Revamp scanf's floating-point-parsing algorithm to support
[+|-]Inf, [+|-]NaN, nan(...), and hexidecimal FP constants. While here, add %a and %A, which are aliases for %e, and add support for long doubles. Reviewed by: standards@
This commit is contained in:
David Schultz
parent
c8718f79da
commit
370077c7a6
@ -81,16 +81,11 @@ __FBSDID("$FreeBSD$");
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#define UNSIGNED 0x8000 /* %[oupxX] conversions */
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/*
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* The following are used in numeric conversions only:
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* SIGNOK, NDIGITS, DPTOK, and EXPOK are for floating point;
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* SIGNOK, NDIGITS, PFXOK, and NZDIGITS are for integral.
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* The following are used in integral conversions only:
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* SIGNOK, NDIGITS, PFXOK, and NZDIGITS
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*/
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#define SIGNOK 0x40 /* +/- is (still) legal */
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#define NDIGITS 0x80 /* no digits detected */
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#define DPTOK 0x100 /* (float) decimal point is still legal */
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#define EXPOK 0x200 /* (float) exponent (e+3, etc) still legal */
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#define PFXOK 0x100 /* 0x prefix is (still) legal */
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#define NZDIGITS 0x200 /* no zero digits detected */
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@ -104,6 +99,9 @@ __FBSDID("$FreeBSD$");
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#define CT_FLOAT 4 /* %[efgEFG] conversion */
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static const u_char *__sccl(char *, const u_char *);
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static int parsefloat(FILE *, char *, char *);
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int __scanfdebug = 0;
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__weak_reference(__vfscanf, vfscanf);
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@ -148,9 +146,6 @@ __svfscanf(FILE *fp, const char *fmt0, va_list ap)
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/* `basefix' is used to avoid `if' tests in the integer scanner */
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static short basefix[17] =
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{ 10, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 };
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#ifdef FLOATING_POINT
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char decimal_point = localeconv()->decimal_point[0];
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#endif
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ORIENT(fp, -1);
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@ -258,8 +253,8 @@ again: c = *fmt++;
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break;
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#ifdef FLOATING_POINT
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case 'E': case 'F': case 'G':
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case 'e': case 'f': case 'g':
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case 'A': case 'E': case 'F': case 'G':
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case 'a': case 'e': case 'f': case 'g':
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c = CT_FLOAT;
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break;
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#endif
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@ -769,96 +764,26 @@ again: c = *fmt++;
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#ifdef FLOATING_POINT
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case CT_FLOAT:
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/* scan a floating point number as if by strtod */
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#ifdef hardway
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if (width == 0 || width > sizeof(buf) - 1)
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width = sizeof(buf) - 1;
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#else
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/* size_t is unsigned, hence this optimisation */
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if (--width > sizeof(buf) - 2)
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width = sizeof(buf) - 2;
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width++;
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#endif
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flags |= SIGNOK | NDIGITS | DPTOK | EXPOK;
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for (p = buf; width; width--) {
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c = *fp->_p;
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/*
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* This code mimicks the integer conversion
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* code, but is much simpler.
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*/
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switch (c) {
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case '0': case '1': case '2': case '3':
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case '4': case '5': case '6': case '7':
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case '8': case '9':
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flags &= ~(SIGNOK | NDIGITS);
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goto fok;
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case '+': case '-':
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if (flags & SIGNOK) {
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flags &= ~SIGNOK;
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goto fok;
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}
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break;
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case 'e': case 'E':
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/* no exponent without some digits */
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if ((flags&(NDIGITS|EXPOK)) == EXPOK) {
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flags =
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(flags & ~(EXPOK|DPTOK)) |
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SIGNOK | NDIGITS;
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goto fok;
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}
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break;
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default:
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if ((char)c == decimal_point &&
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(flags & DPTOK)) {
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flags &= ~(SIGNOK | DPTOK);
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goto fok;
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}
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break;
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}
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break;
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fok:
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*p++ = c;
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if (--fp->_r > 0)
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fp->_p++;
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else if (__srefill(fp))
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break; /* EOF */
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}
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/*
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* If no digits, might be missing exponent digits
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* (just give back the exponent) or might be missing
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* regular digits, but had sign and/or decimal point.
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*/
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if (flags & NDIGITS) {
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if (flags & EXPOK) {
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/* no digits at all */
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while (p > buf)
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__ungetc(*(u_char *)--p, fp);
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goto match_failure;
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}
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/* just a bad exponent (e and maybe sign) */
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c = *(u_char *)--p;
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if (c != 'e' && c != 'E') {
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(void) __ungetc(c, fp);/* sign */
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c = *(u_char *)--p;
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}
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(void) __ungetc(c, fp);
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}
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if ((width = parsefloat(fp, buf, buf + width)) == 0)
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goto match_failure;
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if ((flags & SUPPRESS) == 0) {
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double res;
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*p = 0;
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/* XXX this loses precision for long doubles. */
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res = strtod(buf, (char **) NULL);
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if (flags & LONGDBL)
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if (flags & LONGDBL) {
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long double res = strtold(buf, &p);
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*va_arg(ap, long double *) = res;
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else if (flags & LONG)
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} else if (flags & LONG) {
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double res = strtod(buf, &p);
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*va_arg(ap, double *) = res;
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else
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} else {
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float res = strtof(buf, &p);
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*va_arg(ap, float *) = res;
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}
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if (__scanfdebug && p - buf != width)
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abort();
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nassigned++;
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}
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nread += p - buf;
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nread += width;
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nconversions++;
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break;
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#endif /* FLOATING_POINT */
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@ -982,3 +907,156 @@ __sccl(tab, fmt)
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}
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/* NOTREACHED */
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}
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#ifdef FLOATING_POINT
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static int
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parsefloat(FILE *fp, char *buf, char *end)
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{
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char *commit, *p;
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int infnanpos = 0;
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enum {
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S_START, S_GOTSIGN, S_INF, S_NAN, S_MAYBEHEX,
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S_DIGITS, S_FRAC, S_EXP, S_EXPDIGITS
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} state = S_START;
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unsigned char c;
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char decpt = *localeconv()->decimal_point;
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_Bool gotmantdig = 0, ishex = 0;
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/*
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* We set commit = p whenever the string we have read so far
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* constitutes a valid representation of a floating point
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* number by itself. At some point, the parse will complete
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* or fail, and we will ungetc() back to the last commit point.
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* To ensure that the file offset gets updated properly, it is
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* always necessary to read at least one character that doesn't
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* match; thus, we can't short-circuit "infinity" or "nan(...)".
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*/
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commit = buf - 1;
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for (p = buf; p < end; ) {
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c = *fp->_p;
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reswitch:
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switch (state) {
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case S_START:
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state = S_GOTSIGN;
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if (c == '-' || c == '+')
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break;
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else
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goto reswitch;
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case S_GOTSIGN:
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switch (c) {
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case '0':
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state = S_MAYBEHEX;
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commit = p;
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break;
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case 'I':
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case 'i':
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state = S_INF;
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break;
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case 'N':
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case 'n':
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state = S_NAN;
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break;
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default:
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state = S_DIGITS;
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goto reswitch;
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}
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break;
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case S_INF:
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if (infnanpos > 6 ||
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(c != "nfinity"[infnanpos] &&
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c != "NFINITY"[infnanpos]))
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goto parsedone;
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if (infnanpos == 1 || infnanpos == 6)
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commit = p; /* inf or infinity */
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infnanpos++;
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break;
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case S_NAN:
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switch (infnanpos) {
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case -1: /* XXX kludge to deal with nan(...) */
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goto parsedone;
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case 0:
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if (c != 'A' && c != 'a')
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goto parsedone;
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break;
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case 1:
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if (c != 'N' && c != 'n')
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goto parsedone;
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else
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commit = p;
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break;
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case 2:
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if (c != '(')
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goto parsedone;
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break;
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default:
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if (c == ')') {
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commit = p;
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infnanpos = -2;
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} else if (!isalnum(c) && c != '_')
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goto parsedone;
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break;
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}
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infnanpos++;
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break;
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case S_MAYBEHEX:
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state = S_DIGITS;
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if (c == 'X' || c == 'x') {
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ishex = 1;
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break;
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} else { /* we saw a '0', but no 'x' */
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gotmantdig = 1;
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goto reswitch;
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}
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case S_DIGITS:
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if (ishex && isxdigit(c) || isdigit(c))
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gotmantdig = 1;
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else {
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state = S_FRAC;
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if (c != decpt)
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goto reswitch;
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}
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if (gotmantdig)
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commit = p;
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break;
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case S_FRAC:
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if ((c == 'E' || c == 'e') && !ishex ||
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(c == 'P' || c == 'p') && ishex) {
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if (!gotmantdig)
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goto parsedone;
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else
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state = S_EXP;
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} else if (ishex && isxdigit(c) || isdigit(c)) {
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commit = p;
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gotmantdig = 1;
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} else
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goto parsedone;
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break;
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case S_EXP:
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state = S_EXPDIGITS;
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if (c == '-' || c == '+')
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break;
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else
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goto reswitch;
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case S_EXPDIGITS:
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if (isdigit(c))
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commit = p;
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else
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goto parsedone;
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break;
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default:
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abort();
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}
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*p++ = c;
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if (--fp->_r > 0)
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fp->_p++;
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else if (__srefill(fp))
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break; /* EOF */
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}
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parsedone:
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while (commit < --p)
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__ungetc(*(u_char *)p, fp);
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*++commit = '\0';
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return (commit - buf);
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}
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#endif
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