Issue #19623: Fixed writing to unseekable files in the aifc module.

Lib/aifc.py

@@ -790,7 +790,10 @@ class Aifc_write:
                 self._datalength = (self._datalength + 3) // 4
                 if self._datalength & 1:
                     self._datalength = self._datalength + 1
-        self._form_length_pos = self._file.tell()
+        try:
+            self._form_length_pos = self._file.tell()
+        except (AttributeError, OSError):
+            self._form_length_pos = None
         commlength = self._write_form_length(self._datalength)
         if self._aifc:
             self._file.write(b'AIFC')
@@ -802,7 +805,8 @@ class Aifc_write:
         self._file.write(b'COMM')
         _write_ulong(self._file, commlength)
         _write_short(self._file, self._nchannels)
-        self._nframes_pos = self._file.tell()
+        if self._form_length_pos is not None:
+            self._nframes_pos = self._file.tell()
         _write_ulong(self._file, self._nframes)
         if self._comptype in (b'ULAW', b'ulaw', b'ALAW', b'alaw', b'G722'):
             _write_short(self._file, 8)
@@ -813,7 +817,8 @@ class Aifc_write:
             self._file.write(self._comptype)
             _write_string(self._file, self._compname)
         self._file.write(b'SSND')
-        self._ssnd_length_pos = self._file.tell()
+        if self._form_length_pos is not None:
+            self._ssnd_length_pos = self._file.tell()
         _write_ulong(self._file, self._datalength + 8)
         _write_ulong(self._file, 0)
         _write_ulong(self._file, 0)

Lib/test/test_aifc.py

@@ -14,9 +14,6 @@ class AifcTest(audiotests.AudioWriteTests,
     module = aifc
     close_fd = True
     test_unseekable_read = None
-    test_unseekable_write = None
-    test_unseekable_incompleted_write = None
-    test_unseekable_overflowed_write = None
 
 
 class AifcPCM8Test(AifcTest, unittest.TestCase):

Lib/test/test_sunau.py

@@ -6,10 +6,12 @@ import sys
 import sunau
 
 
-class SunauPCM8Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
+class SunauTest(audiotests.AudioWriteTests,
+                audiotests.AudioTestsWithSourceFile):
     module = sunau
+
+
+class SunauPCM8Test(SunauTest, unittest.TestCase):
     sndfilename = 'pluck-pcm8.au'
     sndfilenframes = 3307
     nchannels = 2
@@ -26,10 +28,7 @@ class SunauPCM8Test(audiotests.AudioWriteTests,
       """)
 
 
-class SunauPCM16Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = sunau
+class SunauPCM16Test(SunauTest, unittest.TestCase):
     sndfilename = 'pluck-pcm16.au'
     sndfilenframes = 3307
     nchannels = 2
@@ -48,10 +47,7 @@ class SunauPCM16Test(audiotests.AudioWriteTests,
       """)
 
 
-class SunauPCM24Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = sunau
+class SunauPCM24Test(SunauTest, unittest.TestCase):
     sndfilename = 'pluck-pcm24.au'
     sndfilenframes = 3307
     nchannels = 2
@@ -76,10 +72,7 @@ class SunauPCM24Test(audiotests.AudioWriteTests,
       """)
 
 
-class SunauPCM32Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = sunau
+class SunauPCM32Test(SunauTest, unittest.TestCase):
     sndfilename = 'pluck-pcm32.au'
     sndfilenframes = 3307
     nchannels = 2
@@ -104,10 +97,7 @@ class SunauPCM32Test(audiotests.AudioWriteTests,
       """)
 
 
-class SunauULAWTest(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = sunau
+class SunauULAWTest(SunauTest, unittest.TestCase):
     sndfilename = 'pluck-ulaw.au'
     sndfilenframes = 3307
     nchannels = 2

Lib/test/test_wave.py

@@ -6,10 +6,12 @@ import sys
 import wave
 
 
-class WavePCM8Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
+class WaveTest(audiotests.AudioWriteTests,
+               audiotests.AudioTestsWithSourceFile):
     module = wave
+
+
+class WavePCM8Test(WaveTest, unittest.TestCase):
     sndfilename = 'pluck-pcm8.wav'
     sndfilenframes = 3307
     nchannels = 2
@@ -26,10 +28,7 @@ class WavePCM8Test(audiotests.AudioWriteTests,
       """)
 
 
-class WavePCM16Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = wave
+class WavePCM16Test(WaveTest, unittest.TestCase):
     sndfilename = 'pluck-pcm16.wav'
     sndfilenframes = 3307
     nchannels = 2
@@ -50,10 +49,7 @@ class WavePCM16Test(audiotests.AudioWriteTests,
         frames = byteswap(frames, 2)
 
 
-class WavePCM24Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = wave
+class WavePCM24Test(WaveTest, unittest.TestCase):
     sndfilename = 'pluck-pcm24.wav'
     sndfilenframes = 3307
     nchannels = 2
@@ -80,10 +76,7 @@ class WavePCM24Test(audiotests.AudioWriteTests,
         frames = byteswap(frames, 3)
 
 
-class WavePCM32Test(audiotests.AudioWriteTests,
-        audiotests.AudioTestsWithSourceFile,
-        unittest.TestCase):
-    module = wave
+class WavePCM32Test(WaveTest, unittest.TestCase):
     sndfilename = 'pluck-pcm32.wav'
     sndfilenframes = 3307
     nchannels = 2

Misc/NEWS

@@ -44,6 +44,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #19623: Fixed writing to unseekable files in the aifc module.
+
 - Issue #19946: multiprocessing.spawn now raises ImportError when the module to
   be used as the main module cannot be imported.