commit 4fec9ce6017c497e884df1a1a3d70d4d8661a3ab
author Benjamin Peterson <benjamin@python.org> Sat Nov 20 17:31:08 2010 +0000
committer Benjamin Peterson <benjamin@python.org> Sat Nov 20 17:31:08 2010 +0000
tree 9f28fbbdd2b762a239dd0941405484dc3e9208b8
parent a731bf17171e7c963492ddec3140c5eb7fdfda20

Merged revisions 86587 via svnmerge from
svn+ssh://pythondev@svn.python.org/python/branches/py3k

........
  r86587 | benjamin.peterson | 2010-11-20 11:24:04 -0600 (Sat, 20 Nov 2010) | 1 line

  correct logic when pos is after the string #10467
........

Modules/_io/bytesio.c

diff --git a/Modules/_io/bytesio.c b/Modules/_io/bytesio.c
index 15dbc33..51fad21 100644
--- a/Modules/_io/bytesio.c
+++ b/Modules/_io/bytesio.c
@@ -391,7 +391,7 @@
 bytesio_readinto(bytesio *self, PyObject *args)
 {
     Py_buffer buf;
-    Py_ssize_t len;
+    Py_ssize_t len, n;
 
     CHECK_CLOSED(self);
 
@@ -399,8 +399,13 @@
         return NULL;
 
     len = buf.len;
-    if (self->pos + len > self->string_size)
-        len = self->string_size - self->pos;
+    /* adjust invalid sizes */
+    n = self->string_size - self->pos;
+    if (len > n) {
+        len = n;
+        if (len < 0)
+            len = 0;
+    }
 
     memcpy(buf.buf, self->buf + self->pos, len);
     assert(self->pos + len < PY_SSIZE_T_MAX);