Class: Ruckus::Str

Inherits:
Parsel show all
Defined in:
lib/ruckus/str.rb

Overview

A Ruckus::Str is a bag of bytes, wrapping a Ruby string

Direct Known Subclasses

MacAddr, Asciiz, Unicode

Constant Summary

Constants inherited from Parsel

Parsel::VERBOTEN

Instance Attribute Summary

Attributes inherited from Parsel

#name, #parent, #rendered_offset, #rendering, #tag, #value

Instance Method Summary collapse

Methods inherited from Parsel

bytes_for_bits, coerce, #each_matching_selector, endian?, factory?, #find_containing, #find_tag, #find_tag_struct, #fixup, #in, #incomplete!, #index_for_selectors, #inspect, #matches_selector?, #method_missing, #native?, native?, #next, #out, #parent_structure, #permute, #prev, #resolve, #respond_to?, #root, #size, #visit, #where_am_i?

Constructor Details

#initialize(opts = {}) ⇒ Str

Options include:

size

:min = :max = :size

min

string will be padded to this size

max

string will be cut off at this size

padding

(Default: “x00”) — what to pad with

value

Normally a string

unicode

Convert to UTF-16-LE before rendering



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# File 'lib/ruckus/str.rb', line 20

def initialize(opts={})
    opts[:bounded_by] ||= -1 if opts[:bounded]

    if opts[:bounded_by]
        opts[:size] = { :offset => opts[:bounded_by], :meth => :value }
    end

    if opts[:size]
        opts[:min] = opts[:size]
        opts[:max] = opts[:size]
        @in_size = opts[:size]
    end
    opts[:padding] ||= "\x00"
    opts[:min] ||= 0

    super(opts)

    @value = @value.clone if @value
    @value ||= ""
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Ruckus::Parsel

Instance Method Details

#capture(str) ⇒ Object

As with Parsel; take a string, return what’s left, capture the value in @value.



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# File 'lib/ruckus/str.rb', line 44

def capture(str)
    if @in_size
        max = resolve(@in_size)
        min = resolve(@in_size)
    end

    max ||= resolve(@max)
    min ||= resolve(@min)
    pad = resolve(@padding)
    nul = resolve(@nul_terminated)
    uni = resolve(@unicode)
    del = resolve(@delimiter)

    @value = nil

    incomplete! if not str

    if (s = size)
        incomplete! if str.size < s
        cap = str[0...s]
    elsif nul
        nterm = str.index(uni ? "\000\000" : "\000")
        if nterm
            cap = str[0...nterm]
        else
            cap = str
        end
    elsif del
        if((idx = str.index(del)))
            cap = str[0...idx]
        else
            cap = str
        end
    else
        cap = str
    end

    cap = cap[0...max] if max
    while cap.size < min
        cap << pad
    end

    # must work on a dup of str here or @value may get clobbered by str.slice!
    @value = uni ? cap.to_ascii : cap.dup

    fin = -1
    mod = nul ? 1 : 0

    str.slice! 0, (cap.size + mod)
    return str
end

#to_s(off = nil) ⇒ Object

As per Parsel, write the string



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# File 'lib/ruckus/str.rb', line 97

def to_s(off=nil)
    @rendered_offset = off || 0

    min = resolve(@min)
    max = resolve(@max)
    uni = resolve(@unicode)
    val = (resolve(@value) || "").to_s
    val = val.clone # gross!
    pad = resolve(@padding)
    nul = resolve(@nul_terminated)
    pto = resolve(@pad_to)

    val << "\x00" if nul and val[-1] != 0

    val = val.to_utf16 if uni

    while min and val.size < min
        val << pad
    end

    if pto
        while ((val.size % pto) != 0) # this is some shameful shit right here
            val << pad
        end
    end

    val = val[0...max] if max

    if off
        return val, off + val.size
    else
        return val
    end
end