Per region file arguments

Current chromium impl.

Current chromium flashrom implements the syntax like this:

   [-i <region>[:<file>]]... -r|-w|-v [<filename>]

Where <filename> can be given anywhere on the command line (non-positional).

Rules:

• if no <filename> is given, all -i arguments must specify a <file>
• For reading:
  • if any -i region:<file> is given along with <filename>, read all included regions into <filename> and all included regions with a <file> specified into the respective file
• For writing and verifying:
  • if any -i region:<file> is given along with <filename>, the data of -i region:<file> takes precedence
  • regions with files given with -i region:<file> must not overlap

More details: https://www.chromium.org/chromium-os/packages/cros-flashrom#TOC-Partial-Reads-and-Writes

More explicit alternative

   [-i <region>]... (-r|-w|-v [<region>:]<filename>)...

Easier to implement, no optional arguments, no non-positional arguments.

Rules for sanity:

• combinations of -r/-w/-v are not allowed
• -r/-w/-v <filename> (i.e. without a <region>) may only be specified once
• if no -r/-w/-v <filename> (i.e. without a <region>) is specified, no -i arguments may be given either

optionally, stricter

Never mix <region>:<file> with the old -i syntax in one invocation:

   ([-i <region>]... (-r|-w|-v <filename>) | (-r|-w|-v <region>:<filename>)...)