlicense
*/
#include "elf_image.h"
#include <cassert>
#include <cstdio>
ELF::ProgramHeader32Table ELF::ProgramHeader32Table::FromBytes(
const DataView &d, const DataEncoding e)
{
if (d.buffer == nullptr || d.size == 0) {
return ELF::ProgramHeader32Table{};
}
assert(d.size % kProgramHeaderSize == 0);
const size_t size = d.size / kProgramHeaderSize;
auto *headers = new ProgramHeader32[size];
assert(headers != nullptr);
for (size_t i = 0; i < size; i++) {
headers[i] = ProgramHeader32::FromBytes(d.buffer + i * kProgramHeaderSize, e);
}
return ELF::ProgramHeader32Table{ headers, size, };
}
static char *ValidateELF(const DataView& d)
{
char *error;
size_t size;
FILE *s = open_memstream(&error, &size);
assert(s);
using namespace ELF;
if (d.size < kHeaderSize) {
fprintf(
s,
"data size (%zu) is lower than minimum ELF header size (%zu): "
"ELF header could not fit",
d.size,
kHeaderSize);
fclose(s);
return error;
}
const auto header_raw = Header32Raw::FromBytes(d.buffer);
const auto header = Header32::FromBytes(d.buffer);
if (!MagicIsValid(header.ident.magic)) {
const uint8_t *m = header.ident.magic;
fprintf(
s,
"ELF Magic is invalid: expected [%02x %02x %02x %02x], got [%02x %02x %02x %02x]",
0x7f, 'E', 'L', 'F',
m[0], m[1], m[2], m[3]);
fclose(s);
return error;
}
if (header.ident.version != Version::kCurrent) {
fprintf(
s,
"version (0x%02x) of ELF header.ident.version is not supported, "
"only \"Current\" version (0x%02x) is supported",
header_raw.ident.version,
static_cast<int>(Version::kCurrent));
fclose(s);
return error;
}
if (header.version != Version::kCurrent) {
fprintf(
s,
"version (0x%02x) of ELF header.version is not supported, "
"only \"Current\" version (0x%02x) is supported",
header_raw.version,
static_cast<int>(Version::kCurrent));
fclose(s);
return error;
}
if (header.type != ObjectType::kExec) {
fprintf(
s,
"object type (0x%02x) is not supported, "
"only Exec (0x%02x) object type is supported",
header_raw.type,
static_cast<int>(ObjectType::kExec));
fclose(s);
return error;
}
if (header.machine != Machine::k68k) {
fprintf(
s,
"machine (0x%02x) is not supported, "
"only Motorola 68k (0x%02x) machine is supported",
header_raw.machine,
static_cast<int>(Machine::k68k));
fclose(s);
return error;
}
if (header.phentsize != kProgramHeaderSize) {
fprintf(
s,
"phentsize is invalid: expected (%zu), got (%zu)",
kProgramHeaderSize,
size_t(header.phentsize));
fclose(s);
return error;
}
if (d.size < header.phoff + header.phentsize * header.phnum) {
fprintf(
s,
"data size (%zu) is lower than program header table end offset (%zu): "
"program header table could not fit",
d.size,
size_t(header.phoff + header.phentsize * header.phnum));
fclose(s);
return error;
}
bool has_segment_with_entry = false;
for (size_t i = 0; i < header.phnum; i++) {
const auto ph = ProgramHeader32::FromBytes(
d.buffer + header.phoff + header.phentsize * i, header.ident.data_encoding);
if (d.size < ph.offset + ph.filesz) {
fprintf(
s,
"data size (%zu) is lower than pht[%zu] segment end offset (%zu): "
"segment could not fit",
d.size,
i,
size_t(ph.offset + ph.filesz));
fclose(s);
return error;
}
const bool is_code = (ph.flags & (kPHFlagX | kPHFlagW | kPHFlagR)) == (kPHFlagX | kPHFlagR);
if (ParsePHType(ph.type) == PHType::kLoad && is_code && ph.vaddr != 0) {
fprintf(
s,
"pht[%zu] segment is a code, but it's vaddr (0x%08x) is not zero: "
"non-zero base address is not supported",
i,
ph.vaddr);
fclose(s);
return error;
}
const bool contains_entry = header.entry >= ph.vaddr && header.entry < ph.vaddr + ph.memsz;
if (ParsePHType(ph.type) == PHType::kLoad && is_code && contains_entry) {
has_segment_with_entry = true;
}
}
if (!has_segment_with_entry) {
fprintf(s, "no code segments containing entry point (0x%08x) found", header.entry);
fclose(s);
return error;
}
fclose(s);
free(error);
return nullptr;
}
ELF::Image::Image(DataBuffer&& data)
: _data(static_cast<DataBuffer&&>(data))
, _error(ValidateELF(_data.View()))
, _h(_error ? ELF::Header32{} : ELF::Header32::FromBytes(_data.View().buffer))
, _pht(_error
? ELF::ProgramHeader32Table{}
: ELF::ProgramHeader32Table::FromBytes(
_data.View(_h.phoff, _h.phnum * kProgramHeaderSize), _h.ident.data_encoding))
{}
ELF::Image::~Image()
{
if (_error) {
free(_error);
}
if (_pht.headers) {
delete [] _pht.headers;
}
}
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