text: #include <stdlib.h>
  #include <stdarg.h>
  #include <ctype.h>
  #include <wchar.h>
  #include <wctype.h>
  #include <limits.h>
  #include <string.h>
  #include <stdint.h>
  
  #include "stdio_impl.h"
  #include "shgetc.h"
  #include "intscan.h"
  #include "floatscan.h"
  
  #define SIZE_hh -2
  #define SIZE_h  -1
  #define SIZE_def 0
  #define SIZE_l   1
  #define SIZE_L   2
  #define SIZE_ll  3
  
  static void store_int(void *dest, int size, unsigned long long i)
  {
  	if (!dest) return;
  	switch (size) {
  	case SIZE_hh:
  		*(char *)dest = i;
  		break;
  	case SIZE_h:
  		*(short *)dest = i;
  		break;
  	case SIZE_def:
  		*(int *)dest = i;
  		break;
  	case SIZE_l:
  		*(long *)dest = i;
  		break;
  	case SIZE_ll:
  		*(long long *)dest = i;
  		break;
  	}
  }
  
  static void *arg_n(va_list ap, unsigned int n)
  {
  	void *p;
  	unsigned int i;
  	va_list ap2;
  	va_copy(ap2, ap);
  	for (i=n; i>1; i--) va_arg(ap2, void *);
  	p = va_arg(ap2, void *);
  	va_end(ap2);
  	return p;
  }
  
  int vfscanf(FILE *restrict f, const char *restrict fmt, va_list ap)
  {
  	int width;
  	int size;
  	int alloc = 0;
  	int base;
  	const unsigned char *p;
  	int c, t;
  	char *s;
  	wchar_t *wcs;
  	mbstate_t st;
  	void *dest=NULL;
  	int invert;
  	int matches=0;
  	unsigned long long x;
  	long double y;
  	off_t pos = 0;
  	unsigned char scanset[257];
  	size_t i, k;
  	wchar_t wc;
  
  	FLOCK(f);
  
  	if (!f->rpos) __toread(f);
  	if (!f->rpos) goto input_fail;
  
  	for (p=(const unsigned char *)fmt; *p; p++) {
  
  		alloc = 0;
  
  		if (isspace(*p)) {
  			while (isspace(p[1])) p++;
  			shlim(f, 0);
  			while (isspace(shgetc(f)));
  			shunget(f);
  			pos += shcnt(f);
  			continue;
  		}
  		if (*p != '%' || p[1] == '%') {
  			shlim(f, 0);
  			if (*p == '%') {
  				p++;
  				while (isspace((c=shgetc(f))));
  			} else {
  				c = shgetc(f);
  			}
  			if (c!=*p) {
  				shunget(f);
  				if (c<0) goto input_fail;
  				goto match_fail;
  			}
  			pos += shcnt(f);
  			continue;
  		}
  
  		p++;
  		if (*p=='*') {
  			dest = 0; p++;
  		} else if (isdigit(*p) && p[1]=='$') {
  			dest = arg_n(ap, *p-'0'); p+=2;
  		} else {
  			dest = va_arg(ap, void *);
  		}
  
  		for (width=0; isdigit(*p); p++) {
  			width = 10*width + *p - '0';
  		}
  
  		if (*p=='m') {
  			wcs = 0;
  			s = 0;
  			alloc = !!dest;
  			p++;
  		} else {
  			alloc = 0;
  		}
  
  		size = SIZE_def;
  		switch (*p++) {
  		case 'h':
  			if (*p == 'h') p++, size = SIZE_hh;
  			else size = SIZE_h;
  			break;
  		case 'l':
  			if (*p == 'l') p++, size = SIZE_ll;
  			else size = SIZE_l;
  			break;
  		case 'j':
  			size = SIZE_ll;
  			break;
  		case 'z':
  		case 't':
  			size = SIZE_l;
  			break;
  		case 'L':
  			size = SIZE_L;
  			break;
  		case 'd': case 'i': case 'o': case 'u': case 'x':
  		case 'a': case 'e': case 'f': case 'g':
  		case 'A': case 'E': case 'F': case 'G': case 'X':
  		case 's': case 'c': case '[':
  		case 'S': case 'C':
  		case 'p': case 'n':
  			p--;
  			break;
  		default:
  			goto fmt_fail;
  		}
  
  		t = *p;
  
  		/* C or S */
  		if ((t&0x2f) == 3) {
  			t |= 32;
  			size = SIZE_l;
  		}
  
  		switch (t) {
  		case 'c':
  			if (width < 1) width = 1;
  		case '[':
  			break;
  		case 'n':
  			store_int(dest, size, pos);
  			/* do not increment match count, etc! */
  			continue;
  		default:
  			shlim(f, 0);
  			while (isspace(shgetc(f)));
  			shunget(f);
  			pos += shcnt(f);
  		}
  
  		shlim(f, width);
  		if (shgetc(f) < 0) goto input_fail;
  		shunget(f);
  
  		switch (t) {
  		case 's':
  		case 'c':
  		case '[':
  			if (t == 'c' || t == 's') {
  				memset(scanset, -1, sizeof scanset);
  				scanset[0] = 0;
  				if (t == 's') {
  					scanset[1+'\t'] = 0;
  					scanset[1+'\n'] = 0;
  					scanset[1+'\v'] = 0;
  					scanset[1+'\f'] = 0;
  					scanset[1+'\r'] = 0;
  					scanset[1+' '] = 0;
  				}
  			} else {
  				if (*++p == '^') p++, invert = 1;
  				else invert = 0;
  				memset(scanset, invert, sizeof scanset);
  				scanset[0] = 0;
  				if (*p == '-') p++, scanset[1+'-'] = 1-invert;
  				else if (*p == ']') p++, scanset[1+']'] = 1-invert;
  				for (; *p != ']'; p++) {
  					if (!*p) goto fmt_fail;
  					if (*p=='-' && p[1] && p[1] != ']')
  						for (c=p++[-1]; c<*p; c++)
  							scanset[1+c] = 1-invert;
  					scanset[1+*p] = 1-invert;
  				}
  			}
  			wcs = 0;
  			s = 0;
  			i = 0;
  			k = t=='c' ? width+1U : 31;
  			if (size == SIZE_l) {
  				if (alloc) {
  					wcs = malloc(k*sizeof(wchar_t));
  					if (!wcs) goto alloc_fail;
  				} else {
  					wcs = dest;
  				}
  				st = (mbstate_t){0};
  				while (scanset[(c=shgetc(f))+1]) {
  					switch (mbrtowc(&wc, &(char){c}, 1, &st)) {
  					case -1:
  						goto input_fail;
  					case -2:
  						continue;
  					}
  					if (wcs) wcs[i++] = wc;
  					if (alloc && i==k) {
  						k+=k+1;
  						wchar_t *tmp = realloc(wcs, k*sizeof(wchar_t));
  						if (!tmp) goto alloc_fail;
  						wcs = tmp;
  					}
  				}
  				if (!mbsinit(&st)) goto input_fail;
  			} else if (alloc) {
  				s = malloc(k);
  				if (!s) goto alloc_fail;
  				while (scanset[(c=shgetc(f))+1]) {
  					s[i++] = c;
  					if (i==k) {
  						k+=k+1;
  						char *tmp = realloc(s, k);
  						if (!tmp) goto alloc_fail;
  						s = tmp;
  					}
  				}
  			} else if ((s = dest)) {
  				while (scanset[(c=shgetc(f))+1])
  					s[i++] = c;
  			} else {
  				while (scanset[(c=shgetc(f))+1]);
  			}
  			shunget(f);
  			if (!shcnt(f)) goto match_fail;
  			if (t == 'c' && shcnt(f) != width) goto match_fail;
  			if (alloc) {
  				if (size == SIZE_l) *(wchar_t **)dest = wcs;
  				else *(char **)dest = s;
  			}
  			if (t != 'c') {
  				if (wcs) wcs[i] = 0;
  				if (s) s[i] = 0;
  			}
  			break;
  		case 'p':
  		case 'X':
  		case 'x':
  			base = 16;
  			goto int_common;
  		case 'o':
  			base = 8;
  			goto int_common;
  		case 'd':
  		case 'u':
  			base = 10;
  			goto int_common;
  		case 'i':
  			base = 0;
  		int_common:
  			x = __intscan(f, base, 0, ULLONG_MAX);
  			if (!shcnt(f)) goto match_fail;
  			if (t=='p' && dest) *(void **)dest = (void *)(uintptr_t)x;
  			else store_int(dest, size, x);
  			break;
  		case 'a': case 'A':
  		case 'e': case 'E':
  		case 'f': case 'F':
  		case 'g': case 'G':
  			y = __floatscan(f, size, 0);
  			if (!shcnt(f)) goto match_fail;
  			if (dest) switch (size) {
  			case SIZE_def:
  				*(float *)dest = y;
  				break;
  			case SIZE_l:
  				*(double *)dest = y;
  				break;
  			case SIZE_L:
  				*(long double *)dest = y;
  				break;
  			}
  			break;
  		}
  
  		pos += shcnt(f);
  		if (dest) matches++;
  	}
  	if (0) {
  fmt_fail:
  alloc_fail:
  input_fail:
  		if (!matches) matches--;
  match_fail:
  		if (alloc) {
  			free(s);
  			free(wcs);
  		}
  	}
  	FUNLOCK(f);
  	return matches;
  }
  
  weak_alias(vfscanf,__isoc99_vfscanf);
  