PSI_CHECK_SYS_UIO() { AC_CHECK_HEADERS(sys/uio.h) PSI_STRUCT(struct iovec, [ void *iov_base, size_t iov_len] ) PSI_DECL(ssize_t readv, [(int fd, struct iovec *iov, int iovcnt)]) PSI_DECL(ssize_t writev, [(int fd, struct iovec *iov, int iovcnt)]) }