fgets.c raw

   1  #include "stdio_impl.h"
   2  #include <string.h>
   3  
   4  #define MIN(a,b) ((a)<(b) ? (a) : (b))
   5  
   6  char *fgets(char *restrict s, int n, FILE *restrict f)
   7  {
   8  	char *p = s;
   9  	unsigned char *z;
  10  	size_t k;
  11  	int c;
  12  
  13  	FLOCK(f);
  14  
  15  	if (n--<=1) {
  16  		f->mode |= f->mode-1;
  17  		FUNLOCK(f);
  18  		if (n) return 0;
  19  		*s = 0;
  20  		return s;
  21  	}
  22  
  23  	while (n) {
  24  		if (f->rpos != f->rend) {
  25  			z = memchr(f->rpos, '\n', f->rend - f->rpos);
  26  			k = z ? z - f->rpos + 1 : f->rend - f->rpos;
  27  			k = MIN(k, n);
  28  			memcpy(p, f->rpos, k);
  29  			f->rpos += k;
  30  			p += k;
  31  			n -= k;
  32  			if (z || !n) break;
  33  		}
  34  		if ((c = getc_unlocked(f)) < 0) {
  35  			if (p==s || !feof(f)) s = 0;
  36  			break;
  37  		}
  38  		n--;
  39  		if ((*p++ = c) == '\n') break;
  40  	}
  41  	if (s) *p = 0;
  42  
  43  	FUNLOCK(f);
  44  
  45  	return s;
  46  }
  47  
  48  weak_alias(fgets, fgets_unlocked);
  49