Re: using libmagic in Emacs?

[joakim]

Stefan Monnier <address@hidden> writes:
>
> I think it's a good idea.  It may require some non-trivial changes on
> the Lisp side, since libmagic's information is not quite the same as
> what Emacs currently uses: we'll probably want to use libmagic to get
> a MIME-type and then have a table mapping mime-types to major modes or
> some such.
>
>
>         Stefan

I attach an early draft filemagic patch.

Some notes:

- The mime type info usualy is less granular than the free
text info:

file --mime /tmp/tst.xcf
/tmp/tst.xcf: application/octet-stream; charset=binary

file /tmp/tst.xcf
/tmp/tst.xcf: GIMP XCF image data, version 0, 640 x 480, RGB Color

This is dependent on the file magic info file used.

- We can probably have much fun debating what the interface should look
  like at the lisp level. Any ideas? 

diff --git a/configure.in b/configure.in
index f4096db..cb74523 100644
--- a/configure.in
+++ b/configure.in
@@ -137,6 +137,8 @@ OPTION_DEFAULT_ON([xft],[don't use XFT for anti aliased 
fonts])
 OPTION_DEFAULT_ON([libotf],[don't use libotf for OpenType font support])
 OPTION_DEFAULT_ON([m17n-flt],[don't use m17n-flt for text shaping])
 
+OPTION_DEFAULT_ON([filemagic],[don't compile with filemagic support])
+
 OPTION_DEFAULT_ON([toolkit-scroll-bars],[don't use Motif or Xaw3d scroll bars])
 OPTION_DEFAULT_ON([xaw3d],[don't use Xaw3d])
 OPTION_DEFAULT_ON([xim],[don't use X11 XIM])
@@ -2223,6 +2225,19 @@ if test x"$ac_cv_func_alloca_works" != xyes; then
    AC_MSG_ERROR( [a system implementation of alloca is required] )
 fi
 
+
+HAVE_LIBMAGIC=no
+if test "${with_filemagic}" != "no"; then
+  #libmagic support
+  AC_CHECK_HEADERS(magic.h, [  
AC_CHECK_LIB(magic,magic_open,HAVE_LIBMAGIC=yes) ])
+fi
+
+if test "${HAVE_LIBMAGIC}" = "yes"; then
+  LIBMAGIC=-lmagic
+  AC_SUBST(LIBMAGIC)
+  AC_DEFINE(HAVE_LIBMAGIC, 1, [Define to 1 if using libmagic.])  
+fi
+
 # fmod, logb, and frexp are found in -lm on most systems.
 # On HPUX 9.01, -lm does not contain logb, so check for sqrt.
 AC_CHECK_LIB(m, sqrt)
@@ -2954,6 +2969,7 @@ echo "  Does Emacs use -lpng?                             
      ${HAVE_PNG}"
 echo "  Does Emacs use -lrsvg-2?                                ${HAVE_RSVG}"
 echo "  Does Emacs use -lgpm?                                   ${HAVE_GPM}"
 echo "  Does Emacs use -ldbus?                                  ${HAVE_DBUS}"
+echo "  Does Emacs use -lmagic?                                 
${HAVE_LIBMAGIC}"
 
 echo "  Does Emacs use -lfreetype?                              
${HAVE_FREETYPE}"
 echo "  Does Emacs use -lm17n-flt?                              
${HAVE_M17N_FLT}"
diff --git a/src/Makefile.in b/src/Makefile.in
index 425cf98..b80255a 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -420,6 +420,7 @@ LIBX= $(LIBXMENU) LD_SWITCH_X_SITE
 #endif /* not HAVE_LIBRESOLV */
 
 LIBSOUND= @LIBSOUND@
+LIBMAGIC= @LIBMAGIC@
 CFLAGS_SOUND= @CFLAGS_SOUND@
 
 RSVG_LIBS= @RSVG_LIBS@
@@ -511,6 +512,12 @@ MSDOS_OBJ = dosfns.o msdos.o w16select.o xmenu.o
 #endif
 #endif
 
+#ifdef HAVE_LIBMAGIC
+FILEMAGIC_OBJ = filemagic.o
+#else
+FILEMAGIC_OBJ =
+#endif
+
 #ifdef CYGWIN
 CYGWIN_OBJ = sheap.o
 #endif
@@ -551,7 +558,7 @@ obj=    dispnew.o frame.o scroll.o xdisp.o menu.o 
$(XMENU_OBJ) window.o \
        syntax.o UNEXEC bytecode.o \
        process.o callproc.o \
        region-cache.o sound.o atimer.o \
-       doprnt.o strftime.o intervals.o textprop.o composite.o md5.o \
+       doprnt.o strftime.o intervals.o textprop.o composite.o md5.o 
${FILEMAGIC_OBJ} \
        $(MSDOS_OBJ) $(NS_OBJ) $(CYGWIN_OBJ) $(FONT_DRIVERS)
 
 /* Object files used on some machine or other.
@@ -878,7 +885,7 @@ SOME_MACHINE_LISP = ../lisp/mouse.elc \
    duplicated symbols.  If the standard libraries were compiled
    with GCC, we might need gnulib again after them.  */
 
-LIBES = $(LOADLIBES) $(LIBS) $(LIBX) $(LIBSOUND) $(RSVG_LIBS) $(DBUS_LIBS) \
+LIBES = $(LOADLIBES) $(LIBS) $(LIBX) $(LIBSOUND) $(LIBMAGIC) $(RSVG_LIBS) 
$(DBUS_LIBS) \
    LIBGPM LIBRESOLV LIBS_SYSTEM LIBS_MACHINE LIBS_TERMCAP \
    LIBS_DEBUG $(GETLOADAVG_LIBS) \
    @FREETYPE_LIBS@ @FONTCONFIG_LIBS@ @LIBOTF_LIBS@ @M17N_FLT_LIBS@ \
diff --git a/src/config.in b/src/config.in
index 404e00b..c966a09 100644
--- a/src/config.in
+++ b/src/config.in
@@ -262,6 +262,9 @@ along with GNU Emacs.  If not, see 
<http://www.gnu.org/licenses/>.  */
 /* Define to 1 if you have the gpm library (-lgpm). */
 #undef HAVE_GPM
 
+/* Define to 1 if you have the filemagic library (-lmagic). */
+#undef HAVE_LIBMAGIC
+
 /* Define to 1 if you have the `grantpt' function. */
 #undef HAVE_GRANTPT
 
diff --git a/src/emacs.c b/src/emacs.c
index 657465d..03d7744 100644
--- a/src/emacs.c
+++ b/src/emacs.c
@@ -1683,6 +1683,9 @@ main (int argc, char **argv)
       syms_of_window ();
       syms_of_xdisp ();
       syms_of_font ();
+#ifdef HAVE_LIBMAGIC
+      syms_of_filemagic();
+#endif
 #ifdef HAVE_WINDOW_SYSTEM
       syms_of_fringe ();
       syms_of_image ();
diff --git a/src/filemagic.c b/src/filemagic.c
new file mode 100644
index 0000000..1dcf065
--- /dev/null
+++ b/src/filemagic.c
@@ -0,0 +1,65 @@
+#include <magic.h>
+#include <config.h>
+#include <stdio.h>
+#include <math.h>
+#include <ctype.h>
+
+#include "lisp.h"
+/*
+
+ */
+/*
+     magic_t
+     magic_open(int flags);
+
+     void
+     magic_close(magic_t cookie);
+
+     const char *
+     magic_error(magic_t cookie);
+
+     int
+     magic_errno(magic_t cookie);
+
+     const char *
+     magic_file(magic_t cookie, const char *filename);
+
+     const char *
+     magic_buffer(magic_t cookie, const void *buffer, size_t length);
+
+     int
+     magic_setflags(magic_t cookie, int flags);
+
+     int
+     magic_check(magic_t cookie, const char *filename);
+
+     int
+     magic_compile(magic_t cookie, const char *filename);
+
+     int
+     magic_load(magic_t cookie, const char *filename);
+*/
+
+
+DEFUN ("file-magic-file", Ffile_magic_file, Sfile_magic_file, 1,1,0,
+       doc: /* return libmagic file description for filename */)
+  (filename)
+     Lisp_Object filename;
+{
+  if (!STRINGP (filename)) return Qnil;
+  printf("filename:%s\n",SDATA(filename));
+  magic_t cookie= magic_open(MAGIC_MIME_TYPE);
+  magic_load(cookie,NULL);
+  printf("cookie:%d\n",cookie);
+  char *rvs=magic_file(cookie, SDATA(filename));
+  printf("rvs:%s\n",rvs);  
+  Lisp_Object rv=intern(rvs);
+  magic_close(cookie);
+  return rv;
+}
+
+void
+syms_of_filemagic ()
+{
+  defsubr (&Sfile_magic_file);
+}


-- 
Joakim Verona