Fixup max safe integer check for open ended byteranges with nonzero start

Author: iamboorrito

src/loader/fragment-preloader.ts

@@ -98,16 +98,10 @@ export default class FragmentPreloader extends FragmentLoader {
       this.abort();
     }
 
-    this.log(
-      `[${this.getStateString()}] create request for [${frag.type}] ${
-        frag.sn
-      }:${part?.index}`,
-    );
-
     let loadPromise;
     if (part !== undefined) {
       // TODO: Use fetch loader to progressively load open-ended byterange requests
-      if (part.byteRangeEndOffset === 2 ** 53 - 1) {
+      if (part?.byteRangeEndOffset === Number.MAX_SAFE_INTEGER) {
         return;
       } else {
         loadPromise = this.loadPart(frag, part, noop);
@@ -116,6 +110,12 @@ export default class FragmentPreloader extends FragmentLoader {
       loadPromise = this.load(frag, noop);
     }
 
+    this.log(
+      `[${this.getStateString()}] create request for [${frag.type}] ${
+        frag.sn
+      }:${part?.index}`,
+    );
+
     const request = {
       frag,
       part,

src/loader/fragment.ts

@@ -58,7 +58,13 @@ export class BaseSegment {
     } else {
       start = parseInt(params[1]);
     }
-    this._byteRange = [start, parseInt(params[0]) + start];
+    const bytelength = parseInt(params[0]);
+    const offsetEnd =
+      Number.isSafeInteger(bytelength) && bytelength !== Number.MAX_SAFE_INTEGER
+        ? start + bytelength
+        : Number.MAX_SAFE_INTEGER;
+
+    this._byteRange = [start, offsetEnd];
   }
 
   get byteRange(): [number, number] | [] {

src/loader/m3u8-parser.ts

@@ -698,11 +698,12 @@ export default class M3U8Parser {
         preloadHintAttrs['BYTERANGE-LENGTH']
       ) {
         const byteRangeStartOffset = preloadHintAttrs['BYTERANGE-START'];
-        let byteRangeLength = preloadHintAttrs['BYTERANGE-LENGTH'];
-        if (byteRangeLength <= 0) {
-          byteRangeLength = 2 ** 53 - 1;
-        }
-        if (isFinite(byteRangeLength) && isFinite(byteRangeStartOffset)) {
+
+        if (isFinite(byteRangeStartOffset)) {
+          let byteRangeLength = preloadHintAttrs['BYTERANGE-LENGTH'];
+          if (!isFinite(byteRangeLength) || byteRangeLength <= 0) {
+            byteRangeLength = Number.MAX_SAFE_INTEGER;
+          }
           byteRange = `${byteRangeLength}@${byteRangeStartOffset}`;
         }
       }