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#include <biscuit/assert.hpp>
#include <biscuit/code_buffer.hpp>
#include <cstring>
#include <utility>
#ifdef BISCUIT_CODE_BUFFER_MMAP
#include <sys/mman.h>
#endif
namespace biscuit {
CodeBuffer::CodeBuffer(size_t capacity)
: m_capacity{capacity}, m_is_managed{true} {
if (capacity == 0) {
return;
}
#ifdef BISCUIT_CODE_BUFFER_MMAP
m_buffer = static_cast<uint8_t*>(mmap(nullptr, capacity,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS,
-1, 0));
BISCUIT_ASSERT(m_buffer != nullptr);
#else
m_buffer = new uint8_t[capacity]();
#endif
m_cursor = m_buffer;
}
CodeBuffer::CodeBuffer(uint8_t* buffer, size_t capacity)
: m_buffer{buffer}, m_cursor{buffer}, m_capacity{capacity} {
BISCUIT_ASSERT(buffer != nullptr);
}
CodeBuffer::CodeBuffer(CodeBuffer&& other) noexcept
: m_buffer{std::exchange(other.m_buffer, nullptr)}
, m_cursor{std::exchange(other.m_cursor, nullptr)}
, m_capacity{std::exchange(other.m_capacity, size_t{0})}
, m_is_managed{std::exchange(other.m_is_managed, false)} {}
CodeBuffer& CodeBuffer::operator=(CodeBuffer&& other) noexcept {
if (this == &other) {
return *this;
}
std::swap(m_buffer, other.m_buffer);
std::swap(m_cursor, other.m_cursor);
std::swap(m_capacity, other.m_capacity);
std::swap(m_is_managed, other.m_is_managed);
return *this;
}
CodeBuffer::~CodeBuffer() noexcept {
if (!m_is_managed) {
return;
}
#ifdef BISCUIT_CODE_BUFFER_MMAP
munmap(m_buffer, m_capacity);
#else
delete[] m_buffer;
#endif
}
void CodeBuffer::Grow(size_t new_capacity) {
BISCUIT_ASSERT(IsManaged());
// No-op, just return.
if (new_capacity <= m_capacity) {
return;
}
const auto cursor_offset = GetCursorOffset();
#ifdef BISCUIT_CODE_BUFFER_MMAP
auto* new_buffer = static_cast<uint8_t*>(mremap(m_buffer, m_capacity, new_capacity, MREMAP_MAYMOVE));
BISCUIT_ASSERT(new_buffer != nullptr);
#else
auto* new_buffer = new uint8_t[new_capacity]();
std::memcpy(new_buffer, m_buffer, m_capacity);
delete[] m_buffer;
#endif
m_buffer = new_buffer;
m_capacity = new_capacity;
m_cursor = m_buffer + cursor_offset;
}
void CodeBuffer::SetExecutable() {
#ifdef BISCUIT_CODE_BUFFER_MMAP
const auto result = mprotect(m_buffer, m_capacity, PROT_READ | PROT_EXEC);
BISCUIT_ASSERT(result == 0);
#else
// Unimplemented/Unnecessary for new
BISCUIT_ASSERT(false);
#endif
}
void CodeBuffer::SetWritable() {
#ifdef BISCUIT_CODE_BUFFER_MMAP
const auto result = mprotect(m_buffer, m_capacity, PROT_READ | PROT_WRITE);
BISCUIT_ASSERT(result == 0);
#else
// Unimplemented/Unnecessary for new
BISCUIT_ASSERT(false);
#endif
}
} // namespace biscuit
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