sys.executable is sometimes wrong

Bug report

Bug description:

On Linux, sys.executable is determined using argv[0], and trying to find that in the PATH. This presumes that the Python interpreter has been started by a shell that interprets PATH in the canonical way. There is no guarantee that this happens at all, so sys.executable may point to something completely different, or is even the empty string.

As an example:

bash -c 'exec -a whatever python -c "import sys;print(sys.executable)"'

should output the path of the Python executable, but simply outputs nothing.

Even worse, one can make Python output a wrong executable, as in

bash -c 'exec -a /usr/bin/python python -c "import sys;print(sys.executable)"'

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-145486

Reproduisez les deux commandes Linux du rapport et examinez comment CPython détermine sys.executable à partir de argv[0] et de PATH. Utilisez les cas avec argv[0] modifié comme scénarios de régression ; le travail est considéré comme terminé lorsque sys.executable identifie l’exécutable Python en cours d’exécution plutôt qu’un chemin vide ou sans rapport. L’issue fait référence à la PR liée gh-145486.