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Check filesize when retrieving thumbnails

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In particular, this handles screenshots from Rigol oscilloscopes,
which reuse the same name series with the same file modification time.
This commit is contained in:
Přemysl Eric Janouch
2023-04-14 03:52:01 +02:00
parent 4317c7e581
commit 05ac3a0651
5 changed files with 92 additions and 49 deletions
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93
fiv-thumbnail.c
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@@ -524,7 +524,7 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size, GError **error)
g_string_append_printf(
thum, "%s%c%ld%c", THUMB_MTIME, 0, (long) st.st_mtime, 0);
g_string_append_printf(
thum, "%s%c%ld%c", THUMB_SIZE, 0, (long) filesize, 0);
thum, "%s%c%llu%c", THUMB_SIZE, 0, (unsigned long long) filesize, 0);
if (cairo_surface_get_type(surface) == CAIRO_SURFACE_TYPE_IMAGE) {
g_string_append_printf(thum, "%s%c%d%c", THUMB_IMAGE_WIDTH, 0,
@@ -563,9 +563,16 @@ fiv_thumbnail_produce(GFile *target, FivThumbnailSize max_size, GError **error)
return max_size_surface;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
typedef struct {
const char *uri; ///< Target URI
time_t mtime; ///< File modification time
guint64 size; ///< File size
} Stat;
static bool
check_wide_thumbnail_texts(GBytes *thum, const char *target, time_t mtime,
bool *sRGB)
check_wide_thumbnail_texts(GBytes *thum, const Stat *st, bool *sRGB)
{
gsize len = 0;
const gchar *s = g_bytes_get_data(thum, &len), *end = s + len;
@@ -579,11 +586,14 @@ check_wide_thumbnail_texts(GBytes *thum, const char *target, time_t mtime,
continue;
} else if (!strcmp(key, THUMB_URI)) {
have_uri = true;
if (strcmp(target, s))
if (strcmp(st->uri, s))
return false;
} else if (!strcmp(key, THUMB_MTIME)) {
have_mtime = true;
if (atol(s) != mtime)
if (atol(s) != st->mtime)
return false;
} else if (!strcmp(key, THUMB_SIZE)) {
if (strtoull(s, NULL, 10) != st->size)
return false;
} else if (!strcmp(key, THUMB_COLORSPACE))
*sRGB = !strcmp(s, THUMB_COLORSPACE_SRGB);
@@ -594,8 +604,7 @@ check_wide_thumbnail_texts(GBytes *thum, const char *target, time_t mtime,
}
static cairo_surface_t *
read_wide_thumbnail(
const char *path, const char *uri, time_t mtime, GError **error)
read_wide_thumbnail(const char *path, const Stat *st, GError **error)
{
gchar *thumbnail_uri = g_filename_to_uri(path, NULL, error);
if (!thumbnail_uri)
@@ -612,7 +621,7 @@ read_wide_thumbnail(
if (!thum) {
g_clear_error(error);
set_error(error, "not a thumbnail");
} else if (!check_wide_thumbnail_texts(thum, uri, mtime, &sRGB)) {
} else if (!check_wide_thumbnail_texts(thum, st, &sRGB)) {
g_clear_error(error);
set_error(error, "mismatch");
} else {
@@ -629,11 +638,8 @@ read_wide_thumbnail(
return NULL;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
static cairo_surface_t *
read_png_thumbnail(
const char *path, const char *uri, time_t mtime, GError **error)
read_png_thumbnail(const char *path, const Stat *st, GError **error)
{
cairo_surface_t *surface = fiv_io_open_png_thumbnail(path, error);
if (!surface)
@@ -650,18 +656,27 @@ read_png_thumbnail(
// but those aren't interesting currently (would be for fast previews).
const char *text_uri = g_hash_table_lookup(texts, THUMB_URI);
const char *text_mtime = g_hash_table_lookup(texts, THUMB_MTIME);
if (!text_uri || strcmp(text_uri, uri) ||
!text_mtime || atol(text_mtime) != mtime) {
const char *text_size = g_hash_table_lookup(texts, THUMB_SIZE);
if (!text_uri || strcmp(text_uri, st->uri) ||
!text_mtime || atol(text_mtime) != st->mtime) {
set_error(error, "mismatch or not a thumbnail");
cairo_surface_destroy(surface);
return NULL;
}
if (text_size && strtoull(text_size, NULL, 10) != st->size) {
set_error(error, "file size mismatch");
cairo_surface_destroy(surface);
return NULL;
}
return surface;
}
// - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
cairo_surface_t *
fiv_thumbnail_lookup(const char *uri, gint64 mtime_msec, FivThumbnailSize size)
fiv_thumbnail_lookup(const char *uri, gint64 mtime_msec, guint64 filesize,
FivThumbnailSize size)
{
g_return_val_if_fail(size >= FIV_THUMBNAIL_SIZE_MIN &&
size <= FIV_THUMBNAIL_SIZE_MAX, NULL);
@@ -673,6 +688,7 @@ fiv_thumbnail_lookup(const char *uri, gint64 mtime_msec, FivThumbnailSize size)
gchar *sum = g_compute_checksum_for_string(G_CHECKSUM_MD5, uri, -1);
gchar *thumbnails_dir = fiv_thumbnail_get_root();
const Stat st = {.uri = uri, .mtime = mtime_msec / 1000, .size = filesize};
// The lookup sequence is: nominal..max, then mirroring back to ..min.
cairo_surface_t *result = NULL;
@@ -685,7 +701,7 @@ fiv_thumbnail_lookup(const char *uri, gint64 mtime_msec, FivThumbnailSize size)
const char *name = fiv_thumbnail_sizes[use].thumbnail_spec_name;
gchar *wide = g_strconcat(thumbnails_dir, G_DIR_SEPARATOR_S "wide-",
name, G_DIR_SEPARATOR_S, sum, ".webp", NULL);
result = read_wide_thumbnail(wide, uri, mtime_msec / 1000, &error);
result = read_wide_thumbnail(wide, &st, &error);
if (error) {
g_debug("%s: %s", wide, error->message);
g_clear_error(&error);
@@ -701,7 +717,7 @@ fiv_thumbnail_lookup(const char *uri, gint64 mtime_msec, FivThumbnailSize size)
gchar *path = g_strconcat(thumbnails_dir, G_DIR_SEPARATOR_S,
name, G_DIR_SEPARATOR_S, sum, ".png", NULL);
result = read_png_thumbnail(path, uri, mtime_msec / 1000, &error);
result = read_png_thumbnail(path, &st, &error);
if (error) {
g_debug("%s: %s", path, error->message);
g_clear_error(&error);
@@ -734,7 +750,7 @@ print_error(GFile *file, GError *error)
}
static gchar *
identify_wide_thumbnail(GMappedFile *mf, time_t *mtime, GError **error)
identify_wide_thumbnail(GMappedFile *mf, Stat *st, GError **error)
{
WebPDemuxer *demux = WebPDemux(&(WebPData) {
.bytes = (const uint8_t *) g_mapped_file_get_contents(mf),
@@ -760,7 +776,9 @@ identify_wide_thumbnail(GMappedFile *mf, time_t *mtime, GError **error)
if (!strcmp(key, THUMB_URI) && !uri)
uri = g_strdup(p);
if (!strcmp(key, THUMB_MTIME))
*mtime = atol(p);
st->mtime = atol(p);
if (!strcmp(key, THUMB_SIZE))
st->size = strtoull(p, NULL, 10);
key = NULL;
} else {
key = p;
@@ -778,16 +796,17 @@ static void
check_wide_thumbnail(GFile *thumbnail, GError **error)
{
// Not all errors are enough of a reason for us to delete something.
GError *tolerable = NULL;
GError *tolerable_error = NULL;
const char *path = g_file_peek_path(thumbnail);
GMappedFile *mf = g_mapped_file_new(path, FALSE, &tolerable);
GMappedFile *mf = g_mapped_file_new(path, FALSE, &tolerable_error);
if (!mf) {
print_error(thumbnail, tolerable);
print_error(thumbnail, tolerable_error);
return;
}
time_t target_mtime = 0;
gchar *target_uri = identify_wide_thumbnail(mf, &target_mtime, error);
// Note that we could enforce the presence of the size field in our spec.
Stat target_st = {.uri = NULL, .mtime = 0, .size = G_MAXUINT64};
gchar *target_uri = identify_wide_thumbnail(mf, &target_st, error);
g_mapped_file_unref(mf);
if (!target_uri)
return;
@@ -809,26 +828,32 @@ check_wide_thumbnail(GFile *thumbnail, GError **error)
GFile *target = g_file_new_for_uri(target_uri);
g_free(target_uri);
GFileInfo *info = g_file_query_info(target,
G_FILE_ATTRIBUTE_STANDARD_NAME "," G_FILE_ATTRIBUTE_TIME_MODIFIED,
G_FILE_QUERY_INFO_NONE, NULL, &tolerable);
G_FILE_ATTRIBUTE_STANDARD_NAME ","
G_FILE_ATTRIBUTE_STANDARD_SIZE ","
G_FILE_ATTRIBUTE_TIME_MODIFIED,
G_FILE_QUERY_INFO_NONE, NULL, &tolerable_error);
g_object_unref(target);
if (g_error_matches(tolerable, G_IO_ERROR, G_IO_ERROR_NOT_FOUND)) {
g_propagate_error(error, tolerable);
if (g_error_matches(tolerable_error, G_IO_ERROR, G_IO_ERROR_NOT_FOUND)) {
g_propagate_error(error, tolerable_error);
return;
} else if (tolerable) {
print_error(thumbnail, tolerable);
} else if (tolerable_error) {
print_error(thumbnail, tolerable_error);
return;
}
guint64 filesize = g_file_info_get_size(info);
GDateTime *mdatetime = g_file_info_get_modification_date_time(info);
g_object_unref(info);
if (!mdatetime) {
set_error(&tolerable, "cannot retrieve file modification time");
print_error(thumbnail, tolerable);
set_error(&tolerable_error, "cannot retrieve file modification time");
print_error(thumbnail, tolerable_error);
return;
}
if (g_date_time_to_unix(mdatetime) != target_mtime)
set_error(error, "mtime mismatch");
if (g_date_time_to_unix(mdatetime) != target_st.mtime)
set_error(error, "modification time mismatch");
else if (target_st.size != G_MAXUINT64 && filesize != target_st.size)
set_error(error, "file size mismatch");
g_date_time_unref(mdatetime);
}