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-rw-r--r--xpcom/base/nsGZFileWriter.h79
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diff --git a/xpcom/base/nsGZFileWriter.h b/xpcom/base/nsGZFileWriter.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef nsGZFileWriter_h
+#define nsGZFileWriter_h
+
+#include "nsISupportsImpl.h"
+#include "zlib.h"
+#include "nsDependentString.h"
+#include <stdio.h>
+
+/**
+ * A simple class for writing to a .gz file.
+ *
+ * Note that the file that this interface produces has a different format than
+ * what you'd get if you compressed your data as a gzip stream and dumped the
+ * result to a file.
+ *
+ * The standard gunzip tool cannot decompress a raw gzip stream, but can handle
+ * the files produced by this interface.
+ */
+class nsGZFileWriter final {
+ virtual ~nsGZFileWriter();
+
+ public:
+ enum Operation { Append, Create };
+
+ explicit nsGZFileWriter(Operation aMode = Create);
+
+ NS_INLINE_DECL_REFCOUNTING(nsGZFileWriter)
+
+ /**
+ * Initialize this object. We'll write our gzip'ed data to the given file,
+ * overwriting its contents if the file exists.
+ *
+ * Init() will return an error if called twice. It's an error to call any
+ * other method on this interface without first calling Init().
+ */
+ [[nodiscard]] nsresult Init(nsIFile* aFile);
+
+ /**
+ * Alternate version of Init() for use when the file is already opened;
+ * e.g., with a FileDescriptor passed over IPC.
+ */
+ [[nodiscard]] nsresult InitANSIFileDesc(FILE* aFile);
+
+ /**
+ * Write the given string to the file.
+ */
+ [[nodiscard]] nsresult Write(const nsACString& aStr);
+
+ /**
+ * Write |length| bytes of |str| to the file.
+ */
+ [[nodiscard]] nsresult Write(const char* aStr, uint32_t aLen) {
+ return Write(nsDependentCSubstring(aStr, aLen));
+ }
+
+ /**
+ * Close this nsGZFileWriter. This method will be run when the underlying
+ * object is destroyed, so it's not strictly necessary to explicitly call it
+ * from your code.
+ *
+ * It's an error to call this method twice, and it's an error to call Write()
+ * after Finish() has been called.
+ */
+ nsresult Finish();
+
+ private:
+ Operation mMode;
+ bool mInitialized;
+ bool mFinished;
+ gzFile mGZFile;
+};
+
+#endif