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Issue #14716: Change integer overflow check in unicode_writer_prepare()

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to compute the limit at compile time instead of runtime. Patch writen by Serhiy
Storchaka.
This commit is contained in:
Victor Stinner 2012-05-07 13:02:44 +02:00
parent 202fdca133
commit 0576f9b4cf
1 changed files with 4 additions and 2 deletions
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6
Objects/unicodeobject.c
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@ -13242,8 +13242,10 @@ unicode_writer_prepare(unicode_writer_t *writer,
newlen = writer->pos + length; newlen = writer->pos + length;
if (newlen > PyUnicode_GET_LENGTH(writer->buffer)) { if (newlen > PyUnicode_GET_LENGTH(writer->buffer)) {
/* overallocate 25% to limit the number of resize */ /* Overallocate 25% to limit the number of resize.
if (newlen <= (PY_SSIZE_T_MAX - newlen / 4)) Check for integer overflow:
(newlen + newlen / 4) <= PY_SSIZE_T_MAX */
if (newlen <= (PY_SSIZE_T_MAX - PY_SSIZE_T_MAX / 5))
newlen += newlen / 4; newlen += newlen / 4;
if (maxchar > writer->maxchar) { if (maxchar > writer->maxchar) {