[Python-checkins] cpython (2.7): fix expandtabs overflow detection to be consistent and not rely on signed

Mon Mar 31 01:54:06 CEST 2014

http://hg.python.org/cpython/rev/a2254f4338e6
changeset: 90056:a2254f4338e6
branch: 2.7
user: Benjamin Peterson <benjamin at python.org>
date: Sun Mar 30 19:47:57 2014 -0400
summary:
 fix expandtabs overflow detection to be consistent and not rely on signed overflow
files:
 Objects/stringlib/transmogrify.h | 38 ++++++++++----------
 1 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/Objects/stringlib/transmogrify.h b/Objects/stringlib/transmogrify.h
--- a/Objects/stringlib/transmogrify.h
+++ b/Objects/stringlib/transmogrify.h
@@ -15,7 +15,7 @@
 {
 const char *e, *p;
 char *q;
- size_t i, j;
+ Py_ssize_t i, j;
 PyObject *u;
 int tabsize = 8;
 
@@ -25,34 +25,30 @@
 /* First pass: determine size of output string */
 i = j = 0;
 e = STRINGLIB_STR(self) + STRINGLIB_LEN(self);
- for (p = STRINGLIB_STR(self); p < e; p++)
+ for (p = STRINGLIB_STR(self); p < e; p++) {
 if (*p == '\t') {
 if (tabsize > 0) {
- j += tabsize - (j % tabsize);
- if (j > PY_SSIZE_T_MAX) {
- PyErr_SetString(PyExc_OverflowError,
- "result is too long");
- return NULL;
- }
+ Py_ssize_t incr = tabsize - (j % tabsize);
+ if (j > PY_SSIZE_T_MAX - incr)
+ goto overflow;
+ j += incr;
 }
 }
 else {
+ if (j > PY_SSIZE_T_MAX - 1)
+ goto overflow;
 j++;
 if (*p == '\n' || *p == '\r') {
+ if (i > PY_SSIZE_T_MAX - j)
+ goto overflow;
 i += j;
 j = 0;
- if (i > PY_SSIZE_T_MAX) {
- PyErr_SetString(PyExc_OverflowError,
- "result is too long");
- return NULL;
- }
 }
 }
+ }
 
- if ((i + j) > PY_SSIZE_T_MAX) {
- PyErr_SetString(PyExc_OverflowError, "result is too long");
- return NULL;
- }
+ if (i > PY_SSIZE_T_MAX - j)
+ goto overflow;
 
 /* Second pass: create output string and fill it */
 u = STRINGLIB_NEW(NULL, i + j);
@@ -62,7 +58,7 @@
 j = 0;
 q = STRINGLIB_STR(u);
 
- for (p = STRINGLIB_STR(self); p < e; p++)
+ for (p = STRINGLIB_STR(self); p < e; p++) {
 if (*p == '\t') {
 if (tabsize > 0) {
 i = tabsize - (j % tabsize);
@@ -77,8 +73,12 @@
 if (*p == '\n' || *p == '\r')
 j = 0;
 }
- 
+ }
+
 return u;
+ overflow:
+ PyErr_SetString(PyExc_OverflowError, "result too long");
+ return NULL;
 }
 
 Py_LOCAL_INLINE(PyObject *)
-- 
Repository URL: http://hg.python.org/cpython
