Zlib: split into Adler32, CRC32, Flate, Gzip and Zlib types

Crystal provides access to the Adler32, CRC32, DEFLATE, gzip and zlib algorithms/formats. It currently does so by binding to zlib (also known as libz). However, zlib is just an implementation detail: this shouldn't leak to type and method names because if we eventually decide to change the library used to implement these, or maybe implement stuff in pure Crystal, we'll be stuck with this name. So, here we split the contents of the Zlib module into: - Adler32, for the Adler32 checksum algorithm - CRC32, for the CRC32 checksum algorithm - Flate: for the DEFLATE compression format (RFC 1951), providing Reader and Writer types (Inflate and Deflate could also work, but Reader and Writer are more obvious and consistent.) Flate is also the name used by Go to provide the same functionality, so it will be familiar to some. - Gzip: for the gzip archive format (RFC 1952), which is just a small wrapper (header and checksum) around the DEFLATE format. Reader and Writer are provided, together with access to the first gzip header. - Zlib: for the zlib archive format (RFC 1950), which is just a small wrapper around the DEFLATE format too (here the format is also named the same as the C library, which brings a lot of confusion). Reader and Writer are provided. By doing this we also remove the need to know how to use the zlib C library, which requires users to provide a cryptic `windowBits` argument to choose the desierd format. Finally, we rename HTTP::DeflateHandler to HTTP::CompressHandler because that's what it does: it compress responses in either gzip or DEFLATE, but not always DEFLATE (so the name was misleading). All of this is a big breaking change, but should be easy to upgrade existing code and makes the standard library more consistent and organized.
crystal-lang · Jan 29, 2017 · bda40f8 · bda40f8
1 parent df10240
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diff --git a/spec/std/adler32_spec.cr b/spec/std/adler32_spec.cr
@@ -0,0 +1,16 @@
+require "spec"
+require "adler32"
+
+describe Adler32 do
+  it "should be able to calculate adler32" do
+    adler = Adler32.checksum("foo").to_s(16)
+    adler.should eq("2820145")
+  end
+
+  it "should be able to calculate adler32 combined" do
+    adler1 = Adler32.checksum("hello")
+    adler2 = Adler32.checksum(" world!")
+    combined = Adler32.combine(adler1, adler2, " world!".size)
+    Adler32.checksum("hello world!").should eq(combined)
+  end
+end
diff --git a/spec/std/crc32_spec.cr b/spec/std/crc32_spec.cr
@@ -0,0 +1,16 @@
+require "spec"
+require "crc32"
+
+describe CRC32 do
+  it "should be able to calculate crc32" do
+    crc = CRC32.checksum("foo").to_s(16)
+    crc.should eq("8c736521")
+  end
+
+  it "should be able to calculate crc32 combined" do
+    crc1 = CRC32.checksum("hello")
+    crc2 = CRC32.checksum(" world!")
+    combined = CRC32.combine(crc1, crc2, " world!".size)
+    CRC32.checksum("hello world!").should eq(combined)
+  end
+end
diff --git a/spec/std/flate/flate_spec.cr b/spec/std/flate/flate_spec.cr
@@ -0,0 +1,47 @@
+require "spec"
+require "flate"
+
+module Flate
+  describe Writer do
+    it "should be able to write" do
+      message = "this is a test string !!!!\n"
+      io = IO::Memory.new
+      writer = Writer.new(io)
+      writer.print message
+      writer.close
+
+      io.rewind
+      reader = Reader.new(io)
+      reader.gets_to_end.should eq(message)
+    end
+
+    it "can be closed without sync" do
+      io = IO::Memory.new
+      writer = Writer.new(io)
+      writer.close
+      writer.closed?.should be_true
+      io.closed?.should be_false
+
+      expect_raises IO::Error, "closed stream" do
+        writer.print "a"
+      end
+    end
+
+    it "can be closed with sync (1)" do
+      io = IO::Memory.new
+      writer = Writer.new(io, sync_close: true)
+      writer.close
+      writer.closed?.should be_true
+      io.closed?.should be_true
+    end
+
+    it "can be closed with sync (2)" do
+      io = IO::Memory.new
+      writer = Writer.new(io)
+      writer.sync_close = true
+      writer.close
+      writer.closed?.should be_true
+      io.closed?.should be_true
+    end
+  end
+end
diff --git a/spec/std/gzip/gzip_spec.cr b/spec/std/gzip/gzip_spec.cr
@@ -0,0 +1,46 @@
+require "spec"
+require "gzip"
+
+describe Gzip do
+  it "writes and reads to memory" do
+    io = IO::Memory.new
+
+    time = Time.new(2016, 1, 2)
+    os = 4_u8
+    extra = Bytes[1, 2, 3]
+    name = "foo.txt"
+    comment = "some comment"
+    contents = "hello world"
+
+    Gzip::Writer.open(io) do |gzip|
+      header = gzip.header
+      header.modification_time = time
+      header.os = os
+      header.extra = extra
+      header.name = name
+      header.comment = comment
+
+      io.bytesize.should eq(0)
+      gzip.flush
+      io.bytesize.should_not eq(0)
+
+      gzip.print contents
+    end
+
+    io.rewind
+
+    Gzip::Reader.open(io) do |gzip|
+      header = gzip.header.not_nil!
+      header.modification_time.should eq(time)
+      header.os.should eq(os)
+      header.extra.should eq(extra)
+      header.name.should eq(name)
+      header.comment.should eq(comment)
+
+      # Reading zero bytes is OK
+      gzip.read(Bytes.empty).should eq(0)
+
+      gzip.gets_to_end.should eq(contents)
+    end
+  end
+end
diff --git a/...p/server/handlers/deflate_handler_spec.cr → .../server/handlers/compress_handler_spec.cr b/...p/server/handlers/deflate_handler_spec.cr → .../server/handlers/compress_handler_spec.cr
@@ -1,14 +1,14 @@
 require "spec"
 require "http/server"
 
-describe HTTP::DeflateHandler do
+describe HTTP::CompressHandler do
   it "doesn't deflates if doesn't have 'deflate' in Accept-Encoding header" do
     io = IO::Memory.new
     request = HTTP::Request.new("GET", "/")
     response = HTTP::Server::Response.new(io)
     context = HTTP::Server::Context.new(request, response)
 
-    handler = HTTP::DeflateHandler.new
+    handler = HTTP::CompressHandler.new
     handler.next = HTTP::Handler::Proc.new do |ctx|
       ctx.response.print "Hello"
     end
@@ -27,7 +27,7 @@ describe HTTP::DeflateHandler do
     response = HTTP::Server::Response.new(io)
     context = HTTP::Server::Context.new(request, response)
 
-    handler = HTTP::DeflateHandler.new
+    handler = HTTP::CompressHandler.new
     handler.next = HTTP::Handler::Proc.new do |ctx|
       ctx.response.print "Hello"
     end
@@ -39,7 +39,7 @@ describe HTTP::DeflateHandler do
     body = response2.body
 
     io2 = IO::Memory.new
-    deflate = Zlib::Deflate.new(io2)
+    deflate = Flate::Writer.new(io2)
     deflate.print "Hello"
     deflate.close
     io2.rewind
@@ -55,7 +55,7 @@ describe HTTP::DeflateHandler do
     response = HTTP::Server::Response.new(io)
     context = HTTP::Server::Context.new(request, response)
 
-    handler = HTTP::DeflateHandler.new
+    handler = HTTP::CompressHandler.new
     handler.next = HTTP::Handler::Proc.new do |ctx|
       ctx.response.print "Hello"
     end
@@ -67,7 +67,7 @@ describe HTTP::DeflateHandler do
     body = response2.body
 
     io2 = IO::Memory.new
-    deflate = Zlib::Deflate.gzip(io2)
+    deflate = Gzip::Writer.new(io2)
     deflate.print "Hello"
     deflate.close
     io2.rewind

diff --git a/spec/std/http/server/server_spec.cr b/spec/std/http/server/server_spec.cr
@@ -310,7 +310,7 @@ module HTTP
     server = Server.new("0.0.0.0", 0, [
       ErrorHandler.new,
       LogHandler.new,
-      DeflateHandler.new,
+      CompressHandler.new,
       StaticFileHandler.new("."),
     ]
     )
@@ -329,7 +329,7 @@ module HTTP
     server = Server.new(0, [
       ErrorHandler.new,
       LogHandler.new,
-      DeflateHandler.new,
+      CompressHandler.new,
       StaticFileHandler.new("."),
     ]
     )

diff --git a/spec/std/zip/zip_spec.cr b/spec/std/zip/zip_spec.cr
@@ -59,19 +59,19 @@ describe Zip do
     io = IO::Memory.new
 
     text = "contents of foo"
-    crc32 = Zlib.crc32(text)
+    crc32 = CRC32.checksum(text)
 
     Zip::Writer.open(io) do |zip|
       entry = Zip::Writer::Entry.new("foo.txt")
       entry.compression_method = Zip::CompressionMethod::STORED
-      entry.crc32 = crc32.to_u32
+      entry.crc32 = crc32
       entry.compressed_size = text.bytesize.to_u32
       entry.uncompressed_size = text.bytesize.to_u32
       zip.add entry, &.print(text)
 
       entry = Zip::Writer::Entry.new("bar.txt")
       entry.compression_method = Zip::CompressionMethod::STORED
-      entry.crc32 = crc32.to_u32
+      entry.crc32 = crc32
       entry.compressed_size = text.bytesize.to_u32
       entry.uncompressed_size = text.bytesize.to_u32
       zip.add entry, &.print(text)

diff --git a/spec/std/zlib/deflate_spec.cr b/spec/std/zlib/deflate_spec.cr
diff --git a/spec/std/zlib/inflate_spec.cr b/spec/std/zlib/inflate_spec.cr