Pipe minor changes: diagnostics, flag support and comments

Author: tiif

src/tools/miri/src/shims/unix/foreign_items.rs

@@ -292,6 +292,13 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
  this.write_scalar(result, dest)?;
 }
 "pipe2" => {
+// Currently this function does not exist on all Unixes, e.g. on macOS.
+if !matches!(&*this.tcx.sess.target.os,"linux" | "freebsd" | "solaris" | "illumos"){
+throw_unsup_format!(
+"`pipe2` is not supported on {}",
+ this.tcx.sess.target.os
+);
+}
 let[pipefd, flags] =
  this.check_shim(abi,Abi::C{unwind:false}, link_name, args)?;
 let result = this.pipe2(pipefd,Some(flags))?;

src/tools/miri/src/shims/unix/unnamed_socket.rs

@@ -163,7 +163,7 @@ impl FileDescription for AnonSocket {
 }else{
 // Blocking socketpair with writer and empty buffer.
 // FIXME: blocking is currently not supported
-throw_unsup_format!("socketpair read: blocking isn't supported yet");
+throw_unsup_format!("socketpair/pipe/pipe2 read: blocking isn't supported yet");
 }
 }
 }
@@ -230,7 +230,7 @@ impl FileDescription for AnonSocket {
 return ecx.set_last_error_and_return(ErrorKind::WouldBlock, dest);
 }else{
 // Blocking socketpair with a full buffer.
-throw_unsup_format!("socketpair write: blocking isn't supported yet");
+throw_unsup_format!("socketpair/pipe/pipe2 write: blocking isn't supported yet");
 }
 }
 // Remember this clock so `read` can synchronize with us.
@@ -267,21 +267,24 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 let this = self.eval_context_mut();
 
 let domain = this.read_scalar(domain)?.to_i32()?;
-letmuttype_ = this.read_scalar(type_)?.to_i32()?;
+letmutflags = this.read_scalar(type_)?.to_i32()?;
 let protocol = this.read_scalar(protocol)?.to_i32()?;
 let sv = this.deref_pointer(sv)?;
 
 letmut is_sock_nonblock = false;
 
-// Parse and remove the type flags that we support.
-// SOCK_NONBLOCK only exists on Linux.
+// Interpret the flag. Every flag we recognize is "subtracted" from `flags`, so
+// if there is anything left at the end, that's an unsupported flag.
 if this.tcx.sess.target.os == "linux"{
-if type_ & this.eval_libc_i32("SOCK_NONBLOCK") == this.eval_libc_i32("SOCK_NONBLOCK"){
+// SOCK_NONBLOCK only exists on Linux.
+let sock_nonblock = this.eval_libc_i32("SOCK_NONBLOCK");
+let sock_cloexec = this.eval_libc_i32("SOCK_CLOEXEC");
+if flags & sock_nonblock == sock_nonblock {
  is_sock_nonblock = true;
-type_ &= !(this.eval_libc_i32("SOCK_NONBLOCK"));
+flags &= !sock_nonblock;
 }
-iftype_&this.eval_libc_i32("SOCK_CLOEXEC") == this.eval_libc_i32("SOCK_CLOEXEC"){
-type_ &= !(this.eval_libc_i32("SOCK_CLOEXEC"));
+ifflags&sock_cloexec == sock_cloexec{
+flags &= !sock_cloexec;
 }
 }
 
@@ -294,11 +297,11 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
  and AF_LOCAL are allowed",
  domain
 );
-}elseiftype_ != this.eval_libc_i32("SOCK_STREAM"){
+}elseifflags != this.eval_libc_i32("SOCK_STREAM"){
 throw_unsup_format!(
 "socketpair: type {:#x} is unsupported, only SOCK_STREAM, \
  SOCK_CLOEXEC and SOCK_NONBLOCK are allowed",
-type_
+flags
 );
 }elseif protocol != 0{
 throw_unsup_format!(
@@ -347,14 +350,26 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 let this = self.eval_context_mut();
 
 let pipefd = this.deref_pointer_as(pipefd, this.machine.layouts.i32)?;
-let flags = match flags {
+letmutflags = match flags {
 Some(flags) => this.read_scalar(flags)?.to_i32()?,
 None => 0,
 };
 
-// As usual we ignore CLOEXEC.
 let cloexec = this.eval_libc_i32("O_CLOEXEC");
-if flags != 0 && flags != cloexec {
+let o_nonblock = this.eval_libc_i32("O_NONBLOCK");
+
+// Interpret the flag. Every flag we recognize is "subtracted" from `flags`, so
+// if there is anything left at the end, that's an unsupported flag.
+letmut is_nonblock = false;
+if flags & o_nonblock == o_nonblock {
+ is_nonblock = true;
+ flags &= !o_nonblock;
+}
+// As usual we ignore CLOEXEC.
+if flags & cloexec == cloexec {
+ flags &= !cloexec;
+}
+if flags != 0{
 throw_unsup_format!("unsupported flags in `pipe2`");
 }
 
@@ -365,13 +380,13 @@ pub trait EvalContextExt<'tcx>: crate::MiriInterpCxExt<'tcx> {
 readbuf:Some(RefCell::new(Buffer::new())),
 peer_fd:OnceCell::new(),
 peer_lost_data:Cell::new(false),
-is_nonblock:false,
+ is_nonblock,
 });
 let fd1 = fds.new_ref(AnonSocket{
 readbuf:None,
 peer_fd:OnceCell::new(),
 peer_lost_data:Cell::new(false),
-is_nonblock:false,
+ is_nonblock,
 });
 
 // Make the file descriptions point to each other.

src/tools/miri/tests/fail-dep/libc/socketpair_read_blocking.stderr

@@ -1,8 +1,8 @@
-error: unsupported operation: socketpair read: blocking isn't supported yet
+error: unsupported operation: socketpair/pipe/pipe2 read: blocking isn't supported yet
  --> tests/fail-dep/libc/socketpair_read_blocking.rs:LL:CC
  |
 LL | let _res = unsafe { libc::read(fds[1], buf.as_mut_ptr().cast(), buf.len() as libc::size_t) };
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ socketpair read: blocking isn't supported yet
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ socketpair/pipe/pipe2 read: blocking isn't supported yet
  |
  = help: this is likely not a bug in the program; it indicates that the program performed an operation that Miri does not support
  = note: BACKTRACE:

src/tools/miri/tests/fail-dep/libc/socketpair_write_blocking.stderr

@@ -1,8 +1,8 @@
-error: unsupported operation: socketpair write: blocking isn't supported yet
+error: unsupported operation: socketpair/pipe/pipe2 write: blocking isn't supported yet
  --> tests/fail-dep/libc/socketpair_write_blocking.rs:LL:CC
  |
 LL | let _ = unsafe { libc::write(fds[0], data as *const libc::c_void, 3) };
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ socketpair write: blocking isn't supported yet
+ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ socketpair/pipe/pipe2 write: blocking isn't supported yet
  |
  = help: this is likely not a bug in the program; it indicates that the program performed an operation that Miri does not support
  = note: BACKTRACE:

src/tools/miri/tests/pass-dep/libc/libc-epoll-blocking.rs

@@ -161,7 +161,7 @@ fn test_epoll_race() {
 // Write to the eventfd instance.
 let sized_8_data:[u8;8] = 1_u64.to_ne_bytes();
 let res = unsafe{ libc::write(fd, sized_8_data.as_ptr()as*const libc::c_void,8)};
-// read returns number of bytes that have been read, which is always 8.
+// write returns number of bytes written, which is always 8.
 assert_eq!(res,8);
 });
  thread::yield_now();

src/tools/miri/tests/pass-dep/libc/libc-pipe.rs

@@ -7,6 +7,14 @@ fn main() {
 test_pipe_threaded();
 test_race();
 test_pipe_array();
+#[cfg(any(
+ target_os = "linux",
+ target_os = "illumos",
+ target_os = "freebsd",
+ target_os = "solaris"
+))]
+// `pipe2` only exists in some specific os.
+test_pipe2();
 }
 
 fntest_pipe(){
@@ -110,3 +118,16 @@ fn test_pipe_array() {
 letmut fds:[i32;2] = [0;2];
 assert_eq!(unsafe{ pipe(&mut fds)},0);
 }
+
+/// Test if pipe2 (including the O_NONBLOCK flag) is supported.
+#[cfg(any(
+ target_os = "linux",
+ target_os = "illumos",
+ target_os = "freebsd",
+ target_os = "solaris"
+))]
+fntest_pipe2(){
+letmut fds = [-1, -1];
+let res = unsafe{ libc::pipe2(fds.as_mut_ptr(), libc::O_NONBLOCK)};
+assert_eq!(res,0);
+}