[MiqFileStorage] Add #magic_number_for

[NickLaMuro]

Used to determine the magic number for a remote uri.

Implementation Notes/Details:

• Only works for magics that are determined by the first N bytes currently.
• By default, just returns the first 256 bytes
• The :accepted param can be passed, which allows you to pass a hash with the values of the hash being the magic values (returns matching key)
  • When passed, only the largest magic's size in data will be returned by the request
• Relies on #download_single being able to support a specific @byte_count to download only what is necessary and writing to a StringIO.

Links

• The following PRs should be merged in order for this function on all file storages:
  • [MiqGenericMountSession] Support @byte_count in #download_single #395 (All Mount types)
  • [MiqFtpStorage] Support @byte_count in #download_single #396 (FTP)
  • [MiqS3Storage] Support @byte_count in #download_single #399 (S3)
  • Add MiqSwiftStorage#download_single #400 (Swift)

[NickLaMuro]

@miq-bot assign @carbonin

[NickLaMuro]

@miq-bot add_label enhancement, hammer/yes

[carbonin]

I'm not sure what this spec name means. Is there a typo here somewhere or maybe some missing words?

[NickLaMuro]

"Nick (LaMuro), you're drunk... go home..."

• Nick (Carboni)

Yeah... let me fix that...

[NickLaMuro]

@carbonin Just an FYI, this also changed as part of my recent push of commits, since I ran into an issue without it.

Prior, this line was just:

result = magics.detect { |_, magic| ri_data.start_with?(magic) }

[carbonin]

Can we keep this as a single line? Code Climate is complaining about the alignment of the end and even though the line would be over 80 characters I think it would be more readable as a single line rather than dealing with the weird spacing caused by the assignment.

[NickLaMuro]

Sure. No prob.

[miq-bot]

Checked commits NickLaMuro/manageiq-gems-pending@a24d703~...f70c48d with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
4 files checked, 3 offenses detected

lib/gems/pending/util/miq_file_storage.rb

• ❗ - Line 187, Col 15 - Layout/ExtraSpacing - Unnecessary spacing detected.
• ❗ - Line 187, Col 19 - Layout/SpaceAroundOperators - Operator = should be surrounded by a single space.
• ❗ - Line 191, Col 9 - Style/SafeNavigation - Use safe navigation (&.) instead of checking if an object exists before calling the method.

[simaishi]

Hammer backport details:

$ git log -1
commit 95c981ff06d3963e95dadd134e4a44d971bddf82
Author: Nick Carboni <ncarboni@redhat.com>
Date:   Fri Nov 9 09:31:27 2018 -0500

    Merge pull request #401 from NickLaMuro/add-magic-number-for-to-miq-file-storage
    
    [MiqFileStorage] Add #magic_number_for
    
    (cherry picked from commit b3f99e12a1daeb9ecdd07173a49be93038da7051)