Ensure that default download directory is writable on daemon startup

[lyoshenka]

Creating a new issue based on lbryio/lbry-sdk#877

• Update ensure_directory_exists() to check that the directory is writable by the current process.
• If it's not, return a useful error
• Add tests to cover the case when
  • download directory does not exist
  • download dir exists but is not writable
  • dir exists and is writable
  • the path refers to a file not a directory

bonus: also check if disk is full when sdk starts. this check should be outside ensure_directory_exists(). it probably goes somewhere near here

[snapperVibes]

"Good first issue" is what I'm looking for! I'll write the code tomorrow.

[jeffreypicard]

PR for this https://github.com/lbryio/lbry-sdk/pull/3276 @snapperVibes sorry, didn't mean to try to snipe you, didn't see your comment until after I finished this!

[snapperVibes]

Your code is cleaner anyways.

[Rishabhraghwendra18]

Hi @snapperVibes is this issue open ?

[snapperVibes]

It's closed

[RyanRussell00]

@lyoshenka Is this issue open or closed?

[tzarebczan]

This issue is open.

[ghost]

The pull request #3457, updating the ensure_directory_exists(), is available for a review.

[ghost]

How impactful is the problem of the absence of the storage capacity fullness check on the start up? What would be a suitable methodology to verify the full storage capacity scenario? Would there be a merit in adding a check to see if the storage will potentially become full after a download? How impactful would the programming effort be?

[ghost]

The ensure_directory_exists() now checks the directory is writable by the process.