Create fronted cache if not found.

[jigar-f]

This PR fixes the issue where a fronted cache file is not found; if it is not found, then it is created.

[myleshorton]

This is already handled here:

https://github.com/getlantern/fronted/blob/main/cache.go#L88

[jigar-f]

Then how come every time it throws error with file being not found.

I might be missing something here.

[jigar-f]

Something like this

Dec 16 07:06:39.628 - 9m48s ERROR fronted: cache.go:90 Unable to save cache to disk: open /private/var/mobile/Containers/Data/Application/9ED85F72-5D40-424F-932E-BD39A3CFB30E/Library/Application Support/Lantern/fronted_cache.json: no such file or directory [error=Unable to save cache to disk: %v error_location=github.com/getlantern/fronted.(*fronted).updateCache (cache.go:90) error_op=open error_text=Unable to save cache to disk: open /private/var/mobile/Containers/Data/Application/9ED85F72-5D40-424F-932E-BD39A3CFB30E/Library/Application Support/Lantern/fronted_cache.json: no such file or directory error_type=errors.Error]
ERROR fronted: cache.go:90   at github.com/getlantern/fronted.(*fronted).updateCache (cache.go:90)
ERROR fronted: cache.go:90   at github.com/getlantern/fronted.(*fronted).maintainCache (cache.go:70)
ERROR fronted: cache.go:90   at runtime.goexit (asm_arm64.s:1222)
ERROR fronted: cache.go:90 Caused by: open /private/var/mobile/Containers/Data/Application/9ED85F72-5D40-424F-932E-BD39A3CFB30E/Library/Application Support/Lantern/fronted_cache.json: no such file or directory
ERROR fronted: cache.go:90 Caused by: no such file or directory

cc @garmr-ulfr

[garmr-ulfr]

Yeah, I'm also getting the same error.

This is already handled here:

https://github.com/getlantern/fronted/blob/main/cache.go#L88

While os.WriteFile does create a file if it doesn't exist, it doesn't create the parent directory, which is what's causing the issue. Instead this PR, we just need to add os.MkdirAll to fronted before trying to write to the file.

[jigar-f]

Thanks, @garmr-ulfr Let me do some testing.

[garmr-ulfr]

Closing as this change was added to fronted instead.