From 2d37cd91c6718316188e7fd99088cda0e627db74 Mon Sep 17 00:00:00 2001 From: Daniel Friesel 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 and for details. Closes #505 --- man/feh.pre | 17 ++++++++++ src/imlib.c | 103 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-- test/feh.t | 2 +- 3 files changed, 118 insertions(+), 4 deletions(-) diff --git a/man/feh.pre b/man/feh.pre index d44f600..6dfa9e7 100644 --- a/man/feh.pre +++ b/man/feh.pre @@ -162,6 +162,23 @@ Use .Cm --conversion-timeout Ar timeout with a non-negative value to enable support for these formats. . +.Pp +. +As Imlib2 may take several seconds to determine whether it can load a file or +not +.Pq e.g. when attempting to open a large video , +.Nm +checks each file's header before loading it. +If it looks like an image, it is passed on to Imlib2, otherwise, it is +assumed to be unloadable. +This greatly improves performance when working in directories with mixed files +.Pq i.e., directories which do not exclusively contain image files . +If you think that Imlib2 can load a file which +.Nm +has determined to be likely not an image, set the environment variable +.Qq FEH_SKIP_MAGIC +to pass all files directly to Imlib2, bypassing the header check. +The environment variable's value does not matter, it just needs to be set. . .Sh OPTIONS . 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 + * and + * . + * + * 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) || diff --git a/test/feh.t b/test/feh.t index baf5ee4..44f705f 100644 --- a/test/feh.t +++ b/test/feh.t @@ -47,7 +47,7 @@ if ( $version =~ m{ Compile-time \s switches : \s .* help }ox ) { } my $re_warning - = qr{${feh_name} WARNING: test/fail/... \- No Imlib2 loader for that file format\n}; + = qr{${feh_name} WARNING: test/fail/... \- Does not look like an image \(magic bytes missing\)\n}; my $re_loadable = qr{test/ok/...}; my $re_unloadable = qr{test/fail/...}; my $re_list_action = qr{test/ok/... 16x16}; -- cgit v1.2.3