From 5013ed3d59403d943aae471c1033f43976cfc11c Mon Sep 17 00:00:00 2001 From: Jeff Davis Date: Tue, 18 Aug 2026 14:57:32 -0700 Subject: [PATCH v2 2/2] pg_locale.h: define casemapping limits. Clearly define casemapping upper bounds that cover all providers, locales, and encodings in pg_locale.h. Also redefine UTF8_CASEMAP_BUFSZ to include room for a NUL for consistency with PG_CASEMAP_BUFSZ. Use PG_CASEMAP_BUFSZ for the static buffer in ltree/crc32.c. Reviewed-by: Heikki Linnakangas Discussion: https://postgr.es/m/2cfbc37ae8deccd3825e36b7f31c391cbf8ff9b8.camel@j-davis.com --- contrib/ltree/crc32.c | 2 +- .../unicode/generate-unicode_case_table.pl | 4 +-- src/include/common/unicode_limits.h | 4 +-- src/include/utils/pg_locale.h | 35 ++++++++++++++----- 4 files changed, 31 insertions(+), 14 deletions(-) diff --git a/contrib/ltree/crc32.c b/contrib/ltree/crc32.c index 617cc652a7a..2082b9ef851 100644 --- a/contrib/ltree/crc32.c +++ b/contrib/ltree/crc32.c @@ -32,7 +32,7 @@ ltree_crc32_sz(const char *buf, int size) INIT_TRADITIONAL_CRC32(crc); while (size > 0) { - char foldstr[UNICODE_CASEMAP_BUFSZ + 1]; + char foldstr[PG_CASEMAP_BUFSZ]; int srclen = pg_mblen_range(p, end); size_t foldlen; diff --git a/src/common/unicode/generate-unicode_case_table.pl b/src/common/unicode/generate-unicode_case_table.pl index d1dd3a5e8f2..059fd1231cf 100644 --- a/src/common/unicode/generate-unicode_case_table.pl +++ b/src/common/unicode/generate-unicode_case_table.pl @@ -280,9 +280,9 @@ print $LIMITS <<"EOS"; /* * The maximum number of UTF8 bytes needed to store the result of case - * mapping a single code point. + * mapping a single code point, including terminating NUL. */ -#define UTF8_CASEMAP_BUFSZ $UTF8_CASEMAP_BUFSZ +#define UTF8_CASEMAP_BUFSZ ($UTF8_CASEMAP_BUFSZ + 1) #endif EOS diff --git a/src/include/common/unicode_limits.h b/src/include/common/unicode_limits.h index 59e307857ed..2307141c823 100644 --- a/src/include/common/unicode_limits.h +++ b/src/include/common/unicode_limits.h @@ -32,8 +32,8 @@ /* * The maximum number of UTF8 bytes needed to store the result of case - * mapping a single code point. + * mapping a single code point, including terminating NUL. */ -#define UTF8_CASEMAP_BUFSZ 6 +#define UTF8_CASEMAP_BUFSZ (6 + 1) #endif diff --git a/src/include/utils/pg_locale.h b/src/include/utils/pg_locale.h index fcd508f5dd6..6f82075c61d 100644 --- a/src/include/utils/pg_locale.h +++ b/src/include/utils/pg_locale.h @@ -13,23 +13,40 @@ #define _PG_LOCALE_ #include "mb/pg_wchar.h" +#include "common/unicode_limits.h" /* use for libc locale names */ #define LOCALE_NAME_BUFLEN 128 /* - * Maximum number of bytes needed to map a single codepoint. Useful for - * mapping and processing a single input codepoint at a time with a - * statically-allocated buffer. + * Expansion factor of string length, not including terminating NUL. That is, + * the upper bound of the number of multibyte characters in the result string + * per multibyte character in the input string. * - * With full case mapping, an input codepoint may be mapped to as many as - * three output codepoints. See Unicode 16.0.0, section 5.18.2, "Change in - * Length": + * NB: assumes no provider exceeds the Unicode-defined maximum. + */ +#define PG_MAX_CASEMAP_MBCHARS UNICODE_MAX_CASEMAP_CODEPOINTS + +/* + * Expansion factor of a string in bytes, not including terminating NUL. + * + * This is a conservative upper bound, assuming that each character in the + * input string is a 1-byte character that maps to PG_MAX_CASEMAP_MBCHARS + * other characters, all requiring MAX_MULTIBYTE_CHAR_LEN bytes. + */ +#define PG_MAX_CASEMAP_EXPANSION (PG_MAX_CASEMAP_MBCHARS * \ + MAX_MULTIBYTE_CHAR_LEN) + +/* + * The maximum number of bytes needed to store the result of case mapping a + * single multibyte character, including terminating NUL. * - * https://www.unicode.org/versions/Unicode16.0.0/core-spec/chapter-5/#G29675 + * This is a conservative upper bound, assuming that a single multibyte + * character can expand into PG_MAX_CASEMAP_MBCHARS other multibyte + * characters, each requiring MAX_MULTIBYTE_CHAR_LEN bytes. */ -#define UNICODE_CASEMAP_LEN 3 -#define UNICODE_CASEMAP_BUFSZ (UNICODE_CASEMAP_LEN * MAX_MULTIBYTE_CHAR_LEN) +#define PG_CASEMAP_BUFSZ ((PG_MAX_CASEMAP_MBCHARS * \ + MAX_MULTIBYTE_CHAR_LEN) + 1) /* GUC settings */ extern PGDLLIMPORT char *locale_messages; -- 2.43.0