account for truncated/expanded static files

When running a static file server, we must account for filesystem
activity outside of our control where files may grow/shrink as
they're being served.

For truncated files, we must abort any persistent connections
downloading a truncated file to avoid confusing clients because
the Content-Length header was already set to the big value.

We also must ensure (we already did so before this commit,
this just adds a test for it) we do not send additional data
when a file grows on us after we've started sending the response.

1 files changed, 61 insertions, 0 deletions

diff --git a/test/test_serve_static.rb b/test/test_serve_static.rb
index b1817f7..4f33b6f 100644
--- a/test/test_serve_static.rb
+++ b/test/test_serve_static.rb
@@ -73,4 +73,65 @@ class TestServeStatic < Testcase
   ensure
     quit_wait(pid)
   end
+
+  def mksparse(tmpdir)
+    sparse = "#{tmpdir}/sparse"
+    off = 100 * 1024 * 1024
+    File.open(sparse, "w") do |fp|
+      fp.sysseek(off)
+      fp.syswrite '.'
+    end
+    [ off + 1, sparse ]
+  end
+
+  def test_truncated_sendfile
+    tmpdir = Dir.mktmpdir
+    size, sparse = mksparse(tmpdir)
+    err, cfg, host, port = @err, Yahns::Config.new, @srv.addr[3], @srv.addr[1]
+    pid = mkserver(cfg) do
+      cfg.instance_eval do
+        app(:rack, Rack::File.new(tmpdir)) { listen "#{host}:#{port}" }
+        stderr_path err.path
+      end
+    end
+    c = get_tcp_client(host, port)
+    c.write "GET /sparse HTTP/1.1\r\nHost: example.com\r\n\r\n"
+    wait_for_full(c)
+    File.truncate(sparse, 5)
+    buf = Timeout.timeout(60) { c.read }
+    c.close
+    assert_operator buf.size, :<, size
+  ensure
+    quit_wait(pid)
+    FileUtils.rm_rf(tmpdir)
+  end
+
+  def test_expanded_sendfile
+    tmpdir = Dir.mktmpdir
+    size, sparse = mksparse(tmpdir)
+    err, cfg, host, port = @err, Yahns::Config.new, @srv.addr[3], @srv.addr[1]
+    pid = mkserver(cfg) do
+      cfg.instance_eval do
+        app(:rack, Rack::File.new(tmpdir)) { listen "#{host}:#{port}" }
+        stderr_path err.path
+      end
+    end
+    c = get_tcp_client(host, port)
+    c.write "GET /sparse\r\n\r\n"
+    wait_for_full(c)
+
+    File.open(sparse, "w") do |fp|
+      fp.sysseek(size * 2)
+      fp.syswrite '.'
+    end
+    Timeout.timeout(60) do
+      bytes = IO.copy_stream(c, "/dev/null")
+      assert_equal bytes, size
+      assert_raises(EOFError) { c.readpartial 1 }
+    end
+    c.close
+  ensure
+    quit_wait(pid)
+    FileUtils.rm_rf(tmpdir)
+  end
 end