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Merge PR #1628: #1617: placeholder GPS block (NUL refs, 0/0 rationals) reads as no location

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aiongg
2026-10-22 02:39:34 +00:00
parent f460cbd90c e22b173ecd
commit 5cd029a40c
1 changed files with 39 additions and 5 deletions
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crates/meta/src/exif.rs
+39 -5
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@@ -127,20 +127,32 @@ pub fn from_tiff(tiff: &Tiff) -> Metadata {
m
}
/// Degrees/minutes/seconds triplet as decimal degrees. A component that is present but not a number (a rational
/// with a zero denominator, as in the placeholder GPS block phones write without a fix) makes the whole value unusable.
fn dms(ifd: &Ifd, tag: u16) -> Option<f64> {
let v = ifd.f64s(tag)?;
let d = *v.first()?;
let deg = d + v.get(1).copied().unwrap_or(0.0) / 60.0 + v.get(2).copied().unwrap_or(0.0) / 3600.0;
let v = ifd.value(tag)?;
let part = |i: usize| if i < v.count() { v.get_f64(i) } else { Some(0.0) };
let d = v.get_f64(0)?;
let deg = d + part(1)? / 60.0 + part(2)? / 3600.0;
deg.is_finite().then_some(deg)
}
/// `Some(true)` for the negative hemisphere (`neg`), `Some(false)` for `pos`, `None` when the ref is missing or invalid.
fn hemisphere(g: &Ifd, tag: u16, pos: char, neg: char) -> Option<bool> {
match g.string(tag)?.trim_start().chars().next()?.to_ascii_uppercase() {
c if c == neg => Some(true),
c if c == pos => Some(false),
_ => None,
}
}
fn read_gps(g: &Ifd) -> Option<Gps> {
let mut lat = dms(g, t::GPS_LATITUDE)?;
let mut lon = dms(g, t::GPS_LONGITUDE)?;
if g.string(t::GPS_LATITUDE_REF).is_some_and(|s| s.starts_with('S')) {
if hemisphere(g, t::GPS_LATITUDE_REF, 'N', 'S')? {
lat = -lat;
}
if g.string(t::GPS_LONGITUDE_REF).is_some_and(|s| s.starts_with('W')) {
if hemisphere(g, t::GPS_LONGITUDE_REF, 'E', 'W')? {
lon = -lon;
}
if !(-90.0..=90.0).contains(&lat) || !(-180.0..=180.0).contains(&lon) {
@@ -382,6 +394,28 @@ pub(crate) mod tests {
}
}
#[test]
fn placeholder_gps_block_is_no_location() {
// Android phones without a fix write NUL refs and 0/0 rationals (#1617).
let read = |lat_ref: &str, lat: Vec<(u32, u32)>| {
let mut gps = IfdBuilder::new();
gps.set(t::GPS_LATITUDE_REF, Value::Ascii(lat_ref.into()));
gps.set(t::GPS_LATITUDE, Value::Rational(lat));
gps.set(t::GPS_LONGITUDE_REF, Value::Ascii("E".into()));
gps.set(t::GPS_LONGITUDE, Value::Rational(vec![(151, 1), (12, 1), (4032, 100)]));
let mut ifd0 = IfdBuilder::new();
ifd0.set_child(t::GPS_IFD, gps);
read_exif(&TiffWriter::new(ByteOrder::Little, false).write(&[ifd0]).unwrap()).gps
};
let valid = vec![(33, 1), (51, 1), (3564, 100)];
assert!(read("N", valid.clone()).is_some());
assert_eq!(read("N", vec![(0, 0), (0, 0), (0, 0)]), None, "0/0 rationals");
assert_eq!(read("N", vec![(33, 1), (0, 0), (0, 0)]), None, "0/0 minutes");
assert_eq!(read("", valid.clone()), None, "NUL ref");
assert_eq!(read("", valid.clone()), None, "empty ref");
assert_eq!(read("X", valid), None, "invalid ref");
}
#[test]
fn exif_prefix_and_garbage() {
let mut b = b"Exif\0\0".to_vec();