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bpo-41524: fix pointer bug in PyOS_mystr{n}icmp #21845

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Merged
merged 3 commits into from
Aug 27, 2020
Merged

bpo-41524: fix pointer bug in PyOS_mystr{n}icmp #21845

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bpo-41524: fix pointer bug in PyOS_mystr{n}icmp
wmeehan Aug 12, 2020
367a8c6
📜🤖 Added by blurb_it.
blurb-it[bot] Aug 12, 2020
597fe28
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wmeehan Aug 12, 2020
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2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/C API/2020-08-12-17-09-06.bpo-41524.u6Xfr2.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fix bug in PyOS_mystrnicmp and PyOS_mystricmp that incremented
pointers beyond the end of a string.
18 changes: 11 additions & 7 deletions Python/pystrcmp.c
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Original file line number Diff line number Diff line change
Expand Up @@ -6,21 +6,25 @@
int
PyOS_mystrnicmp(const char *s1, const char *s2, Py_ssize_t size)
{
const unsigned char *p1, *p2;
if (size == 0)
return 0;
while ((--size > 0) &&
(tolower((unsigned)*s1) == tolower((unsigned)*s2))) {
if (!*s1++ || !*s2++)
break;
p1 = (const unsigned char *)s1;
p2 = (const unsigned char *)s2;
for (; (--size > 0) && *p1 && *p2 && (tolower(*p1) == tolower(*p2));
p1++, p2++) {
;
}
return tolower((unsigned)*s1) - tolower((unsigned)*s2);
return tolower(*p1) - tolower(*p2);
}

int
PyOS_mystricmp(const char *s1, const char *s2)
{
while (*s1 && (tolower((unsigned)*s1++) == tolower((unsigned)*s2++))) {
const unsigned char *p1 = (const unsigned char *)s1;
const unsigned char *p2 = (const unsigned char *)s2;
for (; *p1 && *p2 && (tolower(*p1) == tolower(*p2)); p1++, p2++) {
;
}
return (tolower((unsigned)*s1) - tolower((unsigned)*s2));
return (tolower(*p1) - tolower(*p2));
}