223 lines
7.7 KiB
Ruby
223 lines
7.7 KiB
Ruby
# Various helper methods to update the database of packages
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require 'bzip2'
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module DebImporter
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# This module imports information about packages of a Linux distribution
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# that uses the DEB package format like Debian, Ubuntu or Mint.
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#
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# It starts by loading the Release file of a release to get
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# information about available components and architectures.
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#
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# Next it loads the Packages lists (prefers bz2, falls back to
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# .gz or even the uncompressed version).
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class Release
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attr_reader :architectures, :components, :description, :codename, :origin, :version, :files
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# Load and parse a Release file of an APT repository
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def initialize(dist_url)
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@dist_url = dist_url
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release_url = dist_url + "/Release"
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Rails.logger.debug "Loading Release file from #{release_url}"
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open(release_url) do |release_data|
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fields = get_fields(release_data)
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@architectures = fields[:Architectures]
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@components = fields[:Components]
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@description = fields[:Description]
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@codename = fields[:Codename]
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@origin = fields[:Origin]
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@version = fields[:Version]
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# TODO: check sizes and checksums
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end # open
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end # def initialize
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# Get package information from translation (i18n) files.
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# Returns an enumerator of packages.
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def i18n(component, language)
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url = "#{@dist_url}/#{component}/i18n/Translation-en"
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file = find_and_open_compressed_url(url)
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if file
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return get_paragraphs(file)
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else
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return []
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end
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end
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# Look for the file or URL in various compressed formats
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# (e.g. bz2, gz) and fall back to plain text format.
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def find_and_open_compressed_url(base_url)
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Rails.logger.debug "Looking for files at URL #{base_url} with different compressions"
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for suffix in ['.bz2', '.gz', '']
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begin
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begin
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url = "#{base_url}#{suffix}"
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Rails.logger.debug "Checking if file at #{url} is available"
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file = open(url)
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rescue OpenURI::HTTPError => e
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Rails.logger.debug "Loading #{url} lead to error #{e}. skipping."
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next
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end
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# Decompress file depending on its filename suffix
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case suffix
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when '.bz2'
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file = Bzip2::Reader.new(file)
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when '.gz'
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file = Zlib::GzipReader.new(file)
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end
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Rails.logger.debug "File containing translations is: #{file}"
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return file
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rescue Errno::ENOENT
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Rails.logger.debug "URL #{url} could not be opened. Skipping."
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end
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end
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Rails.logger.error "No file found at #{url} and various compression extensions."
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return nil
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end
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# Try to load the Packages file for a certain component (e.g. "main")
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# and architecture (e.g. "amd64")
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def packages(component, architecture)
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# create path like "main/binary-amd64/Packages"
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packages_path = "#{@dist_url}/#{component}/binary-#{architecture}/Packages"
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Rails.logger.debug "Loading packages from #{packages_path}"
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file = find_and_open_compressed_url(packages_path)
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return get_paragraphs(file)
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end # def packages
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end # class Release
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private
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# Gather the fields of a Debian control file section and return them as a hash
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def get_fields(data)
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fields = {}
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name=value=''
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data.each_line do |line|
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case line
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when /^(.+?): (.+)/ # "Key: Value"
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fields[name.to_sym]=value unless value.empty?
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name,value=$1,$2
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when /^(.+?):$/ # "Key:" (start of multi-line entry without value in line)
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fields[name.to_sym]=value unless value.empty?
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name=$1
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value=''
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when /^\s+(.+)/ # " Indented multi-line value"
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# Add a newline for multi-line entries ("Key: Value\n Foo\n Bar")
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unless value.empty?
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value << "\n"
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end
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value << $1
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when /^\s+$/ # Empty line
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break
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end
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end
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# Any lines left at the end of the input?
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fields[name.to_sym]=value unless value.empty?
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return fields
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end
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# Iterator that splits up the input of a debian control file
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# by empty lines. For example Debian "Packages" files consist
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# of one paragraph for each package listed in it.
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def get_paragraphs(data)
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Enumerator.new do |enum|
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gathered_lines = '' # collects all lines belonging to a field
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data.each_line do |line|
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if line.chomp.empty? # empty line found that seperates paragraphs
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unless gathered_lines.empty? # any lines gathered so far?
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enum.yield get_fields(gathered_lines)
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gathered_lines = ''
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end
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else
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gathered_lines << line
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end
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end # each_line
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# Any lines left after the last empty line and the end of the input?
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unless gathered_lines.empty?
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enum.yield get_fields(gathered_lines)
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end
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end # Enumerator
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end # def
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class Version
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attr_reader :epoch, :version, :revision, :version_string
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def initialize(version_string)
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@version_string = version_string
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# Split into "[epoch:]version[-revision]"
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unless /^(?<epoch>(\d+)\:)?(?<version>.+)(?<revision>\-[\+\.~]+)?/ =~ version_string
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raise ArgumentError, "Cannot parse version string: #{version_string}"
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end
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@epoch = epoch ? epoch : 0
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@version = version
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@revision = revision if revision
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end # /def
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def to_s
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@version_string
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end
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def >(other)
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dpkg_compare_version(@version_string, other, 'gt')
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end
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def <(other)
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dpkg_compare_version(@version_string, other, 'lt')
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end
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private
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# Determine which version string denotes the newer package
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# v1: version of the first package
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# v2: version of the second package
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# op: the comparison operator (default: 'gt' / greater-than)
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#
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# The algorithm is described in the Debian Policy at
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# https://www.debian.org/doc/debian-policy/ch-controlfields.html#s-f-Version
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# The reference implementation is "dpkg --compare-versions …"
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def dpkg_compare_version(v1, v2, op)
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system("dpkg --compare-versions #{v1} #{op} #{v2}")
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end
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# def ___version_compare(x,y)
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# # Compare a version string (like the upstream_version or
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# # debian_revision string) against another version string.
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# # The algorithm works like this:
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# #
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# # The strings are compared from left to right.
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# # First the initial part of each string consisting entirely of non-digit
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# # characters is determined. These two parts (one of which may be empty)
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# # are compared lexically. If a difference is found it is returned.
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# # The lexical comparison is a comparison of ASCII values modified so
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# # that all the letters sort earlier than all the non-letters and so that
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# # a tilde sorts before anything, even the end of a part.
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# # For example, the following parts are in sorted order from
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# # earliest to latest: ~~, ~~a, ~, the empty part, a.[37]
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# #
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# # Then the initial part of the remainder of each string which
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# # consists entirely of digit characters is determined. The
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# # numerical values of these two parts are compared, and any
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# # difference found is returned as the result of the comparison.
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# # For these purposes an empty string (which can only occur at
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# # the end of one or both version strings being compared) counts as zero.
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# #
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# # These two steps (comparing and removing initial non-digit strings
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# # and initial digit strings) are repeated until a difference is
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# # found or both strings are exhausted.
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# (x.chars).zip(y.chars) do |xchar,ychar|
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# puts xchar, ychar
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# end
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# end
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end # /class
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end # module
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