UndertowServletWebServerFactory does not configure a temporary directory

[Roiocam]

Description

I am using Spring Boot undertow construct upload file class, the configuration of the spring.servlet.multipart.location attributes, when the attribute value and the current environment is not configured at the same time, the undertow ManagedServlet setupMultipart method to obtain the servletContext.getDeployment().getDeploymentInfo().getTempPath() returns value. But this method doesn't seem to return the correct value. So the program throw the NPE .

Steps to Reproduce:

In Windows, I use spring.servlet.multipart.location=/opt/jar-application-dir
And then io.undertow.servlet.core.ManagedServlet Line 75 , will return false then in line 78 will throw the NullPointException. The reason is field tempDir was null.

In Linux, I use spring.servlet.multipart.location=C://jar-application-dir and then io.undertow.servlet.core.ManagedServlet Line 75 , will return false then in line 78 will throw the NullPointException. The reason is field tempDir was null.

Seem like the method Path.isAbsolute() can not recognize diffrent OS file system. and then UndertowServletWebServerFactory.createDeploymentManager() didn't init the field tempDir

This is exception stacktrace :

[restartedMain] ERROR org.springframework.boot.SpringApplication.reportFailure:858 - Application run failed
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is java.lang.RuntimeException: java.lang.NullPointerException
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:157)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142)
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
	at com.**************Application.main(*****Application.java:22)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
	at io.undertow.servlet.core.DeploymentManagerImpl.deploy(DeploymentManagerImpl.java:252)
	at org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory.createDeploymentManager(UndertowServletWebServerFactory.java:284)
	at org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory.getWebServer(UndertowServletWebServerFactory.java:208)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:181)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:154)
	... 13 common frames omitted
Caused by: java.lang.NullPointerException: null
	at io.undertow.servlet.core.ManagedServlet.setupMultipart(ManagedServlet.java:107)
	at io.undertow.servlet.spec.ServletRegistrationImpl.setMultipartConfig(ServletRegistrationImpl.java:117)
	at org.springframework.boot.web.servlet.ServletRegistrationBean.configure(ServletRegistrationBean.java:201)
	at org.springframework.boot.web.servlet.ServletRegistrationBean.configure(ServletRegistrationBean.java:51)
	at org.springframework.boot.web.servlet.DynamicRegistrationBean.register(DynamicRegistrationBean.java:115)
	at org.springframework.boot.web.servlet.RegistrationBean.onStartup(RegistrationBean.java:54)
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.selfInitialize(ServletWebServerApplicationContext.java:235)
	at org.springframework.boot.web.embedded.undertow.UndertowServletWebServerFactory$Initializer.onStartup(UndertowServletWebServerFactory.java:616)
	at io.undertow.servlet.core.DeploymentManagerImpl$1.call(DeploymentManagerImpl.java:203)
	at io.undertow.servlet.core.DeploymentManagerImpl$1.call(DeploymentManagerImpl.java:185)
	at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:42)
	at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
	at io.undertow.servlet.core.DeploymentManagerImpl.deploy(DeploymentManagerImpl.java:250)
	... 17 common frames omitted

Fix :

First of all, i think the issue will be 'Undertow' cecause the exception was throw by Undertow Project object. But i trace the running stack,seem like UndertowServletWebServerFactory create an object but didn't giving a default value.So i push this commit , hope it's helpful.

[pivotal-issuemaster]

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[mbhave]

@Roiocam Would it be possible to add a test case for this?

[Roiocam]

@Roiocam Would it be possible to add a test case for this?

@mbhave it's complicated to make a JUint case for this bug. But i make a minimal application to reproduce this. See more detail In header block comment at the top of NpeDemoApplication.java
https://github.com/Roiocam/npe-demo

[snicoll]

@Roiocam thank you for making your first contribution to Spring Boot. They are indeed a couple of cases where Undertow expects the temporary directory to be set as a fallback option, the lack of a valid multipart location being one of them.

Turns out we have an infrastructure to create a temporary directory for the container so I've polished your contribution and used that. I've also added a test (agree it wasn't easy to setup so something we should probably improve).

[Roiocam]

It's great to see that my opinion was helpfully, I've seen how good it isthe change from you about the commit. It's seem that i should be more familiar with the project.