Make TCP connect() handle EINTR correctly

According to the POSIX standard, if connect() is interrupted by a
signal that is caught while blocked waiting to establish a connection,
connect() shall fail and set errno to EINTR, but the connection
request shall not be aborted, and the connection shall be established
asynchronously.

If asynchronous connection was successfully established after EINTR
and before the next connection attempt, OS returns EISCONN that was
handled as an error before. This behavior is fixed now and we handle
it as success.

The problem affects MacOS users: Linux doesn't return EISCONN in this
case, Windows connect() can not be interrupted without an old-fashoin
WSACancelBlockingCall function that is not used in the library.
So current solution gives connect() as OS specific implementation.

5 files changed, 38 insertions, 12 deletions

diff --git a/library/std/src/sys/hermit/net.rs b/library/std/src/sys/hermit/net.rs
index a564f1698ba..bd8b493d65a 100644
--- a/library/std/src/sys/hermit/net.rs
+++ b/library/std/src/sys/hermit/net.rs
@@ -56,6 +56,12 @@ impl Socket {
         unimplemented!()
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        cvt_r(|| unsafe { netc::connect(self.as_raw_fd(), addr.as_ptr(), len) })?;
+        Ok(())
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
         let r = unsafe {
diff --git a/library/std/src/sys/solid/net.rs b/library/std/src/sys/solid/net.rs
index 6adced787f3..1eae0fc0642 100644
--- a/library/std/src/sys/solid/net.rs
+++ b/library/std/src/sys/solid/net.rs
@@ -233,12 +233,15 @@ impl Socket {
         }
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        cvt(unsafe { netc::connect(self.0.raw(), addr.as_ptr(), len) })?;
+        Ok(())
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
-        let r = unsafe {
-            let (addr, len) = addr.into_inner();
-            cvt(netc::connect(self.0.raw(), addr.as_ptr(), len))
-        };
+        let r = self.connect(addr);
         self.set_nonblocking(false)?;
 
         match r {
diff --git a/library/std/src/sys/unix/net.rs b/library/std/src/sys/unix/net.rs
index f450d708dae..5c4d776e18a 100644
--- a/library/std/src/sys/unix/net.rs
+++ b/library/std/src/sys/unix/net.rs
@@ -6,6 +6,7 @@ use crate::net::{Shutdown, SocketAddr};
 use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
 use crate::str;
 use crate::sys::fd::FileDesc;
+use crate::sys::unix::IsMinusOne;
 use crate::sys_common::net::{getsockopt, setsockopt, sockaddr_to_addr};
 use crate::sys_common::{AsInner, FromInner, IntoInner};
 use crate::time::{Duration, Instant};
@@ -140,6 +141,22 @@ impl Socket {
         unimplemented!()
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        loop {
+            let result = unsafe { libc::connect(self.as_raw_fd(), addr.as_ptr(), len) };
+            if result.is_minus_one() {
+                let err = crate::sys::os::errno();
+                match err {
+                    libc::EINTR => continue,
+                    libc::EISCONN => return Ok(()),
+                    _ => return Err(io::Error::from_raw_os_error(err)),
+                }
+            }
+            return Ok(());
+        }
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
         let r = unsafe {
diff --git a/library/std/src/sys/windows/net.rs b/library/std/src/sys/windows/net.rs
index 4b7115f97c5..c29b863665f 100644
--- a/library/std/src/sys/windows/net.rs
+++ b/library/std/src/sys/windows/net.rs
@@ -140,13 +140,15 @@ impl Socket {
         }
     }
 
+    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
+        let (addr, len) = addr.into_inner();
+        let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
+        cvt(result).map(drop)
+    }
+
     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
         self.set_nonblocking(true)?;
-        let result = {
-            let (addr, len) = addr.into_inner();
-            let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
-            cvt(result).map(drop)
-        };
+        let result = self.connect(addr);
         self.set_nonblocking(false)?;
 
         match result {
diff --git a/library/std/src/sys_common/net.rs b/library/std/src/sys_common/net.rs
index 4f5b17deaa2..8712bd2eca7 100644
--- a/library/std/src/sys_common/net.rs
+++ b/library/std/src/sys_common/net.rs
@@ -226,9 +226,7 @@ impl TcpStream {
         init();
 
         let sock = Socket::new(addr, c::SOCK_STREAM)?;
-
-        let (addr, len) = addr.into_inner();
-        cvt_r(|| unsafe { c::connect(sock.as_raw(), addr.as_ptr(), len) })?;
+        sock.connect(addr)?;
         Ok(TcpStream { inner: sock })
     }