@@ -241,6 +241,19 @@ int ByteStreamBuffer::skip(size_t size)
* \retval -ENOSPC no more space is available in the managed memory buffer
*/
+/**
+ * \fn template<typename T> const T *ByteStreamBuffer::read(size_t count)
+ * \brief Read data from the managed memory buffer without performing a copy
+ * \param[in] count Number of data items to read
+ *
+ * This function reads \a count elements of type \a T from the buffer. Unlike
+ * the other read variants, it doesn't copy the data but returns a pointer to
+ * the first element. If data can't be read for any reason (usually due to
+ * reading more data than available), the function returns nullptr.
+ *
+ * \return A pointer to the data on success, or nullptr otherwise
+ */
+
/**
* \fn template<typename T> int ByteStreamBuffer::write(const T *t)
* \brief Write \a t to the managed memory buffer
@@ -259,6 +272,32 @@ int ByteStreamBuffer::skip(size_t size)
* \retval -ENOSPC no more space is available in the managed memory buffer
*/
+const uint8_t *ByteStreamBuffer::read(size_t size, size_t count)
+{
+ if (!read_)
+ return nullptr;
+
+ if (overflow_)
+ return nullptr;
+
+ size_t bytes;
+ if (__builtin_mul_overflow(size, count, &bytes)) {
+ setOverflow();
+ return nullptr;
+ }
+
+ if (read_ + bytes > base_ + size_) {
+ LOG(Serialization, Error)
+ << "Unable to read " << bytes << " bytes: out of bounds";
+ setOverflow();
+ return nullptr;
+ }
+
+ const uint8_t *data = read_;
+ read_ += bytes;
+ return data;
+}
+
int ByteStreamBuffer::read(uint8_t *data, size_t size)
{
if (!read_)
@@ -9,6 +9,7 @@
#include <stddef.h>
#include <stdint.h>
+#include <type_traits>
#include <libcamera/span.h>
@@ -43,6 +44,13 @@ public:
data.size_bytes());
}
+ template<typename T>
+ const std::remove_reference_t<T> *read(size_t count = 1)
+ {
+ using return_type = const std::remove_reference_t<T> *;
+ return reinterpret_cast<return_type>(read(sizeof(T), count));
+ }
+
template<typename T>
int write(const T *t)
{
@@ -63,6 +71,7 @@ private:
void setOverflow();
int read(uint8_t *data, size_t size);
+ const uint8_t *read(size_t size, size_t count);
int write(const uint8_t *data, size_t size);
ByteStreamBuffer *parent_;