add a `file-type' procedure to posix unit

[felix winkelmann]

`(file-type FILENAME-OR-FD)' -> SYMBOL

Should return one of

regular
directory
symlink
fifo
socket
char-device
block-device

[felix winkelmann]

See experimental branch. The file-type predicates (regular-file?, etc.) now also accept a file-descriptor.

[Jim Ursetto]

Unfortunately this change broke the assumption that regular-file?, etc. will return #f if the file does not exist at all. Now, it throws an error. I think quite a bit of code relies on the old behavior--my own does and so does the core itself. For example, posix#create-directory no longer works at all in recursive mode, because it uses directory? to check for directory existence, and non-existent directories will barf.

[felix winkelmann]

The situation is now as follows (master, commit 0cc55fe):

`file-type' takes an optional flag indicating whether a non-existing file should dsignal an error or if the function should return #f (defaults to signalling an error).

All the file-type predicates return #f if given a filename and the file does not exist.

All file-type predicates with the exception of symbolic-link? follow symlinks.

If this agrees with you, please close the ticket.

[Jim Ursetto]

Sorry it took me so long to get around to this.
Tests out ok, thanks!

[felix winkelmann]

Milestone 4.6.0 deleted