Implement read_buf and vectored read/write for SGX stdio

Author: thaliaarchi

std/src/sys/pal/sgx/abi/usercalls/mod.rs

@@ -1,5 +1,7 @@
 use crate::cmp;
-use crate::io::{Error as IoError, ErrorKind, IoSlice, IoSliceMut, Result as IoResult};
+use crate::io::{
+    BorrowedCursor, Error as IoError, ErrorKind, IoSlice, IoSliceMut, Result as IoResult,
+};
 use crate::random::{DefaultRandomSource, Random};
 use crate::time::{Duration, Instant};
 
@@ -36,6 +38,19 @@ pub fn read(fd: Fd, bufs: &mut [IoSliceMut<'_>]) -> IoResult<usize> {
     }
 }
 
+/// Usercall `read` with an uninitialized buffer. See the ABI documentation for
+/// more information.
+#[unstable(feature = "sgx_platform", issue = "56975")]
+pub fn read_buf(fd: Fd, mut buf: BorrowedCursor<'_>) -> IoResult<()> {
+    unsafe {
+        let mut userbuf = alloc::User::<[u8]>::uninitialized(buf.capacity());
+        let len = raw::read(fd, userbuf.as_mut_ptr().cast(), userbuf.len()).from_sgx_result()?;
+        userbuf[..len].copy_to_enclave(&mut buf.as_mut()[..len]);
+        buf.advance_unchecked(len);
+        Ok(())
+    }
+}
+
 /// Usercall `read_alloc`. See the ABI documentation for more information.
 #[unstable(feature = "sgx_platform", issue = "56975")]
 pub fn read_alloc(fd: Fd) -> IoResult<Vec<u8>> {

std/src/sys/pal/sgx/fd.rs

@@ -29,7 +29,7 @@ impl FileDesc {
     }
 
     pub fn read_buf(&self, buf: BorrowedCursor<'_>) -> io::Result<()> {
-        crate::io::default_read_buf(|b| self.read(b), buf)
+        usercalls::read_buf(self.fd, buf)
     }
 
     pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {

std/src/sys/stdio/sgx.rs

@@ -1,6 +1,6 @@
 use fortanix_sgx_abi as abi;
 
-use crate::io;
+use crate::io::{self, BorrowedCursor, IoSlice, IoSliceMut};
 use crate::sys::fd::FileDesc;
 
 pub struct Stdin(());
@@ -24,6 +24,19 @@ impl io::Read for Stdin {
     fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
         with_std_fd(abi::FD_STDIN, |fd| fd.read(buf))
     }
+
+    fn read_buf(&mut self, buf: BorrowedCursor<'_>) -> io::Result<()> {
+        with_std_fd(abi::FD_STDIN, |fd| fd.read_buf(buf))
+    }
+
+    fn read_vectored(&mut self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
+        with_std_fd(abi::FD_STDIN, |fd| fd.read_vectored(bufs))
+    }
+
+    #[inline]
+    fn is_read_vectored(&self) -> bool {
+        true
+    }
 }
 
 impl Stdout {
@@ -40,6 +53,15 @@ impl io::Write for Stdout {
     fn flush(&mut self) -> io::Result<()> {
         with_std_fd(abi::FD_STDOUT, |fd| fd.flush())
     }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        with_std_fd(abi::FD_STDOUT, |fd| fd.write_vectored(bufs))
+    }
+
+    #[inline]
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
 }
 
 impl Stderr {
@@ -56,6 +78,15 @@ impl io::Write for Stderr {
     fn flush(&mut self) -> io::Result<()> {
         with_std_fd(abi::FD_STDERR, |fd| fd.flush())
     }
+
+    fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
+        with_std_fd(abi::FD_STDERR, |fd| fd.write_vectored(bufs))
+    }
+
+    #[inline]
+    fn is_write_vectored(&self) -> bool {
+        true
+    }
 }
 
 pub const STDIN_BUF_SIZE: usize = crate::sys::io::DEFAULT_BUF_SIZE;