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

Comienza con la reproducción de fs.realpathSync('d') en Linux y compárala con fs.realpathSync.native('d'), usando como guía la configuración de symlinks indicada y el comportamiento de strace. Rastrea el punto de entrada fs.realpathSync y su ruta de resolución de symlinks. Se considera hecho cuando el comando devuelve /home/niko/test/a/b/d en lugar de entrar en un bucle, mientras el comportamiento nativo sigue siendo correcto.