* Appender with a buffer chain; for this reason, Appenders assume private
* access to the buffer (you need to call unshare() yourself if necessary).
**/
-namespace folly { namespace io {
+namespace folly {
+namespace io {
namespace detail {
}
template <class T>
- typename std::enable_if<std::is_arithmetic<T>::value, T>::type read() {
- T val;
+ typename std::enable_if<std::is_arithmetic<T>::value, bool>::type tryRead(
+ T& val) {
if (LIKELY(length() >= sizeof(T))) {
val = loadUnaligned<T>(data());
offset_ += sizeof(T);
advanceBufferIfEmpty();
- } else {
- pullSlow(&val, sizeof(T));
+ return true;
+ }
+ return pullAtMostSlow(&val, sizeof(T)) == sizeof(T);
+ }
+
+ template <class T>
+ bool tryReadBE(T& val) {
+ const bool result = tryRead(val);
+ val = Endian::big(val);
+ return result;
+ }
+
+ template <class T>
+ bool tryReadLE(T& val) {
+ const bool result = tryRead(val);
+ val = Endian::little(val);
+ return result;
+ }
+
+ template <class T>
+ T read() {
+ T val{};
+ if (!tryRead(val)) {
+ std::__throw_out_of_range("underflow");
}
return val;
}
size_t cloneAtMost(std::unique_ptr<folly::IOBuf>& buf, size_t len) {
if (!buf) {
- buf = make_unique<folly::IOBuf>();
+ buf = std::make_unique<folly::IOBuf>();
}
return cloneAtMost(*buf, len);
}
BufType* buffer_;
};
-} // namespace detail
+} // namespace detail
class Cursor : public detail::CursorBase<Cursor, const IOBuf> {
public:
using detail::Writable<RWCursor<access>>::pushAtMost;
size_t pushAtMost(const uint8_t* buf, size_t len) {
+ // We have to explicitly check for an input length of 0.
+ // We support buf being nullptr in this case, but we need to avoid calling
+ // memcpy() with a null source pointer, since that is undefined behavior
+ // even if the length is 0.
+ if (len == 0) {
+ return 0;
+ }
+
size_t copied = 0;
for (;;) {
// Fast path: the current buffer is big enough.
using detail::Writable<Appender>::pushAtMost;
size_t pushAtMost(const uint8_t* buf, size_t len) {
+ // We have to explicitly check for an input length of 0.
+ // We support buf being nullptr in this case, but we need to avoid calling
+ // memcpy() with a null source pointer, since that is undefined behavior
+ // even if the length is 0.
+ if (len == 0) {
+ return 0;
+ }
+
size_t copied = 0;
for (;;) {
// Fast path: it all fits in one buffer.
folly::IOBufQueue* queue_;
size_t growth_;
};
-
-}} // folly::io
+} // namespace io
+} // namespace folly
#include <folly/io/Cursor-inl.h>