fs: fix reads with pos > 4GB

PR-URL: #21003
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: mafintosh

lib/fs.js

@@ -593,7 +593,7 @@ fs.read = function(fd, buffer, offset, length, position, callback) {
 
 validateOffsetLengthRead(offset,length,buffer.length);
 
-if(!isUint32(position))
+if(!Number.isSafeInteger(position))
 position=-1;
 
 functionwrapper(err,bytesRead){
@@ -623,7 +623,7 @@ fs.readSync = function(fd, buffer, offset, length, position) {
 
 validateOffsetLengthRead(offset,length,buffer.length);
 
-if(!isUint32(position))
+if(!Number.isSafeInteger(position))
 position=-1;
 
 constctx={};

test/parallel/test-fs-read.js

@@ -53,3 +53,18 @@ test(Buffer.allocUnsafe(expected.length),
 test(newUint8Array(expected.length),
 newUint8Array(expected.length),
 Uint8Array.from(expected));
+
+{
+// Reading beyond file length (3 in this case) should return no data.
+// This is a test for a bug where reads > uint32 would return data
+// from the current position in the file.
+constfd=fs.openSync(filepath,'r');
+constpos=0xffffffff+1;// max-uint32 + 1
+constnRead=fs.readSync(fd,Buffer.alloc(1),0,1,pos);
+assert.strictEqual(nRead,0);
+
+fs.read(fd,Buffer.alloc(1),0,1,pos,common.mustCall((err,nRead)=>{
+assert.ifError(err);
+assert.strictEqual(nRead,0);
+}));
+}