File size: 1,413 Bytes
4e23b01 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | export function pickHeader(
headers: Record<string, unknown>,
name: string,
): string | undefined {
const v = headers[name];
if (v === undefined) return undefined;
return Array.isArray(v) ? (v[0] as string | undefined) : (v as string);
}
export function parseRangeHeader(
raw: string | undefined,
size: number,
): { start: number; end: number; length: number } | null {
if (raw === undefined) return null;
if (!raw.startsWith('bytes=')) return null;
const spec = raw.slice('bytes='.length);
if (spec.includes(',')) return null;
const dash = spec.indexOf('-');
if (dash < 0) return null;
const leftRaw = spec.slice(0, dash);
const rightRaw = spec.slice(dash + 1);
if (leftRaw === '' && rightRaw === '') return null;
let start: number;
let end: number;
if (leftRaw === '') {
const suffix = Number.parseInt(rightRaw, 10);
if (!Number.isFinite(suffix) || suffix <= 0) return null;
start = Math.max(0, size - suffix);
end = size - 1;
} else {
const a = Number.parseInt(leftRaw, 10);
if (!Number.isFinite(a) || a < 0) return null;
start = a;
if (rightRaw === '') {
end = size - 1;
} else {
const b = Number.parseInt(rightRaw, 10);
if (!Number.isFinite(b) || b < a) return null;
end = Math.min(b, size - 1);
}
}
if (start >= size || start > end) return null;
return { start, end, length: end - start + 1 };
}
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