file_mode¶ ↑
- Author
-
Martin Carpenter
-
mcarpenter@free.fr
- Copyright
-
Copyright © Martin Carpenter 2014
About¶ ↑
The file_mode gem assists with manipulation of four-octal-digit UNIX file modes by providing readable method names rather than error-prone bit twiddles. It also provides methods to convert to and from standard ls(1)-style long listing formats. The class methods can be used standalone or this module can be mixed in to a class that has an integer :mode attribute.
Examples¶ ↑
Class method use¶ ↑
require 'file_mode'
FileMode.user_readable?(0o644)
=> true
FileMode.setuid?(0o4755)
=> true
FileMode.int_to_listing(0o644)
=> "rw-r--r--"
FileMode.listing_to_str('rwsr-xr-x')
=> "4755"
Mixin use¶ ↑
require 'file_mode' class FileLikeThing include FileMode attr_accessor :mode end flt = FileLikeThing.new flt.mode = 0o0644 flt.user_readable? => true flt.setuid? => false
Mode formats¶ ↑
The module offers three forms of mode representation:
-
integer (eg 0o0644 or 420 decimal)
-
string (‘0644’)
-
listing (‘rw-r–r–’)
Listing formats are not necessarily identical across UNIX-like operating systems, or even across applications on the same operating system. A case in point is Solaris which shows mandatory file lock permission as ‘l’ with standard ls(1) and ‘L’ with XPG-compatible ls(1).
This module aims to take any standard format as input (listing_to_… methods) and targets Linux/GNU coreutils for output(…_to_listing methods).
Some conversion gotchas¶ ↑
Beware the following standard ruby gotchas when making conversions using #to_i and a solitary leading zero to specify octal mode:
644.to_i => 644 # ok '644'.to_i => 644 # ok 0644.to_i => 420 # ok '0644'.to_i => 644 # ! leading zero is ignored '0o644'.to_i => 0 # ! parsing stops at 'o'
Unit tests¶ ↑
Unit tests are provided particularly for the conversion between the ls(1)-style long-listing format and integer representations. Since the long-listing format can vary between systems a script bin/create_listing_test.rb is provided to generate unit test files.