musl/src/stdio/fread.c

#include "stdio_impl.h"
#include <string.h>

#define MIN(a,b) ((a)<(b) ? (a) : (b))

size_t fread(void *restrict destv, size_t size, size_t nmemb, FILE *restrict f)
{
	unsigned char *dest = destv;
	size_t len = size*nmemb, l = len, k;

	/* Never touch the file if length is zero.. */
	if (!l) return 0;

	FLOCK(f);

	if (f->rend - f->rpos > 0) {
		/* First exhaust the buffer. */
		k = MIN(f->rend - f->rpos, l);
		memcpy(dest, f->rpos, k);
		f->rpos += k;
		dest += k;
		l -= k;
	}
	
	/* Read the remainder directly */
	for (; l; l-=k, dest+=k) {
		k = __toread(f) ? 0 : f->read(f, dest, l);
		if (k+1<=1) {
			FUNLOCK(f);
			return (len-l)/size;
		}
	}

	FUNLOCK(f);
	return nmemb;
}

weak_alias(fread, fread_unlocked);