fs: coerce -0 to +0 in mode flags and watch intervals

panva · aduh95 · commit ceba08a1eae8 · 2026-06-18T10:09:48.000+02:00
Signed-off-by: Filip Skokan <panva.ip@gmail.com> PR-URL: #63556 Reviewed-By: Jordan Harband <ljharb@gmail.com> Reviewed-By: Chemi Atlow <chemi@atlow.co.il>
diff --git a/lib/internal/fs/utils.js b/lib/internal/fs/utils.js
@@ -724,7 +724,8 @@ function getStatFsFromBinding(stats) {
 function stringToFlags(flags, name = 'flags') {
   if (typeof flags === 'number') {
     validateInt32(flags, name);
-    return flags;
+    // Coerce -0 to +0.
+    return flags + 0;
   }
 
   if (flags == null) {
diff --git a/lib/internal/fs/watchers.js b/lib/internal/fs/watchers.js
@@ -176,6 +176,8 @@ StatWatcher.prototype[kFSStatWatcherStart] = function(filename,
 
   filename = getValidatedPath(filename, 'filename');
   validateUint32(interval, 'interval');
+  // Coerce -0 to +0.
+  interval += 0;
   const err = this._handle.start(toNamespacedPath(filename), interval);
   if (err) {
     const error = new UVException({
diff --git a/lib/internal/validators.js b/lib/internal/validators.js
@@ -80,7 +80,8 @@ function parseFileMode(value, name, def) {
   }
 
   validateUint32(value, name);
-  return value;
+  // Coerce -0 to +0.
+  return value + 0;
 }
 
 /**
diff --git a/test/parallel/test-fs-negative-zero.js b/test/parallel/test-fs-negative-zero.js
@@ -0,0 +1,33 @@
+'use strict';
+
+require('../common');
+
+const fs = require('fs');
+const path = require('path');
+const os = require('os');
+
+const missing = path.join(
+  os.tmpdir(),
+  `node-fs-negative-zero-${process.pid}`,
+  'entry',
+);
+
+function ignoreExpectedError(fn) {
+  try {
+    fn();
+  } catch {
+    // Ignore expected file system errors from the missing path.
+  }
+}
+
+const fd = fs.openSync(process.execPath, -0);
+fs.closeSync(fd);
+
+ignoreExpectedError(() => fs.openSync(process.execPath, 'r', -0));
+ignoreExpectedError(() => fs.readFileSync(process.execPath, { flag: -0 }));
+ignoreExpectedError(() => fs.mkdirSync(missing, { mode: -0 }));
+ignoreExpectedError(() => fs.chmodSync(missing, -0));
+ignoreExpectedError(() => fs.writeFileSync(missing, '', { mode: -0 }));
+
+fs.watchFile(missing, { interval: -0 }, () => {});
+fs.unwatchFile(missing);

Original file line number	Diff line number	Diff line change
`@@ -724,7 +724,8 @@ function getStatFsFromBinding(stats) {`
`724`	`724`	`function stringToFlags(flags, name = 'flags') {`
`725`	`725`	`if (typeof flags === 'number') {`
`726`	`726`	`validateInt32(flags, name);`
`727`		`- return flags;`
	`727`	`+ // Coerce -0 to +0.`
	`728`	`+ return flags + 0;`
`728`	`729`	`}`
`729`	`730`
`730`	`731`	`if (flags == null) {`
Original file line number	Diff line number	Diff line change
`@@ -80,7 +80,8 @@ function parseFileMode(value, name, def) {`
`80`	`80`	`}`
`81`	`81`
`82`	`82`	`validateUint32(value, name);`
`83`		`- return value;`
	`83`	`+ // Coerce -0 to +0.`
	`84`	`+ return value + 0;`
`84`	`85`	`}`
`85`	`86`
`86`	`87`	`/**`