From 7fbd9f73be238b15d9ac1746f5c9bcb858ba64a1 Mon Sep 17 00:00:00 2001
From: Sam Clegg <sbc@chromium.org>
Date: Sun, 8 Mar 2026 16:28:20 -0700
Subject: [PATCH] Fix `isatty()` under `NODERAWFS`

---
 src/lib/libnoderawfs.js | 13 +++++++------
 test/test_other.py      |  9 ++++++++-
 test/unistd/isatty.c    | 38 +++++++++++++++++++++++++++++---------
 3 files changed, 44 insertions(+), 16 deletions(-)

diff --git a/src/lib/libnoderawfs.js b/src/lib/libnoderawfs.js
index b805c43302b4f..57387ad233674 100644
--- a/src/lib/libnoderawfs.js
+++ b/src/lib/libnoderawfs.js
@@ -10,6 +10,7 @@ addToLibrary({
     if (!ENVIRONMENT_IS_NODE) {
       throw new Error("NODERAWFS is currently only supported on Node.js environment.")
     }
+    var nodeTTY = require('node:tty');
     function _wrapNodeError(func) {
       return (...args) => {
         try {
@@ -64,11 +65,10 @@ addToLibrary({
       return { path, node: { id: st.ino, mode, node_ops: NODERAWFS, path }};
     },
     createStandardStreams() {
-      // FIXME: tty is set to true to appease isatty(), the underlying ioctl syscalls still need to be implemented, see issue #22264.
-      FS.createStream({ nfd: 0, position: 0, path: '/dev/stdin', flags: 0, tty: true, seekable: false }, 0);
+      FS.createStream({ nfd: 0, position: 0, path: '/dev/stdin', flags: 0, seekable: false }, 0);
       var paths = [,'/dev/stdout', '/dev/stderr'];
       for (var i = 1; i < 3; i++) {
-        FS.createStream({ nfd: i, position: 0, path: paths[i], flags: {{{ cDefs.O_TRUNC | cDefs.O_CREAT | cDefs.O_WRONLY }}}, tty: true, seekable: false }, i);
+        FS.createStream({ nfd: i, position: 0, path: paths[i], flags: {{{ cDefs.O_TRUNC | cDefs.O_CREAT | cDefs.O_WRONLY }}}, seekable: false }, i);
       }
     },
     // generic function for all node creation
@@ -179,10 +179,11 @@ addToLibrary({
     createStream(stream, fd) {
       // Call the original FS.createStream
       var rtn = VFS.createStream(stream, fd);
-      if (typeof rtn.shared.refcnt == 'undefined') {
-        rtn.shared.refcnt = 1;
-      } else {
+      // Detect PIPEFS streams and skip the refcnt/tty initialization in that case.
+      if (!stream.stream_ops) {
+        rtn.shared.refcnt ??= 0;
         rtn.shared.refcnt++;
+        rtn.tty = nodeTTY.isatty(rtn.nfd);
       }
       return rtn;
     },
diff --git a/test/test_other.py b/test/test_other.py
index 936dff4783e1c..a453365822a67 100644
--- a/test/test_other.py
+++ b/test/test_other.py
@@ -1653,7 +1653,7 @@ def test_export_all_and_exported_functions(self):
     self.do_runf('lib.c', 'libfunc\n', cflags=['-sEXPORTED_FUNCTIONS=_libfunc2', '-sEXPORT_ALL', '--pre-js', 'pre.js'])
 
   @all_engines
-  @also_with_wasmfs
+  @with_all_fs
   @crossplatform
   @parameterized({
     '': ([],),
@@ -13128,7 +13128,14 @@ def test_unistd_pathconf(self):
   def test_unistd_swab(self):
     self.do_run_in_out_file_test('unistd/swab.c')
 
+  @also_with_noderawfs
   def test_unistd_isatty(self):
+    if '-DNODERAWFS' in self.cflags:
+      # Under NODERAWFS istty reports accurate information about the file descriptors
+      # of the node process. When we run tests we always capture stdout so we never expect
+      # stdout to be a tty.
+      stdin_isatty = os.isatty(0)
+      self.cflags += ['-DEXPECT_STDOUT=0', f'-DEXPECT_STDIN={int(stdin_isatty)}']
     self.do_runf('unistd/isatty.c', 'success')
 
   def test_unistd_login(self):
diff --git a/test/unistd/isatty.c b/test/unistd/isatty.c
index 8d4ad2f3a8100..c4c858e0c04a9 100644
--- a/test/unistd/isatty.c
+++ b/test/unistd/isatty.c
@@ -13,21 +13,41 @@
 #include <string.h>
 #include <unistd.h>
 
+#ifndef EXPECT_STDIN
+#define EXPECT_STDIN 1
+#endif
+
+#ifndef EXPECT_STDOUT
+#define EXPECT_STDOUT 1
+#endif
+
 int main() {
-  int err;
+  printf("EXPECT_STDIN: %d\n", EXPECT_STDIN);
+  printf("EXPECT_STDOUT: %d\n", EXPECT_STDOUT);
+
+  assert(isatty(0) == EXPECT_STDIN);
+  assert(isatty(1) == EXPECT_STDOUT);
 
-  err = isatty(-1);
-  assert(!err);
+  int err, fd;
+
+  assert(isatty(-1) == 0);
   assert(errno == EBADF);
 
-  err = isatty(open("/dev/stdin", O_RDONLY));
-  assert(err == 1);
+  fd = open("/dev/stdin", O_RDONLY);
+  assert(fd >= 0);
+  assert(isatty(fd) == EXPECT_STDIN);
+
+  fd = open("/dev/stdout", O_RDONLY);
+  assert(fd >= 0);
+  assert(isatty(fd) == EXPECT_STDOUT);
 
-  err = isatty(open("/dev/null", O_RDONLY));
-  assert(!err);
+  fd = open("/dev/null", O_RDONLY);
+  assert(fd >= 0);
+  assert(isatty(fd) == 0);
 
-  err = isatty(open("/dev", O_RDONLY));
-  assert(!err);
+  fd = open("/dev", O_RDONLY);
+  assert(fd >= 0);
+  assert(isatty(fd) == 0);
 
   puts("success");