Update ned_fd.

Author: reitermarkus

library/std/src/sys/unix/net.rs

@@ -17,7 +17,7 @@ pub mod netc {
     #[cfg(target_os = "freertos")]
     extern "C" {
         #[link_name = "lwip_fcntl"]
-        pub fn fcntl(s: c_int, cmd: c_int, val: c_int) -> c_int;
+        pub fn fcntl(s: c_int, cmd: c_int, ...) -> c_int;
         #[link_name = "lwip_close"]
         pub fn close(s: c_int) -> ssize_t;
         #[link_name = "lwip_read"]

library/std/src/sys/unix/net_fd.rs

@@ -3,37 +3,72 @@
 use crate::cmp;
 use crate::io::{self, Initializer, IoSlice, IoSliceMut, Read};
 use crate::mem;
-use crate::sync::atomic::{AtomicBool, Ordering};
 use crate::sys::{
     cvt,
-    net::netc::{self, c_int, c_void, ssize_t},
+    net::netc::{self, c_int, c_void},
 };
 use crate::sys_common::AsInner;
 
 #[derive(Debug)]
+#[rustc_layout_scalar_valid_range_start(0)]
+// libstd/os/raw/mod.rs assures me that every libstd-supported platform has a
+// 32-bit c_int. Below is -2, in two's complement, but that only works out
+// because c_int is 32 bits.
+#[rustc_layout_scalar_valid_range_end(0xFF_FF_FF_FE)]
 pub struct NetFileDesc {
     fd: c_int,
 }
 
-fn max_len() -> usize {
-    // The maximum read limit on most posix-like systems is `SSIZE_MAX`,
-    // with the man page quoting that if the count of bytes to read is
-    // greater than `SSIZE_MAX` the result is "unspecified".
-    //
-    // On macOS, however, apparently the 64-bit libc is either buggy or
-    // intentionally showing odd behavior by rejecting any read with a size
-    // larger than or equal to INT_MAX. To handle both of these the read
-    // size is capped on both platforms.
-    if cfg!(target_os = "macos") {
-        <c_int>::max_value() as usize - 1
-    } else {
-        <ssize_t>::max_value() as usize
-    }
+// The maximum read limit on most POSIX-like systems is `SSIZE_MAX`,
+// with the man page quoting that if the count of bytes to read is
+// greater than `SSIZE_MAX` the result is "unspecified".
+//
+// On macOS, however, apparently the 64-bit libc is either buggy or
+// intentionally showing odd behavior by rejecting any read with a size
+// larger than or equal to INT_MAX. To handle both of these the read
+// size is capped on both platforms.
+#[cfg(target_os = "macos")]
+const READ_LIMIT: usize = c_int::MAX as usize - 1;
+#[cfg(not(target_os = "macos"))]
+const READ_LIMIT: usize = netc::ssize_t::MAX as usize;
+
+#[cfg(any(
+    target_os = "dragonfly",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+))]
+const fn max_iov() -> usize {
+    netc::IOV_MAX as usize
+}
+
+#[cfg(any(target_os = "android", target_os = "emscripten", target_os = "linux"))]
+const fn max_iov() -> usize {
+    netc::UIO_MAXIOV as usize
+}
+
+#[cfg(not(any(
+    target_os = "android",
+    target_os = "dragonfly",
+    target_os = "emscripten",
+    target_os = "freebsd",
+    target_os = "ios",
+    target_os = "linux",
+    target_os = "macos",
+    target_os = "netbsd",
+    target_os = "openbsd",
+)))]
+const fn max_iov() -> usize {
+    16 // The minimum value required by POSIX.
 }
 
 impl NetFileDesc {
     pub fn new(fd: c_int) -> NetFileDesc {
-        NetFileDesc { fd }
+        assert_ne!(fd, -1i32);
+        // SAFETY: we just asserted that the value is in the valid range and isn't `-1` (the only value bigger than `0xFF_FF_FF_FE` unsigned)
+        unsafe { NetFileDesc { fd } }
     }
 
     pub fn raw(&self) -> c_int {
@@ -49,7 +84,7 @@ impl NetFileDesc {
 
     pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
         let ret = cvt(unsafe {
-            netc::read(self.fd, buf.as_mut_ptr() as *mut c_void, cmp::min(buf.len(), max_len()))
+            netc::read(self.fd, buf.as_mut_ptr() as *mut c_void, cmp::min(buf.len(), READ_LIMIT))
         })?;
         Ok(ret as usize)
     }
@@ -59,7 +94,7 @@ impl NetFileDesc {
             netc::readv(
                 self.fd,
                 bufs.as_ptr() as *const netc::iovec,
-                cmp::min(bufs.len(), c_int::max_value() as usize) as c_int,
+                cmp::min(bufs.len(), max_iov()) as c_int,
             )
         })?;
         Ok(ret as usize)
@@ -75,9 +110,38 @@ impl NetFileDesc {
         (&mut me).read_to_end(buf)
     }
 
+    pub fn read_at(&self, buf: &mut [u8], offset: u64) -> io::Result<usize> {
+        #[cfg(target_os = "android")]
+        use super::android::cvt_pread64;
+
+        #[cfg(not(target_os = "android"))]
+        unsafe fn cvt_pread64(
+            fd: c_int,
+            buf: *mut c_void,
+            count: usize,
+            offset: i64,
+        ) -> io::Result<isize> {
+            #[cfg(not(target_os = "linux"))]
+            use netc::pread as pread64;
+            #[cfg(target_os = "linux")]
+            use netc::pread64;
+            cvt(pread64(fd, buf, count, offset))
+        }
+
+        unsafe {
+            cvt_pread64(
+                self.fd,
+                buf.as_mut_ptr() as *mut c_void,
+                cmp::min(buf.len(), READ_LIMIT),
+                offset as i64,
+            )
+            .map(|n| n as usize)
+        }
+    }
+
     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
         let ret = cvt(unsafe {
-            netc::write(self.fd, buf.as_ptr() as *const c_void, cmp::min(buf.len(), max_len()))
+            netc::write(self.fd, buf.as_ptr() as *const c_void, cmp::min(buf.len(), READ_LIMIT))
         })?;
         Ok(ret as usize)
     }
@@ -87,7 +151,7 @@ impl NetFileDesc {
             netc::writev(
                 self.fd,
                 bufs.as_ptr() as *const netc::iovec,
-                cmp::min(bufs.len(), c_int::max_value() as usize) as c_int,
+                cmp::min(bufs.len(), max_iov()) as c_int,
             )
         })?;
         Ok(ret as usize)
@@ -98,10 +162,45 @@ impl NetFileDesc {
         true
     }
 
+    pub fn write_at(&self, buf: &[u8], offset: u64) -> io::Result<usize> {
+        #[cfg(target_os = "android")]
+        use super::android::cvt_pwrite64;
+
+        #[cfg(not(target_os = "android"))]
+        unsafe fn cvt_pwrite64(
+            fd: c_int,
+            buf: *const c_void,
+            count: usize,
+            offset: i64,
+        ) -> io::Result<isize> {
+            #[cfg(not(target_os = "linux"))]
+            use netc::pwrite as pwrite64;
+            #[cfg(target_os = "linux")]
+            use netc::pwrite64;
+            cvt(pwrite64(fd, buf, count, offset))
+        }
+
+        unsafe {
+            cvt_pwrite64(
+                self.fd,
+                buf.as_ptr() as *const c_void,
+                cmp::min(buf.len(), READ_LIMIT),
+                offset as i64,
+            )
+            .map(|n| n as usize)
+        }
+    }
+
     #[cfg(target_os = "linux")]
     pub fn get_cloexec(&self) -> io::Result<bool> {
         unsafe { Ok((cvt(netc::fcntl(self.fd, netc::F_GETFD))? & netc::FD_CLOEXEC) != 0) }
     }
+    // Setting `FD_CLOEXEC` is not supported on FreeRTOS
+    // since there is no `exec` functionality.
+    #[cfg(target_os = "freertos")]
+    pub fn set_cloexec(&self) -> io::Result<()> {
+        Ok(())
+    }
 
     #[cfg(not(any(
         target_env = "newlib",
@@ -112,27 +211,26 @@ impl NetFileDesc {
         target_os = "l4re",
         target_os = "linux",
         target_os = "haiku",
-        target_os = "redox"
+        target_os = "redox",
+        target_os = "vxworks"
     )))]
     pub fn set_cloexec(&self) -> io::Result<()> {
         unsafe {
             cvt(netc::ioctl(self.fd, netc::FIOCLEX))?;
             Ok(())
         }
     }
-    #[cfg(all(
-        any(
-            target_env = "newlib",
-            target_os = "solaris",
-            target_os = "illumos",
-            target_os = "emscripten",
-            target_os = "fuchsia",
-            target_os = "l4re",
-            target_os = "linux",
-            target_os = "haiku",
-            target_os = "redox"
-        ),
-        not(target_os = "freertos")
+    #[cfg(any(
+        all(target_env = "newlib", not(target_os = "freertos")),
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "emscripten",
+        target_os = "fuchsia",
+        target_os = "l4re",
+        target_os = "linux",
+        target_os = "haiku",
+        target_os = "redox",
+        target_os = "vxworks"
     ))]
     pub fn set_cloexec(&self) -> io::Result<()> {
         unsafe {
@@ -145,60 +243,37 @@ impl NetFileDesc {
         }
     }
 
-    // Setting `FD_CLOEXEC` is not supported on FreeRTOS
-    // since there is no `exec` functionality.
-    #[cfg(target_os = "freertos")]
-    pub fn set_cloexec(&self) -> io::Result<()> {
-        Ok(())
+    #[cfg(target_os = "linux")]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        unsafe {
+            let v = nonblocking as c_int;
+            cvt(netc::ioctl(self.fd, netc::FIONBIO, &v))?;
+            Ok(())
+        }
+    }
+
+    #[cfg(not(target_os = "linux"))]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        unsafe {
+            let previous = cvt(netc::fcntl(self.fd, netc::F_GETFL))?;
+            let new = if nonblocking {
+                previous | netc::O_NONBLOCK
+            } else {
+                previous & !netc::O_NONBLOCK
+            };
+            if new != previous {
+                cvt(netc::fcntl(self.fd, netc::F_SETFL, new))?;
+            }
+            Ok(())
+        }
     }
 
     pub fn duplicate(&self) -> io::Result<NetFileDesc> {
         // We want to atomically duplicate this file descriptor and set the
         // CLOEXEC flag, and currently that's done via F_DUPFD_CLOEXEC. This
-        // flag, however, isn't supported on older Linux kernels (earlier than
-        // 2.6.24).
-        //
-        // To detect this and ensure that CLOEXEC is still set, we
-        // follow a strategy similar to musl [1] where if passing
-        // F_DUPFD_CLOEXEC causes `fcntl` to return EINVAL it means it's not
-        // supported (the third parameter, 0, is always valid), so we stop
-        // trying that.
-        //
-        // Also note that Android doesn't have F_DUPFD_CLOEXEC, but get it to
-        // resolve so we at least compile this.
-        //
-        // [1]: http://comments.gmane.org/gmane.linux.lib.musl.general/2963
-        #[cfg(any(target_os = "android", target_os = "haiku"))]
-        use netc::F_DUPFD as F_DUPFD_CLOEXEC;
-        #[cfg(not(any(target_os = "android", target_os = "haiku")))]
-        use netc::F_DUPFD_CLOEXEC;
-
-        let make_filedesc = |fd| {
-            let fd = NetFileDesc::new(fd);
-            fd.set_cloexec()?;
-            Ok(fd)
-        };
-        static TRY_CLOEXEC: AtomicBool = AtomicBool::new(!cfg!(target_os = "android"));
-        let fd = self.raw();
-        if TRY_CLOEXEC.load(Ordering::Relaxed) {
-            match cvt(unsafe { netc::fcntl(fd, F_DUPFD_CLOEXEC, 0) }) {
-                // We *still* call the `set_cloexec` method as apparently some
-                // linux kernel at some point stopped setting CLOEXEC even
-                // though it reported doing so on F_DUPFD_CLOEXEC.
-                Ok(fd) => {
-                    return Ok(if cfg!(target_os = "linux") {
-                        make_filedesc(fd)?
-                    } else {
-                        NetFileDesc::new(fd)
-                    });
-                }
-                Err(ref e) if e.raw_os_error() == Some(netc::EINVAL) => {
-                    TRY_CLOEXEC.store(false, Ordering::Relaxed);
-                }
-                Err(e) => return Err(e),
-            }
-        }
-        cvt(unsafe { netc::fcntl(fd, netc::F_DUPFD, 0) }).and_then(make_filedesc)
+        // is a POSIX flag that was added to Linux in 2.6.24.
+        let fd = cvt(unsafe { netc::fcntl(self.raw(), netc::F_DUPFD_CLOEXEC, 0) })?;
+        Ok(NetFileDesc::new(fd))
     }
 }