From: Andrew M. Kuchling <amk@amk.ca>
Date: Mon, 9 Oct 2000 14:18:10 +0000 (+0000)
Subject: Patch #101810: check whether zst.avail_out is non-zero when getting
X-Git-Tag: v2.0c1~38
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=d92383102740bd143c5221a519433e64c4c9c498;p=python

Patch #101810: check whether zst.avail_out is non-zero when getting
   a Z_BUF_ERROR while decompressing.  If it is, assume that this means
   the data being decompressed is bad and raise an exception, instead of
   just assuming that Z_BUF_ERROR always means that more space is required.
---

diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index 9416528ad4..cb2a2e5c97 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -214,7 +214,21 @@ PyZlib_decompress(PyObject *self, PyObject *args)
         case(Z_STREAM_END):
 	    break;
 	case(Z_BUF_ERROR):
-        case(Z_OK):
+	    /*
+	     * If there is at least 1 byte of room according to zst.avail_out
+	     * and we get this error, assume that it means zlib cannot
+	     * 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);
+              inflateEnd(&zst);
+              Py_DECREF(result_str);
+              return NULL;
+            }
+	    /* fall through */
+	case(Z_OK):
 	    /* need more memory */
 	    if (_PyString_Resize(&result_str, r_strlen << 1) == -1)
             {