fs.realpath infinite loop

Version

v25.0.0

Platform

uname -a
Linux [hostname] 6.8.0-1039-aws #41~22.04.1-Ubuntu SMP Thu Sep 11 10:54:48 UTC 2025 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

fs

What steps will reproduce the bug?

$ mkdir test
$ cd test
$ mkdir -p a/b/{c,d}
$ ln -s a/b/c  # Make symlink to c dir in a/b
$ ln -s "c/../d"  # Make symlink to d dir via c symlink
$ node -e "const fs = require('fs'); console.log(fs.realpathSync('d'));"

The node call never returns. If I call it with strace it's just checking the same file over and over:

...
statx(AT_FDCWD, "/home/niko/test/d", AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW, STATX_ALL, {stx_mask=STATX_ALL|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFLNK|0777, stx_size=6, ...}) = 0
statx(AT_FDCWD, "/home/niko/test/d", AT_STATX_SYNC_AS_STAT|AT_SYMLINK_NOFOLLOW, STATX_ALL, {stx_mask=STATX_ALL|STATX_MNT_ID, stx_attributes=0, stx_mode=S_IFLNK|0777, stx_size=6, ...}) = 0
...

How often does it reproduce? Is there a required condition?

Reproduces every time.

What is the expected behavior? Why is that the expected behavior?

Expected behavior is that the realpath would be printed to the console:

$ node -e "const fs = require('fs'); console.log(fs.realpathSync('d'));"
/home/niko/test/a/b/d

Note that realpathSync.native does work properly:

$ node -e "const fs = require('fs'); console.log(fs.realpathSync.native('d'));"
/home/niko/test/a/b/d

What do you see instead?

An infinite loop (see Steps section above).

Additional information

No response

Beginne mit der Reproduktion von fs.realpathSync('d') unter Linux und vergleiche sie mit fs.realpathSync.native('d'), wobei die gemeldete Symlink-Konfiguration und das Verhalten von strace als Orientierung dienen. Verfolge den Einstiegspunkt fs.realpathSync und den Pfad zur Auflösung des Symlinks. Erledigt ist die Aufgabe, wenn der Befehl /home/niko/test/a/b/d zurückgibt, anstatt in einer Schleife zu laufen, während das native Verhalten weiterhin korrekt bleibt.