Add `od` command

[taran-p]

od mimics the dd command in linux terminals. It copies a given local file to a given remote location in a specified number of parts and part sizes, and returns the time it took to upload the file.

This screenshot shows different ways to use mc od on a 92MiB file.

[harshavardhana]

Some issues

Issue1: Not allowing non-multipart uploads

~ mc od if=/etc/hosts of=play/testbucket/hosts parts=1 
mc: <ERROR> Unable to put target stream. Input part size is smaller than allowed minimum of 5MiB.

This is not correct a single part upload will work < 5MiB - this error is premature - you shouldn't be setting the PartSize here because we didn't provide the size and it must not be set.

Size must be honored only if it's set.

Issue2:

~ mc od if=play/testbucket/hosts of=bigfile1 parts=1
mc: <ERROR> Unable to get source and target URLs: invalid target path bigfile1.

We need to support copy back from the server and parts when specified would download N parts from a file if not specified it downloads the entire object from Object Storage to the local disk.

If the part is specified GetObject() actually as PartNumber configuration to get individual parts.

[donatello]

This is still not working:

$ ./mc od if=/etc/issue of=play/bucket/test
mc: <ERROR> Unable to put object. Input part size is smaller than allowed minimum of 5MiB.

I checked the server->server (same server), server->local, local->local and local->server. All seem to work fine.

Output looks like this:

Transferred: 23 MiB, Parts: 1, Time: 9.15s

We can add an MiB/s to show the speed here.