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/*-------------------------------------------------------------------------
*
* strtof.c
*
* Portions Copyright (c) 2019-2023, PostgreSQL Global Development Group
*
*
* IDENTIFICATION
* src/port/strtof.c
*
*-------------------------------------------------------------------------
*/
#include "c.h"
#include <float.h>
#include <math.h>
/*
* Cygwin has a strtof() which is literally just (float)strtod(), which means
* we can't avoid the double-rounding problem; but using this wrapper does get
* us proper over/underflow checks. (Also, if they fix their strtof(), the
* wrapper doesn't break anything.)
*
* Test results on Mingw suggest that it has the same problem, though looking
* at the code I can't figure out why.
*/
float
pg_strtof(const char *nptr, char **endptr)
{
int caller_errno = errno;
float fresult;
errno = 0;
fresult = (strtof) (nptr, endptr);
if (errno)
{
/* On error, just return the error to the caller. */
return fresult;
}
else if ((*endptr == nptr) || isnan(fresult) ||
((fresult >= FLT_MIN || fresult <= -FLT_MIN) && !isinf(fresult)))
{
/*
* If we got nothing parseable, or if we got a non-0 non-subnormal
* finite value (or NaN) without error, then return that to the caller
* without error.
*/
errno = caller_errno;
return fresult;
}
else
{
/*
* Try again. errno is already 0 here.
*/
double dresult = strtod(nptr, NULL);
if (errno)
{
/* On error, just return the error */
return fresult;
}
else if ((dresult == 0.0 && fresult == 0.0) ||
(isinf(dresult) && isinf(fresult) && (fresult == dresult)))
{
/* both values are 0 or infinities of the same sign */
errno = caller_errno;
return fresult;
}
else if ((dresult > 0 && dresult <= FLT_MIN && (float) dresult != 0.0) ||
(dresult < 0 && dresult >= -FLT_MIN && (float) dresult != 0.0))
{
/* subnormal but nonzero value */
errno = caller_errno;
return (float) dresult;
}
else
{
errno = ERANGE;
return fresult;
}
}
}
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