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

Commencez par reproduire fs.realpathSync('d') sous Linux et comparez-le à fs.realpathSync.native('d'), en vous servant de la configuration de symlinks indiquée et du comportement de strace comme guide. Suivez le point d’entrée fs.realpathSync et son chemin de résolution des symlinks. Le travail est terminé lorsque la commande renvoie /home/niko/test/a/b/d au lieu de boucler, tandis que le comportement natif reste correct.