1#include "stdio_impl.h"
 2#include <sys/uio.h>
 3
 4size_t __stdio_write(FILE *f, const unsigned char *buf, size_t len)
 5{
 6	struct iovec iovs[2] = {
 7		{ .iov_base = f->wbase, .iov_len = f->wpos-f->wbase },
 8		{ .iov_base = (void *)buf, .iov_len = len }
 9	};
10	struct iovec *iov = iovs;
11	size_t rem = iov[0].iov_len + iov[1].iov_len;
12	int iovcnt = 2;
13	ssize_t cnt;
14	for (;;) {
15#ifdef __wasilibc_unmodified_upstream // WASI has no syscall
16		cnt = syscall(SYS_writev, f->fd, iov, iovcnt);
17#else
18		cnt = writev(f->fd, iov, iovcnt);
19#endif
20		if (cnt == rem) {
21			f->wend = f->buf + f->buf_size;
22			f->wpos = f->wbase = f->buf;
23			return len;
24		}
25		if (cnt < 0) {
26			f->wpos = f->wbase = f->wend = 0;
27			f->flags |= F_ERR;
28			return iovcnt == 2 ? 0 : len-iov[0].iov_len;
29		}
30		rem -= cnt;
31		if (cnt > iov[0].iov_len) {
32			cnt -= iov[0].iov_len;
33			iov++; iovcnt--;
34		}
35		iov[0].iov_base = (char *)iov[0].iov_base + cnt;
36		iov[0].iov_len -= cnt;
37	}
38}