From c9a71a7176f13cbd86c8270c523c0e506b2ab424 Mon Sep 17 00:00:00 2001 From: Max Kellermann Date: Wed, 30 Jul 2014 22:26:24 +0200 Subject: fs/GzipOutputStream: new class wrapping zlib --- src/fs/output/GzipOutputStream.cxx | 106 +++++++++++++++++++++++++++++++++++++ src/fs/output/GzipOutputStream.hxx | 71 +++++++++++++++++++++++++ 2 files changed, 177 insertions(+) create mode 100644 src/fs/output/GzipOutputStream.cxx create mode 100644 src/fs/output/GzipOutputStream.hxx (limited to 'src') diff --git a/src/fs/output/GzipOutputStream.cxx b/src/fs/output/GzipOutputStream.cxx new file mode 100644 index 000000000..d05645d9e --- /dev/null +++ b/src/fs/output/GzipOutputStream.cxx @@ -0,0 +1,106 @@ +/* + * 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 "GzipOutputStream.hxx" +#include "util/Error.hxx" +#include "util/Domain.hxx" + +const Domain zlib_domain("zlib"); + +GzipOutputStream::GzipOutputStream(OutputStream &_next, Error &error) + :next(_next) +{ + z.next_in = nullptr; + z.avail_in = 0; + z.zalloc = Z_NULL; + z.zfree = Z_NULL; + z.opaque = Z_NULL; + + constexpr int windowBits = 15; + constexpr int gzip_encoding = 16; + + int result = deflateInit2(&z, Z_DEFAULT_COMPRESSION, Z_DEFLATED, + windowBits | gzip_encoding, + 8, Z_DEFAULT_STRATEGY); + if (result != Z_OK) { + z.opaque = this; + error.Set(zlib_domain, result, zError(result)); + } +} + +GzipOutputStream::~GzipOutputStream() +{ + if (IsDefined()) + deflateEnd(&z); +} + +bool +GzipOutputStream::Flush(Error &error) +{ + /* no more input */ + z.next_in = nullptr; + z.avail_in = 0; + + while (true) { + Bytef output[4096]; + z.next_out = output; + z.avail_out = sizeof(output); + + int result = deflate(&z, Z_FINISH); + if (z.next_out > output && + !next.Write(output, z.next_out - output, error)) + return false; + + if (result == Z_STREAM_END) + return true; + else if (result != Z_OK) { + error.Set(zlib_domain, result, zError(result)); + return false; + } + } +} + +bool +GzipOutputStream::Write(const void *_data, size_t size, Error &error) +{ + /* zlib's API requires non-const input pointer */ + void *data = const_cast(_data); + + z.next_in = reinterpret_cast(data); + z.avail_in = size; + + while (z.avail_in > 0) { + Bytef output[4096]; + z.next_out = output; + z.avail_out = sizeof(output); + + int result = deflate(&z, Z_NO_FLUSH); + if (result != Z_OK) { + error.Set(zlib_domain, result, zError(result)); + return false; + } + + if (z.next_out > output && + !next.Write(output, z.next_out - output, error)) + return false; + } + + return true; +} diff --git a/src/fs/output/GzipOutputStream.hxx b/src/fs/output/GzipOutputStream.hxx new file mode 100644 index 000000000..4f6d8b357 --- /dev/null +++ b/src/fs/output/GzipOutputStream.hxx @@ -0,0 +1,71 @@ +/* + * 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_GZIP_OUTPUT_STREAM_HXX +#define MPD_GZIP_OUTPUT_STREAM_HXX + +#include "check.h" +#include "OutputStream.hxx" + +#include +#include + +class Error; +class Domain; + +extern const Domain zlib_domain; + +/** + * A filter that compresses data written to it using zlib, forwarding + * compressed data in the "gzip" format. + * + * Don't forget to call Flush() before destructing this object. + */ +class GzipOutputStream final : public OutputStream { + OutputStream &next; + + z_stream z; + +public: + /** + * Construct the filter. Call IsDefined() to check whether + * the constructor has succeeded. If not, #error will hold + * information about the failure. + */ + GzipOutputStream(OutputStream &_next, Error &error); + ~GzipOutputStream(); + + /** + * Check whether the constructor has succeeded. + */ + bool IsDefined() const { + return z.opaque == nullptr; + } + + /** + * Finish the file and write all data remaining in zlib's + * output buffer. + */ + bool Flush(Error &error); + + /* virtual methods from class OutputStream */ + bool Write(const void *data, size_t size, Error &error) override; +}; + +#endif -- cgit v1.2.3