scanf.c

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/*
 * Modified by Manuel Novoa III       Mar 13, 2001
 *
 * The vfscanf routine was completely rewritten to add features and remove
 * bugs.  The function __strtold, based on my strtod code in stdlib, was
 * added to provide floating point support for the scanf functions.
 *
 * So far they pass the test cases from glibc-2.1.3, except in two instances.
 * In one case, the test appears to be broken.  The other case is something
 * I need to research further.  This version of scanf assumes it can only
 * peek one character ahead.  Apparently, glibc looks further.  The difference
 * can be seen when parsing a floating point value in the character
 * sequence "100ergs".  glibc is able to back up before the 'e' and return
 * a value of 100, whereas this scanf reports a bad match with the stream
 * pointer at 'r'.  A similar situation can also happen when parsing hex
 * values prefixed by 0x or 0X; a failure would occur for "0xg".  In order to
 * fix this, I need to rework the "ungetc" machinery in stdio.c again.
 * I do have one reference though, that seems to imply scanf has a single
 * character of lookahead.
 *
 * May 20, 2001
 *
 * Quote from ANSI/ISO C99 standard:
 *
 *    fscanf pushes back at most one input character onto the input stream.
 *    Therefore, some sequences that are acceptable to strtod, strtol, etc.,
 *    are unacceptable to fscanf.
 *
 * So uClibc's *scanf functions conform to the standard, and glibc's
 * implementation doesn't for the "100ergs" case mentioned above.
 */

#include <stdlib.h>
#include <unistd.h>
#define __USE_ISOC99
#include <stdio.h>
#include <ctype.h>
#include <string.h>
#include <stdarg.h>

#ifdef L_scanf
#ifdef __STDC__
int scanf(const char *fmt, ...)
#else
int scanf(fmt, va_alist)
__const char *fmt;
va_dcl
#endif
{
	va_list ptr;
	int rv;

	va_start(ptr, fmt);
	rv = vfscanf(stdin, fmt, ptr);
	va_end(ptr);
	return rv;
}
#endif

#ifdef L_sscanf
#ifdef __STDC__
int sscanf(const char *sp, const char *fmt, ...)
#else
int sscanf(sp, fmt, va_alist)
__const char *sp;
__const char *fmt;
va_dcl
#endif
{
	FILE string[1] = {
		{0, (unsigned char *) ((unsigned) -1), 0, 0, (char *) ((unsigned) -1),
		 0, -1, _IOFBF}
	};

	va_list ptr;
	int rv;

	string->bufpos = (unsigned char *) ((void *) sp);
	va_start(ptr, fmt);
	rv = vfscanf(string, fmt, ptr);
	va_end(ptr);
	return rv;
}
#endif

#ifdef L_fscanf
#ifdef __STDC__
int fscanf(FILE * fp, const char *fmt, ...)
#else
int fscanf(fp, fmt, va_alist)
FILE *fp;
__const char *fmt;
va_dcl
#endif
{
	va_list ptr;
	int rv;

	va_start(ptr, fmt);
	rv = vfscanf(fp, fmt, ptr);
	va_end(ptr);
	return rv;
}
#endif

#ifdef L_vscanf
int vscanf(fmt, ap)
__const char *fmt;
va_list ap;
{
	return vfscanf(stdin, fmt, ap);
}
#endif

#ifdef L_vsscanf
int vsscanf(__const char *sp, __const char *fmt, va_list ap)
{
	FILE string[1] = {
		{0, (unsigned char *) ((unsigned) -1), 0, 0, (char *) ((unsigned) -1),
		 0, -1, _IOFBF}
	};

	string->bufpos = (unsigned char *) sp;
	return vfscanf(string, fmt, ap);
}
#endif

#ifdef L_vfscanf

#include <assert.h>
#include <ctype.h>
#include <limits.h>

static int valid_digit(char c, char base)
{
	if (base == 16) {
		return isxdigit(c);
	} else {
		return (isdigit(c) && (c < '0' + base));
	}
}

extern unsigned long long
_strto_ll(const char *str, char **endptr, int base, int uflag);

extern unsigned long
_strto_l(const char *str, char **endptr, int base, int uflag);

struct scan_cookie {
	FILE *fp;
	int nread;
	int width;
	int width_flag;
	int ungot_char;
	int ungot_flag;
};

#ifdef __UCLIBC_HAS_LONG_LONG__
static const char qual[] = "hl" /* "jtz" */ "Lq";
/* char = -2, short = -1, int = 0, long = 1, long long = 2 */
static const char qsz[] = { -1, 1,           2, 2 };
#else
static const char qual[] = "hl" /* "jtz" */;
static const char qsz[] = { -1, 1,         };
#endif

#ifdef __UCLIBC_HAS_FLOATS__
static int __strtold(long double *ld, struct scan_cookie *sc);
						   /*01234567890123456 */
static const char spec[]  = "%n[csoupxXidfeEgG";
#else
static const char spec[]  = "%n[csoupxXid";
#endif
/* radix[i] <-> spec[i+5]     o   u   p   x   X  i   d */
static const char radix[] = { 8, 10, 16, 16, 16, 0, 10 };

static void init_scan_cookie(struct scan_cookie *sc, FILE *fp)
{
	sc->fp = fp;
	sc->nread = 0;
	sc->width_flag = 0;
	sc->ungot_flag = 0;
}

static int scan_getc_nw(struct scan_cookie *sc)
{
	if (sc->ungot_flag == 0) {
		sc->ungot_char = getc(sc->fp);
	} else {
		sc->ungot_flag = 0;
	}
	if (sc->ungot_char > 0) {
		++sc->nread;
	}
	sc->width_flag = 0;
	return sc->ungot_char;
}

static int scan_getc(struct scan_cookie *sc)
{
	if (sc->ungot_flag == 0) {
		sc->ungot_char = getc(sc->fp);
	}
	sc->width_flag = 1;
	if (--sc->width < 0) {
		sc->ungot_flag = 1;
		return 0;
	}
	sc->ungot_flag = 0;
	if (sc->ungot_char > 0) {
		++sc->nread;
	}
	return sc->ungot_char;
}

static void scan_ungetc(struct scan_cookie *sc)
{
	if (sc->ungot_flag != 0) {
		assert(sc->width < 0);
		return;
	}
	if (sc->width_flag) {
		++sc->width;
	}
	sc->ungot_flag = 1;
	if (sc->ungot_char > 0) {	/* not EOF or EOS */
		--sc->nread;
	}
}

static void kill_scan_cookie(struct scan_cookie *sc)
{
	if (sc->ungot_flag) {
		ungetc(sc->ungot_char,sc->fp);
	}
}

int vfscanf(fp, format, ap)
FILE *fp;
const char *format;
va_list ap;
{
#ifdef __UCLIBC_HAS_LONG_LONG__
#define STRTO_L_(s,e,b,u) _strto_ll(s,e,b,u)
#define MAX_DIGITS 64
#define UV_TYPE unsigned long long
#define V_TYPE long long
#else
#define STRTO_L_(s,e,b,u) _strto_l(s,e,b,u)
#define MAX_DIGITS 32
#define UV_TYPE unsigned long
#define V_TYPE long
#endif
#ifdef __UCLIBC_HAS_FLOATS__
	long double ld;
#endif
	UV_TYPE uv;
	struct scan_cookie sc;
	unsigned const char *fmt;
	const char *p;
	unsigned char *b;
	void *vp;
	int cc, i, cnt;
	signed char lval;
	unsigned char store, usflag, base, invert, r0, r1;
	unsigned char buf[MAX_DIGITS+2];
	unsigned char scanset[UCHAR_MAX + 1];

	init_scan_cookie(&sc,fp);

	fmt = (unsigned const char *) format;
	cnt = 0;

	while (*fmt) {
		store = 1;
		lval = 0;
		sc.width = INT_MAX;
		if (*fmt == '%') {		/* Conversion specification. */
			++fmt;
			if (*fmt == '*') {	/* Suppress assignment. */
				store = 0;
				++fmt;
			}
			for (i = 0 ; isdigit(*fmt) ; sc.width = i) {
				i = (i * 10) + (*fmt++ - '0'); /* Get specified width. */
			}
			for (i = 0 ; i < sizeof(qual) ; i++) { /* Optional qualifier. */
				if (qual[i] == *fmt) {
					++fmt;
					lval += qsz[i];
					if ((i < 2) && (qual[i] == *fmt)) {	/* Double h or l. */
						++fmt;
						lval += qsz[i];
					}
					break;
				}
			}
			for (p = spec ; *p ; p++) {	/* Process format specifier. */
				if (*fmt != *p) continue;
				if (p-spec < 1) { /* % - match a '%'*/
					goto matchchar;
				}
				if (p-spec < 2) { /* n - store number of chars read */
					*(va_arg(ap, int *)) = sc.nread;
					scan_getc_nw(&sc);
					goto nextfmt;
				}
				if (p-spec > 3) { /* skip white space if not c or [ */
					while (isspace(scan_getc_nw(&sc)))
						{}
					scan_ungetc(&sc);
				}
				if (p-spec < 5) { /* [,c,s - string conversions */
					invert = 0;
					if (*p == 'c') {
						invert = 1;
						if (sc.width == INT_MAX) {
							sc.width = 1;
						}
					}
					for (i=0 ; i<= UCHAR_MAX ; i++) {
						scanset[i] = ((*p == 's') ? (isspace(i) == 0) : 0);
					}
					if (*p == '[') { /* need to build a scanset */
						if (*++fmt == '^') {
							invert = 1;
							++fmt;
						}
						if (*fmt == ']') {
							scanset[(int)']'] = 1;
							++fmt;
						}
						r0 = 0;
						while (*fmt && *fmt !=']') { /* build scanset */
							if ((*fmt == '-') && r0 && (fmt[1] != ']')) {
								/* range */
								++fmt;
								if (*fmt < r0) {
									r1 = r0;
									r0 = *fmt;
								} else {
									r1 = *fmt;
								}
								for (i=r0 ; i<= r1 ; i++) {
									scanset[i] = 1;
								}
								r0 = 0;
							} else {
								r0 = *fmt;
								scanset[r0] = 1;
							}
							++fmt;
						}
						if (!*fmt) { /* format string exhausted! */
							goto done;
						}