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#include "stdio_impl.h"
#include <sys/uio.h>
size_t __stdio_read(FILE *f, unsigned char *buf, size_t len)
{
struct iovec iov[2] = {
{ .iov_base = buf, .iov_len = len - !!f->buf_size },
{ .iov_base = f->buf, .iov_len = f->buf_size }
};
ssize_t cnt;
#if __EMSCRIPTEN__
size_t num;
if (__wasi_syscall_ret(__wasi_fd_read(f->fd, (struct __wasi_iovec_t*)iov, 2, &num))) {
num = -1;
}
cnt = num;
#else
cnt = iov[0].iov_len ? syscall(SYS_readv, f->fd, iov, 2)
: syscall(SYS_read, f->fd, iov[1].iov_base, iov[1].iov_len);
#endif
if (cnt <= 0) {
f->flags |= cnt ? F_ERR : F_EOF;
return 0;
}
if (cnt <= iov[0].iov_len) return cnt;
cnt -= iov[0].iov_len;
f->rpos = f->buf;
f->rend = f->buf + cnt;
if (f->buf_size) buf[len-1] = *f->rpos++;
return len;
}
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