gecko-dev/xpcom/base/nsGZFileWriter.cpp

99 lines
2.4 KiB
C++

/* -*- 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/. */
#include "nsGZFileWriter.h"
#include "nsIFile.h"
#include "nsString.h"
#include "zlib.h"
#ifdef XP_WIN
#include <io.h>
#define _dup dup
#else
#include <unistd.h>
#endif
NS_IMPL_ISUPPORTS1(nsGZFileWriter, nsIGZFileWriter)
nsGZFileWriter::nsGZFileWriter()
: mInitialized(false)
, mFinished(false)
{}
nsGZFileWriter::~nsGZFileWriter()
{
if (mInitialized && !mFinished) {
Finish();
}
}
NS_IMETHODIMP
nsGZFileWriter::Init(nsIFile* aFile)
{
if (NS_WARN_IF(mInitialized) ||
NS_WARN_IF(mFinished))
return NS_ERROR_FAILURE;
// Get a FILE out of our nsIFile. Convert that into a file descriptor which
// gzip can own. Then close our FILE, leaving only gzip's fd open.
FILE* file;
nsresult rv = aFile->OpenANSIFileDesc("wb", &file);
if (NS_WARN_IF(NS_FAILED(rv)))
return rv;
mGZFile = gzdopen(dup(fileno(file)), "wb");
fclose(file);
// gzdopen returns nullptr on error.
if (NS_WARN_IF(!mGZFile))
return NS_ERROR_FAILURE;
mInitialized = true;
return NS_OK;
}
NS_IMETHODIMP
nsGZFileWriter::Write(const nsACString& aStr)
{
if (NS_WARN_IF(!mInitialized) ||
NS_WARN_IF(mFinished))
return NS_ERROR_FAILURE;
// gzwrite uses a return value of 0 to indicate failure. Otherwise, it
// returns the number of uncompressed bytes written. To ensure we can
// distinguish between success and failure, don't call gzwrite when we have 0
// bytes to write.
if (aStr.IsEmpty()) {
return NS_OK;
}
// gzwrite never does a short write -- that is, the return value should
// always be either 0 or aStr.Length(), and we shouldn't have to call it
// multiple times in order to get it to read the whole buffer.
int rv = gzwrite(mGZFile, aStr.BeginReading(), aStr.Length());
if (NS_WARN_IF(rv != static_cast<int>(aStr.Length())))
return NS_ERROR_FAILURE;
return NS_OK;
}
NS_IMETHODIMP
nsGZFileWriter::Finish()
{
if (NS_WARN_IF(!mInitialized) ||
NS_WARN_IF(mFinished))
return NS_ERROR_FAILURE;
mFinished = true;
gzclose(mGZFile);
// Ignore errors from gzclose; it's not like there's anything we can do about
// it, at this point!
return NS_OK;
}