input/GunzipInputStream: new class

Makefile.am

@@ -529,6 +529,7 @@ libfs_a_CPPFLAGS = $(AM_CPPFLAGS) $(ZLIB_CFLAGS)
 
 if HAVE_ZLIB
 libfs_a_SOURCES += \
+	src/fs/io/GunzipReader.cxx src/fs/io/GunzipReader.hxx \
 	src/fs/io/GzipOutputStream.cxx src/fs/io/GzipOutputStream.hxx
 FS_LIBS += $(ZLIB_LIBS)
 endif
@@ -1617,12 +1618,21 @@ endif
 
 if HAVE_ZLIB
 
-noinst_PROGRAMS += test/run_gzip
+noinst_PROGRAMS += test/run_gzip test/run_gunzip
+
 test_run_gzip_LDADD = \
 	libutil.a \
 	$(FS_LIBS)
 test_run_gzip_SOURCES = test/run_gzip.cxx
 
+test_run_gunzip_SOURCES = test/run_gunzip.cxx \
+	src/Log.cxx src/LogBackend.cxx
+test_run_gunzip_LDADD = \
+	$(GLIB_LIBS) \
+	libutil.a \
+	$(FS_LIBS) \
+	libsystem.a
+
 endif
 
 test_dump_text_file_LDADD = \

src/fs/io/GunzipReader.cxx

@@ -0,0 +1,102 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "GunzipReader.hxx"
+#include "util/Error.hxx"
+#include "util/Domain.hxx"
+
+const Domain zlib_domain("zlib");
+
+GunzipReader::GunzipReader(Reader &_next, Error &error)
+	:next(_next), eof(false)
+{
+	z.next_in = nullptr;
+	z.avail_in = 0;
+	z.zalloc = Z_NULL;
+	z.zfree = Z_NULL;
+	z.opaque = Z_NULL;
+
+	int result = inflateInit2(&z, 16 + MAX_WBITS);
+	if (result != Z_OK) {
+		z.opaque = this;
+		error.Set(zlib_domain, result, zError(result));
+	}
+}
+
+GunzipReader::~GunzipReader()
+{
+	if (IsDefined())
+		inflateEnd(&z);
+}
+
+inline bool
+GunzipReader::FillBuffer(Error &error)
+{
+	auto w = buffer.Write();
+	assert(!w.IsEmpty());
+
+	size_t nbytes = next.Read(w.data, w.size, error);
+	if (nbytes == 0)
+		return false;
+
+	buffer.Append(nbytes);
+	return true;
+}
+
+size_t
+GunzipReader::Read(void *data, size_t size, Error &error)
+{
+	if (eof)
+		return 0;
+
+	z.next_out = (Bytef *)data;
+	z.avail_out = size;
+
+	while (true) {
+		int flush = Z_NO_FLUSH;
+
+		auto r = buffer.Read();
+		if (r.IsEmpty()) {
+			if (FillBuffer(error))
+				r = buffer.Read();
+			else if (error.IsDefined())
+				return 0;
+			else
+				flush = Z_FINISH;
+		}
+
+		z.next_in = r.data;
+		z.avail_in = r.size;
+
+		int result = inflate(&z, flush);
+		if (result == Z_STREAM_END) {
+			eof = true;
+			return size - z.avail_out;
+		} else if (result != Z_OK) {
+			error.Set(zlib_domain, result, zError(result));
+			return 0;
+		}
+
+		buffer.Consume(r.size - z.avail_in);
+
+		if (z.avail_out < size)
+			return size - z.avail_out;
+	}
+}

src/fs/io/GunzipReader.hxx

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef MPD_GUNZIP_READER_HXX
+#define MPD_GUNZIP_READER_HXX
+
+#include "check.h"
+#include "Reader.hxx"
+#include "util/StaticFifoBuffer.hxx"
+
+#include <zlib.h>
+
+class Error;
+class Domain;
+
+extern const Domain zlib_domain;
+
+/**
+ * A filter that decompresses data using zlib.
+ */
+class GunzipReader final : public Reader {
+	Reader &next;
+
+	bool eof;
+
+	z_stream z;
+
+	StaticFifoBuffer<Bytef, 4096> buffer;
+
+public:
+	/**
+	 * Construct the filter.  Call IsDefined() to check whether
+	 * the constructor has succeeded.  If not, #error will hold
+	 * information about the failure.
+	 */
+	GunzipReader(Reader &_next, Error &error);
+	~GunzipReader();
+
+	/**
+	 * Check whether the constructor has succeeded.
+	 */
+	bool IsDefined() const {
+		return z.opaque == nullptr;
+	}
+
+	/* virtual methods from class Reader */
+	virtual size_t Read(void *data, size_t size, Error &error) override;
+
+private:
+	bool FillBuffer(Error &error);
+};
+
+#endif

test/run_gunzip.cxx

@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2003-2014 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "fs/io/GunzipReader.hxx"
+#include "fs/io/FileReader.hxx"
+#include "fs/io/StdioOutputStream.hxx"
+#include "util/Error.hxx"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+static bool
+Copy(OutputStream &dest, Reader &src, Error &error)
+{
+	while (true) {
+		char buffer[4096];
+		size_t nbytes = src.Read(buffer, sizeof(buffer), error);
+		if (nbytes == 0)
+			return !error.IsDefined();
+
+		if (!dest.Write(buffer, nbytes, error))
+			return false;
+	}
+}
+
+static bool
+CopyGunzip(OutputStream &dest, Reader &_src, Error &error)
+{
+	GunzipReader src(_src, error);
+	return src.IsDefined() && Copy(dest, src, error);
+}
+
+static bool
+CopyGunzip(FILE *_dest, Path src_path, Error &error)
+{
+	StdioOutputStream dest(_dest);
+	FileReader src(src_path, error);
+	return src.IsDefined() && CopyGunzip(dest, src, error);
+}
+
+int
+main(int argc, gcc_unused char **argv)
+{
+	if (argc != 2) {
+		fprintf(stderr, "Usage: run_gunzip PATH\n");
+		return EXIT_FAILURE;
+	}
+
+	Path path = Path::FromFS(argv[1]);
+
+	Error error;
+	if (!CopyGunzip(stdout, path, error)) {
+		fprintf(stderr, "%s\n", error.GetMessage());
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}