Fix OpenHarmony's tzdata parsing

Cargo.toml

@@ -23,7 +23,7 @@ alloc = []
 libc = []
 winapi = ["windows-link"]
 std = ["alloc"]
-clock = ["winapi", "iana-time-zone", "android-tzdata", "now"]
+clock = ["winapi", "iana-time-zone", "now"]
 now = ["std"]
 oldtime = []
 wasmbind = ["wasm-bindgen", "js-sys"]
@@ -57,9 +57,6 @@ windows-bindgen = { version = "0.60" } # MSRV is 1.74
 [target.'cfg(unix)'.dependencies]
 iana-time-zone = { version = "0.1.45", optional = true, features = ["fallback"] }
 
-[target.'cfg(target_os = "android")'.dependencies]
-android-tzdata = { version = "0.1.1", optional = true }
-
 [dev-dependencies]
 serde_json = { version = "1" }
 serde_derive = { version = "1", default-features = false }

src/offset/local/mod.rs

@@ -28,6 +28,9 @@ mod inner;
 #[allow(unreachable_pub)]
 mod win_bindings;
 
+#[cfg(all(any(target_os = "android", target_env = "ohos", test), feature = "clock"))]
+mod tz_data;
+
 #[cfg(all(
     not(unix),
     not(windows),

src/offset/local/tz_data.rs

@@ -0,0 +1,267 @@
+//! Rust parser of ZoneInfoDb(`tzdata`) on Android and OpenHarmony
+//!
+//! Ported from: https://android.googlesource.com/platform/prebuilts/fullsdk/sources/+/refs/heads/androidx-appcompat-release/android-34/com/android/i18n/timezone/ZoneInfoDb.java
+use std::{
+    ffi::CStr,
+    fmt::Debug,
+    fs::File,
+    io::{Error, ErrorKind, Read, Result, Seek, SeekFrom},
+};
+
+/// Get timezone data from the `tzdata` file of HarmonyOS NEXT.
+#[cfg(target_env = "ohos")]
+pub(crate) fn for_zone(tz_string: &str) -> Result<Option<Vec<u8>>> {
+    let mut file = File::open("/system/etc/zoneinfo/tzdata")?;
+    find_tz_data::<OHOS_ENTRY_LEN>(&mut file, tz_string.as_bytes())
+}
+
+/// Get timezone data from the `tzdata` file of Android.
+#[cfg(target_os = "android")]
+pub(crate) fn for_zone(tz_string: &str) -> Result<Option<Vec<u8>>> {
+    let mut file = open_android_tz_data_file()?;
+    find_tz_data::<ANDROID_ENTRY_LEN>(&mut file, tz_string.as_bytes())
+}
+
+/// Open the `tzdata` file of Android from the environment variables.
+#[cfg(target_os = "android")]
+fn open_android_tz_data_file() -> Result<File> {
+    for (env_var, path) in
+        [("ANDROID_DATA", "/misc/zoneinfo"), ("ANDROID_ROOT", "/usr/share/zoneinfo")]
+    {
+        if let Ok(env_value) = std::env::var(env_var) {
+            if let Ok(file) = File::open(format!("{}{}/tzdata", env_value, path)) {
+                return Ok(file);
+            }
+        }
+    }
+    Err(Error::from(ErrorKind::NotFound))
+}
+
+/// Get timezone data from the `tzdata` file reader
+#[cfg(any(test, target_env = "ohos", target_os = "android"))]
+fn find_tz_data<const ENTRY_LEN: usize>(
+    mut reader: impl Read + Seek,
+    tz_name: &[u8],
+) -> Result<Option<Vec<u8>>> {
+    let header = TzDataHeader::new(&mut reader)?;
+    let index = TzDataIndexes::new::<ENTRY_LEN>(&mut reader, &header)?;
+    Ok(if let Some(entry) = index.find_timezone(tz_name) {
+        Some(index.find_tzdata(reader, &header, entry)?)
+    } else {
+        None
+    })
+}
+
+/// Header of the `tzdata` file.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+struct TzDataHeader {
+    version: [u8; 5],
+    index_offset: u32,
+    data_offset: u32,
+    zonetab_offset: u32,
+}
+
+impl TzDataHeader {
+    /// Parse the header of the `tzdata` file.
+    fn new(mut data: impl Read) -> Result<Self> {
+        let version = {
+            let mut magic = [0; TZDATA_VERSION_LEN];
+            data.read_exact(&mut magic)?;
+            if !magic.starts_with(b"tzdata") || magic[TZDATA_VERSION_LEN - 1] != 0 {
+                return Err(Error::new(ErrorKind::Other, "invalid tzdata header magic"));
+            }
+            let mut version = [0; 5];
+            version.copy_from_slice(&magic[6..11]);
+            version
+        };
+
+        let mut offset = [0; 4];
+        data.read_exact(&mut offset)?;
+        let index_offset = u32::from_be_bytes(offset);
+        data.read_exact(&mut offset)?;
+        let data_offset = u32::from_be_bytes(offset);
+        data.read_exact(&mut offset)?;
+        let zonetab_offset = u32::from_be_bytes(offset);
+
+        Ok(Self { version, index_offset, data_offset, zonetab_offset })
+    }
+}
+
+/// Indexes of the `tzdata` file.
+struct TzDataIndexes {
+    indexes: Vec<TzDataIndex>,
+}
+
+impl TzDataIndexes {
+    /// Create a new `TzDataIndexes` from the `tzdata` file reader.
+    fn new<const ENTRY_LEN: usize>(mut reader: impl Read, header: &TzDataHeader) -> Result<Self> {
+        let mut buf = vec![0; header.data_offset.saturating_sub(header.index_offset) as usize];
+        reader.read_exact(&mut buf)?;
+        // replace chunks with array_chunks when it's stable
+        Ok(TzDataIndexes {
+            indexes: buf
+                .chunks(ENTRY_LEN)
+                .filter_map(|chunk| {
+                    from_bytes_until_nul(&chunk[..TZ_NAME_LEN]).map(|name| {
+                        let name = name.to_bytes().to_vec().into_boxed_slice();
+                        let offset = u32::from_be_bytes(
+                            chunk[TZ_NAME_LEN..TZ_NAME_LEN + 4].try_into().unwrap(),
+                        );
+                        let length = u32::from_be_bytes(
+                            chunk[TZ_NAME_LEN + 4..TZ_NAME_LEN + 8].try_into().unwrap(),
+                        );
+                        TzDataIndex { name, offset, length }
+                    })
+                })
+                .collect(),
+        })
+    }
+
+    /// Find a timezone by name.
+    fn find_timezone(&self, timezone: &[u8]) -> Option<&TzDataIndex> {
+        // timezones in tzdata are sorted by name.
+        self.indexes.binary_search_by_key(&timezone, |x| &x.name).map(|x| &self.indexes[x]).ok()
+    }
+
+    /// Retrieve a chunk of timezone data by the index.
+    fn find_tzdata(
+        &self,
+        mut reader: impl Read + Seek,
+        header: &TzDataHeader,
+        index: &TzDataIndex,
+    ) -> Result<Vec<u8>> {
+        reader.seek(SeekFrom::Start(index.offset as u64 + header.data_offset as u64))?;
+        let mut buffer = vec![0; index.length as usize];
+        reader.read_exact(&mut buffer)?;
+        Ok(buffer)
+    }
+}
+
+/// Index entry of the `tzdata` file.
+struct TzDataIndex {
+    name: Box<[u8]>,
+    offset: u32,
+    length: u32,
+}
+
+/// TODO: Change this `CStr::from_bytes_until_nul` once MSRV was bumped above 1.72.0
+fn from_bytes_until_nul(bytes: &[u8]) -> Option<&CStr> {
+    let nul_pos = bytes.iter().position(|&b| b == 0)?;
+    // SAFETY:
+    // 1. nul_pos + 1 <= bytes.len()
+    // 2. We know there is a nul byte at nul_pos, so this slice (ending at the nul byte) is a well-formed C string.
+    Some(unsafe { CStr::from_bytes_with_nul_unchecked(&bytes[..=nul_pos]) })
+}
+
+/// Ohos tzdata index entry size: `name + offset + length`
+#[cfg(any(test, target_env = "ohos"))]
+const OHOS_ENTRY_LEN: usize = TZ_NAME_LEN + 2 * size_of::<u32>();
+/// Android tzdata index entry size: `name + offset + length + raw_utc_offset(legacy)`:
+/// [reference](https://android.googlesource.com/platform/prebuilts/fullsdk/sources/+/refs/heads/androidx-appcompat-release/android-34/com/android/i18n/timezone/ZoneInfoDb.java#271)
+#[cfg(any(test, target_os = "android"))]
+const ANDROID_ENTRY_LEN: usize = TZ_NAME_LEN + 3 * size_of::<u32>();
+/// The database reserves 40 bytes for each id.
+const TZ_NAME_LEN: usize = 40;
+/// Size of the version string in the header of `tzdata` file.
+/// e.g. `tzdata2024b\0`
+const TZDATA_VERSION_LEN: usize = 12;
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_ohos_tzdata_header_and_index() {
+        let file = File::open("./tests/ohos/tzdata").unwrap();
+        let header = TzDataHeader::new(&file).unwrap();
+        assert_eq!(header.version, *b"2024a");
+        assert_eq!(header.index_offset, 24);
+        assert_eq!(header.data_offset, 21240);
+        assert_eq!(header.zonetab_offset, 272428);
+
+        let iter = TzDataIndexes::new::<OHOS_ENTRY_LEN>(&file, &header).unwrap();
+        assert_eq!(iter.indexes.len(), 442);
+        assert!(iter.find_timezone(b"Asia/Shanghai").is_some());
+        assert!(iter.find_timezone(b"Pacific/Noumea").is_some());
+    }
+
+    #[test]
+    fn test_ohos_tzdata_loading() {
+        let file = File::open("./tests/ohos/tzdata").unwrap();
+        let header = TzDataHeader::new(&file).unwrap();
+        let iter = TzDataIndexes::new::<OHOS_ENTRY_LEN>(&file, &header).unwrap();
+        let timezone = iter.find_timezone(b"Asia/Shanghai").unwrap();
+        let tzdata = iter.find_tzdata(&file, &header, timezone).unwrap();
+        assert_eq!(tzdata.len(), 393);
+    }
+
+    #[test]
+    fn test_invalid_tzdata_header() {
+        TzDataHeader::new(&b"tzdaaa2024aaaaaaaaaaaaaaa\0"[..]).unwrap_err();
+    }
+
+    #[test]
+    fn test_android_tzdata_header_and_index() {
+        let file = File::open("./tests/android/tzdata").unwrap();
+        let header = TzDataHeader::new(&file).unwrap();
+        assert_eq!(header.version, *b"2021a");
+        assert_eq!(header.index_offset, 24);
+        assert_eq!(header.data_offset, 30860);
+        assert_eq!(header.zonetab_offset, 491837);
+
+        let iter = TzDataIndexes::new::<ANDROID_ENTRY_LEN>(&file, &header).unwrap();
+        assert_eq!(iter.indexes.len(), 593);
+        assert!(iter.find_timezone(b"Asia/Shanghai").is_some());
+        assert!(iter.find_timezone(b"Pacific/Noumea").is_some());
+    }
+
+    #[test]
+    fn test_android_tzdata_loading() {
+        let file = File::open("./tests/android/tzdata").unwrap();
+        let header = TzDataHeader::new(&file).unwrap();
+        let iter = TzDataIndexes::new::<ANDROID_ENTRY_LEN>(&file, &header).unwrap();
+        let timezone = iter.find_timezone(b"Asia/Shanghai").unwrap();
+        let tzdata = iter.find_tzdata(&file, &header, timezone).unwrap();
+        assert_eq!(tzdata.len(), 573);
+    }
+
+    #[test]
+    fn test_ohos_tzdata_find() {
+        let file = File::open("./tests/ohos/tzdata").unwrap();
+        let tzdata = find_tz_data::<OHOS_ENTRY_LEN>(file, b"Asia/Shanghai").unwrap().unwrap();
+        assert_eq!(tzdata.len(), 393);
+    }
+
+    #[test]
+    fn test_ohos_tzdata_find_missing() {
+        let file = File::open("./tests/ohos/tzdata").unwrap();
+        assert!(find_tz_data::<OHOS_ENTRY_LEN>(file, b"Asia/Sjasdfai").unwrap().is_none());
+    }
+
+    #[test]
+    fn test_android_tzdata_find() {
+        let file = File::open("./tests/android/tzdata").unwrap();
+        let tzdata = find_tz_data::<ANDROID_ENTRY_LEN>(file, b"Asia/Shanghai").unwrap().unwrap();
+        assert_eq!(tzdata.len(), 573);
+    }
+
+    #[test]
+    fn test_android_tzdata_find_missing() {
+        let file = File::open("./tests/android/tzdata").unwrap();
+        assert!(find_tz_data::<ANDROID_ENTRY_LEN>(file, b"Asia/S000000i").unwrap().is_none());
+    }
+
+    #[cfg(target_env = "ohos")]
+    #[test]
+    fn test_ohos_machine_tz_data_loading() {
+        let tzdata = for_zone(b"Asia/Shanghai").unwrap().unwrap();
+        assert!(!tzdata.is_empty());
+    }
+
+    #[cfg(target_os = "android")]
+    #[test]
+    fn test_android_machine_tz_data_loading() {
+        let tzdata = for_zone(b"Asia/Shanghai").unwrap().unwrap();
+        assert!(!tzdata.is_empty());
+    }
+}

src/offset/local/tz_info/timezone.rs

@@ -8,8 +8,6 @@ use std::{cmp::Ordering, fmt, str};
 use super::rule::{AlternateTime, TransitionRule};
 use super::{DAYS_PER_WEEK, Error, SECONDS_PER_DAY, parser};
 use crate::NaiveDateTime;
-#[cfg(target_env = "ohos")]
-use crate::offset::local::tz_info::parser::Cursor;
 
 /// Time zone
 #[derive(Debug, Clone, Eq, PartialEq)]
@@ -46,19 +44,13 @@ impl TimeZone {
         }
 
         // attributes are not allowed on if blocks in Rust 1.38
-        #[cfg(target_os = "android")]
+        #[cfg(any(target_os = "android", target_env = "ohos"))]
         {
-            if let Ok(bytes) = android_tzdata::find_tz_data(tz_string) {
+            if let Ok(Some(bytes)) = crate::offset::local::tz_data::for_zone(tz_string) {
                 return Self::from_tz_data(&bytes);
             }
         }
 
-        // ohos merge all file into tzdata since ver35
-        #[cfg(target_env = "ohos")]
-        {
-            return Self::from_tz_data(&find_ohos_tz_data(tz_string)?);
-        }
-
         let mut chars = tz_string.chars();
         if chars.next() == Some(':') {
             return Self::from_file(&mut find_tz_file(chars.as_str())?);
@@ -635,58 +627,6 @@ fn find_tz_file(path: impl AsRef<Path>) -> Result<File, Error> {
     }
 }
 
-#[cfg(target_env = "ohos")]
-fn from_tzdata_bytes(bytes: &mut Vec<u8>, tz_string: &str) -> Result<Vec<u8>, Error> {
-    const VERSION_SIZE: usize = 12;
-    const OFFSET_SIZE: usize = 4;
-    const INDEX_CHUNK_SIZE: usize = 48;
-    const ZONENAME_SIZE: usize = 40;
-
-    let mut cursor = Cursor::new(&bytes);
-    // version head
-    let _ = cursor.read_exact(VERSION_SIZE)?;
-    let index_offset_offset = cursor.read_be_u32()?;
-    let data_offset_offset = cursor.read_be_u32()?;
-    // final offset
-    let _ = cursor.read_be_u32()?;
-
-    cursor.seek_after(index_offset_offset as usize)?;
-    let mut idx = index_offset_offset;
-    while idx < data_offset_offset {
-        let index_buf = cursor.read_exact(ZONENAME_SIZE)?;
-        let offset = cursor.read_be_u32()?;
-        let length = cursor.read_be_u32()?;
-        let zone_name = str::from_utf8(index_buf)?.trim_end_matches('\0');
-        if zone_name != tz_string {
-            idx += INDEX_CHUNK_SIZE as u32;
-            continue;
-        }
-        cursor.seek_after((data_offset_offset + offset) as usize)?;
-        return match cursor.read_exact(length as usize) {
-            Ok(result) => Ok(result.to_vec()),
-            Err(_err) => Err(Error::InvalidTzFile("invalid ohos tzdata chunk")),
-        };
-    }
-
-    Err(Error::InvalidTzString("cannot find tz string within tzdata"))
-}
-
-#[cfg(target_env = "ohos")]
-fn from_tzdata_file(file: &mut File, tz_string: &str) -> Result<Vec<u8>, Error> {
-    let mut bytes = Vec::new();
-    file.read_to_end(&mut bytes)?;
-    from_tzdata_bytes(&mut bytes, tz_string)
-}
-
-#[cfg(target_env = "ohos")]
-fn find_ohos_tz_data(tz_string: &str) -> Result<Vec<u8>, Error> {
-    const TZDATA_PATH: &str = "/system/etc/zoneinfo/tzdata";
-    match File::open(TZDATA_PATH) {
-        Ok(mut file) => from_tzdata_file(&mut file, tz_string),
-        Err(err) => Err(err.into()),
-    }
-}
-
 // Possible system timezone directories
 #[cfg(unix)]
 const ZONE_INFO_DIRECTORIES: [&str; 4] =