From 71d1d9e2b594f122177f5788c1f21584ee8fdf00 Mon Sep 17 00:00:00 2001
From: Tim Schumacher <timschumi@gmx.de>
Date: Mon, 28 Nov 2022 15:57:44 +0100
Subject: [PATCH] LibArchive: Port `TarFileStream` to `Core::Stream`

---
 Userland/Libraries/LibArchive/TarStream.cpp | 49 +++++----------------
 Userland/Libraries/LibArchive/TarStream.h   | 16 +++----
 Userland/Utilities/tar.cpp                  | 14 +++---
 3 files changed, 26 insertions(+), 53 deletions(-)

diff --git a/Userland/Libraries/LibArchive/TarStream.cpp b/Userland/Libraries/LibArchive/TarStream.cpp
index 9a16109fd7..adcfeb858a 100644
--- a/Userland/Libraries/LibArchive/TarStream.cpp
+++ b/Userland/Libraries/LibArchive/TarStream.cpp
@@ -17,29 +17,24 @@ TarFileStream::TarFileStream(TarInputStream& tar_stream)
 {
 }
 
-size_t TarFileStream::read(Bytes bytes)
+ErrorOr<Bytes> TarFileStream::read(Bytes bytes)
 {
-    // verify that the stream has not advanced
+    // Verify that the stream has not advanced.
     VERIFY(m_tar_stream.m_generation == m_generation);
 
-    if (has_any_error())
-        return 0;
-
-    auto header_size_or_error = m_tar_stream.header().size();
-    if (header_size_or_error.is_error())
-        return 0;
-    auto header_size = header_size_or_error.release_value();
+    auto header_size = TRY(m_tar_stream.header().size());
 
     auto to_read = min(bytes.size(), header_size - m_tar_stream.m_file_offset);
 
     auto nread = m_tar_stream.m_stream.read(bytes.trim(to_read));
     m_tar_stream.m_file_offset += nread;
-    return nread;
+
+    return bytes.slice(0, nread);
 }
 
-bool TarFileStream::unreliable_eof() const
+bool TarFileStream::is_eof() const
 {
-    // verify that the stream has not advanced
+    // Verify that the stream has not advanced.
     VERIFY(m_tar_stream.m_generation == m_generation);
 
     auto header_size_or_error = m_tar_stream.header().size();
@@ -51,34 +46,10 @@ bool TarFileStream::unreliable_eof() const
         || m_tar_stream.m_file_offset >= header_size;
 }
 
-bool TarFileStream::read_or_error(Bytes bytes)
+ErrorOr<size_t> TarFileStream::write(ReadonlyBytes)
 {
-    // verify that the stream has not advanced
-    VERIFY(m_tar_stream.m_generation == m_generation);
-
-    if (read(bytes) < bytes.size()) {
-        set_fatal_error();
-        return false;
-    }
-
-    return true;
-}
-
-bool TarFileStream::discard_or_error(size_t count)
-{
-    // verify that the stream has not advanced
-    VERIFY(m_tar_stream.m_generation == m_generation);
-
-    auto header_size_or_error = m_tar_stream.header().size();
-    if (header_size_or_error.is_error())
-        return false;
-    auto header_size = header_size_or_error.release_value();
-
-    if (count > header_size - m_tar_stream.m_file_offset) {
-        return false;
-    }
-    m_tar_stream.m_file_offset += count;
-    return m_tar_stream.m_stream.discard_or_error(count);
+    // This is purely for wrapping and representing file contents in an archive.
+    VERIFY_NOT_REACHED();
 }
 
 TarInputStream::TarInputStream(InputStream& stream)
diff --git a/Userland/Libraries/LibArchive/TarStream.h b/Userland/Libraries/LibArchive/TarStream.h
index d871638313..a13ae8ac87 100644
--- a/Userland/Libraries/LibArchive/TarStream.h
+++ b/Userland/Libraries/LibArchive/TarStream.h
@@ -8,20 +8,20 @@
 #pragma once
 
 #include <AK/Span.h>
-#include <AK/Stream.h>
 #include <LibArchive/Tar.h>
+#include <LibCore/Stream.h>
 
 namespace Archive {
 
 class TarInputStream;
 
-class TarFileStream : public InputStream {
+class TarFileStream : public Core::Stream::Stream {
 public:
-    size_t read(Bytes) override;
-    bool unreliable_eof() const override;
-
-    bool read_or_error(Bytes) override;
-    bool discard_or_error(size_t count) override;
+    virtual ErrorOr<Bytes> read(Bytes) override;
+    virtual ErrorOr<size_t> write(ReadonlyBytes) override;
+    virtual bool is_eof() const override;
+    virtual bool is_open() const override { return true; };
+    virtual void close() override {};
 
 private:
     TarFileStream(TarInputStream& stream);
@@ -77,7 +77,7 @@ inline ErrorOr<void> TarInputStream::for_each_extended_header(F func)
 
     auto header_size = TRY(header().size());
     ByteBuffer file_contents_buffer = TRY(ByteBuffer::create_zeroed(header_size));
-    VERIFY(file_stream.read(file_contents_buffer) == header_size);
+    VERIFY(TRY(file_stream.read(file_contents_buffer)).size() == header_size);
 
     StringView file_contents { file_contents_buffer };
 
diff --git a/Userland/Utilities/tar.cpp b/Userland/Utilities/tar.cpp
index 48e65b0cce..8f157193e6 100644
--- a/Userland/Utilities/tar.cpp
+++ b/Userland/Utilities/tar.cpp
@@ -136,10 +136,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                 StringBuilder long_name;
 
                 Array<u8, buffer_size> buffer;
-                size_t bytes_read;
 
-                while ((bytes_read = file_stream.read(buffer)) > 0)
-                    long_name.append(reinterpret_cast<char*>(buffer.data()), bytes_read);
+                while (!file_stream.is_eof()) {
+                    auto slice = TRY(file_stream.read(buffer));
+                    long_name.append(reinterpret_cast<char*>(slice.data()), slice.size());
+                }
 
                 local_overrides.set("path", long_name.to_string());
                 TRY(tar_stream.advance());
@@ -171,9 +172,10 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
                     int fd = TRY(Core::System::open(absolute_path, O_CREAT | O_WRONLY, header_mode));
 
                     Array<u8, buffer_size> buffer;
-                    size_t bytes_read;
-                    while ((bytes_read = file_stream.read(buffer)) > 0)
-                        TRY(Core::System::write(fd, buffer.span().slice(0, bytes_read)));
+                    while (!file_stream.is_eof()) {
+                        auto slice = TRY(file_stream.read(buffer));
+                        TRY(Core::System::write(fd, slice));
+                    }
 
                     TRY(Core::System::close(fd));
                     break;