#include <stdio.h>
#include <string.h>
#include "fileutil.h"

size_t fread(void *data, size_t membsize, size_t nmemb, FILE *fp)
{
	size_t size;
	if(__builtin_umul_overflow(membsize, nmemb, &size)) {
		fp->error = 1;
		return 0;
	}

	if(!fp->buf) {
		ssize_t rc = __fp_read(fp, data, size);
		return (rc == EOF) ? 0 : rc;
	}

	__fp_buffer_mode_read(fp);

	size_t size_read = 0;
	while(size_read < size) {
		/* Take what's available in the buffer (may be 0, but only
		   during the first iteration) */
		size_t size_frag = fp->bufread - fp->bufpos;
		if(size_frag > size - size_read)
			size_frag = size - size_read;
		memcpy(data + size_read, fp->buf + fp->bufpos, size_frag);
		size_read += size_frag;
		fp->bufpos += size_frag;

		if(fp->bufpos >= fp->bufread) {
			fp->bufread = 0;
			fp->bufpos = 0;
		}
		if(size_read >= size)
			break;

		/* Get more data */
		ssize_t rc = __fp_read(fp, fp->buf, fp->bufsize);
		if(rc <= 0) /* EOF or error */
			break;
		fp->bufread = rc;
	}

	return size_read;
}