Issue #8681: Make the zlib module's error messages more informative when
the zlib itself doesn't give any detailed explanation.
diff --git a/Lib/test/test_zlib.py b/Lib/test/test_zlib.py
index 2fc4313..cbc3ed4 100644
--- a/Lib/test/test_zlib.py
+++ b/Lib/test/test_zlib.py
@@ -135,6 +135,13 @@
x = zlib.compress(data)
self.assertEqual(zlib.decompress(x), data)
+ def test_incomplete_stream(self):
+ # An useful error message is given
+ x = zlib.compress(HAMLET_SCENE)
+ self.assertRaisesRegexp(zlib.error,
+ "Error -5 while decompressing data: incomplete or truncated stream",
+ zlib.decompress, x[:-1])
+
# Memory use of the following functions takes into account overallocation
@precisionbigmemtest(size=_1G + 1024 * 1024, memuse=3)
diff --git a/Misc/NEWS b/Misc/NEWS
index e46162d..803e060 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -62,6 +62,9 @@
Library
-------
+- Issue #8681: Make the zlib module's error messages more informative when
+ the zlib itself doesn't give any detailed explanation.
+
- Issue #8571: Fix an internal error when compressing or decompressing a
chunk larger than 1GB with the zlib module's compressor and decompressor
objects.
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index bb52fdc..183f01e 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -72,10 +72,24 @@
static void
zlib_error(z_stream zst, int err, char *msg)
{
- if (zst.msg == Z_NULL)
+ const char *zmsg = zst.msg;
+ if (zmsg == Z_NULL) {
+ switch (err) {
+ case Z_BUF_ERROR:
+ zmsg = "incomplete or truncated stream";
+ break;
+ case Z_STREAM_ERROR:
+ zmsg = "inconsistent stream state";
+ break;
+ case Z_DATA_ERROR:
+ zmsg = "invalid input data";
+ break;
+ }
+ }
+ if (zmsg == Z_NULL)
PyErr_Format(ZlibError, "Error %d %s", err, msg);
else
- PyErr_Format(ZlibError, "Error %d %s: %.200s", err, msg, zst.msg);
+ PyErr_Format(ZlibError, "Error %d %s: %.200s", err, msg, zmsg);
}
PyDoc_STRVAR(compressobj__doc__,
@@ -248,8 +262,7 @@
* process the inflate call() due to an error in the data.
*/
if (zst.avail_out > 0) {
- PyErr_Format(ZlibError, "Error %i while decompressing data",
- err);
+ zlib_error(zst, err, "while decompressing data");
inflateEnd(&zst);
goto error;
}