86 lines
2.0 KiB
C
86 lines
2.0 KiB
C
/*-------------------------------------------------------------------------
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*
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* strtof.c
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*
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* Portions Copyright (c) 2019-2024, PostgreSQL Global Development Group
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*
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*
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* IDENTIFICATION
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* src/port/strtof.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "c.h"
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#include <float.h>
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#include <math.h>
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/*
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* Cygwin has a strtof() which is literally just (float)strtod(), which means
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* we can't avoid the double-rounding problem; but using this wrapper does get
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* us proper over/underflow checks. (Also, if they fix their strtof(), the
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* wrapper doesn't break anything.)
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*
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* Test results on Mingw suggest that it has the same problem, though looking
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* at the code I can't figure out why.
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*/
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float
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pg_strtof(const char *nptr, char **endptr)
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{
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int caller_errno = errno;
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float fresult;
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errno = 0;
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fresult = (strtof) (nptr, endptr);
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if (errno)
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{
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/* On error, just return the error to the caller. */
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return fresult;
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}
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else if ((*endptr == nptr) || isnan(fresult) ||
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((fresult >= FLT_MIN || fresult <= -FLT_MIN) && !isinf(fresult)))
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{
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/*
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* If we got nothing parseable, or if we got a non-0 non-subnormal
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* finite value (or NaN) without error, then return that to the caller
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* without error.
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*/
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errno = caller_errno;
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return fresult;
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}
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else
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{
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/*
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* Try again. errno is already 0 here.
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*/
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double dresult = strtod(nptr, NULL);
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if (errno)
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{
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/* On error, just return the error */
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return fresult;
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}
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else if ((dresult == 0.0 && fresult == 0.0) ||
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(isinf(dresult) && isinf(fresult) && (fresult == dresult)))
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{
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/* both values are 0 or infinities of the same sign */
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errno = caller_errno;
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return fresult;
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}
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else if ((dresult > 0 && dresult <= FLT_MIN && (float) dresult != 0.0) ||
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(dresult < 0 && dresult >= -FLT_MIN && (float) dresult != 0.0))
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{
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/* subnormal but nonzero value */
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errno = caller_errno;
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return (float) dresult;
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}
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else
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{
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errno = ERANGE;
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return fresult;
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}
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}
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}
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