From ddc5eb689d4d5801778e1f8f5b5a1056a44a001b Mon Sep 17 00:00:00 2001 From: Jeff Davis Date: Sun, 26 Oct 2025 15:04:58 -0700 Subject: [PATCH v7 4/9] Avoid global LC_CTYPE dependency in scansup.c. Call char_tolower() instead of tolower() in downcase_identifier(). The function downcase_identifier() may be called before locale support is initialized -- e.g. during GUC processing in the postmaster -- so if the locale is unavailable, char_tolower() uses plain ASCII semantics. That can result in a difference in behavior during that early stage of processing, but previously it would have depended on the postmaster environment variable LC_CTYPE, which would have been fragile anyway. --- src/backend/parser/scansup.c | 5 +++-- src/backend/utils/adt/pg_locale.c | 16 ++++++++++++++-- 2 files changed, 17 insertions(+), 4 deletions(-) diff --git a/src/backend/parser/scansup.c b/src/backend/parser/scansup.c index 2feb2b6cf5a..872075ba220 100644 --- a/src/backend/parser/scansup.c +++ b/src/backend/parser/scansup.c @@ -18,6 +18,7 @@ #include "mb/pg_wchar.h" #include "parser/scansup.h" +#include "utils/pg_locale.h" /* @@ -67,8 +68,8 @@ downcase_identifier(const char *ident, int len, bool warn, bool truncate) if (ch >= 'A' && ch <= 'Z') ch += 'a' - 'A'; - else if (enc_is_single_byte && IS_HIGHBIT_SET(ch) && isupper(ch)) - ch = tolower(ch); + else if (enc_is_single_byte && IS_HIGHBIT_SET(ch)) + ch = char_tolower(ch, NULL); result[i] = (char) ch; } result[i] = '\0'; diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c index 9631d274611..7e13c601643 100644 --- a/src/backend/utils/adt/pg_locale.c +++ b/src/backend/utils/adt/pg_locale.c @@ -1568,11 +1568,17 @@ char_is_cased(char ch, pg_locale_t locale) * * Convert single-byte char to lowercase. Not correct for multibyte encodings, * but needed for historical compatibility purposes. + * + * If locale is NULL, use the default database locale. This function may be + * called before the database locale is initialized, in which case it uses + * plain ASCII semantics. */ char char_tolower(unsigned char ch, pg_locale_t locale) { - if (locale->ctype == NULL) + if (locale == NULL) + locale = default_locale; + if (locale == NULL || locale->ctype == NULL) { if (ch >= 'A' && ch <= 'Z') return ch + ('a' - 'A'); @@ -1586,11 +1592,17 @@ char_tolower(unsigned char ch, pg_locale_t locale) * * Convert single-byte char to uppercase. Not correct for multibyte encodings, * but needed for historical compatibility purposes. + * + * If locale is NULL, use the default database locale. This function may be + * called before the database locale is initialized, in which case it uses + * plain ASCII semantics. */ char char_toupper(unsigned char ch, pg_locale_t locale) { - if (locale->ctype == NULL) + if (locale == NULL) + locale = default_locale; + if (locale == NULL || locale->ctype == NULL) { if (ch >= 'a' && ch <= 'z') return ch - ('a' - 'A'); -- 2.43.0