tzif_codec/
write.rs

1use crate::{
2    common::{TimeSize, HEADER_RESERVED_LEN, TZIF_MAGIC},
3    validate::validate_file,
4    DataBlock, TzifError, TzifFile, Version,
5};
6
7impl TzifFile {
8    /// Encodes this file to `TZif` bytes after validating it.
9    ///
10    /// # Errors
11    ///
12    /// Returns an error if the file is invalid or contains counts or timestamps that
13    /// cannot be represented by the selected `TZif` version.
14    pub fn to_bytes(&self) -> Result<Vec<u8>, TzifError> {
15        validate_file(self)?;
16        let mut out = Vec::new();
17        write_header(&mut out, self.version, &self.v1)?;
18        write_data_block(&mut out, &self.v1, TimeSize::ThirtyTwo)?;
19        if self.version.is_v2_plus() {
20            let block = self
21                .v2_plus
22                .as_ref()
23                .ok_or(TzifError::MissingV2PlusData(self.version))?;
24            write_header(&mut out, self.version, block)?;
25            write_data_block(&mut out, block, TimeSize::SixtyFour)?;
26            out.push(b'\n');
27            out.extend_from_slice(self.footer.as_deref().unwrap_or("").as_bytes());
28            out.push(b'\n');
29        }
30        Ok(out)
31    }
32}
33
34fn write_header(out: &mut Vec<u8>, version: Version, block: &DataBlock) -> Result<(), TzifError> {
35    out.extend_from_slice(TZIF_MAGIC);
36    out.push(version.byte());
37    out.extend_from_slice(&[0; HEADER_RESERVED_LEN]);
38    write_u32(out, block.ut_local_indicators.len())?;
39    write_u32(out, block.standard_wall_indicators.len())?;
40    write_u32(out, block.leap_seconds.len())?;
41    write_u32(out, block.transition_times.len())?;
42    write_u32(out, block.local_time_types.len())?;
43    write_u32(out, block.designations.len())?;
44    Ok(())
45}
46
47fn write_data_block(
48    out: &mut Vec<u8>,
49    block: &DataBlock,
50    time_size: TimeSize,
51) -> Result<(), TzifError> {
52    for (index, &time) in block.transition_times.iter().enumerate() {
53        write_time(out, time, time_size, index, "transition")?;
54    }
55    out.extend_from_slice(&block.transition_types);
56    for local_time_type in &block.local_time_types {
57        out.extend_from_slice(&local_time_type.utc_offset.to_be_bytes());
58        out.push(u8::from(local_time_type.is_dst));
59        out.push(local_time_type.designation_index);
60    }
61    out.extend_from_slice(&block.designations);
62    for (index, leap_second) in block.leap_seconds.iter().enumerate() {
63        write_time(out, leap_second.occurrence, time_size, index, "leap")?;
64        out.extend_from_slice(&leap_second.correction.to_be_bytes());
65    }
66    for &is_standard in &block.standard_wall_indicators {
67        out.push(u8::from(is_standard));
68    }
69    for &is_ut in &block.ut_local_indicators {
70        out.push(u8::from(is_ut));
71    }
72    Ok(())
73}
74
75fn write_time(
76    out: &mut Vec<u8>,
77    value: i64,
78    time_size: TimeSize,
79    index: usize,
80    kind: &'static str,
81) -> Result<(), TzifError> {
82    match time_size {
83        TimeSize::ThirtyTwo => {
84            let value = i32::try_from(value).map_err(|_| match kind {
85                "transition" => TzifError::Version1TransitionOutOfRange { index, value },
86                _ => TzifError::Version1LeapSecondOutOfRange { index, value },
87            })?;
88            out.extend_from_slice(&value.to_be_bytes());
89        }
90        TimeSize::SixtyFour => out.extend_from_slice(&value.to_be_bytes()),
91    }
92    Ok(())
93}
94
95fn write_u32(out: &mut Vec<u8>, value: usize) -> Result<(), TzifError> {
96    let value = u32::try_from(value).map_err(|_| TzifError::CountOverflow {
97        field: "count",
98        count: value,
99    })?;
100    out.extend_from_slice(&value.to_be_bytes());
101    Ok(())
102}
tzif_codec/write.rs

tzif_codec/
write.rs
