fix #48 by detecting file type using jmimemagic Java library

[kumarshantanu]

This PR uses jMimeMagic to detect file type if the file extension is not one among the white-listed types. Also adds .cljx and .edn to known Clojure file extensions.

[oakes]

Thanks very much. Are you sure there isn't a built-in solution for reading the mime type of a file? I found some suggestions here. I only ask because this library adds 1.8MB to the final jar file size. It's fine if there is no other way; I'm just looking at the other options.

[oakes]

I found that if you add :exclusions [commons-logging junit log4j] to the dependency line, it adds 1.4MB, so that's an improvement.

[kumarshantanu]

If we can make the minimum requirement to be Java 7 for running Nightcode, we do not need any 3rd party library to detect the file type. Java 7 has the API to probe the content. This might be a breaking change for some; Nightcode should switch to version 0.2.0 to include this change. Please let me know what you think - I will update the pull request.

[oakes]

A lot of Mac users are still using Java 6, because that's what it comes with. I wonder if there is a simpler solution. Maybe we should just remove the contains? check entirely, and just put a sane upper limit on the file size (such as 10MB). That way, if you accidentally click on a binary file, it will display gibberish in the editor but won't accidentally load a 1GB file into memory. What do you think?

[kumarshantanu]

I tried running Nightcode on Java 6 and got the below exception:

Exception in thread "AWT-EventQueue-0" java.lang.NoClassDefFoundError: java/awt/Window$Type
    at java.lang.Class.getDeclaredMethods0(Native Method)
    at java.lang.Class.privateGetDeclaredMethods(Class.java:2436)
    at java.lang.Class.getDeclaredMethod(Class.java:1937)
    at java.awt.Component.isCoalesceEventsOverriden(Component.java:5982)
    at java.awt.Component.access$500(Component.java:169)
    at java.awt.Component$3.run(Component.java:5936)
    at java.awt.Component$3.run(Component.java:5934)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.awt.Component.checkCoalescing(Component.java:5933)
    at java.awt.Component.<init>(Component.java:5902)
    at java.awt.Container.<init>(Container.java:249)
    at java.awt.Window.<init>(Window.java:432)
    at java.awt.Frame.<init>(Frame.java:403)
    at java.awt.Frame.<init>(Frame.java:368)
    at javax.swing.JFrame.<init>(JFrame.java:158)
    at seesaw.core.proxy$javax.swing.JFrame$Tag$a79ba523.<init>(Unknown Source)
    at seesaw.core$frame.doInvoke(core.clj:2870)
    at clojure.lang.RestFn.invoke(RestFn.java:805)
    at nightcode.core$_main$fn__11277.invoke(core.clj:124)
    at clojure.lang.AFn.applyToHelper(AFn.java:159)
    at clojure.lang.AFn.applyTo(AFn.java:151)
    at clojure.core$apply.invoke(core.clj:617)
    at seesaw.invoke$invoke_later_STAR_$fn__485.invoke(invoke.clj:14)
    at clojure.lang.AFn.run(AFn.java:24)
    at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:209)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:672)
    at java.awt.EventQueue.access$400(EventQueue.java:81)
    at java.awt.EventQueue$2.run(EventQueue.java:633)
    at java.awt.EventQueue$2.run(EventQueue.java:631)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.AccessControlContext$1.doIntersectionPrivilege(AccessControlContext.java:87)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:642)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
Caused by: java.lang.ClassNotFoundException: java.awt.Window$Type
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    ... 38 more

It seems that Nightcode already requires Java 7 to run. My plan was to use the Java-7 feature dynamically if available else fallback to 10MB-limit based detection, which would be unnecessary if Java 7 is a requirement.

[birdspider]

JRE6 had its end in Feb2013 (http://www.oracle.com/technetwork/java/eol-135779.html),
JRE7 is installable on mac (>=Lion AFAIK)

-- just my 2c

[oakes]

I wasn't aware there were still problems running it with Java 6. I compiled the latest version with OpenJDK 6, so that is puzzling. Perhaps requiring Java 7 is the best option then. If you modify the PR with the change I'd be happy to accept. I'll make sure to mention the change when I release it.

[kumarshantanu]

It was my fault that I built the JAR with Java 7 and ran it on Java 6 - the problem turned out to be AOT compilation that required Java 7 classes. I have updated the PR in a way that on Java 7 the detection will work using Java-7 API via reflection and on Java 6 it falls back on length check.

Will appreciate if somebody can test in other ways - I might have forgotten about corner cases.

[oakes]

I tried the change and it seems to have issues when I select any file with a non-whitelisted extension. I don't see any error output in the console, however.

[oakes]

Maybe reflecting Java 7 functions won't work since we are targeting Java 6 in the project.clj? It may be less error prone to just check the file size.

[kumarshantanu]

Did you run into the issue on Java 7? It's working on Java 7 + 64-bit Ubuntu for me. Only in Java 6 I can see somehow the non-whitelisted files are not working.

[oakes]

I switched to compile with OpenJDK 7 and it seems to work now. Technically this may still cause issues for Mac users running Java 6 -- see this issue for reference. For some reason, Java 6 on OS X has problems running Swing apps compiled with JDK 7, even when they target Java 6. That said, I think it's an OK trade-off to make since Java 6 is so outdated.

[kumarshantanu]

I found the issue - I was not catching ClassNotFoundException. Now it works on both Java 7 (type detection) and Java 6 (size detection) but the behavior would appear inconsistent to the user. Should I fix it by disallowing to open non-whitelisted file types on Java 6? Should I send a new PR?

[oakes]

Sure please do. Would this allow me to compile with OpenJDK 6?
On Dec 10, 2013 12:04 PM, "Shantanu Kumar" notifications@github.com wrote:

I found the issue - I was not catching ClassNotFoundException. Now it
works on both Java 7 (type detection) and Java 6 (size detection) but the
behavior would appear inconsistent to the user. Should I fix it by
disallowing to open non-whitelisted file types on Java 6? Should I send a
new PR?

—
Reply to this email directly or view it on GitHubhttps://github.com//pull/49#issuecomment-30246381
.

[kumarshantanu]

I believe it should. I compiled using Sun JDK 6 and ran using both Sun JDK 6 and Sun JDK 7.