Merge #901

901: Implement sendfile on FreeBSD and Darwin r=Susurrus a=morrowa

This PR exposes the `sendfile` system call on libc's supported BSD-likes:
* FreeBSD
* Darwin (macOS/iOS)

DragonFly could be supported in the future, but I was unable to build rustc to test.

Note that NetBSD has no equivalent system call.

Co-authored-by: Andrew Morrow <andrew.d.morrow@gmail.com>

CHANGELOG.md

@@ -6,6 +6,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased]
 
 ### Added
+- Added `sendfile` on FreeBSD and Darwin.
+  ([#901](https://github.com/nix-rust/nix/pull/901))
 - Added `pselect`
   ([#894](https://github.com/nix-rust/nix/pull/894))
 - Exposed `preadv` and `pwritev` on the BSDs.

src/sys/mod.rs

@@ -49,8 +49,11 @@ pub mod reboot;
 
 pub mod select;
 
-// TODO: Add support for dragonfly, freebsd, and ios/macos.
-#[cfg(any(target_os = "android", target_os = "linux"))]
+#[cfg(any(target_os = "android",
+          target_os = "freebsd",
+          target_os = "ios",
+          target_os = "linux",
+          target_os = "macos"))]
 pub mod sendfile;
 
 pub mod signal;

src/sys/sendfile.rs

@@ -6,8 +6,195 @@ use libc::{self, off_t};
 use Result;
 use errno::Errno;
 
-pub fn sendfile(out_fd: RawFd, in_fd: RawFd, offset: Option<&mut off_t>, count: usize) -> Result<usize> {
-    let offset = offset.map(|offset| offset as *mut _).unwrap_or(ptr::null_mut());
+/// Copy up to `count` bytes to `out_fd` from `in_fd` starting at `offset`.
+///
+/// Returns a `Result` with the number of bytes written.
+///
+/// If `offset` is `None`, `sendfile` will begin reading at the current offset of `in_fd`and will
+/// update the offset of `in_fd`. If `offset` is `Some`, `sendfile` will begin at the specified
+/// offset and will not update the offset of `in_fd`. Instead, it will mutate `offset` to point to
+/// the byte after the last byte copied.
+///
+/// `in_fd` must support `mmap`-like operations and therefore cannot be a socket.
+///
+/// For more information, see [the sendfile(2) man page.](http://man7.org/linux/man-pages/man2/sendfile.2.html)
+#[cfg(any(target_os = "android", target_os = "linux"))]
+pub fn sendfile(
+    out_fd: RawFd,
+    in_fd: RawFd,
+    offset: Option<&mut off_t>,
+    count: usize,
+) -> Result<usize> {
+    let offset = offset
+        .map(|offset| offset as *mut _)
+        .unwrap_or(ptr::null_mut());
     let ret = unsafe { libc::sendfile(out_fd, in_fd, offset, count) };
     Errno::result(ret).map(|r| r as usize)
 }
+
+cfg_if! {
+    if #[cfg(any(target_os = "freebsd",
+                 target_os = "ios",
+                 target_os = "macos"))] {
+        use sys::uio::IoVec;
+
+        #[allow(missing_debug_implementations)]
+        struct SendfileHeaderTrailer<'a>(
+            libc::sf_hdtr,
+            Option<Vec<IoVec<&'a [u8]>>>,
+            Option<Vec<IoVec<&'a [u8]>>>,
+        );
+
+        impl<'a> SendfileHeaderTrailer<'a> {
+            fn new(
+                headers: Option<&'a [&'a [u8]]>,
+                trailers: Option<&'a [&'a [u8]]>
+            ) -> SendfileHeaderTrailer<'a> {
+                let header_iovecs: Option<Vec<IoVec<&[u8]>>> =
+                    headers.map(|s| s.iter().map(|b| IoVec::from_slice(b)).collect());
+                let trailer_iovecs: Option<Vec<IoVec<&[u8]>>> =
+                    trailers.map(|s| s.iter().map(|b| IoVec::from_slice(b)).collect());
+                SendfileHeaderTrailer(
+                    libc::sf_hdtr {
+                        headers: {
+                            header_iovecs
+                                .as_ref()
+                                .map_or(ptr::null(), |v| v.as_ptr()) as *mut libc::iovec
+                        },
+                        hdr_cnt: header_iovecs.as_ref().map(|v| v.len()).unwrap_or(0) as i32,
+                        trailers: {
+                            trailer_iovecs
+                                .as_ref()
+                                .map_or(ptr::null(), |v| v.as_ptr()) as *mut libc::iovec
+                        },
+                        trl_cnt: trailer_iovecs.as_ref().map(|v| v.len()).unwrap_or(0) as i32
+                    },
+                    header_iovecs,
+                    trailer_iovecs,
+                )
+            }
+        }
+    }
+}
+
+cfg_if! {
+    if #[cfg(target_os = "freebsd")] {
+        use libc::c_int;
+
+        libc_bitflags!{
+            /// Configuration options for [`sendfile`.](fn.sendfile.html)
+            pub struct SfFlags: c_int {
+                /// Causes `sendfile` to return EBUSY instead of blocking when attempting to read a
+                /// busy page.
+                SF_NODISKIO;
+                /// Causes `sendfile` to sleep until the network stack releases its reference to the
+                /// VM pages read. When `sendfile` returns, the data is not guaranteed to have been
+                /// sent, but it is safe to modify the file.
+                SF_SYNC;
+                /// Causes `sendfile` to cache exactly the number of pages specified in the
+                /// `readahead` parameter, disabling caching heuristics.
+                SF_USER_READAHEAD;
+                /// Causes `sendfile` not to cache the data read.
+                SF_NOCACHE;
+            }
+        }
+
+        /// Read up to `count` bytes from `in_fd` starting at `offset` and write to `out_sock`.
+        ///
+        /// Returns a `Result` and a count of bytes written. Bytes written may be non-zero even if
+        /// an error occurs.
+        ///
+        /// `in_fd` must describe a regular file or shared memory object. `out_sock` must describe a
+        /// stream socket.
+        ///
+        /// If `offset` falls past the end of the file, the function returns success and zero bytes
+        /// written.
+        ///
+        /// If `count` is `None` or 0, bytes will be read from `in_fd` until reaching the end of
+        /// file (EOF).
+        ///
+        /// `headers` and `trailers` specify optional slices of byte slices to be sent before and
+        /// after the data read from `in_fd`, respectively. The length of headers and trailers sent
+        /// is included in the returned count of bytes written. The values of `offset` and `count`
+        /// do not apply to headers or trailers.
+        ///
+        /// `readahead` specifies the minimum number of pages to cache in memory ahead of the page
+        /// currently being sent.
+        ///
+        /// For more information, see
+        /// [the sendfile(2) man page.](https://www.freebsd.org/cgi/man.cgi?query=sendfile&sektion=2)
+        pub fn sendfile(
+            in_fd: RawFd,
+            out_sock: RawFd,
+            offset: off_t,
+            count: Option<usize>,
+            headers: Option<&[&[u8]]>,
+            trailers: Option<&[&[u8]]>,
+            flags: SfFlags,
+            readahead: u16
+        ) -> (Result<()>, off_t) {
+            // Readahead goes in upper 16 bits
+            // Flags goes in lower 16 bits
+            // see `man 2 sendfile`
+            let flags: u32 = ((readahead as u32) << 16) | (flags.bits() as u32);
+            let mut bytes_sent: off_t = 0;
+            let hdtr = headers.or(trailers).map(|_| SendfileHeaderTrailer::new(headers, trailers));
+            let hdtr_ptr = hdtr.as_ref().map_or(ptr::null(), |s| &s.0 as *const libc::sf_hdtr);
+            let return_code = unsafe {
+                libc::sendfile(in_fd,
+                               out_sock,
+                               offset,
+                               count.unwrap_or(0),
+                               hdtr_ptr as *mut libc::sf_hdtr,
+                               &mut bytes_sent as *mut off_t,
+                               flags as c_int)
+            };
+            (Errno::result(return_code).and(Ok(())), bytes_sent)
+        }
+    } else if #[cfg(any(target_os = "ios", target_os = "macos"))] {
+        /// Read bytes from `in_fd` starting at `offset` and write up to `count` bytes to
+        /// `out_sock`.
+        ///
+        /// Returns a `Result` and a count of bytes written. Bytes written may be non-zero even if
+        /// an error occurs.
+        ///
+        /// `in_fd` must describe a regular file. `out_sock` must describe a stream socket.
+        ///
+        /// If `offset` falls past the end of the file, the function returns success and zero bytes
+        /// written.
+        ///
+        /// If `count` is `None` or 0, bytes will be read from `in_fd` until reaching the end of
+        /// file (EOF).
+        ///
+        /// `hdtr` specifies an optional list of headers and trailers to be sent before and after
+        /// the data read from `in_fd`, respectively. The length of headers and trailers sent is
+        /// included in the returned count of bytes written. If any headers are specified and
+        /// `count` is non-zero, the length of the headers will be counted in the limit of total
+        /// bytes sent. Trailers do not count toward the limit of bytes sent and will always be sent
+        /// regardless. The value of `offset` does not affect headers or trailers.
+        ///
+        /// For more information, see
+        /// [the sendfile(2) man page.](https://developer.apple.com/legacy/library/documentation/Darwin/Reference/ManPages/man2/sendfile.2.html)
+        pub fn sendfile(
+            in_fd: RawFd,
+            out_sock: RawFd,
+            offset: off_t,
+            count: Option<off_t>,
+            headers: Option<&[&[u8]]>,
+            trailers: Option<&[&[u8]]>
+        ) -> (Result<()>, off_t) {
+            let mut len = count.unwrap_or(0);
+            let hdtr = headers.or(trailers).map(|_| SendfileHeaderTrailer::new(headers, trailers));
+            let hdtr_ptr = hdtr.as_ref().map_or(ptr::null(), |s| &s.0 as *const libc::sf_hdtr);
+            let return_code = unsafe {
+                libc::sendfile(in_fd,
+                               out_sock,
+                               offset,
+                               &mut len as *mut off_t,
+                               hdtr_ptr as *mut libc::sf_hdtr,
+                               0)
+            };
+            (Errno::result(return_code).and(Ok(())), len)
+        }
+    }
+}

test/test.rs

@@ -22,7 +22,11 @@ mod test_net;
 mod test_nix_path;
 mod test_poll;
 mod test_pty;
-#[cfg(any(target_os = "linux", target_os = "android"))]
+#[cfg(any(target_os = "android",
+          target_os = "freebsd",
+          target_os = "ios",
+          target_os = "linux",
+          target_os = "macos"))]
 mod test_sendfile;
 mod test_stat;
 mod test_unistd;

test/test_sendfile.rs

@@ -1,15 +1,22 @@
 use std::io::prelude::*;
 use std::os::unix::prelude::*;
 
-use tempfile::tempfile;
-
 use libc::off_t;
+use nix::sys::sendfile::*;
+use tempfile::tempfile;
 
-use nix::unistd::{close, pipe, read};
-use nix::sys::sendfile::sendfile;
+cfg_if! {
+    if #[cfg(any(target_os = "android", target_os = "linux"))] {
+        use nix::unistd::{close, pipe, read};
+    } else if #[cfg(any(target_os = "freebsd", target_os = "ios", target_os = "macos"))] {
+        use std::net::Shutdown;
+        use std::os::unix::net::UnixStream;
+    }
+}
 
+#[cfg(any(target_os = "android", target_os = "linux"))]
 #[test]
-fn test_sendfile() {
+fn test_sendfile_linux() {
     const CONTENTS: &[u8] = b"abcdef123456";
     let mut tmp = tempfile().unwrap();
     tmp.write_all(CONTENTS).unwrap();
@@ -28,3 +35,95 @@ fn test_sendfile() {
     close(rd).unwrap();
     close(wr).unwrap();
 }
+
+#[cfg(target_os = "freebsd")]
+#[test]
+fn test_sendfile_freebsd() {
+    // Declare the content
+    let header_strings = vec!["HTTP/1.1 200 OK\n", "Content-Type: text/plain\n", "\n"];
+    let body = "Xabcdef123456";
+    let body_offset = 1;
+    let trailer_strings = vec!["\n", "Served by Make Believe\n"];
+
+    // Write the body to a file
+    let mut tmp = tempfile().unwrap();
+    tmp.write_all(body.as_bytes()).unwrap();
+
+    // Prepare headers and trailers for sendfile
+    let headers: Vec<&[u8]> = header_strings.iter().map(|s| s.as_bytes()).collect();
+    let trailers: Vec<&[u8]> = trailer_strings.iter().map(|s| s.as_bytes()).collect();
+
+    // Prepare socket pair
+    let (mut rd, wr) = UnixStream::pair().unwrap();
+
+    // Call the test method
+    let (res, bytes_written) = sendfile(
+        tmp.as_raw_fd(),
+        wr.as_raw_fd(),
+        body_offset as off_t,
+        None,
+        Some(headers.as_slice()),
+        Some(trailers.as_slice()),
+        SfFlags::empty(),
+        0,
+    );
+    assert!(res.is_ok());
+    wr.shutdown(Shutdown::Both).unwrap();
+
+    // Prepare the expected result
+    let expected_string =
+        header_strings.concat() + &body[body_offset..] + &trailer_strings.concat();
+
+    // Verify the message that was sent
+    assert_eq!(bytes_written as usize, expected_string.as_bytes().len());
+
+    let mut read_string = String::new();
+    let bytes_read = rd.read_to_string(&mut read_string).unwrap();
+    assert_eq!(bytes_written as usize, bytes_read);
+    assert_eq!(expected_string, read_string);
+}
+
+#[cfg(any(target_os = "ios", target_os = "macos"))]
+#[test]
+fn test_sendfile_darwin() {
+    // Declare the content
+    let header_strings = vec!["HTTP/1.1 200 OK\n", "Content-Type: text/plain\n", "\n"];
+    let body = "Xabcdef123456";
+    let body_offset = 1;
+    let trailer_strings = vec!["\n", "Served by Make Believe\n"];
+
+    // Write the body to a file
+    let mut tmp = tempfile().unwrap();
+    tmp.write_all(body.as_bytes()).unwrap();
+
+    // Prepare headers and trailers for sendfile
+    let headers: Vec<&[u8]> = header_strings.iter().map(|s| s.as_bytes()).collect();
+    let trailers: Vec<&[u8]> = trailer_strings.iter().map(|s| s.as_bytes()).collect();
+
+    // Prepare socket pair
+    let (mut rd, wr) = UnixStream::pair().unwrap();
+
+    // Call the test method
+    let (res, bytes_written) = sendfile(
+        tmp.as_raw_fd(),
+        wr.as_raw_fd(),
+        body_offset as off_t,
+        None,
+        Some(headers.as_slice()),
+        Some(trailers.as_slice()),
+    );
+    assert!(res.is_ok());
+    wr.shutdown(Shutdown::Both).unwrap();
+
+    // Prepare the expected result
+    let expected_string =
+        header_strings.concat() + &body[body_offset..] + &trailer_strings.concat();
+
+    // Verify the message that was sent
+    assert_eq!(bytes_written as usize, expected_string.as_bytes().len());
+
+    let mut read_string = String::new();
+    let bytes_read = rd.read_to_string(&mut read_string).unwrap();
+    assert_eq!(bytes_written as usize, bytes_read);
+    assert_eq!(expected_string, read_string);
+}