Issue #4842, patch 1/2: fix pickle in Python 3.x so that pickling with the

'L' opcode always appends an 'L' on output, just as 2.x does.  When
unpickling, remove the trailing 'L' (if present) before passing the
result to PyLong_FromString.

1 files changed, 28 insertions, 8 deletions

diff --git a/Modules/_pickle.c b/Modules/_pickle.c
index 6cc90b3..02a3e44 100644
--- a/Modules/_pickle.c
+++ b/Modules/_pickle.c
@@ -846,8 +846,8 @@ save_int(PicklerObject *self, long x)
         /* Text-mode pickle, or long too big to fit in the 4-byte
          * signed BININT format:  store as a string.
          */
-        pdata[0] = LONG;        /* use LONG for consistence with pickle.py */
-        PyOS_snprintf(pdata + 1, sizeof(pdata) - 1, "%ld\n", x);
+        pdata[0] = LONG;        /* use LONG for consistency with pickle.py */
+        PyOS_snprintf(pdata + 1, sizeof(pdata) - 1, "%ldL\n", x);
         if (pickler_write(self, pdata, strlen(pdata)) < 0)
             return -1;
     }
@@ -977,8 +977,9 @@ save_long(PicklerObject *self, PyObject *obj)
     else {
         char *string;
 
-        /* proto < 2:  write the repr and newline.  This is quadratic-time
-           (in the number of digits), in both directions. */
+        /* proto < 2: write the repr and newline.  This is quadratic-time (in
+           the number of digits), in both directions.  We add a trailing 'L'
+           to the repr, for compatibility with Python 2.x. */
 
         repr = PyObject_Repr(obj);
         if (repr == NULL)
@@ -990,7 +991,7 @@ save_long(PicklerObject *self, PyObject *obj)
 
         if (pickler_write(self, &long_op, 1) < 0 ||
             pickler_write(self, string, size) < 0 ||
-            pickler_write(self, "\n", 1) < 0)
+            pickler_write(self, "L\n", 2) < 0)
             goto error;
     }
 
@@ -2880,7 +2881,7 @@ static int
 load_long(UnpicklerObject *self)
 {
     PyObject *value;
-    char *s;
+    char *s, *ss;
     Py_ssize_t len;
 
     if ((len = unpickler_readline(self, &s)) < 0)
@@ -2888,8 +2889,27 @@ load_long(UnpicklerObject *self)
     if (len < 2)
         return bad_readline();
 
-    /* XXX: Should the base argument explicitly set to 10? */
-    if ((value = PyLong_FromString(s, NULL, 0)) == NULL)
+    /* s[len-2] will usually be 'L' (and s[len-1] is '\n'); we need to remove
+       the 'L' before calling PyLong_FromString.  In order to maintain
+       compatibility with Python 3.0.0, we don't actually *require*
+       the 'L' to be present. */
+    if (s[len-2] == 'L') {
+        ss = (char *)PyMem_Malloc(len-1);
+        if (ss == NULL) {
+            PyErr_NoMemory();
+            return -1;
+        }
+        strncpy(ss, s, len-2);
+        ss[len-2] = '\0';
+
+        /* XXX: Should the base argument explicitly set to 10? */
+        value = PyLong_FromString(ss, NULL, 0);
+        PyMem_Free(ss);
+    }
+    else {
+        value = PyLong_FromString(s, NULL, 0);
+    }
+    if (value == NULL)
         return -1;
 
     PDATA_PUSH(self->stack, value, -1);