source: asp3_tinet_ecnl_rx/trunk/musl-1.1.18/src/stdio/__stdio_write.c@ 337

#include "stdio_impl.h"
#include <sys/uio.h>

size_t __stdio_write(FILE *f, const unsigned char *buf, size_t len)
{
        struct iovec iovs[2] = {
                { .iov_base = f->wbase, .iov_len = f->wpos-f->wbase },
                { .iov_base = (void *)buf, .iov_len = len }
        };
        struct iovec *iov = iovs;
        size_t rem = iov[0].iov_len + iov[1].iov_len;
        int iovcnt = 2;
        ssize_t cnt;
        for (;;) {
                cnt = syscall(SYS_writev, f->fd, iov, iovcnt);
                if (cnt == rem) {
                        f->wend = f->buf + f->buf_size;
                        f->wpos = f->wbase = f->buf;
                        return len;
                }
                if (cnt < 0) {
                        f->wpos = f->wbase = f->wend = 0;
                        f->flags |= F_ERR;
                        return iovcnt == 2 ? 0 : len-iov[0].iov_len;
                }
                rem -= cnt;
                if (cnt > iov[0].iov_len) {
                        cnt -= iov[0].iov_len;
                        iov++; iovcnt--;
                }
                iov[0].iov_base = (char *)iov[0].iov_base + cnt;
                iov[0].iov_len -= cnt;
        }
}