Use readlink to read /proc/self/exe

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

Author: FFY00

Modules/getpath.c

@@ -797,6 +797,11 @@ progname_to_dict(PyObject *dict, const char *key)
         PyMem_RawFree(path);
         break;
     }
+#elif defined(HAVE_READLINK)
+    wchar_t resolved[MAXPATHLEN + 1];
+    if (_Py_wreadlink(L"/proc/self/exe", resolved, Py_ARRAY_LENGTH(resolved)) != -1) {
+        return wchar_to_dict(dict, key, resolved);
+    }
 #endif
     return PyDict_SetItemString(dict, key, Py_None) == 0;
 }

Modules/getpath.py

@@ -265,13 +265,6 @@ 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)
@@ -287,6 +280,17 @@ def search_up(prefix, *landmarks, test=isfile):
     # whether we are in a build tree. This is true even if the
     # executable path was provided in the config.
     real_executable = executable
+elif os_name == 'posix':
+    # real_executable is more accurate than the value we have computed for
+    # executable, so use it instead if it resolves to a different path
+    # (eg. GH-124241).
+    # If real_executable and executable resolve to the same path, prefer
+    # executable, as that is much more likely to be the path the user is using.
+    try:
+        if realpath(executable) != real_executable:
+            executable = real_executable
+    except OSError:
+        pass
 
 if not executable and program_name and ENV_PATH:
     # Resolve names against PATH.