1 files changed, 111 insertions, 0 deletions
diff --git a/externals/biscuit/src/code_buffer.cpp b/externals/biscuit/src/code_buffer.cpp
new file mode 100644
index 00000000..386be375
--- /dev/null
+++ b/externals/biscuit/src/code_buffer.cpp
@@ -0,0 +1,111 @@
+#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