[ARROW-10942] [C++] S3FileSystem::Impl::IsEmptyDirectory fails on Amazon S3

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.0.0
• Fix Version/s: 3.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/26869
• Assignee: Antoine Pitrou
• Reporter: Juan Galvez
• Created: 16/Dec/20 16:41
• Updated: 11/Jan/23 08:16
• Resolved: 17/Dec/20 15:12

Description

Running S3FileSystem::GetFileInfo() where the path is in the form "bucket-name/dir-name" and this is a bucket on AWS S3, it throws the following error:

"When reading information for key 'dir-name' in bucket 'bucket-name': AWS Error [code 15]: No response body.

I tracked down the issue to the IsEmptyDirectory method, and noticed that removing kSep from this line:
req.SetKey(ToAwsString(key) + kSep);

fixes the issue.

However, I don't know why kSep is needed in the first place so I'm not sure what a good solution would be.
Also, the key variable on entering IsEmptyDirectory is just the name of the directory (doesn't have separators).

Issue Links

• links to: GitHub Pull Request #8941