bring back close() error checking

Summary:
In stack ending at D66275420, several call sites were migrated from
RawFd with explicit `libc::close()` or `nix::unistd::close()` which
admit the possibility of failure. Now, `close()` failures are
unactionable -- you certainly cannot retry the close operation or risk
closing some other FD -- but it may be worth logging when they happen.

Bring back explicit close operations and error checking.

Reviewed By: jasonwhite

Differential Revision: D67157487

fbshipit-source-id: 254cace779c6f993117fbaaf6e0453df6bdc70e5

detcore/tests/lit/child_should_inherit_fds/main.rs

@@ -12,6 +12,7 @@
 
 use std::os::fd::AsRawFd;
 
+use close_err::Closable;
 use nix::sys::wait::waitpid;
 use nix::sys::wait::WaitStatus;
 use nix::unistd::fork;
@@ -25,7 +26,7 @@ fn main() {
     let msg: [u8; 8] = [0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7, 0x8];
     match unsafe { fork().unwrap() } {
         ForkResult::Parent { child, .. } => {
-            drop(fdwrite);
+            fdwrite.close().expect("close failed");
             let mut buf: [u8; 8] = [0; 8];
             // XXX: The following SYS_read would timeout due to detcore issue.
             // add a 5 seconds timeout to abort.
@@ -36,7 +37,7 @@ fn main() {
             unsafe { libc::syscall(libc::SYS_exit_group, 0) };
         }
         ForkResult::Child => {
-            drop(fdread);
+            fdread.close().expect("close failed");
             assert_eq!(write(&fdwrite, &msg), Ok(8));
             unsafe { libc::syscall(libc::SYS_exit_group, 0) };
         }

detcore/tests/lit/close_on_exec/main.rs

@@ -16,6 +16,7 @@
 use std::os::fd::AsRawFd;
 use std::ptr;
 
+use close_err::Closable;
 use nix::errno::Errno;
 use nix::fcntl::OFlag;
 use nix::sys::stat::fstat;
@@ -46,7 +47,7 @@ fn main() {
 
     match unsafe { fork().unwrap() } {
         ForkResult::Parent { child, .. } => {
-            drop(fdwrite);
+            fdwrite.close().expect("close failed");
 
             let mut msg = [0u8; 4];
 
@@ -59,7 +60,7 @@ fn main() {
             assert_eq!(waitpid(child, None), Ok(WaitStatus::Exited(child, 0)));
         }
         ForkResult::Child => {
-            drop(fdread);
+            fdread.close().expect("close failed");
 
             let proc_self = "/proc/self/exe\0".as_ptr() as *const libc::c_char;
 

detcore/tests/lit/dup2_existing_fd/main.rs

@@ -9,6 +9,7 @@
 // RUN: %me
 use std::os::fd::AsRawFd;
 
+use close_err::Closable;
 use nix::sys::wait::waitpid;
 use nix::sys::wait::WaitStatus;
 use nix::unistd::alarm;
@@ -26,7 +27,7 @@ fn main() {
 
     match unsafe { fork().unwrap() } {
         ForkResult::Parent { child, .. } => {
-            drop(fdwrite);
+            fdwrite.close().expect("close failed");
             let mut buf = [0u8; 8];
 
             // If the file descriptor newfd was previously open,
@@ -45,7 +46,7 @@ fn main() {
             assert_eq!(waitpid(child, None), Ok(WaitStatus::Exited(child, 0)));
         }
         ForkResult::Child => {
-            drop(fdread);
+            fdread.close().expect("close failed");
             assert_eq!(write(fdwrite, &msg), Ok(msg.len()));
         }
     }

detcore/tests/lit/no_close_on_exec/main.rs

@@ -17,6 +17,7 @@ use std::os::fd::AsRawFd;
 use std::os::fd::BorrowedFd;
 use std::ptr;
 
+use close_err::Closable;
 use nix::fcntl::OFlag;
 use nix::sys::wait::waitpid;
 use nix::sys::wait::WaitStatus;
@@ -49,7 +50,7 @@ fn main() {
 
     match unsafe { fork().unwrap() } {
         ForkResult::Parent { child, .. } => {
-            drop(fdwrite);
+            fdwrite.close().expect("close failed");
 
             let mut msg = [0u8; 6];
 
@@ -60,7 +61,7 @@ fn main() {
             assert_eq!(waitpid(child, None), Ok(WaitStatus::Exited(child, 0)));
         }
         ForkResult::Child => {
-            drop(fdread);
+            fdread.close().expect("close failed");
 
             let proc_self = "/proc/self/exe\0".as_ptr() as *const libc::c_char;
 

detcore/tests/lit/openat_next_lowest_fd/main.rs

@@ -9,6 +9,7 @@
 // RUN: %me
 use std::os::fd::AsRawFd;
 
+use close_err::Closable;
 use nix::fcntl::openat;
 use nix::fcntl::OFlag;
 use nix::sys::stat::Mode;
@@ -18,7 +19,7 @@ fn main() {
     assert_eq!(fd4.as_raw_fd(), fd3.as_raw_fd() + 1);
 
     let fd3_raw = fd3.as_raw_fd();
-    drop(fd3);
+    fd3.close().expect("close failed");
 
     assert_eq!(
         openat(None, "/dev/null", OFlag::O_RDONLY, Mode::S_IRUSR),

detcore/tests/lit/pipe_creates_valid_fds/main.rs

@@ -9,13 +9,14 @@
 // RUN: %me
 use std::os::fd::AsRawFd;
 
+use close_err::Closable;
 use nix::sys::stat::fstat;
 use nix::unistd::pipe;
 
 fn main() {
     let (fd_read, fd_write) = pipe().unwrap();
     assert!(fstat(fd_read.as_raw_fd()).is_ok());
     assert!(fstat(fd_write.as_raw_fd()).is_ok());
-    drop(fd_write);
-    drop(fd_read);
+    fd_write.close().expect("close failed");
+    fd_read.close().expect("close failed");
 }

tests/Cargo.toml

@@ -161,6 +161,7 @@ name = "standalone_stacktrace_events"
 path = "standalone/stacktrace_events.rs"
 
 [dependencies]
+close-err = "1.0.2"
 detcore = { version = "0.0.0", path = "../detcore" }
 libc = "0.2.139"
 nix = { version = "0.29.0", features = ["dir", "event", "hostname", "inotify", "ioctl", "mman", "mount", "net", "poll", "ptrace", "reboot", "resource", "sched", "term", "time", "user", "zerocopy"] }

tests/helpers.bzl

@@ -212,6 +212,7 @@ def hermit_rust_test(path, raw, run, no_sequentialize_threads, no_deterministic_
         srcs = [path, paths.dirname(path) + "/test_utils/mod.rs"],
         crate_root = path,
         deps = [
+            "fbsource//third-party/rust:close-err",
             "fbsource//third-party/rust:libc",
             "fbsource//third-party/rust:nix",
             "fbsource//third-party/rust:tempfile",

tests/rust/pipe_basics.rs

@@ -9,6 +9,7 @@
 use std::os::fd::AsRawFd;
 use std::str;
 
+use close_err::Closable;
 use nix::unistd;
 
 fn main() {
@@ -19,15 +20,15 @@ fn main() {
             assert_eq!(unistd::read(fdread.as_raw_fd(), &mut buf), Ok(14));
             println!("Child received message: {}", str::from_utf8(&buf).unwrap());
         }
-        drop(fdread);
+        fdread.close().expect("close failed");
     });
 
     for ix in 10..20 {
         println!("Parent writing to pipe..");
         let msg = format!("hello world {}", ix);
         assert_eq!(unistd::write(&fdwrite, msg.as_bytes()), Ok(14));
     }
-    drop(fdwrite);
+    fdwrite.close().expect("close failed");
 
     println!("Joining child..");
     handle.join().unwrap();

tests/rust/poll_spin.rs

@@ -31,6 +31,7 @@ use std::sync::Arc;
 use std::thread;
 use std::time;
 
+use close_err::Closable;
 use nix::poll::poll;
 use nix::poll::PollFd;
 use nix::poll::PollFlags;
@@ -64,6 +65,7 @@ fn main() {
                 break;
             }
         }
+        fdread.close().expect("close failed");
     });
 
     while count2.load(Ordering::SeqCst) == 0 {
@@ -73,7 +75,7 @@ fn main() {
     println!("Parent writing to pipe..");
     let msg = "hello world\n";
     assert_eq!(unistd::write(&fdwrite, msg.as_bytes()), Ok(12));
-    drop(fdwrite);
+    fdwrite.close().expect("close failed");
 
     println!("Joining child..");
     handle.join().unwrap();