tempfile: minor changes to handle tempfile encoding exceptions

CHANGES.txt

@@ -81,6 +81,11 @@ RELEASE  VERSION/DATE TO BE FILLED IN LATER
       tar bz2 and xz tests should be skipped on Windows 10 and GitHub
       windows-2022. The packaging tar bz2 and xz tests should be run on
       Windows 11 and GitHub windows-2025.
+    - TEMPFILE: Move encoding the tempfile contents before creating the
+      tempfile due to possible encoding errors. Ensure the tempfile file
+      handle is closed after writing the tempfile contents. Raise a
+      TempFileEncodeError exception when the tempfile contents encoding fails
+      for known exception types.
 
   From William Deegan:
     - Fix Issue #4746. TEMPFILE's are written with utf-8 encoding, In case

RELEASE.txt

@@ -44,6 +44,10 @@ CHANGED/ENHANCED EXISTING FUNCTIONALITY
   these variables and values are propagated to the user's SCons
   environment after running the MSVC batch files.
 
+- TEMPFILE: A TempFileEncodeError exception is raised when encoding
+  the contents of the tempfile fails due to a limited set of expected
+  exceptions (e.g., UnicodeError).
+
 FIXES
 -----
 

SCons/Platform/__init__.py

@@ -57,6 +57,16 @@
 import SCons.Util
 
 
+TEMPFILE_DEFAULT_ENCODING = "utf-8"
+
+
+class TempFileEncodeError(SCons.Errors.UserError):
+
+    def __init__(self, message):
+        message = f"{self.__class__.__name__}: {message!s}"
+        super().__init__(message)
+
+
 def platform_default():
     r"""Return the platform string for our execution environment.
 
@@ -246,6 +256,24 @@ def __call__(self, target, source, env, for_signature):
         if cmdlist is not None:
             return cmdlist
 
+        tempfile_esc_func = env.get('TEMPFILEARGESCFUNC', SCons.Subst.quote_spaces)
+        args = [tempfile_esc_func(arg) for arg in cmd[1:]]
+        join_char = env.get('TEMPFILEARGJOIN', ' ')
+        contents = join_char.join(args) + "\n"
+        encoding = env.get('TEMPFILEENCODING', TEMPFILE_DEFAULT_ENCODING)
+
+        try:
+            tempfile_contents = bytes(contents, encoding=encoding)
+        except (UnicodeError, LookupError, TypeError):
+            exc_type, exc_value, _ = sys.exc_info()
+            if 'TEMPFILEENCODING' in env:
+                encoding_msg = "env['TEMPFILEENCODING']"
+            else:
+                encoding_msg = "default"
+            err_msg = f"[{exc_type.__name__}] {exc_value!s}"
+            err_msg += f"\n  {type(self).__name__} encoding: {encoding_msg} = {encoding!r}"
+            raise TempFileEncodeError(err_msg)
+
         # Default to the .lnk suffix for the benefit of the Phar Lap
         # linkloc linker, which likes to append an .lnk suffix if
         # none is given.
@@ -262,6 +290,12 @@ def __call__(self, target, source, env, for_signature):
 
         # default is binary - encode the tempfile contents later
         fd, tmp = tempfile.mkstemp(suffix, dir=tempfile_dir)
+
+        try:
+            os.write(fd, tempfile_contents)
+        finally:
+            os.close(fd)
+
         native_tmp = SCons.Util.get_native_path(tmp)
 
         # arrange for cleanup on exit:
@@ -281,13 +315,6 @@ def tmpfile_cleanup(file) -> None:
         else:
             prefix = "@"
 
-        tempfile_esc_func = env.get('TEMPFILEARGESCFUNC', SCons.Subst.quote_spaces)
-        args = [tempfile_esc_func(arg) for arg in cmd[1:]]
-        join_char = env.get('TEMPFILEARGJOIN', ' ')
-        encoding = env.get('TEMPFILEENCODING', 'utf-8')
-        os.write(fd, bytes(join_char.join(args) + "\n", encoding=encoding))
-        os.close(fd)
-
         # XXX Using the SCons.Action.print_actions value directly
         # like this is bogus, but expedient.  This class should
         # really be rewritten as an Action that defines the

test/TEMPFILE/TEMPFILEENCODING.py

@@ -0,0 +1,129 @@
+#!/usr/bin/env python
+#
+# MIT License
+#
+# Copyright The SCons Foundation
+#
+# Permission is hereby granted, free of charge, to any person obtaining
+# a copy of this software and associated documentation files (the
+# "Software"), to deal in the Software without restriction, including
+# without limitation the rights to use, copy, modify, merge, publish,
+# distribute, sublicense, and/or sell copies of the Software, and to
+# permit persons to whom the Software is furnished to do so, subject to
+# the following conditions:
+#
+# The above copyright notice and this permission notice shall be included
+# in all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
+# KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
+# WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+
+"""
+Verify that setting the $TEMPFILEENCODING variable will be used for
+encoding the file contents when writing the generated tempfile used
+for long command lines.
+"""
+
+
+import TestSCons
+
+test = TestSCons.TestSCons()
+
+SCONSTRUCT_TEMPLATE="""
+import SCons.Platform
+
+command = 'xyz ./test€/file.c'
+encoding = {encoding!r}
+
+tempfileencoding = {tempfileencoding}
+defaultencoding = {defaultencoding}
+
+DefaultEnvironment()
+
+if defaultencoding:
+    SCons.Platform.TEMPFILE_DEFAULT_ENCODING = encoding
+    print("SCons.Platform.TEMPFILE_DEFAULT_ENCODING = {encoding!r}")
+
+env = Environment(
+    tools=[],
+    MAXLINELENGTH=2,
+)
+
+if tempfileencoding:
+    env['TEMPFILEENCODING'] = encoding
+
+tfm = SCons.Platform.TempFileMunge(command)
+
+try:
+    tfm(None, None, env, 0)
+except SCons.Platform.TempFileEncodeError as e:
+    print(str(e))
+"""
+
+expected_pass = """\
+Using tempfile \\S+ for command line:
+xyz \\S+
+scons\:.*
+"""
+
+expected_fail = """\
+TempFileEncodeError: \[{exception}\] .+
+  TempFileMunge encoding\: env\['TEMPFILEENCODING'\] = {encoding!r}
+scons\:.*
+"""
+
+expected_pass_default = """\
+SCons\.Platform\.TEMPFILE_DEFAULT_ENCODING = {encoding!r}
+""" + expected_pass
+
+expected_fail_default = """\
+SCons\.Platform\.TEMPFILE_DEFAULT_ENCODING = {encoding!r}
+TempFileEncodeError: \[{exception}\] .+
+  TempFileMunge encoding\: default = {encoding!r}
+scons\:.*
+"""
+
+for test_encoding, test_tempfileencoding, test_defaultencoding, test_expected in [
+
+    # expected pass
+    ('',          False, False, expected_pass),
+    ('utf-8',      True, False, expected_pass),
+    ('utf-8-sig',  True, False, expected_pass),
+    ('utf-16',     True, False, expected_pass),
+    ('utf-16',    False,  True, expected_pass_default.format(encoding='utf-16')),
+
+    # expected fail
+    ('ascii',    True, False, expected_fail.format(exception='UnicodeEncodeError', encoding='ascii')),
+    ('missing',  True, False, expected_fail.format(exception='LookupError', encoding='missing')),
+    ('',         True, False, expected_fail.format(exception='LookupError', encoding='')),
+    (None,       True, False, expected_fail.format(exception='TypeError', encoding=None)),
+    ('ascii',   False,  True, expected_fail_default.format(exception='UnicodeEncodeError', encoding='ascii')),
+
+]:
+
+    sconstruct = SCONSTRUCT_TEMPLATE.format(
+        encoding = test_encoding,
+        tempfileencoding = test_tempfileencoding,
+        defaultencoding = test_defaultencoding,
+    )
+
+    test.write('SConstruct', sconstruct)
+
+    test.run(
+        arguments='-n -Q .',
+        stdout=test_expected,
+        match=TestSCons.match_re,
+    )
+
+test.pass_test()
+
+# Local Variables:
+# tab-width:4
+# indent-tabs-mode:nil
+# End:
+# vim: set expandtab tabstop=4 shiftwidth=4: