Add a command line option to extract thumbnails

Only use LibRaw for now, which probably has the most impact
using the least amount of effort.

fiv-browser.c

@@ -555,8 +555,9 @@ thumbnailer_reprocess_entry(FivBrowser *self, GBytes *output, Entry *entry)
 {
 	g_clear_object(&entry->icon);
 	g_clear_pointer(&entry->thumbnail, cairo_surface_destroy);
+	guint64 dummy;
 	if (!output || !(entry->thumbnail = rescale_thumbnail(
-			fiv_io_deserialize(output), self->item_height))) {
+			fiv_io_deserialize(output, &dummy), self->item_height))) {
 		entry_add_thumbnail(entry, self);
 		materialize_icon(self, entry);
 	} else {

fiv-thumbnail.c

@@ -30,6 +30,10 @@
 #include "fiv-thumbnail.h"
 #include "xdg.h"
 
+#ifdef HAVE_LIBRAW
+#include <libraw.h>
+#endif  // HAVE_LIBRAW
+
 #ifndef __linux__
 #define st_mtim st_mtimespec
 #endif  // ! __linux__
@@ -104,6 +108,91 @@ fiv_thumbnail_get_root(void)
 
 // - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 
+static cairo_surface_t *
+render(GFile *target, GBytes *data, gboolean *color_managed, GError **error)
+{
+	FivIoOpenContext ctx = {
+		.uri = g_file_get_uri(target),
+		.screen_profile = fiv_io_profile_new_sRGB(),
+		.screen_dpi = 96,
+		.first_frame_only = TRUE,
+		// Only using this array as a redirect.
+		.warnings = g_ptr_array_new_with_free_func(g_free),
+	};
+
+	cairo_surface_t *surface = fiv_io_open_from_data(
+		g_bytes_get_data(data, NULL), g_bytes_get_size(data), &ctx, error);
+	g_free((gchar *) ctx.uri);
+	g_ptr_array_free(ctx.warnings, TRUE);
+	if ((*color_managed = !!ctx.screen_profile))
+		fiv_io_profile_free(ctx.screen_profile);
+	g_bytes_unref(data);
+	return surface;
+}
+
+cairo_surface_t *
+fiv_thumbnail_extract(GFile *target, GError **error)
+{
+	const char *path = g_file_peek_path(target);
+	if (!path) {
+		set_error(error, "thumbnails will only be extracted from local files");
+		return NULL;
+	}
+
+	GMappedFile *mf = g_mapped_file_new(path, FALSE, error);
+	if (!mf)
+		return NULL;
+
+	cairo_surface_t *surface = NULL;
+#ifndef HAVE_LIBRAW
+	// TODO(p): Implement our own thumbnail extractors.
+	set_error(error, "unsupported file");
+#else  // HAVE_LIBRAW
+	libraw_data_t *iprc = libraw_init(
+		LIBRAW_OPIONS_NO_MEMERR_CALLBACK | LIBRAW_OPIONS_NO_DATAERR_CALLBACK);
+	if (!iprc) {
+		set_error(error, "failed to obtain a LibRaw handle");
+		goto fail;
+	}
+
+	int err = 0;
+	if ((err = libraw_open_buffer(iprc, (void *) g_mapped_file_get_contents(mf),
+			 g_mapped_file_get_length(mf))) ||
+		(err = libraw_unpack_thumb(iprc))) {
+		set_error(error, libraw_strerror(err));
+		goto fail_libraw;
+	}
+
+	libraw_processed_image_t *image = libraw_dcraw_make_mem_thumb(iprc, &err);
+	if (!image) {
+		set_error(error, libraw_strerror(err));
+		goto fail_libraw;
+	}
+
+	gboolean dummy = FALSE;
+	switch (image->type) {
+	case LIBRAW_IMAGE_JPEG:
+		surface = render(
+			target, g_bytes_new(image->data, image->data_size), &dummy, error);
+		break;
+	case LIBRAW_IMAGE_BITMAP:
+		// TODO(p): Implement this one as well.
+	default:
+		set_error(error, "unsupported embedded thumbnail");
+	}
+
+	libraw_dcraw_clear_mem(image);
+fail_libraw:
+	libraw_close(iprc);
+#endif  // HAVE_LIBRAW
+
+fail:
+	g_mapped_file_unref(mf);
+	return surface;
+}
+
+// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+
 // In principle similar to rescale_thumbnail() from fiv-browser.c.
 static cairo_surface_t *
 adjust_thumbnail(cairo_surface_t *thumbnail, double row_height)
@@ -238,30 +327,7 @@ save_thumbnail(cairo_surface_t *thumbnail, const char *path, GString *thum)
 }
 
 static cairo_surface_t *
-render(GFile *target, GBytes *data, gboolean *color_managed, GError **error)
+produce_fallback(GFile *target, FivThumbnailSize size, GError **error)
-{
-	FivIoOpenContext ctx = {
-		.uri = g_file_get_uri(target),
-		.screen_profile = fiv_io_profile_new_sRGB(),
-		.screen_dpi = 96,
-		.first_frame_only = TRUE,
-		// Only using this array as a redirect.
-		.warnings = g_ptr_array_new_with_free_func(g_free),
-	};
-
-	cairo_surface_t *surface = fiv_io_open_from_data(
-		g_bytes_get_data(data, NULL), g_bytes_get_size(data), &ctx, error);
-	g_free((gchar *) ctx.uri);
-	g_ptr_array_free(ctx.warnings, TRUE);
-	if ((*color_managed = !!ctx.screen_profile))
-		fiv_io_profile_free(ctx.screen_profile);
-	g_bytes_unref(data);
-	return surface;
-}
-
-static gboolean
-produce_fallback(GFile *target, FivThumbnailSize size,
-	cairo_surface_t **surface, GError **error)
 {
 	goffset filesize = 0;
 	GFileInfo *info = g_file_query_info(target,
@@ -276,40 +342,39 @@ produce_fallback(GFile *target, FivThumbnailSize size,
 	// For example, we can employ magic checks.
 	if (filesize > 10 << 20) {
 		set_error(error, "oversize, not thumbnailing");
-		return FALSE;
+		return NULL;
 	}
 
 	GBytes *data = g_file_load_bytes(target, NULL, NULL, error);
 	if (!data)
-		return FALSE;
+		return NULL;
 
 	gboolean color_managed = FALSE;
-	cairo_surface_t *result = render(target, data, &color_managed, error);
+	cairo_surface_t *surface = render(target, data, &color_managed, error);
-	if (!result)
+	if (!surface)
-		return FALSE;
+		return NULL;
 
-	if (!*surface)
+	cairo_surface_t *result =
-		*surface = adjust_thumbnail(result, fiv_thumbnail_sizes[size].size);
+		adjust_thumbnail(surface, fiv_thumbnail_sizes[size].size);
-	cairo_surface_destroy(result);
+	cairo_surface_destroy(surface);
-	return TRUE;
+	return result;
 }
 
-gboolean
+cairo_surface_t *
-fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
+fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size, GError **error)
-	cairo_surface_t **max_size_surface, GError **error)
 {
 	g_return_val_if_fail(max_size >= FIV_THUMBNAIL_SIZE_MIN &&
 		max_size <= FIV_THUMBNAIL_SIZE_MAX, FALSE);
 
 	const gchar *path = g_file_peek_path(target);
 	if (!path || !g_file_is_native(target) /* Don't save sftp://. */)
-		return produce_fallback(target, max_size, max_size_surface, error);
+		return produce_fallback(target, max_size, error);
 
 	// Make the TOCTTOU issue favour unnecessary reloading.
 	GStatBuf st = {};
 	if (g_stat(path, &st)) {
 		set_error(error, g_strerror(errno));
-		return FALSE;
+		return NULL;
 	}
 
 	GError *e = NULL;
@@ -317,7 +382,7 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
 	if (!mf) {
 		g_debug("%s: %s", path, e->message);
 		g_error_free(e);
-		return produce_fallback(target, max_size, max_size_surface, error);
+		return produce_fallback(target, max_size, error);
 	}
 
 	gsize filesize = g_mapped_file_get_length(mf);
@@ -326,7 +391,7 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
 		render(target, g_mapped_file_get_bytes(mf), &color_managed, error);
 	g_mapped_file_unref(mf);
 	if (!surface)
-		return FALSE;
+		return NULL;
 
 	// Boilerplate copied from fiv_thumbnail_lookup().
 	gchar *uri = g_file_get_uri(target);
@@ -354,6 +419,7 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
 			thum, "%s%c%s%c", THUMB_COLORSPACE, 0, THUMB_COLORSPACE_SRGB, 0);
 	}
 
+	cairo_surface_t *max_size_surface = NULL;
 	for (int use = max_size; use >= FIV_THUMBNAIL_SIZE_MIN; use--) {
 		cairo_surface_t *scaled =
 			adjust_thumbnail(surface, fiv_thumbnail_sizes[use].size);
@@ -362,8 +428,8 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
 		save_thumbnail(scaled, path, thum);
 		g_free(path);
 
-		if (!*max_size_surface)
+		if (!max_size_surface)
-			*max_size_surface = scaled;
+			max_size_surface = scaled;
 		else
 			cairo_surface_destroy(scaled);
 	}
@@ -374,7 +440,7 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
 	g_free(sum);
 	g_free(uri);
 	cairo_surface_destroy(surface);
-	return TRUE;
+	return max_size_surface;
 }
 
 static bool

fiv-thumbnail.h

@@ -55,10 +55,13 @@ extern cairo_user_data_key_t fiv_thumbnail_key_lq;
 /// Returns this user's root thumbnail directory.
 gchar *fiv_thumbnail_get_root(void);
 
+/// Attempts to extract any low-quality thumbnail from fast targets.
+cairo_surface_t *fiv_thumbnail_extract(GFile *target, GError **error);
+
 /// Generates wide thumbnails of up to the specified size, saves them in cache.
-/// Returns the surface used for the maximum size (if the pointer was NULL).
+/// Returns the surface used for the maximum size, or an error.
-gboolean fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size,
+cairo_surface_t *fiv_thumbnail_produce(
-	cairo_surface_t **max_size_surface, GError **error);
+	GFile *target, FivThumbnailSize max_size, GError **error);
 
 /// Retrieves a thumbnail of the most appropriate quality and resolution
 /// for the target file.

fiv.c

@@ -1767,11 +1767,47 @@ static const char stylesheet[] = "@define-color fiv-tile @content_view_bg; \
 	} \
 	.fiv-information label { padding: 0 4px; }";
 
+static void
+output_thumbnail(const char *path_arg, gboolean extract, const char *size_arg)
+{
+	if (!path_arg)
+		exit_fatal("no path given");
+
+	FivThumbnailSize size = 0;
+	if (size_arg) {
+		for (; size < FIV_THUMBNAIL_SIZE_COUNT; size++) {
+			if (!strcmp(
+					fiv_thumbnail_sizes[size].thumbnail_spec_name, size_arg))
+				break;
+		}
+		if (size >= FIV_THUMBNAIL_SIZE_COUNT)
+			exit_fatal("unknown thumbnail size: %s", size_arg);
+	}
+
+	GError *error = NULL;
+	GFile *file = g_file_new_for_commandline_arg(path_arg);
+	cairo_surface_t *surface = NULL;
+	if (extract && (surface = fiv_thumbnail_extract(file, &error)))
+		fiv_io_serialize_to_stdout(surface, FIV_IO_SERIALIZE_LOW_QUALITY);
+	else if (size_arg &&
+		(g_clear_error(&error),
+			(surface = fiv_thumbnail_produce(file, size, &error))))
+		fiv_io_serialize_to_stdout(surface, 0);
+	else
+		g_assert(error != NULL);
+
+	g_object_unref(file);
+	if (error)
+		exit_fatal("%s", error->message);
+
+	cairo_surface_destroy(surface);
+}
+
 int
 main(int argc, char *argv[])
 {
 	gboolean show_version = FALSE, show_supported_media_types = FALSE,
-		invalidate_cache = FALSE, browse = FALSE;
+		invalidate_cache = FALSE, browse = FALSE, extract_thumbnail = FALSE;
 	gchar **path_args = NULL, *thumbnail_size = NULL;
 	const GOptionEntry options[] = {
 		{G_OPTION_REMAINING, 0, 0, G_OPTION_ARG_FILENAME_ARRAY, &path_args,
@@ -1782,9 +1818,12 @@ main(int argc, char *argv[])
 		{"browse", 0, G_OPTION_FLAG_IN_MAIN,
 			G_OPTION_ARG_NONE, &browse,
 			"Start in filesystem browsing mode", NULL},
+		{"extract-thumbnail", 0, G_OPTION_FLAG_IN_MAIN,
+			G_OPTION_ARG_NONE, &extract_thumbnail,
+			"Output any embedded thumbnail (superseding --thumbnail)", NULL},
 		{"thumbnail", 0, G_OPTION_FLAG_IN_MAIN,
 			G_OPTION_ARG_STRING, &thumbnail_size,
-			"Generate thumbnails for an image, up to the given size", "SIZE"},
+			"Generate thumbnails, up to SIZE, and output that size", "SIZE"},
 		{"invalidate-cache", 0, G_OPTION_FLAG_IN_MAIN,
 			G_OPTION_ARG_NONE, &invalidate_cache,
 			"Invalidate the wide thumbnail cache", NULL},
@@ -1820,27 +1859,8 @@ main(int argc, char *argv[])
 	// TODO(p): Complain to the user if there's more than one argument.
 	// Best show the help message, if we can figure that out.
 	const gchar *path_arg = path_args ? path_args[0] : NULL;
-	if (thumbnail_size) {
+	if (extract_thumbnail || thumbnail_size) {
-		if (!path_arg)
+		output_thumbnail(path_arg, extract_thumbnail, thumbnail_size);
-			exit_fatal("no path given");
-
-		FivThumbnailSize size = 0;
-		for (; size < FIV_THUMBNAIL_SIZE_COUNT; size++)
-			if (!strcmp(fiv_thumbnail_sizes[size].thumbnail_spec_name,
-					thumbnail_size))
-				break;
-		if (size >= FIV_THUMBNAIL_SIZE_COUNT)
-			exit_fatal("unknown thumbnail size: %s", thumbnail_size);
-
-		GFile *target = g_file_new_for_commandline_arg(path_arg);
-		cairo_surface_t *surface = NULL;
-		if (!fiv_thumbnail_produce(target, size, &surface, &error))
-			exit_fatal("%s", error->message);
-		g_object_unref(target);
-		if (surface) {
-			fiv_io_serialize_to_stdout(surface);
-			cairo_surface_destroy(surface);
-		}
 		return 0;
 	}