From 102fdf630544cc3d28d9db67c13e0c879baaa9d8 Mon Sep 17 00:00:00 2001
From: Lucas CHOLLET <lucas.chollet@free.fr>
Date: Tue, 6 Jun 2023 13:52:56 -0400
Subject: [PATCH] AK: Override `read_until_filled` in `FixedMemoryStream`

This specialized method allow significant performance improvements for
the user.
---
 AK/MemoryStream.cpp | 11 +++++++++++
 AK/MemoryStream.h   |  1 +
 2 files changed, 12 insertions(+)

diff --git a/AK/MemoryStream.cpp b/AK/MemoryStream.cpp
index 19448bfbbe..1f92e9146d 100644
--- a/AK/MemoryStream.cpp
+++ b/AK/MemoryStream.cpp
@@ -54,6 +54,17 @@ ErrorOr<Bytes> FixedMemoryStream::read_some(Bytes bytes)
     return bytes.trim(to_read);
 }
 
+ErrorOr<void> FixedMemoryStream::read_until_filled(AK::Bytes bytes)
+{
+    if (remaining() < bytes.size())
+        return Error::from_string_view_or_print_error_and_return_errno("Can't read past the end of the stream memory"sv, EINVAL);
+
+    m_bytes.slice(m_offset).copy_trimmed_to(bytes);
+    m_offset += bytes.size();
+
+    return {};
+}
+
 ErrorOr<size_t> FixedMemoryStream::seek(i64 offset, SeekMode seek_mode)
 {
     switch (seek_mode) {
diff --git a/AK/MemoryStream.h b/AK/MemoryStream.h
index f069b222a3..7a9ce7d8ec 100644
--- a/AK/MemoryStream.h
+++ b/AK/MemoryStream.h
@@ -24,6 +24,7 @@ public:
     virtual void close() override;
     virtual ErrorOr<void> truncate(size_t) override;
     virtual ErrorOr<Bytes> read_some(Bytes bytes) override;
+    virtual ErrorOr<void> read_until_filled(Bytes bytes) override;
 
     virtual ErrorOr<size_t> seek(i64 offset, SeekMode seek_mode = SeekMode::SetPosition) override;