LibCore: Add Stream::read_all()

Author: https://github.com/msvisser
Commit: 68772463cb
Pull-request: https://github.com/SerenityOS/serenity/pull/13384
Reviewed-by: https://github.com/Lubrsi
Reviewed-by: https://github.com/alimpfard
Reviewed-by: https://github.com/creator1creeper1
Reviewed-by: https://github.com/kleinesfilmroellchen ✅

Userland/Libraries/LibCore/Stream.cpp

@@ -47,6 +47,22 @@ bool Stream::read_or_error(Bytes buffer)
     return true;
 }
 
+ErrorOr<ByteBuffer> Stream::read_all()
+{
+    ByteBuffer output;
+    u8 buffer_raw[4096];
+    Bytes buffer { buffer_raw, 4096 };
+
+    while (true) {
+        Bytes read_bytes = TRY(read(buffer));
+        if (read_bytes.is_empty())
+            break;
+        output.append(read_bytes);
+    }
+
+    return output;
+}
+
 bool Stream::write_or_error(ReadonlyBytes buffer)
 {
     VERIFY(buffer.size());

Userland/Libraries/LibCore/Stream.h

@@ -37,6 +37,7 @@ public:
     /// Tries to fill the entire buffer through reading. Returns whether the
     /// buffer was filled without an error.
     virtual bool read_or_error(Bytes);
+    ErrorOr<ByteBuffer> read_all();
 
     virtual bool is_writable() const { return false; }
     /// Tries to write the entire contents of the buffer. It is possible for