Commit 4affafe9 authored by Christian Hesse's avatar Christian Hesse
Browse files

use libmagic to detect valid file formats 

Writing our own magic bytes detection is prone to errors and an
everlasting catch-up-game. Let's use libmagic to get things right,
this is less code and makes things more reliable.

Building without libmagic is still possible. That will make the code
act like specifying FEH_SKIP_MAGIC=1, effectively passing everything
to imlib2.
parent 617e1f3a

README.md

+2 −0
Original line number Diff line number Diff line
@@ -22,6 +22,7 @@ Dependencies 


 * Imlib2

 * libcurl (disable with make curl=0)

 * libmagic (disable with make magic=0)

 * libpng

 * libX11

 * libXinerama (disable with make xinerama=0)
@@ -91,6 +92,7 @@ indicates that the corresponding feature is enabled by default. 
| help | 0 | include help text (refers to the manpage otherwise) |

| inotify | 0 | enable inotify, needed for `--auto-reload` |

| stat64 | 0 | Support CIFS shares from 64bit hosts on 32bit machines |

| magic | 1 | Build against libmagic to filter unsupported file formats |

| mkstemps | 1 | Whether your libc provides `mkstemps()`. If set to 0, feh will be unable to load gif images via libcurl |

| verscmp | 1 | Whether your libc provides `strvercmp()`. If set to 0, feh will use an internal implementation. |

| xinerama | 1 | Support Xinerama/XRandR multiscreen setups |

config.mk

+6 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ curl ?= 1 
debug ?= 0

exif ?= 0

help ?= 0

magic ?= 1

mkstemps ?= 1

verscmp ?= 1

xinerama ?= 1
@@ -68,6 +69,11 @@ ifeq (${mkstemps},1) 
	CFLAGS += -DHAVE_MKSTEMPS

endif



ifeq (${magic},1)

	CFLAGS += -DHAVE_LIBMAGIC

	LDLIBS += -lmagic

endif



ifeq (${verscmp},1)

	CFLAGS += -DHAVE_STRVERSCMP

endif

src/imlib.c

+51 −83
Original line number Diff line number Diff line
@@ -44,6 +44,10 @@ CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 
#include "exif.h"

#endif



#ifdef HAVE_LIBMAGIC

#include <magic.h>

#endif



Display *disp = NULL;

Visual *vis = NULL;

Screen *scr = NULL;
@@ -242,98 +246,62 @@ void feh_print_load_error(char *file, winwidget w, Imlib_Load_Error err, enum fe 
 * avoid calling Imlib2 for files it probably cannot handle. See

 * <https://phab.enlightenment.org/T8739> and

 * <https://github.com/derf/feh/issues/505>.

 *

 * Note that this drops support for bz2-compressed files, unless

 * FEH_SKIP_MAGIC is set

 */

int feh_is_image(feh_file * file)

{

	unsigned char buf[16];

	FILE *fh = fopen(file->filename, "r");

	if (!fh) {

		return 0;

	}

	// Files smaller than buf will be padded with zeroes

	memset(buf, 0, sizeof(buf));

	if (fread(buf, 1, 16, fh) <= 0) {

		fclose(fh);

		return 0;

	}

	fclose(fh);

#ifdef HAVE_LIBMAGIC

	magic_t magic;

	const char * mime_type;

	int is_image = 0;



	if (buf[0] == 0xff && buf[1] == 0xd8) {

		// JPEG

		return 1;

	}

	if (!memcmp(buf, "\x89PNG\x0d\x0a\x1a\x0a", 8)) {

		// PNG

		return 1;

	}

	if (buf[0] == 'A' && buf[1] == 'R' && buf[2] == 'G' && buf[3] == 'B') {

		// ARGB

		return 1;

	}

	if (buf[0] == 'B' && buf[1] == 'M') {

		// BMP

		return 1;

	}

	if (!memcmp(buf, "farbfeld", 8)) {

		// farbfeld

		return 1;

	}

	if (buf[0] == 'G' && buf[1] == 'I' && buf[2] == 'F') {

		// GIF

		return 1;

	}

	if (buf[0] == 0x00 && buf[1] == 0x00 && buf[2] <= 0x02 && buf[3] == 0x00) {

		// ICO

		return 1;

	}

	if (!memcmp(buf, "FORM", 4)) {

		// Amiga IFF ILBM

		return 1;

	}

	if (buf[0] == 'P' && buf[1] >= '1' && buf[1] <= '7') {

		// PNM et al.

	if (getenv("FEH_SKIP_MAGIC")) {

		return 1;

	}

	if (strstr(file->filename, ".tga")) {

		// TGA

		return 1;



	if (!(magic = magic_open(MAGIC_MIME_TYPE | MAGIC_SYMLINK))) {

		weprintf("unable to initialize magic library\n");

		return 0;

	}

	if (!memcmp(buf, "II\x2a\x00", 4) || !memcmp(buf, "MM\x00\x2a", 4)) {

		// TIFF

		return 1;



	if (magic_load(magic, NULL) != 0) {

		weprintf("cannot load magic database: %s\n", magic_error(magic));

		magic_close(magic);

		return 0;

	}

	if (!memcmp(buf, "RIFF", 4)) {

		// might be webp

		return 1;



	mime_type = magic_file(magic, file->filename);



	if (mime_type) {

		D(("file %s has mime type: %s\n", file->filename, mime_type));



		if (strncmp(mime_type, "image/", 6) == 0) {

			is_image = 1;

		}

	if (!memcmp(buf + 4, "ftyphei", 7) || !memcmp(buf + 4, "ftypmif1", 8)) {

		// HEIC/HEIF - note that this is only supported in imlib2-heic. Ordinary

		// imlib2 releases do not support heic/heif images as of 2021-01.

		return 1;



		/* imlib2 supports loading compressed images, let's have a look inside */

		if (strcmp(mime_type, "application/gzip") == 0 ||

		    strcmp(mime_type, "application/x-bzip2") == 0 ||

		    strcmp(mime_type, "application/x-xz") == 0) {

			magic_setflags(magic, magic_getflags(magic) | MAGIC_COMPRESS);

			mime_type = magic_file(magic, file->filename);



			if (mime_type) {

				D(("uncompressed file %s has mime type: %s\n", file->filename, mime_type));



				if (strncmp(mime_type, "image/", 6) == 0) {

					is_image = 1;

				}

	if ((buf[0] == 0xff && buf[1] == 0x0a) || !memcmp(buf, "\x00\x00\x00\x0cJXL \x0d\x0a\x87\x0a", 12)) {

		// JXL - note that this is only supported in imlib2-jxl. Ordinary

		// imlib2 releases do not support JXL images as of 2021-06.

		return 1;

			}

	buf[15] = 0;

	if (strstr((char *)buf, "XPM")) {

		// XPM

		return 1;

		}

	if (strstr(file->filename, ".bz2") || strstr(file->filename, ".gz")) {

		// Imlib2 supports compressed images. It relies on the filename to

		// determine the appropriate loader and does not use magic bytes here.

		return 1;

	}

	// moved to the end as this variable won't be set in most cases

	if (getenv("FEH_SKIP_MAGIC")) {



	magic_close(magic);



	return is_image;

#else

	(void)file;

	return 1;

	}

	return 0;

#endif

}



int feh_load_image(Imlib_Image * im, feh_file * file)