From 2d37cd91c6718316188e7fd99088cda0e627db74 Mon Sep 17 00:00:00 2001
From: Daniel Friesel <derf@finalrewind.org>
Date: Mon, 30 Nov 2020 19:21:43 +0100
Subject: Check magic bytes before passing a file to Imlib2's loader
This works around a regression in Imlib2, which makes (un)loadable file
detection quite slow when handling e.g. large video files. See
<https://phab.enlightenment.org/T8739> and
<https://github.com/derf/feh/issues/505> for details.
Closes #505
---
src/imlib.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 100 insertions(+), 3 deletions(-)
(limited to 'src')
diff --git a/src/imlib.c b/src/imlib.c
index e06a813..4e8e790 100644
--- a/src/imlib.c
+++ b/src/imlib.c
@@ -181,7 +181,11 @@ void feh_imlib_print_load_error(char *file, winwidget w, Imlib_Load_Error err)
break;
case IMLIB_LOAD_ERROR_UNKNOWN:
case IMLIB_LOAD_ERROR_NO_LOADER_FOR_FILE_FORMAT:
- im_weprintf(w, "%s - No Imlib2 loader for that file format", file);
+ if (getenv("FEH_SKIP_MAGIC")) {
+ im_weprintf(w, "%s - No Imlib2 loader for that file format", file);
+ } else {
+ im_weprintf(w, "%s - Does not look like an image (magic bytes missing)", file);
+ }
break;
case IMLIB_LOAD_ERROR_PATH_TOO_LONG:
im_weprintf(w, "%s - Path specified is too long", file);
@@ -215,6 +219,94 @@ void feh_imlib_print_load_error(char *file, winwidget w, Imlib_Load_Error err)
}
}
+/*
+ * This is a workaround for an Imlib2 regression, causing unloadable image
+ * detection to be excessively slow (and, thus, causing feh to hang for a while
+ * when encountering an unloadable image). We use magic byte detection to
+ * 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;
+ }
+ if (fread(buf, 1, 16, fh) != 16) {
+ return 0;
+ }
+ fclose(fh);
+
+ 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.
+ return 1;
+ }
+ if (strstr(file->filename, ".tga")) {
+ // TGA
+ return 1;
+ }
+ if (!memcmp(buf, "II\x2a\x00", 4) || !memcmp(buf, "MM\x00\x2a", 4)) {
+ // TIFF
+ return 1;
+ }
+ if (!memcmp(buf, "RIFF", 4)) {
+ // might be webp
+ 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")) {
+ return 1;
+ }
+ return 0;
+}
+
int feh_load_image(Imlib_Image * im, feh_file * file)
{
Imlib_Load_Error err = IMLIB_LOAD_ERROR_NONE;
@@ -239,8 +331,13 @@ int feh_load_image(Imlib_Image * im, feh_file * file)
if (!tmpname)
err = IMLIB_LOAD_ERROR_NO_LOADER_FOR_FILE_FORMAT;
}
- else
- *im = imlib_load_image_with_error_return(file->filename, &err);
+ else {
+ if (feh_is_image(file)) {
+ *im = imlib_load_image_with_error_return(file->filename, &err);
+ } else {
+ err = IMLIB_LOAD_ERROR_NO_LOADER_FOR_FILE_FORMAT;
+ }
+ }
if (opt.conversion_timeout >= 0 && (
(err == IMLIB_LOAD_ERROR_UNKNOWN) ||
--
cgit v1.2.3