1 files changed, 232 insertions, 0 deletions

diff --git a/src/decompress.c b/src/decompress.c
new file mode 100644
index 00000000000..dc9f4b72d93
--- /dev/null
+++ b/src/decompress.c
@@ -0,0 +1,232 @@
+/* Interface to zlib.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+
+This file is part of GNU Emacs.
+
+GNU Emacs is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+GNU Emacs is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <config.h>
+
+#ifdef HAVE_ZLIB
+
+#include <zlib.h>
+
+#include "lisp.h"
+#include "character.h"
+#include "buffer.h"
+
+#include <verify.h>
+
+static Lisp_Object Qzlib_dll;
+
+#ifdef WINDOWSNT
+#include <windows.h>
+#include "w32.h"
+
+/* Macro for defining functions that will be loaded from the zlib DLL.  */
+#define DEF_ZLIB_FN(rettype,func,args) static rettype (FAR CDECL *fn_##func)args
+
+/* Macro for loading zlib functions from the library.  */
+#define LOAD_ZLIB_FN(lib,func) {                                        \
+    fn_##func = (void *) GetProcAddress (lib, #func);                   \
+    if (!fn_##func) return false;                                       \
+  }
+
+DEF_ZLIB_FN (int, inflateInit2_,
+             (z_streamp strm, int  windowBits, const char *version, int stream_size));
+
+DEF_ZLIB_FN (int, inflate,
+             (z_streamp strm, int flush));
+
+DEF_ZLIB_FN (int, inflateEnd,
+             (z_streamp strm));
+
+static bool zlib_initialized;
+
+static bool
+init_zlib_functions (void)
+{
+  HMODULE library = w32_delayed_load (Qzlib_dll);
+
+  if (!library)
+    {
+      message1 ("zlib library not found");
+      return false;
+    }
+
+  LOAD_ZLIB_FN (library, inflateInit2_);
+  LOAD_ZLIB_FN (library, inflate);
+  LOAD_ZLIB_FN (library, inflateEnd);
+  return true;
+}
+
+#define fn_inflateInit2(strm, windowBits) \
+        fn_inflateInit2_((strm), (windowBits), ZLIB_VERSION, sizeof(z_stream))
+
+#else /* !WINDOWSNT */
+
+#define fn_inflateInit2         inflateInit2
+#define fn_inflate              inflate
+#define fn_inflateEnd           inflateEnd
+
+#endif  /* WINDOWSNT */
+
+
+struct decompress_unwind_data
+{
+  ptrdiff_t old_point, start, nbytes;
+  z_stream *stream;
+};
+
+static void
+unwind_decompress (void *ddata)
+{
+  struct decompress_unwind_data *data = ddata;
+  fn_inflateEnd (data->stream);
+
+  /* Delete any uncompressed data already inserted on error.  */
+  if (data->start)
+    del_range (data->start, data->start + data->nbytes);
+
+  /* Put point where it was, or if the buffer has shrunk because the
+     compressed data is bigger than the uncompressed, at
+     point-max.  */
+  SET_PT (min (data->old_point, ZV));
+}
+
+DEFUN ("zlib-available-p", Fzlib_available_p, Szlib_available_p, 0, 0, 0,
+       doc: /* Return t if zlib decompression is available in this instance of Emacs.  */)
+     (void)
+{
+#ifdef WINDOWSNT
+  Lisp_Object found = Fassq (Qzlib_dll, Vlibrary_cache);
+  if (CONSP (found))
+    return XCDR (found);
+  else
+    {
+      Lisp_Object status;
+      zlib_initialized = init_zlib_functions ();
+      status = zlib_initialized ? Qt : Qnil;
+      Vlibrary_cache = Fcons (Fcons (Qzlib_dll, status), Vlibrary_cache);
+      return status;
+    }
+#else
+  return Qt;
+#endif
+}
+
+DEFUN ("zlib-decompress-region", Fzlib_decompress_region,
+       Szlib_decompress_region,
+       2, 2, 0,
+       doc: /* Decompress a gzip- or zlib-compressed region.
+Replace the text in the region by the decompressed data.
+On failure, return nil and leave the data in place.
+This function can be called only in unibyte buffers.  */)
+  (Lisp_Object start, Lisp_Object end)
+{
+  ptrdiff_t istart, iend, pos_byte;
+  z_stream stream;
+  int inflate_status;
+  struct decompress_unwind_data unwind_data;
+  ptrdiff_t count = SPECPDL_INDEX ();
+
+  validate_region (&start, &end);
+
+  if (! NILP (BVAR (current_buffer, enable_multibyte_characters)))
+    error ("This function can be called only in unibyte buffers");
+
+#ifdef WINDOWSNT
+  if (!zlib_initialized)
+    zlib_initialized = init_zlib_functions ();
+  if (!zlib_initialized)
+    return Qnil;
+#endif
+
+  /* This is a unibyte buffer, so character positions and bytes are
+     the same.  */
+  istart = XINT (start);
+  iend = XINT (end);
+  move_gap_both (iend, iend);
+
+  stream.zalloc = Z_NULL;
+  stream.zfree = Z_NULL;
+  stream.opaque = Z_NULL;
+  stream.avail_in = 0;
+  stream.next_in = Z_NULL;
+
+  /* The magic number 32 apparently means "autodetect both the gzip and
+     zlib formats" according to zlib.h.  */
+  if (fn_inflateInit2 (&stream, MAX_WBITS + 32) != Z_OK)
+    return Qnil;
+
+  unwind_data.start = iend;
+  unwind_data.stream = &stream;
+  unwind_data.old_point = PT;
+  unwind_data.nbytes = 0;
+  record_unwind_protect_ptr (unwind_decompress, &unwind_data);
+
+  /* Insert the decompressed data at the end of the compressed data.  */
+  SET_PT (iend);
+
+  pos_byte = istart;
+
+  /* Keep calling 'inflate' until it reports an error or end-of-input.  */
+  do
+    {
+      /* Maximum number of bytes that one 'inflate' call should read and write.
+         Do not make avail_out too large, as that might unduly delay C-g.
+         zlib requires that avail_in and avail_out not exceed UINT_MAX.  */
+      ptrdiff_t avail_in = min (iend - pos_byte, UINT_MAX);
+      int avail_out = 16 * 1024;
+      int decompressed;
+
+      if (GAP_SIZE < avail_out)
+        make_gap (avail_out - GAP_SIZE);
+      stream.next_in = BYTE_POS_ADDR (pos_byte);
+      stream.avail_in = avail_in;
+      stream.next_out = GPT_ADDR;
+      stream.avail_out = avail_out;
+      inflate_status = fn_inflate (&stream, Z_NO_FLUSH);
+      pos_byte += avail_in - stream.avail_in;
+      decompressed = avail_out - stream.avail_out;
+      insert_from_gap (decompressed, decompressed, 0);
+      unwind_data.nbytes += decompressed;
+      QUIT;
+    }
+  while (inflate_status == Z_OK);
+
+  if (inflate_status != Z_STREAM_END)
+    return unbind_to (count, Qnil);
+
+  unwind_data.start = 0;
+
+  /* Delete the compressed data.  */
+  del_range (istart, iend);
+
+  return unbind_to (count, Qt);
+}
+
+
+/***********************************************************************
+                            Initialization
+ ***********************************************************************/
+void
+syms_of_decompress (void)
+{
+  DEFSYM (Qzlib_dll, "zlib");
+  defsubr (&Szlib_decompress_region);
+  defsubr (&Szlib_available_p);
+}
+
+#endif /* HAVE_ZLIB */