Class: Omnizip::Formats::Zip::UnixExtraField

Inherits:
Object
  • Object
show all
Defined in:
lib/omnizip/formats/zip/unix_extra_field.rb

Overview

Info-ZIP Unix extra field (tag 0x7875) Stores Unix-specific metadata including symbolic link targets

Constant Summary collapse

UNIX_EXTRA_FIELD_TAG = 
0x7875

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(version: 1, uid: nil, gid: nil, link_target: nil) ⇒ UnixExtraField

Returns a new instance of UnixExtraField.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 13

def initialize(
  version: 1,
  uid: nil,
  gid: nil,
  link_target: nil
)
  @version = version
  @uid = uid
  @gid = gid
  @link_target = link_target

  # Calculate sizes
  @uid_size = uid ? [uid].pack("V").bytesize : 0
  @gid_size = gid ? [gid].pack("V").bytesize : 0
end

Instance Attribute Details

#gid ⇒ Object

Returns the value of attribute gid.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 11

def gid
  @gid
end

#gid_size ⇒ Object

Returns the value of attribute gid_size.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 11

def gid_size
  @gid_size
end

#link_target ⇒ Object

Returns the value of attribute link_target.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 11

def link_target
  @link_target
end

#uid ⇒ Object

Returns the value of attribute uid.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 11

def uid
  @uid
end

#uid_size ⇒ Object

Returns the value of attribute uid_size.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 11

def uid_size
  @uid_size
end

#version ⇒ Object

Returns the value of attribute version.



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 11

def version
  @version
end

Class Method Details

.find_in_extra_field(extra_field_data) ⇒ Object

Parse extra field from complete extra field data



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 97

def self.find_in_extra_field(extra_field_data)
  return nil if extra_field_data.nil? || extra_field_data.empty?

  offset = 0
  while offset < extra_field_data.bytesize - 4
    tag, size = extra_field_data[offset, 4].unpack("vv")

    if tag == UNIX_EXTRA_FIELD_TAG
      field_data = extra_field_data[offset + 4, size]
      return from_binary(field_data)
    end

    offset += 4 + size
  end

  nil
end

.for_hardlink(uid: nil, gid: nil) ⇒ Object

Create a Unix extra field for a hard link



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 126

def self.for_hardlink(uid: nil, gid: nil)
  new(
    version: 1,
    uid: uid,
    gid: gid,
    link_target: nil,
  )
end

.for_symlink(target, uid: nil, gid: nil) ⇒ Object

Create a Unix extra field for a symbolic link



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 116

def self.for_symlink(target, uid: nil, gid: nil)
  new(
    version: 1,
    uid: uid,
    gid: gid,
    link_target: target,
  )
end

.from_binary(data) ⇒ Object

Parse from binary data



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 65

def self.from_binary(data)
  return nil if data.nil? || data.bytesize < 3

  version = data.unpack1("C")
  offset = 1

  # Read UID
  uid_size = data[offset].unpack1("C")
  offset += 1
  uid = (data[offset, uid_size].unpack1("V") if uid_size.positive?)
  offset += uid_size

  # Read GID
  gid_size = data[offset].unpack1("C")
  offset += 1
  gid = (data[offset, gid_size].unpack1("V") if gid_size.positive?)
  offset += gid_size

  # Read link target if present
  link_target = if offset < data.bytesize
                  data[offset..].force_encoding("UTF-8")
                end

  new(
    version: version,
    uid: uid,
    gid: gid,
    link_target: link_target,
  )
end

Instance Method Details

#size ⇒ Object

Get the size of this extra field in bytes



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 136

def size
  to_binary.bytesize
end

#symlink? ⇒ Boolean

Check if this field contains a symbolic link target

Returns:

  • (Boolean) 


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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 30

def symlink?
  !@link_target.nil? && !@link_target.empty?
end

#to_binary ⇒ Object

Serialize to binary format



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 35

def to_binary
  data = [version].pack("C")

  # Add UID if present
  if @uid
    data << [@uid_size].pack("C")
    data << [@uid].pack("V")[0, @uid_size]
  else
    data << [0].pack("C")
  end

  # Add GID if present
  if @gid
    data << [@gid_size].pack("C")
    data << [@gid].pack("V")[0, @gid_size]
  else
    data << [0].pack("C")
  end

  # Add link target if present (for symbolic links)
  data << @link_target.b if @link_target

  # Return with tag and size
  [
    UNIX_EXTRA_FIELD_TAG,
    data.bytesize,
  ].pack("vv") + data
end

#to_h ⇒ Object

Convert to hash representation



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# File 'lib/omnizip/formats/zip/unix_extra_field.rb', line 141

def to_h
  {
    tag: UNIX_EXTRA_FIELD_TAG,
    version: @version,
    uid: @uid,
    gid: @gid,
    link_target: @link_target,
  }
end