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require 'open-uri'
class Downloader
def self.gnu(name)
"http://git.savannah.gnu.org/gitweb/?p=config.git;a=blob_plain;f=#{name};hb=HEAD"
end
def self.rubygems(name)
"https://rubygems.org/downloads/#{name}"
end
def self.uri_to_download(url, name)
from, url = url
case from
when :gnu
url = gnu(url || name)
when :rubygems, :gems
url = rubygems(url || name)
when Symbol
raise ArgumentError, "unkonwn site - #{from}"
else
url = from
end
URI(url)
end
def self.mode_for(data)
data.start_with?("#!") ? 0755 : 0644
end
def self.http_options(file, since)
options = {}
if since
case since
when true
since = (File.mtime(file).httpdate rescue nil)
when Time
since = since.httpdate
end
if since
options['If-Modified-Since'] = since
end
end
options
end
# Downloader.download(url, name, [dir, [ims]])
#
# Update a file from url if newer version is available.
# Creates the file if the file doesn't yet exist; however, the
# directory where the file is being created has to exist already.
# If +ims+ is false, always download url regardless of its last
# modified time.
#
# Example usage:
# download 'http://www.unicode.org/Public/UCD/latest/ucd/UnicodeData.txt',
# 'enc/unicode/data/UnicodeData.txt'
def self.download(url, name, dir = nil, ims = true)
file = dir ? File.join(dir, name) : name
url = uri_to_download(url, name)
begin
data = url.read(http_options(file, ims))
rescue OpenURI::HTTPError => http_error
return http_error.message =~ /^304 / # 304 Not Modified
raise
end
mtime = nil
open(file, "wb", 0600) do |f|
f.write(data)
f.chmod(mode_for(data))
mtime = data.meta["last-modified"]
end
if mtime
mtime = Time.httpdate(mtime)
File.utime(mtime, mtime, file)
end
true
rescue => e
raise e.class, "failed to download #{name}\n#{e.message}: #{url}", e.backtrace
end
def self.download_if_modified_since(url, name, dir = nil)
download(url, name, dir)
end
end
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