Issue #16828: Fix error incorrectly raised by bz2.compress('').

Patch by Martin Packman.

Lib/test/test_bz2.py

@@ -24,6 +24,7 @@ class BaseTest(unittest.TestCase):
     TEXT = b'root:x:0:0:root:/root:/bin/bash\nbin:x:1:1:bin:/bin:\ndaemon:x:2:2:daemon:/sbin:\nadm:x:3:4:adm:/var/adm:\nlp:x:4:7:lp:/var/spool/lpd:\nsync:x:5:0:sync:/sbin:/bin/sync\nshutdown:x:6:0:shutdown:/sbin:/sbin/shutdown\nhalt:x:7:0:halt:/sbin:/sbin/halt\nmail:x:8:12:mail:/var/spool/mail:\nnews:x:9:13:news:/var/spool/news:\nuucp:x:10:14:uucp:/var/spool/uucp:\noperator:x:11:0:operator:/root:\ngames:x:12:100:games:/usr/games:\ngopher:x:13:30:gopher:/usr/lib/gopher-data:\nftp:x:14:50:FTP User:/var/ftp:/bin/bash\nnobody:x:65534:65534:Nobody:/home:\npostfix:x:100:101:postfix:/var/spool/postfix:\nniemeyer:x:500:500::/home/niemeyer:/bin/bash\npostgres:x:101:102:PostgreSQL Server:/var/lib/pgsql:/bin/bash\nmysql:x:102:103:MySQL server:/var/lib/mysql:/bin/bash\nwww:x:103:104::/var/www:/bin/false\n'
     DATA = b'BZh91AY&SY.\xc8N\x18\x00\x01>_\x80\x00\x10@\x02\xff\xf0\x01\x07n\x00?\xe7\xff\xe00\x01\x99\xaa\x00\xc0\x03F\x86\x8c#&\x83F\x9a\x03\x06\xa6\xd0\xa6\x93M\x0fQ\xa7\xa8\x06\x804hh\x12$\x11\xa4i4\xf14S\xd2<Q\xb5\x0fH\xd3\xd4\xdd\xd5\x87\xbb\xf8\x94\r\x8f\xafI\x12\xe1\xc9\xf8/E\x00pu\x89\x12]\xc9\xbbDL\nQ\x0e\t1\x12\xdf\xa0\xc0\x97\xac2O9\x89\x13\x94\x0e\x1c7\x0ed\x95I\x0c\xaaJ\xa4\x18L\x10\x05#\x9c\xaf\xba\xbc/\x97\x8a#C\xc8\xe1\x8cW\xf9\xe2\xd0\xd6M\xa7\x8bXa<e\x84t\xcbL\xb3\xa7\xd9\xcd\xd1\xcb\x84.\xaf\xb3\xab\xab\xad`n}\xa0lh\tE,\x8eZ\x15\x17VH>\x88\xe5\xcd9gd6\x0b\n\xe9\x9b\xd5\x8a\x99\xf7\x08.K\x8ev\xfb\xf7xw\xbb\xdf\xa1\x92\xf1\xdd|/";\xa2\xba\x9f\xd5\xb1#A\xb6\xf6\xb3o\xc9\xc5y\\\xebO\xe7\x85\x9a\xbc\xb6f8\x952\xd5\xd7"%\x89>V,\xf7\xa6z\xe2\x9f\xa3\xdf\x11\x11"\xd6E)I\xa9\x13^\xca\xf3r\xd0\x03U\x922\xf26\xec\xb6\xed\x8b\xc3U\x13\x9d\xc5\x170\xa4\xfa^\x92\xacDF\x8a\x97\xd6\x19\xfe\xdd\xb8\xbd\x1a\x9a\x19\xa3\x80ankR\x8b\xe5\xd83]\xa9\xc6\x08\x82f\xf6\xb9"6l$\xb8j@\xc0\x8a\xb0l1..\xbak\x83ls\x15\xbc\xf4\xc1\x13\xbe\xf8E\xb8\x9d\r\xa8\x9dk\x84\xd3n\xfa\xacQ\x07\xb1%y\xaav\xb4\x08\xe0z\x1b\x16\xf5\x04\xe9\xcc\xb9\x08z\x1en7.G\xfc]\xc9\x14\xe1B@\xbb!8`'
     DATA_CRLF = b'BZh91AY&SY\xaez\xbbN\x00\x01H\xdf\x80\x00\x12@\x02\xff\xf0\x01\x07n\x00?\xe7\xff\xe0@\x01\xbc\xc6`\x86*\x8d=M\xa9\x9a\x86\xd0L@\x0fI\xa6!\xa1\x13\xc8\x88jdi\x8d@\x03@\x1a\x1a\x0c\x0c\x83 \x00\xc4h2\x19\x01\x82D\x84e\t\xe8\x99\x89\x19\x1ah\x00\r\x1a\x11\xaf\x9b\x0fG\xf5(\x1b\x1f?\t\x12\xcf\xb5\xfc\x95E\x00ps\x89\x12^\xa4\xdd\xa2&\x05(\x87\x04\x98\x89u\xe40%\xb6\x19\'\x8c\xc4\x89\xca\x07\x0e\x1b!\x91UIFU%C\x994!DI\xd2\xfa\xf0\xf1N8W\xde\x13A\xf5\x9cr%?\x9f3;I45A\xd1\x8bT\xb1<l\xba\xcb_\xc00xY\x17r\x17\x88\x08\x08@\xa0\ry@\x10\x04$)`\xf2\xce\x89z\xb0s\xec\x9b.iW\x9d\x81\xb5-+t\x9f\x1a\'\x97dB\xf5x\xb5\xbe.[.\xd7\x0e\x81\xe7\x08\x1cN`\x88\x10\xca\x87\xc3!"\x80\x92R\xa1/\xd1\xc0\xe6mf\xac\xbd\x99\xcca\xb3\x8780>\xa4\xc7\x8d\x1a\\"\xad\xa1\xabyBg\x15\xb9l\x88\x88\x91k"\x94\xa4\xd4\x89\xae*\xa6\x0b\x10\x0c\xd6\xd4m\xe86\xec\xb5j\x8a\x86j\';\xca.\x01I\xf2\xaaJ\xe8\x88\x8cU+t3\xfb\x0c\n\xa33\x13r2\r\x16\xe0\xb3(\xbf\x1d\x83r\xe7M\xf0D\x1365\xd8\x88\xd3\xa4\x92\xcb2\x06\x04\\\xc1\xb0\xea//\xbek&\xd8\xe6+t\xe5\xa1\x13\xada\x16\xder5"w]\xa2i\xb7[\x97R \xe2IT\xcd;Z\x04dk4\xad\x8a\t\xd3\x81z\x10\xf1:^`\xab\x1f\xc5\xdc\x91N\x14$+\x9e\xae\xd3\x80'
+    EMPTY_DATA = b'BZh9\x17rE8P\x90\x00\x00\x00\x00'
 
     with open(findfile("testbz2_bigmem.bz2"), "rb") as f:
         DATA_BIGMEM = f.read()
@@ -303,6 +304,12 @@ class BZ2CompressorTest(BaseTest):
         data += bz2c.flush()
         self.assertEqual(self.decompress(data), self.TEXT)
 
+    def testCompressEmptyString(self):
+        bz2c = BZ2Compressor()
+        data = bz2c.compress(b'')
+        data += bz2c.flush()
+        self.assertEqual(data, self.EMPTY_DATA)
+
     def testCompressChunks10(self):
         # "Test BZ2Compressor.compress()/flush() with chunks of 10 bytes"
         bz2c = BZ2Compressor()
@@ -383,6 +390,10 @@ class FuncTest(BaseTest):
         data = bz2.compress(self.TEXT)
         self.assertEqual(self.decompress(data), self.TEXT)
 
+    def testCompressEmptyString(self):
+        text = bz2.compress(b'')
+        self.assertEqual(text, self.EMPTY_DATA)
+
     def testDecompress(self):
         # "Test decompress() function"
         text = bz2.decompress(self.DATA)
@@ -393,6 +404,10 @@ class FuncTest(BaseTest):
         text = bz2.decompress(b"")
         self.assertEqual(text, b"")
 
+    def testDecompressToEmptyString(self):
+        text = bz2.decompress(self.EMPTY_DATA)
+        self.assertEqual(text, b'')
+
     def testDecompressIncomplete(self):
         # "Test decompress() function with incomplete data"
         self.assertRaises(ValueError, bz2.decompress, self.DATA[:-10])

Misc/ACKS

@@ -801,6 +801,7 @@ Michael Otteneder
 R. M. Oudkerk
 Russel Owen
 Joonas Paalasmaa
+Martin Packman
 Shriphani Palakodety
 Ondrej Palkovsky
 Mike Pall

Misc/NEWS

@@ -188,6 +188,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #16828: Fix error incorrectly raised by bz2.compress(''). Patch by
+  Martin Packman.
+
 - Issue #16541: tk_setPalette() now works with keyword arguments.
 
 - Issue #16820: In configparser, `parser.popitem()` no longer raises ValueError.

Modules/bz2module.c

@@ -1979,7 +1979,7 @@ bz2_compress(PyObject *self, PyObject *args, PyObject *kwargs)
         return NULL;
     }
 
-    action = BZ_RUN;
+    action = input_left > 0 ? BZ_RUN : BZ_FINISH;
 
     for (;;) {
         char *saved_next_out;