pythonGH-124241: try reading /proc/self/exe to determine sys.executable

Signed-off-by: Filipe Laíns <lains@riseup.net>

Author: FFY00

Misc/NEWS.d/next/Core_and_Builtins/2026-03-03-21-45-16.gh-issue-124241._GLhVo.rst

@@ -0,0 +1,2 @@
+On POSIX, we now try to read the symlink target from ``/proc/self/exe`` to
+determine :data:`sys.executable`.

Modules/getpath.py

@@ -265,6 +265,13 @@ def search_up(prefix, *landmarks, test=isfile):
     if not executable:
         executable = real_executable
 
+if not executable and os_name == 'posix':
+    # On Linux, try resolving the executable path via procfs
+    try:
+        executable = realpath('/proc/self/exe')
+    except (OSError, MemoryError):
+        pass
+
 if not executable and SEP in program_name:
     # Resolve partial path program_name against current directory
     executable = abspath(program_name)