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Commit96bf88d

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Always use our own versions of *printf().
We've spent an awful lot of effort over the years in coping withplatform-specific vagaries of the *printf family of functions. Let's justforget all that mess and standardize on always using src/port/snprintf.c.This gets rid of a lot of configure logic, and it will allow a sanerapproach to dealing with %m (though actually changing that is left fora follow-on patch).Preliminary performance testing suggests that as it stands, snprintf.c isfaster than the native printf functions for some tasks on some platforms,and slower for other cases. A pending patch will improve that, thoughcases with floating-point conversions will doubtless remain slower unlesswe want to put a *lot* of effort into that. Still, we've not observedthat *printf is really a performance bottleneck for most workloads, soI doubt this matters much.Patch by me, reviewed by Michael PaquierDiscussion:https://postgr.es/m/2975.1526862605@sss.pgh.pa.us
1 parent758ce9b commit96bf88d

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16 files changed

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-509
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16 files changed

+19
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‎config/c-compiler.m4

Lines changed: 2 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -20,15 +20,8 @@ fi])# PGAC_C_SIGNED
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# PGAC_C_PRINTF_ARCHETYPE
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# -----------------------
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# Select the format archetype to be used by gcc to check printf-type functions.
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# We prefer "gnu_printf", which matches the features glibc supports, notably
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# %m, 'z' and 'll' width modifiers ('ll' only matters if int64 requires it),
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# and argument order control if we're doing --enable-nls. On platforms where
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# the native printf doesn't have 'z'/'ll' or arg control, we replace it with
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# src/port/snprintf.c which does, so that the only potential mismatch here is
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# whether or not %m is supported. We need that for elog/ereport, so we live
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# with the fact that erroneous use of %m in plain printf calls won't be
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# detected. (It appears that many versions of gcc/clang wouldn't report it
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# even if told to check according to plain printf archetype, anyway.)
23+
# We prefer "gnu_printf", as that most closely matches the features supported
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# by src/port/snprintf.c (particularly the %m conversion spec).
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AC_DEFUN([PGAC_PRINTF_ARCHETYPE],
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[AC_CACHE_CHECK([for printf format archetype],pgac_cv_printf_archetype,
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[ac_save_c_werror_flag=$ac_c_werror_flag

‎config/c-library.m4

Lines changed: 0 additions & 100 deletions
Original file line numberDiff line numberDiff line change
@@ -171,106 +171,6 @@ AC_DEFUN([PGAC_STRUCT_ADDRINFO],
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])])# PGAC_STRUCT_ADDRINFO
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# PGAC_FUNC_SNPRINTF_ARG_CONTROL
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# ---------------------------------------
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# Determine if snprintf supports %1$ argument selection, e.g. %5$ selects
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# the fifth argument after the printf format string.
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# This is not in the C99 standard, but in the Single Unix Specification (SUS).
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# It is used in our language translation strings.
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#
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AC_DEFUN([PGAC_FUNC_SNPRINTF_ARG_CONTROL],
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[AC_MSG_CHECKING([whether snprintf supports argument control])
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AC_CACHE_VAL(pgac_cv_snprintf_arg_control,
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[AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <stdio.h>
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#include <string.h>
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int main()
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{
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char buf[100];
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/* can it swap arguments? */
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snprintf(buf, 100, "%2\$d %1\$d", 3, 4);
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if (strcmp(buf, "4 3") != 0)
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return 1;
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return 0;
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}]])],
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[pgac_cv_snprintf_arg_control=yes],
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[pgac_cv_snprintf_arg_control=no],
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[pgac_cv_snprintf_arg_control=cross])
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])dnl AC_CACHE_VAL
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AC_MSG_RESULT([$pgac_cv_snprintf_arg_control])
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])# PGAC_FUNC_SNPRINTF_ARG_CONTROL
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# PGAC_FUNC_SNPRINTF_SIZE_T_SUPPORT
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# ---------------------------------
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# Determine if snprintf supports the z length modifier for printing
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# size_t-sized variables. That's supported by C99 and POSIX but not
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# all platforms play ball, so we must test whether it's working.
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#
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AC_DEFUN([PGAC_FUNC_SNPRINTF_SIZE_T_SUPPORT],
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[AC_MSG_CHECKING([whether snprintf supports the %z modifier])
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AC_CACHE_VAL(pgac_cv_snprintf_size_t_support,
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[AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <stdio.h>
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#include <string.h>
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int main()
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{
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char bufz[100];
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char buf64[100];
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/*
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* Print the largest unsigned number fitting in a size_t using both %zu
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* and the previously-determined format for 64-bit integers. Note that
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* we don't run this code unless we know snprintf handles 64-bit ints.
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*/
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bufz[0] = '\0'; /* in case snprintf fails to emit anything */
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snprintf(bufz, sizeof(bufz), "%zu", ~((size_t) 0));
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snprintf(buf64, sizeof(buf64), "%" INT64_MODIFIER "u",
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(unsigned PG_INT64_TYPE) ~((size_t) 0));
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if (strcmp(bufz, buf64) != 0)
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return 1;
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return 0;
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}]])],
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[pgac_cv_snprintf_size_t_support=yes],
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[pgac_cv_snprintf_size_t_support=no],
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[pgac_cv_snprintf_size_t_support=cross])
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])dnl AC_CACHE_VAL
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AC_MSG_RESULT([$pgac_cv_snprintf_size_t_support])
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])# PGAC_FUNC_SNPRINTF_SIZE_T_SUPPORT
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# PGAC_FUNC_SNPRINTF_C99_RESULT
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# -----------------------------
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# Determine whether snprintf returns the desired buffer length when
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# it overruns the actual buffer length. That's required by C99 and POSIX
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# but ancient platforms don't behave that way, so we must test.
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# While we're at it, let's just verify that it doesn't physically overrun
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# the buffer.
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#
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AC_DEFUN([PGAC_FUNC_SNPRINTF_C99_RESULT],
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[AC_MSG_CHECKING([whether snprintf handles buffer overrun per C99])
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AC_CACHE_VAL(pgac_cv_snprintf_c99_result,
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[AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <stdio.h>
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#include <string.h>
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int main()
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{
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char buf[10];
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strcpy(buf, "abcdefghi");
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if (snprintf(buf, 4, "%d", 123456) != 6)
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return 1;
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if (strcmp(buf, "123") != 0 || buf[4] != 'e')
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return 1;
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return 0;
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}]])],
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[pgac_cv_snprintf_c99_result=yes],
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[pgac_cv_snprintf_c99_result=no],
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[pgac_cv_snprintf_c99_result=cross])
269-
])dnl AC_CACHE_VAL
270-
AC_MSG_RESULT([$pgac_cv_snprintf_c99_result])
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])# PGAC_FUNC_SNPRINTF_C99_RESULT
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273-
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# PGAC_TYPE_LOCALE_T
275175
# ------------------
276176
# Check for the locale_t type and find the right header file. macOS

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