253 lines
11 KiB
Zig
253 lines
11 KiB
Zig
const std = @import("std.zig");
|
|
const builtin = @import("builtin");
|
|
|
|
pub const Transition = struct {
|
|
ts: i64,
|
|
timetype: *Timetype,
|
|
};
|
|
|
|
pub const Timetype = struct {
|
|
offset: i32,
|
|
flags: u8,
|
|
name_data: [6:0]u8,
|
|
|
|
pub fn name(self: *const Timetype) [:0]const u8 {
|
|
return std.mem.sliceTo(self.name_data[0..], 0);
|
|
}
|
|
|
|
pub fn isDst(self: Timetype) bool {
|
|
return (self.flags & 0x01) > 0;
|
|
}
|
|
|
|
pub fn standardTimeIndicator(self: Timetype) bool {
|
|
return (self.flags & 0x02) > 0;
|
|
}
|
|
|
|
pub fn utIndicator(self: Timetype) bool {
|
|
return (self.flags & 0x04) > 0;
|
|
}
|
|
};
|
|
|
|
pub const Leapsecond = struct {
|
|
occurrence: i48,
|
|
correction: i16,
|
|
};
|
|
|
|
pub const Tz = struct {
|
|
allocator: std.mem.Allocator,
|
|
transitions: []const Transition,
|
|
timetypes: []const Timetype,
|
|
leapseconds: []const Leapsecond,
|
|
footer: ?[]const u8,
|
|
|
|
const Header = extern struct {
|
|
magic: [4]u8,
|
|
version: u8,
|
|
reserved: [15]u8,
|
|
counts: extern struct {
|
|
isutcnt: u32,
|
|
isstdcnt: u32,
|
|
leapcnt: u32,
|
|
timecnt: u32,
|
|
typecnt: u32,
|
|
charcnt: u32,
|
|
},
|
|
};
|
|
|
|
pub fn parse(allocator: std.mem.Allocator, reader: anytype) !Tz {
|
|
var legacy_header = try reader.readStruct(Header);
|
|
if (!std.mem.eql(u8, &legacy_header.magic, "TZif")) return error.BadHeader;
|
|
if (legacy_header.version != 0 and legacy_header.version != '2' and legacy_header.version != '3') return error.BadVersion;
|
|
|
|
if (builtin.target.cpu.arch.endian() != std.builtin.Endian.big) {
|
|
std.mem.byteSwapAllFields(@TypeOf(legacy_header.counts), &legacy_header.counts);
|
|
}
|
|
|
|
if (legacy_header.version == 0) {
|
|
return parseBlock(allocator, reader, legacy_header, true);
|
|
} else {
|
|
// If the format is modern, just skip over the legacy data
|
|
const skipv = legacy_header.counts.timecnt * 5 + legacy_header.counts.typecnt * 6 + legacy_header.counts.charcnt + legacy_header.counts.leapcnt * 8 + legacy_header.counts.isstdcnt + legacy_header.counts.isutcnt;
|
|
try reader.skipBytes(skipv, .{});
|
|
|
|
var header = try reader.readStruct(Header);
|
|
if (!std.mem.eql(u8, &header.magic, "TZif")) return error.BadHeader;
|
|
if (header.version != '2' and header.version != '3') return error.BadVersion;
|
|
if (builtin.target.cpu.arch.endian() != std.builtin.Endian.big) {
|
|
std.mem.byteSwapAllFields(@TypeOf(header.counts), &header.counts);
|
|
}
|
|
|
|
return parseBlock(allocator, reader, header, false);
|
|
}
|
|
}
|
|
|
|
fn parseBlock(allocator: std.mem.Allocator, reader: anytype, header: Header, legacy: bool) !Tz {
|
|
if (header.counts.isstdcnt != 0 and header.counts.isstdcnt != header.counts.typecnt) return error.Malformed; // rfc8536: isstdcnt [...] MUST either be zero or equal to "typecnt"
|
|
if (header.counts.isutcnt != 0 and header.counts.isutcnt != header.counts.typecnt) return error.Malformed; // rfc8536: isutcnt [...] MUST either be zero or equal to "typecnt"
|
|
if (header.counts.typecnt == 0) return error.Malformed; // rfc8536: typecnt [...] MUST NOT be zero
|
|
if (header.counts.charcnt == 0) return error.Malformed; // rfc8536: charcnt [...] MUST NOT be zero
|
|
if (header.counts.charcnt > 256 + 6) return error.Malformed; // Not explicitly banned by rfc8536 but nonsensical
|
|
|
|
var leapseconds = try allocator.alloc(Leapsecond, header.counts.leapcnt);
|
|
errdefer allocator.free(leapseconds);
|
|
var transitions = try allocator.alloc(Transition, header.counts.timecnt);
|
|
errdefer allocator.free(transitions);
|
|
var timetypes = try allocator.alloc(Timetype, header.counts.typecnt);
|
|
errdefer allocator.free(timetypes);
|
|
|
|
// Parse transition types
|
|
var i: usize = 0;
|
|
while (i < header.counts.timecnt) : (i += 1) {
|
|
transitions[i].ts = if (legacy) try reader.readInt(i32, .big) else try reader.readInt(i64, .big);
|
|
}
|
|
|
|
i = 0;
|
|
while (i < header.counts.timecnt) : (i += 1) {
|
|
const tt = try reader.readByte();
|
|
if (tt >= timetypes.len) return error.Malformed; // rfc8536: Each type index MUST be in the range [0, "typecnt" - 1]
|
|
transitions[i].timetype = &timetypes[tt];
|
|
}
|
|
|
|
// Parse time types
|
|
i = 0;
|
|
while (i < header.counts.typecnt) : (i += 1) {
|
|
const offset = try reader.readInt(i32, .big);
|
|
if (offset < -2147483648) return error.Malformed; // rfc8536: utoff [...] MUST NOT be -2**31
|
|
const dst = try reader.readByte();
|
|
if (dst != 0 and dst != 1) return error.Malformed; // rfc8536: (is)dst [...] The value MUST be 0 or 1.
|
|
const idx = try reader.readByte();
|
|
if (idx > header.counts.charcnt - 1) return error.Malformed; // rfc8536: (desig)idx [...] Each index MUST be in the range [0, "charcnt" - 1]
|
|
timetypes[i] = .{
|
|
.offset = offset,
|
|
.flags = dst,
|
|
.name_data = undefined,
|
|
};
|
|
|
|
// Temporarily cache idx in name_data to be processed after we've read the designator names below
|
|
timetypes[i].name_data[0] = idx;
|
|
}
|
|
|
|
var designators_data: [256 + 6]u8 = undefined;
|
|
try reader.readNoEof(designators_data[0..header.counts.charcnt]);
|
|
const designators = designators_data[0..header.counts.charcnt];
|
|
if (designators[designators.len - 1] != 0) return error.Malformed; // rfc8536: charcnt [...] includes the trailing NUL (0x00) octet
|
|
|
|
// Iterate through the timetypes again, setting the designator names
|
|
for (timetypes) |*tt| {
|
|
const name = std.mem.sliceTo(designators[tt.name_data[0]..], 0);
|
|
// We are mandating the "SHOULD" 6-character limit so we can pack the struct better, and to conform to POSIX.
|
|
if (name.len > 6) return error.Malformed; // rfc8536: Time zone designations SHOULD consist of at least three (3) and no more than six (6) ASCII characters.
|
|
@memcpy(tt.name_data[0..name.len], name);
|
|
tt.name_data[name.len] = 0;
|
|
}
|
|
|
|
// Parse leap seconds
|
|
i = 0;
|
|
while (i < header.counts.leapcnt) : (i += 1) {
|
|
const occur: i64 = if (legacy) try reader.readInt(i32, .big) else try reader.readInt(i64, .big);
|
|
if (occur < 0) return error.Malformed; // rfc8536: occur [...] MUST be nonnegative
|
|
if (i > 0 and leapseconds[i - 1].occurrence + 2419199 > occur) return error.Malformed; // rfc8536: occur [...] each later value MUST be at least 2419199 greater than the previous value
|
|
if (occur > std.math.maxInt(i48)) return error.Malformed; // Unreasonably far into the future
|
|
|
|
const corr = try reader.readInt(i32, .big);
|
|
if (i == 0 and corr != -1 and corr != 1) return error.Malformed; // rfc8536: The correction value in the first leap-second record, if present, MUST be either one (1) or minus one (-1)
|
|
if (i > 0 and leapseconds[i - 1].correction != corr + 1 and leapseconds[i - 1].correction != corr - 1) return error.Malformed; // rfc8536: The correction values in adjacent leap-second records MUST differ by exactly one (1)
|
|
if (corr > std.math.maxInt(i16)) return error.Malformed; // Unreasonably large correction
|
|
|
|
leapseconds[i] = .{
|
|
.occurrence = @as(i48, @intCast(occur)),
|
|
.correction = @as(i16, @intCast(corr)),
|
|
};
|
|
}
|
|
|
|
// Parse standard/wall indicators
|
|
i = 0;
|
|
while (i < header.counts.isstdcnt) : (i += 1) {
|
|
const stdtime = try reader.readByte();
|
|
if (stdtime == 1) {
|
|
timetypes[i].flags |= 0x02;
|
|
}
|
|
}
|
|
|
|
// Parse UT/local indicators
|
|
i = 0;
|
|
while (i < header.counts.isutcnt) : (i += 1) {
|
|
const ut = try reader.readByte();
|
|
if (ut == 1) {
|
|
timetypes[i].flags |= 0x04;
|
|
if (!timetypes[i].standardTimeIndicator()) return error.Malformed; // rfc8536: standard/wall value MUST be one (1) if the UT/local value is one (1)
|
|
}
|
|
}
|
|
|
|
// Footer
|
|
var footer: ?[]u8 = null;
|
|
if (!legacy) {
|
|
if ((try reader.readByte()) != '\n') return error.Malformed; // An rfc8536 footer must start with a newline
|
|
var footerdata_buf: [128]u8 = undefined;
|
|
const footer_mem = reader.readUntilDelimiter(&footerdata_buf, '\n') catch |err| switch (err) {
|
|
error.StreamTooLong => return error.OverlargeFooter, // Read more than 128 bytes, much larger than any reasonable POSIX TZ string
|
|
else => return err,
|
|
};
|
|
if (footer_mem.len != 0) {
|
|
footer = try allocator.dupe(u8, footer_mem);
|
|
}
|
|
}
|
|
errdefer if (footer) |ft| allocator.free(ft);
|
|
|
|
return Tz{
|
|
.allocator = allocator,
|
|
.transitions = transitions,
|
|
.timetypes = timetypes,
|
|
.leapseconds = leapseconds,
|
|
.footer = footer,
|
|
};
|
|
}
|
|
|
|
pub fn deinit(self: *Tz) void {
|
|
if (self.footer) |footer| {
|
|
self.allocator.free(footer);
|
|
}
|
|
self.allocator.free(self.leapseconds);
|
|
self.allocator.free(self.transitions);
|
|
self.allocator.free(self.timetypes);
|
|
}
|
|
};
|
|
|
|
test "slim" {
|
|
const data = @embedFile("tz/asia_tokyo.tzif");
|
|
var in_stream = std.io.fixedBufferStream(data);
|
|
|
|
var tz = try std.Tz.parse(std.testing.allocator, in_stream.reader());
|
|
defer tz.deinit();
|
|
|
|
try std.testing.expectEqual(tz.transitions.len, 9);
|
|
try std.testing.expect(std.mem.eql(u8, tz.transitions[3].timetype.name(), "JDT"));
|
|
try std.testing.expectEqual(tz.transitions[5].ts, -620298000); // 1950-05-06 15:00:00 UTC
|
|
try std.testing.expectEqual(tz.leapseconds[13].occurrence, 567993613); // 1988-01-01 00:00:00 UTC (+23s in TAI, and +13 in the data since it doesn't store the initial 10 second offset)
|
|
}
|
|
|
|
test "fat" {
|
|
const data = @embedFile("tz/antarctica_davis.tzif");
|
|
var in_stream = std.io.fixedBufferStream(data);
|
|
|
|
var tz = try std.Tz.parse(std.testing.allocator, in_stream.reader());
|
|
defer tz.deinit();
|
|
|
|
try std.testing.expectEqual(tz.transitions.len, 8);
|
|
try std.testing.expect(std.mem.eql(u8, tz.transitions[3].timetype.name(), "+05"));
|
|
try std.testing.expectEqual(tz.transitions[4].ts, 1268251224); // 2010-03-10 20:00:00 UTC
|
|
}
|
|
|
|
test "legacy" {
|
|
// Taken from Slackware 8.0, from 2001
|
|
const data = @embedFile("tz/europe_vatican.tzif");
|
|
var in_stream = std.io.fixedBufferStream(data);
|
|
|
|
var tz = try std.Tz.parse(std.testing.allocator, in_stream.reader());
|
|
defer tz.deinit();
|
|
|
|
try std.testing.expectEqual(tz.transitions.len, 170);
|
|
try std.testing.expect(std.mem.eql(u8, tz.transitions[69].timetype.name(), "CET"));
|
|
try std.testing.expectEqual(tz.transitions[123].ts, 1414285200); // 2014-10-26 01:00:00 UTC
|
|
}
|