Revert "using for readv/writev the same interface like UNIX"

This reverts commit 6f195a2.

src/syscalls/mod.rs

@@ -73,7 +73,7 @@ struct iovec {
 	pub iov_len: usize,
 }
 
-const IOV_MAX: i32 = 1024;
+const IOV_MAX: usize = 1024;
 
 pub(crate) fn init() {
 	Lazy::force(&SYS);
@@ -450,7 +450,7 @@ pub unsafe extern "C" fn sys_read(fd: FileDescriptor, buf: *mut u8, len: usize)
 /// before proceeding to the next.
 #[hermit_macro::system]
 #[no_mangle]
-pub unsafe extern "C" fn sys_readv(fd: i32, iov: *const iovec, iovcnt: i32) -> isize {
+pub unsafe extern "C" fn sys_readv(fd: i32, iov: *const iovec, iovcnt: usize) -> isize {
 	if !(0..=IOV_MAX).contains(&iovcnt) {
 		return (-crate::errno::EINVAL).try_into().unwrap();
 	}
@@ -511,7 +511,7 @@ pub unsafe extern "C" fn sys_write(fd: FileDescriptor, buf: *const u8, len: usiz
 /// complete area before proceeding to the next.
 #[hermit_macro::system]
 #[no_mangle]
-pub unsafe extern "C" fn sys_writev(fd: FileDescriptor, iov: *const iovec, iovcnt: i32) -> isize {
+pub unsafe extern "C" fn sys_writev(fd: FileDescriptor, iov: *const iovec, iovcnt: usize) -> isize {
 	if !(0..=IOV_MAX).contains(&iovcnt) {
 		return (-crate::errno::EINVAL).try_into().unwrap();
 	}