python · vstinner · Dec 17, 2018 · Dec 17, 2018 · Dec 17, 2018
diff --git a/Doc/library/platform.rst b/Doc/library/platform.rst
@@ -35,10 +35,9 @@ Cross Platform
    ``sizeof(long)`` on Python version < 1.5.2) is used as indicator for the
    supported pointer size.
 
-   The function relies on the system's :file:`file` command to do the actual work.
-   This is available on most if not all Unix  platforms and some non-Unix platforms
-   and then only if the executable points to the Python interpreter.  Reasonable
-   defaults are used when the above needs are not met.
+   If the *executable* parameter is set, the function relies on the system's
+   :file:`file` command to do the actual work. This is available on most Unix
+   platforms.
 
    .. note::
 
@@ -50,6 +49,10 @@ Cross Platform
 
          is_64bits = sys.maxsize > 2**32
 
+   .. versionchanged:: 3.8
+      The system's :file:`file` command is now longer used if the *executable*
+      parameter is not set.
+
 
 .. function:: machine()
 

diff --git a/Lib/platform.py b/Lib/platform.py
@@ -171,7 +171,7 @@ def libc_ver(executable=None, lib='', version='', chunksize=16384):
         The file is read and scanned in chunks of chunksize bytes.
 
     """
-    if executable is None:
+    if executable is None or executable == sys.executable:
         try:
             ver = os.confstr('CS_GNU_LIBC_VERSION')
             # parse 'glibc 2.28' as ('glibc', '2.28')
@@ -618,15 +618,9 @@ def _syscmd_file(target, default=''):
 
 ### Information about the used architecture
 
-# Default values for architecture; non-empty strings override the
-# defaults given as parameters
-_default_architecture = {
-    'win32': ('', 'WindowsPE'),
-    'win16': ('', 'Windows'),
-    'dos': ('', 'MSDOS'),
-}
+_DEFAULT_LINKAGE = {'win32': 'WindowsPE'}
 
-def architecture(executable=sys.executable, bits='', linkage=''):
+def architecture(executable=None, bits='', linkage=''):
 
     """ Queries the given executable (defaults to the Python interpreter
         binary) for various architecture information.
@@ -640,11 +634,9 @@ def architecture(executable=sys.executable, bits='', linkage=''):
         (or sizeof(long) on Python version < 1.5.2) is used as
         indicator for the supported pointer size.
 
-        The function relies on the system's "file" command to do the
-        actual work. This is available on most if not all Unix
-        platforms. On some non-Unix platforms where the "file" command
-        does not exist and the executable is set to the Python interpreter
-        binary defaults from _default_architecture are used.
+        If the executable parameter is set, the function relies on the system's
+        "file" command to do the actual work. This is available on most Unix
+        platforms.
 
     """
     # Use the sizeof(pointer) as default number of bits if nothing
@@ -654,24 +646,17 @@ def architecture(executable=sys.executable, bits='', linkage=''):
         size = struct.calcsize('P')
         bits = str(size * 8) + 'bit'
 
+    # bpo-35348: For Python executable, don't use the file command
+    if executable is None or executable == sys.executable:
+        linkage = _DEFAULT_LINKAGE.get(sys.platform, linkage)
+        return bits, linkage
+
     # Get data from the 'file' system command
     if executable:
         fileout = _syscmd_file(executable, '')
     else:
         fileout = ''
 
-    if not fileout and \
-       executable == sys.executable:
-        # "file" command did not return anything; we'll try to provide
-        # some sensible defaults then...
-        if sys.platform in _default_architecture:
-            b, l = _default_architecture[sys.platform]
-            if b:
-                bits = b
-            if l:
-                linkage = l
-        return bits, linkage
-
     if 'executable' not in fileout:
         # Format not supported
         return bits, linkage

diff --git a/Lib/test/test_platform.py b/Lib/test/test_platform.py
@@ -1,5 +1,6 @@
 import os
 import platform
+import struct
 import subprocess
 import sys
 import sysconfig
@@ -16,7 +17,13 @@ def clear_caches(self):
         platform._uname_cache = None
 
     def test_architecture(self):
-        res = platform.architecture()
+        bits, linkage = platform.architecture()
+        pointer_bits = struct.calcsize('P') * 8
+        self.assertEqual(bits, f"{pointer_bits}bit")
+        if sys.platform == 'win32':
+            self.assertEqual(linkage, 'WindowsPE')
+        else:
+            self.assertEqual(linkage, '')
 
     @support.skip_unless_symlink
     def test_architecture_via_symlink(self): # issue3762

diff --git a/Misc/NEWS.d/next/Library/2018-12-17-10-01-15.bpo-35348.rUPsJI.rst b/Misc/NEWS.d/next/Library/2018-12-17-10-01-15.bpo-35348.rUPsJI.rst
@@ -0,0 +1,2 @@
+Fix :func:`platform.architecture` for macOS universal binaries: it no longer
+uses the system's ``file`` command if the *executable* parameter is not set.
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Fix :func:`platform.architecture` for macOS universal binaries: it no longer
		uses the system's ``file`` command if the executable parameter is not set.