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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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
#ifndef COMM_MAILNEWS_BASE_SRC_MBOXMSGOUTPUTSTREAM_H_
#define COMM_MAILNEWS_BASE_SRC_MBOXMSGOUTPUTSTREAM_H_
#include "nsCOMPtr.h"
#include "nsIOutputStream.h"
#include "nsISafeOutputStream.h"
#include "nsISeekableStream.h"
#include "nsString.h"
/**
* MboxMsgOutputStream writes a single message out to an underlying mbox
* stream.
* It's a nsISafeOutputStream so callers need to "commit" the written data
* by calling nsISafeOutputStream::Finish() when done.
* Just calling Close(), or letting the stream go out of scope will
* cause a rollback, and the underlying mbox file will be truncated back
* to the size it was.
*
* Aims:
* - Byte exact. What you write is exactly what should come back out when
* read.
* NOTE: There is one exception. Messages with an unterminated
* final line will have an EOL added. Without this, there's no way to
* ensure the proper message separation required for a well-formed mbox.
* - Handles malformed messages - everything is just stored verbatim.
* - Uses reversible "From " escaping, as per mboxrd. "From " lines are
* prefixed with '>'. If already prefixed, another '>' is added.
* e.g. "From Bob Smith" => ">From Bob Smith".
* ">>>>From here..." => ">>>>>From here..."
* - Avoid intermediate copies of data. The only time buffering is required is
* where "From " parts are split across Write() calls.
* - Handle processing lines of any length, without extra memory usage.
* - Leaves output buffering up to the target mbox stream.
* - Provide a reasonable rollback mechanism (as nsISafeOutputStream).
*
* mboxrd descriptions:
*/
class MboxMsgOutputStream : public nsIOutputStream, nsISafeOutputStream {
public:
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIOUTPUTSTREAM
NS_DECL_NSISAFEOUTPUTSTREAM
// The underlying mboxStream must be nsISeekable.
explicit MboxMsgOutputStream(nsIOutputStream* mboxStream,
bool closeInnerWhenDone = false);
MboxMsgOutputStream() = delete;
private:
virtual ~MboxMsgOutputStream();
// The actual stream we're writing the mbox into.
nsCOMPtr<nsIOutputStream> mInner;
// QIed version of mInner.
nsCOMPtr<nsISeekableStream> mSeekable;
// Start offset, so we can roll back.
int64_t mStartPos{-1};
// Should the underlying mInner be closed when done?
bool mCloseInnerWhenDone;
enum {
eInitial, // No "From " line written yet.
eStartOfLine, // Ready to start a new line.
eMidLine, // Unfinished line (wrote the beginning, but no EOL yet).
eStartAwaitingData, // Start of line, but more data is required to decide
// whether escaping is needed. mStartFragment stores
// what we've got so far.
eError, // An error occurred (saved in in mError). Can still Close().
eClosed, // File has been closed via Close().
} mState{eInitial};
nsresult mStatus{NS_OK};
// Growable buffer to handle fragments from the start of the line when
// we can't yet decide whether escaping is needed, e.g. we have processed
// ">>Fro" and are awaiting further data to see if it is "m ".
nsAutoCStringN<16> mStartFragment;
nsresult Emit(nsACString const& data);
nsresult Emit(const char* data, uint32_t numBytes);
};
#endif // COMM_MAILNEWS_BASE_SRC_MBOXMSGOUTPUTSTREAM_H_