From b7d7ae501e7416d29c867fc8f10e7e447af084dd Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Thu, 5 Mar 2026 21:38:46 +1300 Subject: [PATCH v2 06/19] Use stack buffer in locale code. Use stack buffers for temporary C strings, wchar_t strings, pg_wchar strings with the new API. Some cases were already using open-coded arrays, while others nearby were not but are obvious candidates, so let's change them too. These cases used TEXTBUFLEN (1KB), and they now inherit that same amount of available space by using: DECLARE_STACK_BUFFER_LARGE(); Discussion: --- src/backend/utils/adt/pg_locale.c | 6 - src/backend/utils/adt/pg_locale_icu.c | 59 +++------- src/backend/utils/adt/pg_locale_libc.c | 150 +++++++++---------------- 3 files changed, 71 insertions(+), 144 deletions(-) diff --git a/src/backend/utils/adt/pg_locale.c b/src/backend/utils/adt/pg_locale.c index 6c5c1019e1e..3a6190892a7 100644 --- a/src/backend/utils/adt/pg_locale.c +++ b/src/backend/utils/adt/pg_locale.c @@ -60,12 +60,6 @@ #define PGLOCALE_SUPPORT_ERROR(provider) \ elog(ERROR, "unsupported collprovider for %s: %c", __func__, provider) -/* - * This should be large enough that most strings will fit, but small enough - * that we feel comfortable putting it on the stack - */ -#define TEXTBUFLEN 1024 - #define MAX_L10N_DATA 80 /* pg_locale_builtin.c */ diff --git a/src/backend/utils/adt/pg_locale_icu.c b/src/backend/utils/adt/pg_locale_icu.c index 352b4c3885f..e64aff82738 100644 --- a/src/backend/utils/adt/pg_locale_icu.c +++ b/src/backend/utils/adt/pg_locale_icu.c @@ -39,16 +39,9 @@ #include "utils/formatting.h" #include "utils/memutils.h" #include "utils/pg_locale.h" +#include "utils/stack_buffer.h" #include "utils/syscache.h" -/* - * Size of stack buffer to use for string transformations, used to avoid heap - * allocations in typical cases. This should be large enough that most strings - * will fit, but small enough that we feel comfortable putting it on the - * stack. - */ -#define TEXTBUFLEN 1024 - extern pg_locale_t create_pg_locale_icu(Oid collid, MemoryContext context); #ifdef USE_ICU @@ -755,23 +748,17 @@ size_t strnxfrm_icu(char *dest, size_t destsize, const char *src, ssize_t srclen, pg_locale_t locale) { - char sbuf[TEXTBUFLEN]; - char *buf = sbuf; UChar *uchar; int32_t ulen; - size_t uchar_bsize; Size result_bsize; + DECLARE_STACK_BUFFER_LARGE(); + init_icu_converter(); ulen = uchar_length(icu_converter, src, srclen); - uchar_bsize = (ulen + 1) * sizeof(UChar); - - if (uchar_bsize > TEXTBUFLEN) - buf = palloc(uchar_bsize); - - uchar = (UChar *) buf; + uchar = stack_buffer_alloc_array(UChar, ulen + 1); ulen = uchar_convert(icu_converter, uchar, ulen + 1, src, srclen); @@ -786,8 +773,7 @@ strnxfrm_icu(char *dest, size_t destsize, const char *src, ssize_t srclen, Assert(result_bsize > 0); result_bsize--; - if (buf != sbuf) - pfree(buf); + stack_buffer_free(uchar); /* if dest is defined, it should be nul-terminated */ Assert(result_bsize >= destsize || dest[result_bsize] == '\0'); @@ -1020,16 +1006,14 @@ static int strncoll_icu(const char *arg1, ssize_t len1, const char *arg2, ssize_t len2, pg_locale_t locale) { - char sbuf[TEXTBUFLEN]; - char *buf = sbuf; int32_t ulen1; int32_t ulen2; - size_t bufsize1; - size_t bufsize2; UChar *uchar1, *uchar2; int result; + DECLARE_STACK_BUFFER_LARGE(); + /* if encoding is UTF8, use more efficient strncoll_icu_utf8 */ #ifdef HAVE_UCOL_STRCOLLUTF8 Assert(GetDatabaseEncoding() != PG_UTF8); @@ -1040,14 +1024,8 @@ strncoll_icu(const char *arg1, ssize_t len1, ulen1 = uchar_length(icu_converter, arg1, len1); ulen2 = uchar_length(icu_converter, arg2, len2); - bufsize1 = (ulen1 + 1) * sizeof(UChar); - bufsize2 = (ulen2 + 1) * sizeof(UChar); - - if (bufsize1 + bufsize2 > TEXTBUFLEN) - buf = palloc(bufsize1 + bufsize2); - - uchar1 = (UChar *) buf; - uchar2 = (UChar *) (buf + bufsize1); + uchar1 = stack_buffer_alloc_array(UChar, ulen1 + 1); + uchar2 = stack_buffer_alloc_array(UChar, ulen2 + 1); ulen1 = uchar_convert(icu_converter, uchar1, ulen1 + 1, arg1, len1); ulen2 = uchar_convert(icu_converter, uchar2, ulen2 + 1, arg2, len2); @@ -1056,8 +1034,8 @@ strncoll_icu(const char *arg1, ssize_t len1, uchar1, ulen1, uchar2, ulen2); - if (buf != sbuf) - pfree(buf); + stack_buffer_free(uchar1); + stack_buffer_free(uchar2); return result; } @@ -1068,16 +1046,15 @@ strnxfrm_prefix_icu(char *dest, size_t destsize, const char *src, ssize_t srclen, pg_locale_t locale) { - char sbuf[TEXTBUFLEN]; - char *buf = sbuf; UCharIterator iter; uint32_t state[2]; UErrorCode status; int32_t ulen = -1; UChar *uchar = NULL; - size_t uchar_bsize; Size result_bsize; + DECLARE_STACK_BUFFER_LARGE(); + /* if encoding is UTF8, use more efficient strnxfrm_prefix_icu_utf8 */ Assert(GetDatabaseEncoding() != PG_UTF8); @@ -1085,12 +1062,7 @@ strnxfrm_prefix_icu(char *dest, size_t destsize, ulen = uchar_length(icu_converter, src, srclen); - uchar_bsize = (ulen + 1) * sizeof(UChar); - - if (uchar_bsize > TEXTBUFLEN) - buf = palloc(uchar_bsize); - - uchar = (UChar *) buf; + uchar = stack_buffer_alloc_array(UChar, ulen + 1); ulen = uchar_convert(icu_converter, uchar, ulen + 1, src, srclen); @@ -1108,8 +1080,7 @@ strnxfrm_prefix_icu(char *dest, size_t destsize, (errmsg("sort key generation failed: %s", u_errorName(status)))); - if (buf != sbuf) - pfree(buf); + stack_buffer_free(uchar); return result_bsize; } diff --git a/src/backend/utils/adt/pg_locale_libc.c b/src/backend/utils/adt/pg_locale_libc.c index 78f6ea161a0..6f51c32814a 100644 --- a/src/backend/utils/adt/pg_locale_libc.c +++ b/src/backend/utils/adt/pg_locale_libc.c @@ -23,6 +23,7 @@ #include "utils/formatting.h" #include "utils/memutils.h" #include "utils/pg_locale.h" +#include "utils/stack_buffer.h" #include "utils/syscache.h" #ifdef __GLIBC__ @@ -72,14 +73,6 @@ * NB: the coding here assumes pg_wchar is an unsigned type. */ -/* - * Size of stack buffer to use for string transformations, used to avoid heap - * allocations in typical cases. This should be large enough that most strings - * will fit, but small enough that we feel comfortable putting it on the - * stack. - */ -#define TEXTBUFLEN 1024 - extern pg_locale_t create_pg_locale_libc(Oid collid, MemoryContext context); static int strncoll_libc(const char *arg1, ssize_t len1, @@ -502,6 +495,8 @@ strlower_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, size_t curr_char; size_t max_size; + DECLARE_STACK_BUFFER_LARGE(); + if (srclen < 0) srclen = strlen(src); @@ -512,7 +507,7 @@ strlower_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, errmsg("out of memory"))); /* Output workspace cannot have more codes than input bytes */ - workspace = palloc_array(wchar_t, srclen + 1); + workspace = stack_buffer_alloc_array(wchar_t, srclen + 1); char2wchar(workspace, srclen + 1, src, srclen, loc); @@ -523,7 +518,7 @@ strlower_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, * Make result large enough; case change might change number of bytes */ max_size = curr_char * pg_database_encoding_max_length(); - result = palloc(max_size + 1); + result = stack_buffer_alloc(max_size + 1); result_size = wchar2char(result, workspace, max_size + 1, loc); @@ -533,8 +528,8 @@ strlower_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, dest[result_size] = '\0'; } - pfree(workspace); - pfree(result); + stack_buffer_free(workspace); + stack_buffer_free(result); return result_size; } @@ -607,6 +602,8 @@ strtitle_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, size_t curr_char; size_t max_size; + DECLARE_STACK_BUFFER_LARGE(); + if (srclen < 0) srclen = strlen(src); @@ -617,7 +614,7 @@ strtitle_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, errmsg("out of memory"))); /* Output workspace cannot have more codes than input bytes */ - workspace = palloc_array(wchar_t, srclen + 1); + workspace = stack_buffer_alloc_array(wchar_t, srclen + 1); char2wchar(workspace, srclen + 1, src, srclen, loc); @@ -634,7 +631,7 @@ strtitle_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, * Make result large enough; case change might change number of bytes */ max_size = curr_char * pg_database_encoding_max_length(); - result = palloc(max_size + 1); + result = stack_buffer_alloc(max_size + 1); result_size = wchar2char(result, workspace, max_size + 1, loc); @@ -644,8 +641,8 @@ strtitle_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, dest[result_size] = '\0'; } - pfree(workspace); - pfree(result); + stack_buffer_free(workspace); + stack_buffer_free(result); return result_size; } @@ -700,6 +697,8 @@ strupper_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, size_t curr_char; size_t max_size; + DECLARE_STACK_BUFFER_LARGE(); + if (srclen < 0) srclen = strlen(src); @@ -710,7 +709,7 @@ strupper_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, errmsg("out of memory"))); /* Output workspace cannot have more codes than input bytes */ - workspace = palloc_array(wchar_t, srclen + 1); + workspace = stack_buffer_alloc_array(wchar_t, srclen + 1); char2wchar(workspace, srclen + 1, src, srclen, loc); @@ -721,7 +720,7 @@ strupper_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, * Make result large enough; case change might change number of bytes */ max_size = curr_char * pg_database_encoding_max_length(); - result = palloc(max_size + 1); + result = stack_buffer_alloc(max_size + 1); result_size = wchar2char(result, workspace, max_size + 1, loc); @@ -731,8 +730,8 @@ strupper_libc_mb(char *dest, size_t destsize, const char *src, ssize_t srclen, dest[result_size] = '\0'; } - pfree(workspace); - pfree(result); + stack_buffer_free(workspace); + stack_buffer_free(result); return result_size; } @@ -896,48 +895,25 @@ int strncoll_libc(const char *arg1, ssize_t len1, const char *arg2, ssize_t len2, pg_locale_t locale) { - char sbuf[TEXTBUFLEN]; - char *buf = sbuf; - size_t bufsize1 = (len1 == -1) ? 0 : len1 + 1; - size_t bufsize2 = (len2 == -1) ? 0 : len2 + 1; - const char *arg1n; - const char *arg2n; + char *cstr1 = NULL; + char *cstr2 = NULL; int result; - if (bufsize1 + bufsize2 > TEXTBUFLEN) - buf = palloc(bufsize1 + bufsize2); + DECLARE_STACK_BUFFER_LARGE(); /* nul-terminate arguments if necessary */ - if (len1 == -1) - { - arg1n = arg1; - } - else - { - char *buf1 = buf; + if (len1 != -1) + arg1 = cstr1 = stack_buffer_strdup_with_len(arg1, len1); - memcpy(buf1, arg1, len1); - buf1[len1] = '\0'; - arg1n = buf1; - } + if (len2 != -1) + arg2 = cstr2 = stack_buffer_strdup_with_len(arg2, len2); - if (len2 == -1) - { - arg2n = arg2; - } - else - { - char *buf2 = buf + bufsize1; - - memcpy(buf2, arg2, len2); - buf2[len2] = '\0'; - arg2n = buf2; - } + result = strcoll_l(arg1, arg2, locale->lt); - result = strcoll_l(arg1n, arg2n, locale->lt); - - if (buf != sbuf) - pfree(buf); + if (cstr1) + stack_buffer_free(cstr1); + if (cstr2) + stack_buffer_free(cstr2); return result; } @@ -953,25 +929,17 @@ size_t strnxfrm_libc(char *dest, size_t destsize, const char *src, ssize_t srclen, pg_locale_t locale) { - char sbuf[TEXTBUFLEN]; - char *buf = sbuf; - size_t bufsize = srclen + 1; + char *cstr; size_t result; + DECLARE_STACK_BUFFER_LARGE(); + if (srclen == -1) return strxfrm_l(dest, src, destsize, locale->lt); - if (bufsize > TEXTBUFLEN) - buf = palloc(bufsize); - - /* nul-terminate argument */ - memcpy(buf, src, srclen); - buf[srclen] = '\0'; - - result = strxfrm_l(dest, buf, destsize, locale->lt); - - if (buf != sbuf) - pfree(buf); + cstr = stack_buffer_strdup_with_len(src, srclen); + result = strxfrm_l(dest, cstr, destsize, locale->lt); + stack_buffer_free(cstr); /* if dest is defined, it should be nul-terminated */ Assert(result >= destsize || dest[result] == '\0'); @@ -1057,15 +1025,13 @@ static int strncoll_libc_win32_utf8(const char *arg1, ssize_t len1, const char *arg2, ssize_t len2, pg_locale_t locale) { - char sbuf[TEXTBUFLEN]; - char *buf = sbuf; - char *a1p, - *a2p; - int a1len; - int a2len; + wchar_t *w1p; + wchar_t *w2p; int r; int result; + DECLARE_STACK_BUFFER_LARGE(); + Assert(GetDatabaseEncoding() == PG_UTF8); if (len1 == -1) @@ -1073,50 +1039,42 @@ strncoll_libc_win32_utf8(const char *arg1, ssize_t len1, const char *arg2, if (len2 == -1) len2 = strlen(arg2); - a1len = len1 * 2 + 2; - a2len = len2 * 2 + 2; - - if (a1len + a2len > TEXTBUFLEN) - buf = palloc(a1len + a2len); - - a1p = buf; - a2p = buf + a1len; + w1p = stack_buffer_alloc_array(wchar_t, len1 + 1); + w2p = stack_buffer_alloc_array(wchar_t, len2 + 1); /* API does not work for zero-length input */ if (len1 == 0) r = 0; else { - r = MultiByteToWideChar(CP_UTF8, 0, arg1, len1, - (LPWSTR) a1p, a1len / 2); + r = MultiByteToWideChar(CP_UTF8, 0, arg1, len1, w1p, len1); if (!r) ereport(ERROR, (errmsg("could not convert string to UTF-16: error code %lu", GetLastError()))); } - ((LPWSTR) a1p)[r] = 0; + w1p[r] = 0; if (len2 == 0) r = 0; else { - r = MultiByteToWideChar(CP_UTF8, 0, arg2, len2, - (LPWSTR) a2p, a2len / 2); + r = MultiByteToWideChar(CP_UTF8, 0, arg2, len2, w2p, len2); if (!r) ereport(ERROR, (errmsg("could not convert string to UTF-16: error code %lu", GetLastError()))); } - ((LPWSTR) a2p)[r] = 0; + w2p[r] = 0; errno = 0; - result = wcscoll_l((LPWSTR) a1p, (LPWSTR) a2p, locale->lt); + result = wcscoll_l(w1p, w2p, locale->lt); if (result == 2147483647) /* _NLSCMPERROR; missing from mingw headers */ ereport(ERROR, (errmsg("could not compare Unicode strings: %m"))); - if (buf != sbuf) - pfree(buf); + stack_buffer_free(w1p); + stack_buffer_free(w2p); return result; } @@ -1289,8 +1247,12 @@ char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen, else #endif /* WIN32 */ { + char *str; + + DECLARE_STACK_BUFFER_LARGE(); + /* mbstowcs requires ending '\0' */ - char *str = pnstrdup(from, fromlen); + str = stack_buffer_strdup_with_len(from, fromlen); if (loc == (locale_t) 0) { @@ -1303,7 +1265,7 @@ char2wchar(wchar_t *to, size_t tolen, const char *from, size_t fromlen, result = mbstowcs_l(to, str, tolen, loc); } - pfree(str); + stack_buffer_free(str); } if (result == -1) -- 2.53.0