Implementing automatic .gz support for https and pipe URIs

src/tl/tl/tlHttpStream.h

@@ -112,7 +112,6 @@ public:
    *  @brief Polling: call this function regularly to explicitly establish polling
    *  (in the Qt framework, this is done automatically within the event loop)
    *  May throw a tl::CancelException to stop.
-   *  Returns true if a message has arrived.
    */
   void tick ();
 
@@ -209,6 +208,21 @@ private:
   InputHttpStreamCallback *mp_callback;
 };
 
+/**
+ *  @brief A HTTP stream with .gz support
+ */
+class TL_PUBLIC InflatingInputHttpStream
+  : public inflating_input_stream<InputHttpStream>
+{
+public:
+  /**
+   *  @brief Open a stream with the given URL
+   */
+  InflatingInputHttpStream (const std::string &url)
+    : inflating_input_stream<InputHttpStream> (new InputHttpStream (url))
+  { }
+};
+
 }
 
 #endif

src/tl/tl/tlStream.cc

@@ -140,6 +140,125 @@ public:
   gzFile zs;
 };
 
+// ---------------------------------------------------------------
+//  inflating_input_stream implementation
+
+/**
+ *  @brief A wrapper that adds generic .gz support
+ */
+template <class Base>
+inflating_input_stream<Base>::inflating_input_stream (Base *delegate)
+  : m_inflating_stream (delegate), m_is_compressed (false), mp_delegate (delegate)
+{
+  enter_inflate ();
+}
+
+template <class Base>
+size_t
+inflating_input_stream<Base>::read (char *b, size_t n)
+{
+  //  TODO: this is somewhat inefficient, but we only use it for pipe and HTTP streams
+  size_t i = 0;
+  while (i < n) {
+
+    if (m_is_compressed || m_inflating_stream.blen () == 0) {
+
+      const char *read = m_inflating_stream.get (1);
+      if (! read) {
+        break;
+      }
+      *b++ = *read;
+      i += 1;
+
+    } else {
+
+      size_t nn = std::min (n - i, m_inflating_stream.blen ());
+      const char *read = m_inflating_stream.get (nn);
+      tl_assert (read != 0);
+      memcpy (b, read, nn);
+      b += nn;
+      i += nn;
+
+    }
+
+  }
+  return i;
+}
+
+template <class Base>
+void
+inflating_input_stream<Base>::enter_inflate ()
+{
+  //  identify and skip header for .gz file
+  if (auto_detect_gz ()) {
+    m_is_compressed = true;
+    m_inflating_stream.inflate (true /* stop after inflated block */);
+  } else {
+    m_inflating_stream.unget (m_inflating_stream.pos ());
+  }
+}
+
+template <class Base>
+bool
+inflating_input_stream<Base>::auto_detect_gz ()
+{
+  std::string header = m_inflating_stream.read_all (10);
+  if (header.size () < 10) {
+    return false;
+  }
+
+  const unsigned char *header_data = (const unsigned char *) header.c_str ();
+  unsigned char flags = header_data[3];
+  if (header_data[0] != 0x1f || header_data[1] != 0x8b || header_data[2] != 0x08 || (flags & 0xe0) != 0) {
+    return false;
+  }
+
+  //  .gz signature found
+
+  bool has_fhcrc = (flags & 0x02) != 0;
+  bool has_extra = (flags & 0x04) != 0;
+  bool has_fname = (flags & 0x08) != 0;
+  bool has_comment = (flags & 0x10) != 0;
+
+  if (has_extra) {
+    const unsigned char *xlen = (const unsigned char *) m_inflating_stream.get (2);
+    if (! xlen) {
+      throw tl::Exception (tl::to_string (tr ("Corrupt .gz header - missing XLEN field")));
+    }
+    const char *xdata = m_inflating_stream.get (size_t (xlen[0]) + (size_t (xlen[1]) << 8));
+    if (! xdata) {
+      throw tl::Exception (tl::to_string (tr ("Corrupt .gz header - missing EXTRA data")));
+    }
+  }
+
+  if (has_fname) {
+    const char *c;
+    while ((c = m_inflating_stream.get (1)) != 0 && *c)
+      ;
+    if (! c) {
+      throw tl::Exception (tl::to_string (tr ("Corrupt .gz header - missing FNAME data trailing zero byte")));
+    }
+  }
+
+  if (has_comment) {
+    const char *c;
+    while ((c = m_inflating_stream.get (1)) != 0 && *c)
+      ;
+    if (! c) {
+      throw tl::Exception (tl::to_string (tr ("Corrupt .gz header - missing COMMENT data trailing zero byte")));
+    }
+  }
+
+  if (has_fhcrc) {
+    const char *crc16 = m_inflating_stream.get (2);
+    if (! crc16) {
+      throw tl::Exception (tl::to_string (tr ("Corrupt .gz header - missing CRC16 data")));
+    }
+  }
+
+  return true;
+}
+
 // ---------------------------------------------------------------
 //  InputStream implementation
 
@@ -175,7 +294,7 @@ public:
 }
 
 InputStream::InputStream (InputStreamBase &delegate)
-  : m_pos (0), mp_bptr (0), mp_delegate (&delegate), m_owns_delegate (false), mp_inflate (0), m_inflate_always (false)
+  : m_pos (0), mp_bptr (0), mp_delegate (&delegate), m_owns_delegate (false), mp_inflate (0), m_inflate_always (false), m_stop_after_inflate (false)
 { 
   m_bcap = 4096; // initial buffer capacity
   m_blen = 0;
@@ -183,7 +302,7 @@ InputStream::InputStream (InputStreamBase &delegate)
 }
 
 InputStream::InputStream (InputStreamBase *delegate)
-  : m_pos (0), mp_bptr (0), mp_delegate (delegate), m_owns_delegate (true), mp_inflate (0), m_inflate_always (false)
+  : m_pos (0), mp_bptr (0), mp_delegate (delegate), m_owns_delegate (true), mp_inflate (0), m_inflate_always (false), m_stop_after_inflate (false)
 {
   m_bcap = 4096; // initial buffer capacity
   m_blen = 0;
@@ -191,7 +310,7 @@ InputStream::InputStream (InputStreamBase *delegate)
 }
 
 InputStream::InputStream (const std::string &abstract_path)
-  : m_pos (0), mp_bptr (0), mp_delegate (0), m_owns_delegate (false), mp_inflate (0), m_inflate_always (false)
+  : m_pos (0), mp_bptr (0), mp_delegate (0), m_owns_delegate (false), mp_inflate (0), m_inflate_always (false), m_stop_after_inflate (false)
 { 
   m_bcap = 4096; // initial buffer capacity
   m_blen = 0;
@@ -252,7 +371,7 @@ InputStream::InputStream (const std::string &abstract_path)
 
   } else if (ex.test ("pipe:")) {
 
-    mp_delegate = new InputPipe (ex.get ());
+    mp_delegate = new InflatingInputPipe (ex.get ());
 
   } else {
 
@@ -260,7 +379,7 @@ InputStream::InputStream (const std::string &abstract_path)
 
     if (uri.scheme () == "http" || uri.scheme () == "https") {
 #if defined(HAVE_CURL) || defined(HAVE_QT)
-      mp_delegate = new InputHttpStream (abstract_path);
+      mp_delegate = new InflatingInputHttpStream (abstract_path);
 #else
       throw tl::Exception (tl::to_string (tr ("HTTP support not enabled - HTTP/HTTPS paths are not available")));
 #endif
@@ -337,9 +456,16 @@ InputStream::get (size_t n, bool bypass_inflate)
       tl_assert (r != 0);  //  since deflate did not report at_end()
       return r;
 
+    } else if (m_stop_after_inflate) {
+
+      //  report EOF after the inflator has finished
+      return 0;
+
     } else {
+
       delete mp_inflate;
       mp_inflate = 0;
+
     }
   }
 
@@ -384,9 +510,16 @@ InputStream::get (size_t n, bool bypass_inflate)
 void
 InputStream::unget (size_t n)
 {
+  if (n == 0) {
+    return;
+  }
+
   if (mp_inflate) {
+    //  TODO: this will not work if mp_inflate just got destroyed
+    //  (no unget into previous compressed block)
     mp_inflate->unget (n);
   } else {
+    tl_assert (mp_buffer + n <= mp_bptr);
     mp_bptr -= n;
     m_blen += n;
     m_pos -= n;
@@ -476,10 +609,11 @@ void InputStream::copy_to (tl::OutputStream &os)
 }
 
 void
-InputStream::inflate ()
+InputStream::inflate (bool stop_after)
 {
   tl_assert (mp_inflate == 0);
   mp_inflate = new tl::InflateFilter (*this);
+  m_stop_after_inflate = stop_after;
 }
 
 void

src/tl/tl/tlStream.h

@@ -310,8 +310,7 @@ public:
    *  an error occurs - commonly if the command cannot be executed.
    *  This implementation is based on popen ().
    *
-   *  @param cmd The command to execute
+   *  @param source The command to execute
-   *  @param read True, if the file should be read, false on write.
    */
   InputPipe (const std::string &source);
 
@@ -473,8 +472,11 @@ public:
    *  the uncompressed data rather than the raw data, until the
    *  compressed block is finished.
    *  The stream must not be in inflate state yet.
+   *
+   *  If "stop_after" is true, the stream will stop after the inflated
+   *  block has finished.
    */
-  void inflate ();
+  void inflate (bool stop_after = false);
 
   /**
    *  @brief Enables "inflate" right from the beginning
@@ -577,12 +579,87 @@ private:
   //  inflate support 
   InflateFilter *mp_inflate;
   bool m_inflate_always;
+  bool m_stop_after_inflate;
 
   //  No copying currently
   InputStream (const InputStream &);
   InputStream &operator= (const InputStream &);
 };
 
+/**
+ *  @brief A wrapper that adds generic .gz support
+ */
+template <class Base>
+class TL_PUBLIC_TEMPLATE inflating_input_stream
+  : public InputStreamBase
+{
+public:
+  inflating_input_stream (Base *delegate);
+
+  Base *delegate ()
+  {
+    return mp_delegate;
+  }
+
+  virtual size_t read (char *b, size_t n);
+
+  virtual void reset ()
+  {
+    m_inflating_stream.reset ();
+    enter_inflate ();
+  }
+
+  virtual void close ()
+  {
+    m_inflating_stream.close ();
+  }
+
+  virtual std::string source () const
+  {
+    return m_inflating_stream.source ();
+  }
+
+  virtual std::string absolute_path () const
+  {
+    return m_inflating_stream.absolute_path ();
+  }
+
+  virtual std::string filename () const
+  {
+    return m_inflating_stream.filename ();
+  }
+
+private:
+  tl::InputStream m_inflating_stream;
+  bool m_is_compressed;
+  Base *mp_delegate;
+
+  void enter_inflate ();
+  bool auto_detect_gz ();
+};
+
+/**
+ *  @brief A pipe stream with .gz support
+ */
+class TL_PUBLIC InflatingInputPipe
+  : public inflating_input_stream<InputPipe>
+{
+public:
+  /**
+   *  @brief Open a stream by connecting with the stdout of a given command
+   *
+   *  Opening a pipe is a prerequisite for reading from the
+   *  object. open() will throw a FilePOpenErrorException if
+   *  an error occurs - commonly if the command cannot be executed.
+   *  This implementation is based on popen ().
+   *
+   *  @param source The command to execute
+   */
+  InflatingInputPipe (const std::string &source)
+    : inflating_input_stream<InputPipe> (new InputPipe (source))
+  { }
+};
+
 // ---------------------------------------------------------------------------------
 
 /**

src/tl/unit_tests/tlHttpStreamTests.cc

@@ -24,8 +24,10 @@
 #include "tlHttpStream.h"
 #include "tlUnitTest.h"
 #include "tlTimer.h"
+#include "tlStream.h"
 
 static std::string test_url1 ("http://www.klayout.org/svn-public/klayout-resources/trunk/testdata/text");
+static std::string test_url1_gz ("http://www.klayout.org/svn-public/klayout-resources/trunk/testdata/text.gz");
 static std::string test_url2 ("http://www.klayout.org/svn-public/klayout-resources/trunk/testdata/dir1");
 
 TEST(1)
@@ -125,3 +127,29 @@ TEST(3)
   EXPECT_EQ (res, "hello, world.\n");
 }
 
+//  tl::Stream embedding
+TEST(4)
+{
+  if (! tl::InputHttpStream::is_available ()) {
+    throw tl::CancelException ();
+  }
+
+  tl::InputStream stream (test_url1);
+
+  std::string res = stream.read_all ();
+  EXPECT_EQ (res, "hello, world.\n");
+}
+
+//  tl::Stream embedding with automatic unzip
+TEST(5)
+{
+  if (! tl::InputHttpStream::is_available ()) {
+    throw tl::CancelException ();
+  }
+
+  tl::InputStream stream (test_url1_gz);
+
+  std::string res = stream.read_all ();
+  EXPECT_EQ (res, "hello, world.\n");
+}
+

src/tl/unit_tests/tlStreamTests.cc

@@ -52,6 +52,13 @@ TEST(InputPipe2)
   EXPECT_NE (ret, 0);
 }
 
+TEST(InputPipe3)
+{
+  tl::InputStream str ("pipe:echo HELLOWORLD");
+  tl::TextInputStream tstr (str);
+  EXPECT_EQ (tstr.get_line (), "HELLOWORLD");
+}
+
 TEST(OutputPipe1)
 {
   std::string tf = tmp_file ("pipe_out");
@@ -455,3 +462,5 @@ TEST(Backups)
   }
 }
 
+
+