Add "Check for updates" feature

[jiveaxe]

I have just started and now the first problem.

I got a segmentation fault with this code:

...
QTemporaryFile file;
if(!file.open()) {
	...
}
 
QUrl url("http://localhost/mysite");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/lastrelease.xml", &file);
http->close();

...
QTemporaryFile file;
if(!file.open()) {
	...
}

QUrl url("http://localhost/mysite");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/lastrelease.xml", &file);
http->close();

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If I comment http->get no more error. The temporary file is created with this path: /tmp//qt_temp.xxxx . Is it normal the double '/' ?

Before somebody asks me, the local server is running and http://localhost/mysite/lastrelease.xml exists.

If I use QFile instead of QTemporaryFile:

QFile file("/tmp/lastrelease.xml");
if(!file.open(QIODevice::ReadWrite)){...}

QFile file("/tmp/lastrelease.xml");
if(!file.open(QIODevice::ReadWrite)){...}

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I have no segmentation fault at all but the file created in /tmp is empty. In the console I have this line:

QIODevice::write: ReadOnly device

Where is the mistake?

Thanks

[bender86]

...
QTemporaryFile file;
if(!file.open()) {
	...
}
 
QUrl url("http://localhost/mysite");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/lastrelease.xml", &file);
http->close();

...
QTemporaryFile file;
if(!file.open()) {
	...
}

QUrl url("http://localhost/mysite");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/lastrelease.xml", &file);
http->close();

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I think it should be:

http->setHost("localhost");
http->get("/mysite/lastrelease.xml");

http->setHost("localhost");
http->get("/mysite/lastrelease.xml");

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The temporary file is created with this path: /tmp//qt_temp.xxxx . Is it normal the double '/' ?

Multiple / are ignored. You can check with ls /usr////src or similar.

QIODevice::write: ReadOnly device

Is /tmp writable? Try another directory (like $HOME).

[jiveaxe]

[CODE]...
I think it should be:

http->setHost("localhost");
http->get("/mysite/lastrelease.xml");

http->setHost("localhost");
http->get("/mysite/lastrelease.xml");

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It gives the same problem.

I have also tried to get some page from the remote site, but nothing changes. Using QTemporaryFile gives the segmentation fault; with QFile an empty output.

Try this:

QTemporaryFile file;
if(!file.open()) {
	QMessageBox::critical(0,QString(),tr("Can't open the file!"));
}
 
QUrl url("http://www.bzip.org");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/docs.html", &file);
http->close();

QTemporaryFile file;
if(!file.open()) {
	QMessageBox::critical(0,QString(),tr("Can't open the file!"));
}

QUrl url("http://www.bzip.org");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/docs.html", &file);
http->close();

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or this:

QFile file("/tmp/output.html");
if(!file.open(QIODevice::ReadWrite)) {
	QMessageBox::critical(0,QString(),tr("Can't open the file!"));
}
 
QUrl url("http://www.bzip.org");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/docs.html", &file);
http->close();

QFile file("/tmp/output.html");
if(!file.open(QIODevice::ReadWrite)) {
	QMessageBox::critical(0,QString(),tr("Can't open the file!"));
}

QUrl url("http://www.bzip.org");
http = new QHttp;
http->setHost(url.host(), url.port(80));
http->get("/docs.html", &file);
http->close();

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Is /tmp writable? Try another directory (like $HOME).

Of course /tmp is writable.

Regards

[bender86]

You have to close the QFile after writing into.
You can catch QHttp::dataReadProgress(int done, int total). If done == total, then download is complete, and you can close file (you will need an event loop, so call QCoreApplication::exec()).
Check also QHttp example.

For QTemporaryFile, keep in mind that if you create it on stack, it will be destroyed when gone out of scope (usually after a }). If you pass his address to http.get("/file",&tempFile), QHttp will try to write to a invalid address.

[jiveaxe]

Check also QHttp example.

I give it a try.

For QTemporaryFile, keep in mind that if you create it on stack, it will be destroyed when gone out of scope (usually after a }). If you pass his address to http.get("/file",&tempFile), QHttp will try to write to a invalid address.

As I wrote in my previous code QTemporaryFile should be in the same scope of http.

Bye

[bender86]

As I wrote in my previous code QTemporaryFile should be in the same scope of http.

QHttp::get() is asynchronous. If you do something like this:

void f() {
    QTemporaryFile temp;
    temp.open();
    QHttp *http = new QHttp;
    http->setHost("localhost");
    http->get("/file",&file);
}

void f() {
    QTemporaryFile temp;
    temp.open();
    QHttp *http = new QHttp;
    http->setHost("localhost");
    http->get("/file",&file);
}

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QHttp::get returns immediately, before actually download file. http is a heap allocated object, so it survives at and of f(), but file not, and is destroyed. When http obtains file from webserver, tries to write to an invalid location (because file is no longer existant).
You should declare both QHttp and QTemporaryFile as pointers and create their instances with new, and catch QHttp signal to know when http request is finished. However QHttp example explains well.

[jiveaxe]

Finally I have made a working code; if It may help somebody else here it is:

MainWindow::MainWindow()
{
	...
	http = new QHttp(this);
	connect(http, SIGNAL(requestFinished(int, bool)), this, SLOT(httpRequestFinished(int, bool)));
	connect(http, SIGNAL(responseHeaderReceived(const QHttpResponseHeader &)), this, SLOT(readResponseHeader(const QHttpResponseHeader &)));
 
	file = 0;
	downloadFile();
}
 
MainWindow::~MainWindow()
{
	if(file) {
		delete file;
		file = 0;
	}
}
 
void MainWindow::downloadFile()
{
	if(file) {
		delete file;
		file = 0;
	}
 
	QUrl url("http://localhost/sito/lastrelease.xml");
 
	file = new QTemporaryFile;
	if (!file->open()) {
		statusBar()->showMessage(tr("Impossible to save the file %1: %2.").arg(file->fileName()).arg(file->errorString()));
		delete file;
		file = 0;
		return;
	}
 
	http->setHost(url.host(), url.port(80));
 
	httpRequestAborted = false;
	httpGetId = http->get(url.path(), file);
}
 
void MainWindow::httpRequestFinished(int requestId, bool error)
{
	if (requestId != httpGetId)
		return;
	if (httpRequestAborted) {
		if(file) {
			file->close();
			file->remove();
		}
		return;
	}
 
	if (requestId != httpGetId)
		return;
 
	file->close();
 
	if (error) {
		file->remove();
		statusBar()->showMessage(tr("Download failed: %1.").arg(http->errorString()));
	} else {
		statusBar()->showMessage(tr("lastrelease downloaded"));
	}
}
 
void MainWindow::readResponseHeader(const QHttpResponseHeader &responseHeader)
{
	if (responseHeader.statusCode() != 200) {
		statusBar()->showMessage(tr("Download failed: %1.").arg(responseHeader.reasonPhrase()));
		httpRequestAborted = true;
		http->abort();
		return;
	}
}

MainWindow::MainWindow()
{
	...
	http = new QHttp(this);
	connect(http, SIGNAL(requestFinished(int, bool)), this, SLOT(httpRequestFinished(int, bool)));
	connect(http, SIGNAL(responseHeaderReceived(const QHttpResponseHeader &)), this, SLOT(readResponseHeader(const QHttpResponseHeader &)));

	file = 0;
	downloadFile();
}

MainWindow::~MainWindow()
{
	if(file) {
		delete file;
		file = 0;
	}
}

void MainWindow::downloadFile()
{
	if(file) {
		delete file;
		file = 0;
	}

	QUrl url("http://localhost/sito/lastrelease.xml");

	file = new QTemporaryFile;
	if (!file->open()) {
		statusBar()->showMessage(tr("Impossible to save the file %1: %2.").arg(file->fileName()).arg(file->errorString()));
		delete file;
		file = 0;
		return;
	}

	http->setHost(url.host(), url.port(80));

	httpRequestAborted = false;
	httpGetId = http->get(url.path(), file);
}

void MainWindow::httpRequestFinished(int requestId, bool error)
{
	if (requestId != httpGetId)
		return;
	if (httpRequestAborted) {
		if(file) {
			file->close();
			file->remove();
		}
		return;
	}

	if (requestId != httpGetId)
		return;

	file->close();

	if (error) {
		file->remove();
		statusBar()->showMessage(tr("Download failed: %1.").arg(http->errorString()));
	} else {
		statusBar()->showMessage(tr("lastrelease downloaded"));
	}
}

void MainWindow::readResponseHeader(const QHttpResponseHeader &responseHeader)
{
	if (responseHeader.statusCode() != 200) {
		statusBar()->showMessage(tr("Download failed: %1.").arg(responseHeader.reasonPhrase()));
		httpRequestAborted = true;
		http->abort();
		return;
	}
}

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Also the xml part of the work is ok. I have to decide where store the current versions of application/database: for application probably is better in the code for simple retrieving; for database I don't know if is better to store it in a table or in the name of the db file (db-20070115 for example). Perhaps the first solution is simpler. What do you say?

Thanks

[jiveaxe]

Hi,
I have choosen to store database version on one table of the db itself. Now I have to work on compressed archive for distributing the updates. I have found an interesting article on qtnode about Self-Extracting Installer. It seems what I was looking for but I haven't well understand the usage. My update package should contain a sqlite file (appdb for example) and a folder containing some images. Can I store all of this as they are or Self-Extracting_Installer can stores only files and not folders? In the latter case after extracting the qcompress archive I should do something like this:

cp appdb QDir::homePath() + QDir::separator() + ".appname";
cp *.png QDir::homePath() + QDir::separator() + ".appname/images";

Am I right?

One more question: which extension should have the final package?

Thanks

EDIT:
Ok, ok; with some trying I have understand the usage. The files must be appended to stub (which is an executable): so the final package is an executable (and in windows should have .exe exention). Regards paths, when a file is stored, it is stored even the path given during compression, so

qcompress images/image1.png update-20080116
qcompress appdb update-20080116

gives during decompression the following files:

appdb
images/image1.png

Than I can move all together

cp -r * QDir::homePath + QDir::separator + ".appname/";

Regards

[jiveaxe]

I diverted on QuaZIP a qt widget for accessing zip files.

Bye

[jiveaxe]

I have a new problem with an undesidered requestFinished signal. For clearness I list here the steps of the code section:

1: Click download button

2: http->get(...);

(when requestFinished(...) signal is emitted)

3: QMessageBox: Need to quit MainApp before install

(if OK)

4: quit MainApp

5: install new files

6: QMessageBox: now restart MainApp and quit updater

(if OK)

7: updater closed and MainApp restarted

If I follow the steps without pause the code works good but if I don't click any button on the QMessageBox at step 6 after 10-15 seconds is emitted a new requestFinished signal and the QMessageBox of the step 3 pops up while that at step 6 is still running.

Here the code:

void Updater::httpRequestFinished(int requestId, bool error)
{
	if (requestId != httpGetId)
		return;
	if (httpRequestAborted) {
		if (file) {
			file->close();
			file->remove();
			delete file;
			file = 0;
		}
 
		progressDialog->hide();
		return;
	}
 
	progressDialog->hide();
	file->close();
 
	if (error) {
		file->remove();
		QMessageBox::information(this, tr("HTTP"),
						trUtf8("Download failed: %1.")
						 .arg(http->errorString()));
	}
}

void Updater::httpRequestFinished(int requestId, bool error)
{
	if (requestId != httpGetId)
		return;
	if (httpRequestAborted) {
		if (file) {
			file->close();
			file->remove();
			delete file;
			file = 0;
		}

		progressDialog->hide();
		return;
	}

	progressDialog->hide();
	file->close();

	if (error) {
		file->remove();
		QMessageBox::information(this, tr("HTTP"),
						trUtf8("Download failed: %1.")
						 .arg(http->errorString()));
	}
}

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(httpRequestFinished is connected with requestFinished)
I tryed using http->close() and http->clearPendingRequests() at the end of httpRequestFinished() but the signal is still emitted.

Hoping I was clear enough, someone can tell me what I have missed?

Thanks

[will49]

Did you ever find a solution for this double "requestFinished" signal being sent? I'm having the same problem. I'm closing the temporary file I use to download the page when I get the first "requestFinished" signal, but then sometimes I get another "requestFinished" signal with the same id and error=0.

This causes the application to crash - I presume because I'm deleting the temporary file used in the Qhttp get().

I'm using Qt 4.3.4 on Windows.

It also seems that if I don't display a dialog to the user when I get the "requestFinished" signal then this doesn't happen. So maybe Qt is sending another signal if the first one is blocked by the dialog being shown?

[will49]

FYI - I got around this by not displaying the dialog box immediately. Instead I used a timer to delay it. I found that it would only happen on the non-Debug build and only if the dialog is displayed as soon as I get the "requestFinished" signal. Also it has nothing to do with closing the temporary file used in the Qhttp get().

Weird.....