Allow relative paths on non-existent directories by tresf · Pull Request #4271 · LMMS/lmms

tresf · 2018-03-22T17:28:04Z

Switch SampleBuffer::tryToMakeRelative(...) to use cleanPath instead of canonicalFilePath.

canonicalFilePath has several limitations including:

Failure to handle a non-existant path (Working directory gets reset when the path doesn't exist #4267)
Possible undesired symlink handling

PhysSong · 2018-03-23T05:34:49Z

 	{
 		// Normalize the path
-		QString f = QFileInfo( file ).canonicalFilePath().replace( QDir::separator(), '/' );
+		QString f( QDir::cleanPath( file ).replace( QDir::separator(), '/' ) );


Just a reminder, .replace( QDir::separator(), '/' ) can be removed when Qt4 support is completely dropped later.

Just a reminder, .replace( QDir::separator(), '/' ) can be removed when Qt4 support is completely dropped later.

Good to know... can you elaborate? Is the default behavior to use / in Qt5? If so where is this documented and is this across all Qt functions?

Documented in http://doc.qt.io/qt-5/qdir.html#cleanPath

Documented in http://doc.qt.io/qt-5/qdir.html#cleanPath

Yeah that doesn't have any "since qt5" warnings, so I just thought it was an example. Thanks for clarification.

For comparison:

4.8:

Removes all multiple directory separators "/" and resolves any "."s or ".."s found in the path, path.

5.x:

Returns path with directory separators normalized (converted to "/") and redundant ones removed, and "."s and ".."s resolved (as far as possible).

So I hope you understand my hesitation. :)

Hmm.... Here's the code for posterity...

static QString qt_cleanPath(const QString &path, bool *ok) -- { if (path.isEmpty()) return path; QString name = path; QChar dir_separator = QDir::separator(); if (dir_separator != QLatin1Char('/')) name.replace(dir_separator, QLatin1Char('/')); QString ret = qt_normalizePathSegments(name, OSSupportsUncPaths, ok); // Strip away last slash except for root directories if (ret.length() > 1 && ret.endsWith(QLatin1Char('/'))) { #if defined (Q_OS_WIN) # if defined(Q_OS_WINRT) if (!((ret.length() == 3 \|\| ret.length() == QDir::rootPath().length()) && ret.at(1) == QLatin1Char(':'))) # else if (!(ret.length() == 3 && ret.at(1) == QLatin1Char(':'))) # endif #endif ret.chop(1); } return ret; }

The only function that seems like it would touch \\ would be the qt_normalizePathSegments.cpp, but that specifically says in the source

// This method is shared with QUrl, so it doesn't deal with QDir::separator() ...

I guess I'll take your word for it. :)

@tresf it's about a third of the way down in that qt_cleanPath function:

name.replace(dir_separator, QLatin1Char('/'));

How do you feel about adding a short code comment explaining why we run .replace( QDir::separator(), '/' ) (maybe just linking to #4271 ) so that nobody else accidentally removes it, forgetting about Qt4 support?

Looking into Qt4's code, I found that even Qt 4.0 has the replacement logic. So we can safely remove that.

dir_separator, got it! Missed that one. Thanks!

So we can safely remove that.

Agreed. Will do.

tresf · 2018-03-23T05:39:42Z

I haven't actually tested any of this code myself (e.g for regressions to #4267). For starters, I was confused that QDir::cleanPath(...) actually returns a file path and not the parent folder. Fortunately the unit tests caught my mistake.

@PhysSong I'll let you merge this one since you're the bug submitter and the most likely to have tested this. :)

tresf · 2018-03-23T15:11:48Z

Seems like a lot of chatter over a string replacement, but this knowledge is only going to benefit the project for years to come. Thanks for the digging.

PhysSong · 2018-03-25T06:53:40Z

I found some more places where cleanPath can be used. Should I replace them in a separate PR?

Wallacoloo · 2018-03-25T19:49:08Z

@PhysSong Given this PR is from a tresf branch, I don't think you can easily add your own changes on top of this PR. I would say merge this one and then create a new PR for your changes.

tresf · 2018-03-25T19:57:48Z

Actually GitHub allows PRs to be modified now. It's a great feature especially for abandoned ones. we do it fairly often now. :)

PhysSong · 2018-03-26T06:51:07Z

What I'd like to do is using QDir::cleanPath to normalize data:/ search paths.

index 141085dd2..62bebff7c 100644
--- a/src/core/SampleBuffer.cpp
+++ b/src/core/SampleBuffer.cpp
@@ -1425,7 +1425,7 @@ QString SampleBuffer::tryToMakeRelative( const QString & file )
                // Iterate over all valid "data:/" searchPaths
                for ( const QString & path : QDir::searchPaths( "data" ) )
                {
-                       QString samplesPath = QString( path + samplesSuffix ).replace( QDir::separator(), '/' );
+                       QString samplesPath = QDir::cleanPath( path + samplesSuffix ) + "/";
                        if ( f.startsWith( samplesPath ) )
                        {
                                return QString( f ).mid( samplesPath.length() );

tresf · 2018-03-26T12:54:24Z

Not sure how well the data: portion is handled, but if it works, we can add it here.

tresf · 2018-03-27T00:34:48Z

 		for ( const QString & path : QDir::searchPaths( "data" ) )
 		{
-			QString samplesPath = QString( path + samplesSuffix ).replace( QDir::separator(), '/' );
+			QString samplesPath = QDir::cleanPath( path + samplesSuffix ) + "/";


I believe ensureTrailingSlash may be better here. The previous logic doesn't add any slashes.

Maybe, but don't have to be. QDir::cleanPath always strips trailing slash and previous logic always gives a path with trailing slash.
BTW, ensureTrailingSlash is defined in ConfigManager.cpp. If you want to use that function, you should move that into an header first.

tresf · 2018-03-27T01:09:15Z

Didn't know about trailing slash strip. That's nice. Looks good then. Merge?

* Use cleanPath for calculating relative directories Closes LMMS#4267

tresf added 2 commits March 22, 2018 13:24

Allow relative paths on non-existent directories

68b9dac

Closes LMMS#4267

Remove unused var

99711de

tresf requested a review from PhysSong March 22, 2018 17:28

Remove redundant fileName

259bf0b

Wallacoloo self-requested a review March 23, 2018 01:41

Wallacoloo approved these changes Mar 23, 2018

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PhysSong reviewed Mar 23, 2018

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PhysSong approved these changes Mar 23, 2018

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Remove redundant replace

3a87e57

Use normalized search paths in tryToMakeRelative

d2e94f6

tresf commented Mar 27, 2018

View reviewed changes

tresf merged commit 3673e84 into LMMS:stable-1.2 Mar 27, 2018

tresf deleted the relative branch March 27, 2018 01:51

sdasda7777 pushed a commit to sdasda7777/lmms that referenced this pull request Jun 28, 2022

Allow relative paths on non-existent directories (LMMS#4271)

fc4ddd5

* Use cleanPath for calculating relative directories Closes LMMS#4267

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tresf commented Mar 23, 2018

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PhysSong commented Mar 25, 2018

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tresf commented Mar 27, 2018

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tresf commented Mar 22, 2018 •

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