Userland: add gunzip utility.

Author: https://github.com/asynts
Commit: https://github.com/SerenityOS/serenity/commit/c288b499aab
Pull-request: https://github.com/SerenityOS/serenity/pull/3341
Reviewed-by: https://github.com/stelar7

Userland/CMakeLists.txt

@@ -39,5 +39,6 @@ target_link_libraries(test-compress LibCompress)
 target_link_libraries(test-js LibJS LibLine LibCore)
 target_link_libraries(test-web LibWeb)
 target_link_libraries(tt LibPthread)
+target_link_libraries(gunzip LibCompress)
 
 add_subdirectory(Tests)

Userland/gunzip.cpp

@@ -0,0 +1,81 @@
+/*
+ * Copyright (c) 2020, the SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibCompress/Gzip.h>
+#include <LibCore/ArgsParser.h>
+#include <LibCore/FileStream.h>
+
+static void decompress_file(Core::InputFileStream input_stream, Core::OutputFileStream output_stream)
+{
+    auto gzip_stream = Compress::GzipDecompressor { input_stream };
+
+    u8 buffer[4096];
+
+    while (!gzip_stream.eof()) {
+        const auto nread = gzip_stream.read({ buffer, sizeof(buffer) });
+        output_stream.write_or_error({ buffer, nread });
+    }
+
+    input_stream.close();
+    output_stream.close();
+}
+
+int main(int argc, char** argv)
+{
+    Vector<const char*> filenames;
+    bool keep_input_files { false };
+    bool write_to_stdout { false };
+
+    Core::ArgsParser args_parser;
+    args_parser.add_option(keep_input_files, "Keep (don't delete) input files", "keep", 'k');
+    args_parser.add_option(write_to_stdout, "Write to stdout, keep original files unchanged", "stdout", 'c');
+    args_parser.add_positional_argument(filenames, "File to decompress", "FILE");
+    args_parser.parse(argc, argv);
+
+    if (write_to_stdout)
+        keep_input_files = true;
+
+    for (StringView filename : filenames) {
+        ASSERT(filename.ends_with(".gz"));
+
+        const auto input_filename = filename;
+        const auto output_filename = filename.substring_view(0, filename.length() - 3);
+
+        auto input_stream_result = Core::InputFileStream::open(input_filename);
+
+        if (write_to_stdout) {
+            decompress_file(input_stream_result.value(), Core::OutputFileStream::stdout());
+        } else {
+            auto output_stream_result = Core::OutputFileStream::open(output_filename);
+            decompress_file(input_stream_result.value(), output_stream_result.value());
+        }
+
+        if (!keep_input_files) {
+            const auto retval = unlink(String { input_filename }.characters());
+            ASSERT(retval == 0);
+        }
+    }
+}