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gh-137273: Fix debug assertion failure in locale.setlocale() on Windows #137300

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Merged
serhiy-storchaka merged 3 commits into from
Aug 1, 2025
Merged

gh-137273: Fix debug assertion failure in locale.setlocale() on Windows #137300

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gh-137273: Fix debug assertion failure in locale.setlocale() on Windows
serhiy-storchaka Aug 1, 2025
3031948
Add more tests and comments.
serhiy-storchaka Aug 1, 2025
eae0bc4
MAX_ENCODING_SIZE -> MAX_CP_LEN
serhiy-storchaka Aug 1, 2025
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MAX_ENCODING_SIZE -> MAX_CP_LEN
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@serhiy-storchaka
serhiy-storchaka committed Aug 1, 2025
commit eae0bc4e7309902ae7d170fdfffd647cf35f0f70
6 changes: 3 additions & 3 deletions Modules/_localemodule.c
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Expand Up @@ -89,16 +89,16 @@ copy_grouping(const char* s)

#if defined(MS_WINDOWS)

// The number of elements in the szCodePage field
// 16 is the number of elements in the szCodePage field
// of the __crt_locale_strings structure.
#define MAX_ENCODING_SIZE 16
#define MAX_CP_LEN 15

static int
check_locale_name(const char *locale, const char *end)
{
size_t len = end ? (size_t)(end - locale) : strlen(locale);
const char *dot = memchr(locale, '.', len);
if (dot && locale + len - dot > MAX_ENCODING_SIZE) {
if (dot && locale + len - dot - 1 > MAX_CP_LEN) {
return -1;
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@malemburg malemburg Aug 1, 2025

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Where did you get the "16" from ?
Please include some comments to explain where you got it from and why this check is necessary. Thanks.

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@malemburg malemburg Aug 1, 2025

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BTW: It's better to make this limit configurable via a constant.

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@zooba zooba Aug 1, 2025

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Comes from https://github.com/huangqinjin/ucrt/blob/d6e817a4cc90f6f1fe54f8a0aa4af4fff0bb647d/inc/corecrt_internal.h#L401, though I don't think that constant is available for us at compile time (the internal headers for the CRT are, well, internal).

A constant at least gives it a name though, and using MAX_CP_LEN may help someone find an updated definition in the future.

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@malemburg malemburg Aug 1, 2025

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Looks good now.

}
return 0;
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