From b3b5716dbbb28405d33479dd5f27398d6c4b41b1 Mon Sep 17 00:00:00 2001
From: Mark McCaskey <mark@wasmer.io>
Date: Fri, 17 May 2019 13:31:41 -0700
Subject: [PATCH] add files in runtime_Core

---
 lib/runtime-core/src/file_descriptor.rs | 25 ++++++++
 lib/runtime-core/src/stdio.rs           | 85 +++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 lib/runtime-core/src/file_descriptor.rs
 create mode 100644 lib/runtime-core/src/stdio.rs

diff --git a/lib/runtime-core/src/file_descriptor.rs b/lib/runtime-core/src/file_descriptor.rs
new file mode 100644
index 000000000..6e6053cdc
--- /dev/null
+++ b/lib/runtime-core/src/file_descriptor.rs
@@ -0,0 +1,25 @@
+use std::io;
+use std::io::Error;
+use std::io::ErrorKind;
+use std::io::Read;
+
+pub struct FileDescriptor(libc::c_int);
+
+impl FileDescriptor {
+    pub fn new(file_descriptor_number: libc::c_int) -> FileDescriptor {
+        FileDescriptor(file_descriptor_number)
+    }
+}
+
+impl Read for FileDescriptor {
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        let file_descriptor: libc::c_int = self.0;
+        let count =
+            unsafe { libc::read(file_descriptor, buf.as_mut_ptr() as *mut libc::c_void, 1) };
+        if count < 0 {
+            Err(Error::new(ErrorKind::Other, "read error"))
+        } else {
+            Ok(count as usize)
+        }
+    }
+}
diff --git a/lib/runtime-core/src/stdio.rs b/lib/runtime-core/src/stdio.rs
new file mode 100644
index 000000000..2b95bafc7
--- /dev/null
+++ b/lib/runtime-core/src/stdio.rs
@@ -0,0 +1,85 @@
+use super::file_descriptor::FileDescriptor;
+use libc;
+use std::io::BufReader;
+use std::io::Read;
+
+// A struct to hold the references to the base stdout and the captured one
+pub struct StdioCapturer {
+    stdout_backup: libc::c_int,
+    stderr_backup: libc::c_int,
+    stdout_reader: libc::c_int,
+    stderr_reader: libc::c_int,
+}
+
+#[cfg(not(target_os = "windows"))]
+use libc::{STDERR_FILENO, STDOUT_FILENO};
+
+#[cfg(target_os = "windows")]
+const _STDIN_FILENO: libc::c_int = 0;
+#[cfg(target_os = "windows")]
+const STDOUT_FILENO: libc::c_int = 1;
+#[cfg(target_os = "windows")]
+const STDERR_FILENO: libc::c_int = 2;
+
+// Implementation inspired in
+// https://github.com/rust-lang/rust/blob/7d52cbce6db83e4fc2d8706b4e4b9c7da76cbcf8/src/test/run-pass/issues/issue-30490.rs
+// Currently only works in Unix systems (Mac, Linux)
+impl StdioCapturer {
+    fn pipe() -> (libc::c_int, libc::c_int) {
+        let mut fds = [0; 2];
+
+        #[cfg(not(target_os = "windows"))]
+        assert_eq!(unsafe { libc::pipe(fds.as_mut_ptr()) }, 0);
+        #[cfg(target_os = "windows")]
+        assert_eq!(
+            unsafe { libc::pipe(fds.as_mut_ptr(), 1000, libc::O_TEXT) },
+            0
+        );
+
+        (fds[0], fds[1])
+    }
+
+    pub fn new() -> Self {
+        let stdout_backup = unsafe { libc::dup(STDOUT_FILENO) };
+        let stderr_backup = unsafe { libc::dup(STDERR_FILENO) };
+
+        let (stdout_reader, stdout_writer) = Self::pipe();
+        let (stderr_reader, stderr_writer) = Self::pipe();
+
+        assert!(unsafe { libc::dup2(stdout_writer, STDOUT_FILENO) } > -1);
+        assert!(unsafe { libc::dup2(stderr_writer, STDERR_FILENO) } > -1);
+
+        // Make sure we close any duplicates of the writer end of the pipe,
+        // otherwise we can get stuck reading from the pipe which has open
+        // writers but no one supplying any input
+        assert_eq!(unsafe { libc::close(stdout_writer) }, 0);
+        assert_eq!(unsafe { libc::close(stderr_writer) }, 0);
+
+        StdioCapturer {
+            stdout_backup,
+            stderr_backup,
+            stdout_reader,
+            stderr_reader,
+        }
+    }
+
+    pub fn end(self) -> Result<(String, String), std::io::Error> {
+        // The Stdio passed into the Command took over (and closed) std{out, err}
+        // so we should restore them as they were.
+
+        assert!(unsafe { libc::dup2(self.stdout_backup, STDOUT_FILENO) } > -1);
+        assert!(unsafe { libc::dup2(self.stderr_backup, STDERR_FILENO) } > -1);
+
+        let fd = FileDescriptor::new(self.stdout_reader);
+        let mut reader = BufReader::new(fd);
+        let mut stdout_read = "".to_string();
+        let _ = reader.read_to_string(&mut stdout_read)?;
+
+        let fd = FileDescriptor::new(self.stderr_reader);
+        let mut reader = BufReader::new(fd);
+        let mut stderr_read = "".to_string();
+        let _ = reader.read_to_string(&mut stderr_read)?;
+
+        Ok((stdout_read, stderr_read))
+    }
+}