Issue #10276: Fix the results of zlib.crc32() and zlib.adler32() on buffers
larger than 4GB. Patch by Nadeem Vawda.
diff --git a/Modules/zlibmodule.c b/Modules/zlibmodule.c
index a03045e..e439c5b 100644
--- a/Modules/zlibmodule.c
+++ b/Modules/zlibmodule.c
@@ -945,8 +945,18 @@
/* Releasing the GIL for very small buffers is inefficient
and may lower performance */
if (pbuf.len > 1024*5) {
+ void *buf = pbuf.buf;
+ Py_ssize_t len = pbuf.len;
+
Py_BEGIN_ALLOW_THREADS
- adler32val = adler32(adler32val, pbuf.buf, pbuf.len);
+ /* Avoid truncation of length for very large buffers. adler32() takes
+ length as an unsigned int, which may be narrower than Py_ssize_t. */
+ while (len > (Py_ssize_t)UINT_MAX) {
+ adler32val = adler32(adler32val, buf, UINT_MAX);
+ buf += UINT_MAX;
+ len -= UINT_MAX;
+ }
+ adler32val = adler32(adler32val, buf, len);
Py_END_ALLOW_THREADS
} else {
adler32val = adler32(adler32val, pbuf.buf, pbuf.len);
@@ -973,8 +983,18 @@
/* Releasing the GIL for very small buffers is inefficient
and may lower performance */
if (pbuf.len > 1024*5) {
+ void *buf = pbuf.buf;
+ Py_ssize_t len = pbuf.len;
+
Py_BEGIN_ALLOW_THREADS
- signed_val = crc32(crc32val, pbuf.buf, pbuf.len);
+ /* Avoid truncation of length for very large buffers. crc32() takes
+ length as an unsigned int, which may be narrower than Py_ssize_t. */
+ while (len > (Py_ssize_t)UINT_MAX) {
+ crc32val = crc32(crc32val, buf, UINT_MAX);
+ buf += UINT_MAX;
+ len -= UINT_MAX;
+ }
+ signed_val = crc32(crc32val, buf, len);
Py_END_ALLOW_THREADS
} else {
signed_val = crc32(crc32val, pbuf.buf, pbuf.len);