Add zlib support via the `decompress-gzipped-region' function

This adds a new file, src/decompress.c, as well as tests for the
presence of -lz.

ChangeLog

+2013-08-11  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* configure.ac: Test for zlib.
+
 2013-08-10  Eli Zaretskii  <eliz@gnu.org>
 
 	* configure.ac: Define and substitute UPDATE_MANIFEST.

configure.ac

@@ -2942,6 +2942,24 @@ elif test "${HAVE_X11}" = "yes" || test "${HAVE_W32}" = "yes"; then
 fi
 AC_SUBST(LIBPNG)
 
+HAVE_ZLIB=no
+LIBZ=
+if test "${HAVE_PNG}" = "yes"; then
+  ### PNG depends on zlib, so if we have PNG, we have zlib.
+  HAVE_ZLIB=yes
+  AC_DEFINE(HAVE_ZLIB, 1, [Define to 1 if you have the zlib library (-lz).])
+else
+  ### No PNG, so check zlib ourselves.
+  LIBS="-lz $LIBS"
+  AC_CHECK_LIB(z, inflateEnd, HAVE_ZLIB=yes, HAVE_ZLIB=no)
+  if test "${HAVE_ZLIB}" = "yes"; then
+    AC_DEFINE(HAVE_ZLIB, 1, [Define to 1 if you have the zlib library (-lz).])
+    LIBZ=-lz
+  fi
+fi
+AC_SUBST(LIBZ)
+
+
 ### Use -ltiff if available, unless `--with-tiff=no'.
 ### mingw32 doesn't use -ltiff, since it loads the library dynamically.
 HAVE_TIFF=no

etc/ChangeLog

+2013-08-11  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* NEWS: Mention -lz and `decompress-gzipped-region'.
+
 2013-08-08  Juanma Barranquero  <lekktu@gmail.com>
 
 	* NEWS: Document new keybinding of `C-x r f' to frameset-to-register.

etc/NEWS

@@ -41,6 +41,10 @@ specially.
 ** Directories passed to configure option `--enable-locallisppath' are
 no longer created during installation.
 
+** Emacs can be compiled with zlib support.  If this library is present
+(which it normally is on most systems), the function
+`decompress-gzipped-region' becomes available.
+
 ---
 ** Emacs for NS (OSX, GNUStep) can be built with ImageMagick support.
 pkg-config is required to find ImageMagick libraries.

src/ChangeLog

+2013-08-11  Lars Magne Ingebrigtsen  <larsi@gnus.org>
+
+	* lisp.h: Include decompress.c support.
+
+	* emacs.c (main): Include decompress.c support.
+
+	* Makefile.in: Include -lz if present.
+
 2013-08-11  Jan Djärv  <jan.h.d@swipnet.se>
 
 	* nsmenu.m (ns_update_menubar): Call fillWithWidgetValue:frame:

src/Makefile.in

@@ -243,6 +243,8 @@ IMAGEMAGICK_CFLAGS= @IMAGEMAGICK_CFLAGS@
 LIBXML2_LIBS = @LIBXML2_LIBS@
 LIBXML2_CFLAGS = @LIBXML2_CFLAGS@
 
+LIBZ = @LIBZ@
+
 XRANDR_LIBS = @XRANDR_LIBS@
 XRANDR_CFLAGS = @XRANDR_CFLAGS@
 
@@ -374,7 +376,7 @@ base_obj = dispnew.o frame.o scroll.o xdisp.o menu.o $(XMENU_OBJ) window.o \
 	process.o gnutls.o callproc.o \
 	region-cache.o sound.o atimer.o \
 	doprnt.o intervals.o textprop.o composite.o xml.o $(NOTIFY_OBJ) \
-	profiler.o \
+	profiler.o decompress.o \
 	$(MSDOS_OBJ) $(MSDOS_X_OBJ) $(NS_OBJ) $(CYGWIN_OBJ) $(FONT_OBJ) \
 	$(W32_OBJ) $(WINDOW_SYSTEM_OBJ) $(XGSELOBJ)
 obj = $(base_obj) $(NS_OBJC_OBJ)
@@ -429,7 +431,7 @@ LIBES = $(LIBS) $(W32_LIBS) $(LIBS_GNUSTEP) $(LIBX_BASE) $(LIBIMAGE) \
    $(LIBS_TERMCAP) $(GETLOADAVG_LIBS) $(SETTINGS_LIBS) $(LIBSELINUX_LIBS) \
    $(FREETYPE_LIBS) $(FONTCONFIG_LIBS) $(LIBOTF_LIBS) $(M17N_FLT_LIBS) \
    $(LIBGNUTLS_LIBS) $(LIB_PTHREAD) $(LIB_PTHREAD_SIGMASK) \
-   $(GFILENOTIFY_LIBS) $(LIB_MATH)
+   $(GFILENOTIFY_LIBS) $(LIB_MATH) $(LIBZ)
 
 all: emacs$(EXEEXT) $(OTHER_FILES)
 .PHONY: all

src/decompress.c

+/* 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"
+
+
+#define BUFFER_SIZE 16384
+
+struct decompress_unwind_data {
+  ptrdiff_t old_point, start;
+  z_stream *stream;
+};
+
+static void
+unwind_decompress (void *ddata) {
+  struct decompress_unwind_data *data = ddata;
+  inflateEnd (data->stream);
+  /* Delete any uncompressed data already inserted and restore
+     point. */
+  if (data->start) {
+    del_range (data->start, PT);
+    SET_PT (data->old_point);
+  }
+}
+
+DEFUN ("decompress-gzipped-region", Fdecompress_gzipped_region,
+       Sdecompress_gzipped_region,
+       2, 2, 0,
+       doc: /* Decompress a gzip-compressed region.
+The text in the region will be replaced by the decompressed data.
+On failure, nil is returned and the data is left in place.
+This function can only be called in unibyte buffers.*/)
+  (Lisp_Object start, Lisp_Object end)
+{
+  ptrdiff_t istart, iend, point = PT;
+  z_stream stream;
+  int decompressed;
+  char out[16384];
+  struct decompress_unwind_data unwind_data;
+  ptrdiff_t count = SPECPDL_INDEX ();
+
+  validate_region (&start, &end);
+  move_gap_both (iend, iend);
+
+  if (! NILP (BVAR (current_buffer, enable_multibyte_characters)))
+    error ("This function can only be called in unibyte buffers");
+
+  /* This is a unibyte buffer, so character positions and bytes are
+     the same. */
+  istart = XINT (start);
+  iend = XINT (end);
+
+  stream.zalloc = Z_NULL;
+  stream.zfree = Z_NULL;
+  stream.opaque = Z_NULL;
+  stream.avail_in = 0;
+  stream.next_in = Z_NULL;
+
+  /* This magic number apparently means "this is gzip". */
+  if (inflateInit2 (&stream, 16 + MAX_WBITS) != Z_OK)
+    return Qnil;
+
+  /* We're inserting the decompressed data at the end of the
+     compressed data. */
+  SET_PT (iend);
+
+  stream.avail_in = iend - istart;
+  stream.next_in = (char *) BYTE_POS_ADDR (istart);
+
+  unwind_data.start = iend;
+  unwind_data.stream = &stream;
+  unwind_data.old_point = point;
+  record_unwind_protect_ptr (unwind_decompress, &unwind_data);
+
+  immediate_quit = 1;
+
+  /* Run inflate() on input until the output buffer isn't full. */
+  do {
+    stream.avail_out = BUFFER_SIZE;
+    stream.next_out = out;
+    switch (inflate (&stream, Z_NO_FLUSH)) {
+    case Z_STREAM_ERROR:
+    case Z_NEED_DICT:
+    case Z_DATA_ERROR:
+    case Z_MEM_ERROR:
+      unbind_to (count, Qnil);
+      return Qnil;
+    }
+
+    decompressed = BUFFER_SIZE - stream.avail_out;
+    insert_1_both (out, decompressed, decompressed, 0, 0, 0);
+    QUIT;
+  } while (stream.avail_out == 0);
+
+  immediate_quit = 0;
+
+  unwind_data.start = 0;
+  unbind_to (count, Qnil);
+
+  /* Delete the compressed data. */
+  del_range (istart, iend);
+
+  return Qt;
+}
+
+
+/***********************************************************************
+			    Initialization
+ ***********************************************************************/
+void
+syms_of_decompress (void)
+{
+  defsubr (&Sdecompress_gzipped_region);
+}
+
+#endif /* HAVE_ZLIB */

src/emacs.c

@@ -1406,6 +1406,10 @@ Using an Emacs configured with --with-x-toolkit=lucid does not have this problem
       syms_of_xml ();
 #endif
 
+#ifdef HAVE_ZLIB
+      syms_of_decompress ();
+#endif
+
       syms_of_menu ();
 
 #ifdef HAVE_NTGUI

src/lisp.h

@@ -4213,6 +4213,11 @@ extern void syms_of_xml (void);
 extern void xml_cleanup_parser (void);
 #endif
 
+#ifdef HAVE_ZLIB
+/* Defined in decompress.c.  */
+extern void syms_of_decompress (void);
+#endif
+
 #ifdef HAVE_DBUS
 /* Defined in dbusbind.c.  */
 void syms_of_dbusbind (void);