From 3219ce3d61f42dfcbeb0483a24539cd7b8f4723b Mon Sep 17 00:00:00 2001
From: Idan Horowitz <idan.horowitz@gmail.com>
Date: Tue, 15 Feb 2022 23:25:25 +0200
Subject: AK: Return KString instead of String from encode_hex in the Kernel

This let's us propagate allocation errors from this API.
---
 AK/Hex.cpp  | 12 ++++++++++++
 AK/Hex.h    | 11 ++++++++++-
 AK/UUID.cpp | 15 ++++++++++-----
 3 files changed, 32 insertions(+), 6 deletions(-)

diff --git a/AK/Hex.cpp b/AK/Hex.cpp
index ca35477968..dfd0d410ef 100644
--- a/AK/Hex.cpp
+++ b/AK/Hex.cpp
@@ -35,6 +35,17 @@ ErrorOr<ByteBuffer> decode_hex(StringView input)
     return { move(output) };
 }
 
+#ifdef KERNEL
+ErrorOr<NonnullOwnPtr<Kernel::KString>> encode_hex(const ReadonlyBytes input)
+{
+    StringBuilder output(input.size() * 2);
+
+    for (auto ch : input)
+        TRY(output.try_appendff("{:02x}", ch));
+
+    return Kernel::KString::try_create(output.string_view());
+}
+#else
 String encode_hex(const ReadonlyBytes input)
 {
     StringBuilder output(input.size() * 2);
@@ -44,5 +55,6 @@ String encode_hex(const ReadonlyBytes input)
 
     return output.build();
 }
+#endif
 
 }
diff --git a/AK/Hex.h b/AK/Hex.h
index ba21c3a761..b421e9ac25 100644
--- a/AK/Hex.h
+++ b/AK/Hex.h
@@ -8,9 +8,14 @@
 
 #include <AK/ByteBuffer.h>
 #include <AK/Error.h>
-#include <AK/String.h>
 #include <AK/StringView.h>
 
+#ifdef KERNEL
+#    include <Kernel/KString.h>
+#else
+#    include <AK/String.h>
+#endif
+
 namespace AK {
 
 constexpr u8 decode_hex_digit(char digit)
@@ -26,7 +31,11 @@ constexpr u8 decode_hex_digit(char digit)
 
 ErrorOr<ByteBuffer> decode_hex(StringView);
 
+#ifdef KERNEL
+ErrorOr<NonnullOwnPtr<Kernel::KString>> encode_hex(ReadonlyBytes);
+#else
 String encode_hex(ReadonlyBytes);
+#endif
 
 }
 
diff --git a/AK/UUID.cpp b/AK/UUID.cpp
index 8353c49c1e..c04f10cd88 100644
--- a/AK/UUID.cpp
+++ b/AK/UUID.cpp
@@ -80,15 +80,20 @@ UUID::UUID(StringView uuid_string_view, Endianness endianness)
 ErrorOr<NonnullOwnPtr<Kernel::KString>> UUID::to_string() const
 {
     StringBuilder builder(36);
-    TRY(builder.try_append(encode_hex(m_uuid_buffer.span().trim(4)).view()));
+    auto nibble0 = TRY(encode_hex(m_uuid_buffer.span().trim(4)));
+    TRY(builder.try_append(nibble0->view()));
     TRY(builder.try_append('-'));
-    TRY(builder.try_append(encode_hex(m_uuid_buffer.span().slice(4).trim(2)).view()));
+    auto nibble1 = TRY(encode_hex(m_uuid_buffer.span().slice(4).trim(2)));
+    TRY(builder.try_append(nibble1->view()));
     TRY(builder.try_append('-'));
-    TRY(builder.try_append(encode_hex(m_uuid_buffer.span().slice(6).trim(2)).view()));
+    auto nibble2 = TRY(encode_hex(m_uuid_buffer.span().slice(6).trim(2)));
+    TRY(builder.try_append(nibble2->view()));
     TRY(builder.try_append('-'));
-    TRY(builder.try_append(encode_hex(m_uuid_buffer.span().slice(8).trim(2)).view()));
+    auto nibble3 = TRY(encode_hex(m_uuid_buffer.span().slice(8).trim(2)));
+    TRY(builder.try_append(nibble3->view()));
     TRY(builder.try_append('-'));
-    TRY(builder.try_append(encode_hex(m_uuid_buffer.span().slice(10).trim(6)).view()));
+    auto nibble4 = TRY(encode_hex(m_uuid_buffer.span().slice(10).trim(6)));
+    TRY(builder.try_append(nibble4->view()));
     return Kernel::KString::try_create(builder.string_view());
 }
 #else
-- 
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