Pipeline looks for temp folder env variable which is not present on *nix machines

[suhasj]

The BufferingHelper tries to get the path to the temporary folder by reading the environmental variables 'ASPNET_TEMP' and 'TEMP'. Code
The issue is *nix machines don't have the mandatory 'TEMP' variable set by default.

@Tratcher @Praburaj discussed that Path.GetTempPath was not advised to be used while Environment.SpecialFolder is not present for Core CLR.

This leaves us with two options

• Find a variable similar to 'TEMP' which is set by default and read the path value from there
• Document this and have administrators set this variable on the machines.

The second one I am not comfortable with while the first one, I was not able to get a consistent variable that is similar to 'TEMP'. The OSX has 'TMPDIR' but this is not present in Linux machines. With the latest bits, running applications without either of these variables set results in error which are not very obvious either. Can we come at a consensus on what the guidelines should be ?

[davidfowl]

Mono's implementation of Path.GetTempPath() - https://github.com/mono/mono/blob/master/mcs/class/corlib/System.IO/Path.cs#L468

[muratg]

@Praburaj Can you have a look?

[Praburaj]

@muratg sure.

[akoeplinger]

To save everyone a few clicks, this is what Mono ends up doing: https://github.com/mono/mono/blob/effa4c07ba850bedbe1ff54b2a5df281c058ebcb/eglib/src/gmisc-unix.c#L132-L151

[Praburaj]

I have a proposal on this to check for folders in the following order (1 & 2 is what we have today).

1. ASPNET_TEMP - User set location for ASP.NET apps
2. TEMP - Works on windows points to appdata\local
3. TMPDIR - works on Mac and some linux distributions like Ubuntu
4. TMP
5. /tmp Looks like this is a recommendation - http://www.pathname.com/fhs/pub/fhs-2.3.html#TMPTEMPORARYFILES

Thoughts?

[davidfowl]

I like it. I would file a bug on the corefx repository with this as well. Ideally we'd use Path.GetTempPath() and it would do the right thing.

ASPNET_TEMP can be used to override if course.

[Praburaj]

@Tratcher I remember you mentioning that Path.GetTemppath is not used here to avoid falling back to userprofile. Are you okay if I just change code to use Path.GetTempPath and just check for %ASPNET_TEMP% before?

[Tratcher]

Ask @GrabYourPitchforks

[Praburaj]

@davidfowl - I talked with @GrabYourPitchforks on this. I think it is okay to use Path.GetTempPath as long as we check for ASPNET_TEMP first. I'll update the PR with this change.

[davidfowl]