separate flock implementations into separate modules

compiler/rustc_data_structures/src/flock.rs

@@ -7,225 +7,20 @@
 #![allow(non_camel_case_types)]
 #![allow(nonstandard_style)]
 
-use std::fs::{File, OpenOptions};
-use std::io;
-use std::path::Path;
-
 cfg_if! {
-    // We use `flock` rather than `fcntl` on Linux, because WSL1 does not support
-    // `fcntl`-style advisory locks properly (rust-lang/rust#72157).
-    //
-    // For other Unix targets we still use `fcntl` because it's more portable than
-    // `flock`.
     if #[cfg(target_os = "linux")] {
-        use std::os::unix::prelude::*;
-
-        #[derive(Debug)]
-        pub struct Lock {
-            _file: File,
-        }
-
-        impl Lock {
-            pub fn new(p: &Path,
-                       wait: bool,
-                       create: bool,
-                       exclusive: bool)
-                       -> io::Result<Lock> {
-                let file = OpenOptions::new()
-                    .read(true)
-                    .write(true)
-                    .create(create)
-                    .mode(libc::S_IRWXU as u32)
-                    .open(p)?;
-
-                let mut operation = if exclusive {
-                    libc::LOCK_EX
-                } else {
-                    libc::LOCK_SH
-                };
-                if !wait {
-                    operation |= libc::LOCK_NB
-                }
-
-                let ret = unsafe { libc::flock(file.as_raw_fd(), operation) };
-                if ret == -1 {
-                    Err(io::Error::last_os_error())
-                } else {
-                    Ok(Lock { _file: file })
-                }
-            }
-
-            pub fn error_unsupported(err: &io::Error) -> bool {
-                matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
-            }
-        }
-
-        // Note that we don't need a Drop impl to execute `flock(fd, LOCK_UN)`. Lock acquired by
-        // `flock` is associated with the file descriptor and closing the file release it
-        // automatically.
+        mod linux;
+        use linux as imp;
     } else if #[cfg(unix)] {
-        use std::mem;
-        use std::os::unix::prelude::*;
-
-        #[derive(Debug)]
-        pub struct Lock {
-            file: File,
-        }
-
-        impl Lock {
-            pub fn new(p: &Path,
-                       wait: bool,
-                       create: bool,
-                       exclusive: bool)
-                       -> io::Result<Lock> {
-                let file = OpenOptions::new()
-                    .read(true)
-                    .write(true)
-                    .create(create)
-                    .mode(libc::S_IRWXU as u32)
-                    .open(p)?;
-
-                let lock_type = if exclusive {
-                    libc::F_WRLCK
-                } else {
-                    libc::F_RDLCK
-                };
-
-                let mut flock: libc::flock = unsafe { mem::zeroed() };
-                flock.l_type = lock_type as libc::c_short;
-                flock.l_whence = libc::SEEK_SET as libc::c_short;
-                flock.l_start = 0;
-                flock.l_len = 0;
-
-                let cmd = if wait { libc::F_SETLKW } else { libc::F_SETLK };
-                let ret = unsafe {
-                    libc::fcntl(file.as_raw_fd(), cmd, &flock)
-                };
-                if ret == -1 {
-                    Err(io::Error::last_os_error())
-                } else {
-                    Ok(Lock { file })
-                }
-            }
-
-            pub fn error_unsupported(err: &io::Error) -> bool {
-                matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
-            }
-        }
-
-        impl Drop for Lock {
-            fn drop(&mut self) {
-                let mut flock: libc::flock = unsafe { mem::zeroed() };
-                flock.l_type = libc::F_UNLCK as libc::c_short;
-                flock.l_whence = libc::SEEK_SET as libc::c_short;
-                flock.l_start = 0;
-                flock.l_len = 0;
-
-                unsafe {
-                    libc::fcntl(self.file.as_raw_fd(), libc::F_SETLK, &flock);
-                }
-            }
-        }
+        mod unix;
+        use unix as imp;
     } else if #[cfg(windows)] {
-        use std::mem;
-        use std::os::windows::prelude::*;
-
-        use winapi::shared::winerror::ERROR_INVALID_FUNCTION;
-        use winapi::um::minwinbase::{OVERLAPPED, LOCKFILE_FAIL_IMMEDIATELY, LOCKFILE_EXCLUSIVE_LOCK};
-        use winapi::um::fileapi::LockFileEx;
-        use winapi::um::winnt::{FILE_SHARE_DELETE, FILE_SHARE_READ, FILE_SHARE_WRITE};
-
-        #[derive(Debug)]
-        pub struct Lock {
-            _file: File,
-        }
-
-        impl Lock {
-            pub fn new(p: &Path,
-                       wait: bool,
-                       create: bool,
-                       exclusive: bool)
-                       -> io::Result<Lock> {
-                assert!(p.parent().unwrap().exists(),
-                    "Parent directory of lock-file must exist: {}",
-                    p.display());
-
-                let share_mode = FILE_SHARE_DELETE | FILE_SHARE_READ | FILE_SHARE_WRITE;
-
-                let mut open_options = OpenOptions::new();
-                open_options.read(true)
-                            .share_mode(share_mode);
-
-                if create {
-                    open_options.create(true)
-                                .write(true);
-                }
-
-                debug!("attempting to open lock file `{}`", p.display());
-                let file = match open_options.open(p) {
-                    Ok(file) => {
-                        debug!("lock file opened successfully");
-                        file
-                    }
-                    Err(err) => {
-                        debug!("error opening lock file: {}", err);
-                        return Err(err)
-                    }
-                };
-
-                let ret = unsafe {
-                    let mut overlapped: OVERLAPPED = mem::zeroed();
-
-                    let mut dwFlags = 0;
-                    if !wait {
-                        dwFlags |= LOCKFILE_FAIL_IMMEDIATELY;
-                    }
-
-                    if exclusive {
-                        dwFlags |= LOCKFILE_EXCLUSIVE_LOCK;
-                    }
-
-                    debug!("attempting to acquire lock on lock file `{}`",
-                           p.display());
-                    LockFileEx(file.as_raw_handle(),
-                               dwFlags,
-                               0,
-                               0xFFFF_FFFF,
-                               0xFFFF_FFFF,
-                               &mut overlapped)
-                };
-                if ret == 0 {
-                    let err = io::Error::last_os_error();
-                    debug!("failed acquiring file lock: {}", err);
-                    Err(err)
-                } else {
-                    debug!("successfully acquired lock");
-                    Ok(Lock { _file: file })
-                }
-            }
-
-            pub fn error_unsupported(err: &io::Error) -> bool {
-                err.raw_os_error() == Some(ERROR_INVALID_FUNCTION as i32)
-            }
-        }
-
-        // Note that we don't need a Drop impl on the Windows: The file is unlocked
-        // automatically when it's closed.
+        mod windows;
+        use windows as imp;
     } else {
-        #[derive(Debug)]
-        pub struct Lock(());
-
-        impl Lock {
-            pub fn new(_p: &Path, _wait: bool, _create: bool, _exclusive: bool)
-                -> io::Result<Lock>
-            {
-                let msg = "file locks not supported on this platform";
-                Err(io::Error::new(io::ErrorKind::Other, msg))
-            }
-
-            pub fn error_unsupported(_err: &io::Error) -> bool {
-                true
-            }
-        }
+        mod unsupported;
+        use unsupported as imp;
     }
 }
+
+pub use imp::Lock;

compiler/rustc_data_structures/src/flock/linux.rs

@@ -0,0 +1,40 @@
+//! We use `flock` rather than `fcntl` on Linux, because WSL1 does not support
+//! `fcntl`-style advisory locks properly (rust-lang/rust#72157). For other Unix
+//! targets we still use `fcntl` because it's more portable than `flock`.
+
+use std::fs::{File, OpenOptions};
+use std::io;
+use std::os::unix::prelude::*;
+use std::path::Path;
+
+#[derive(Debug)]
+pub struct Lock {
+    _file: File,
+}
+
+impl Lock {
+    pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
+        let file = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .create(create)
+            .mode(libc::S_IRWXU as u32)
+            .open(p)?;
+
+        let mut operation = if exclusive { libc::LOCK_EX } else { libc::LOCK_SH };
+        if !wait {
+            operation |= libc::LOCK_NB
+        }
+
+        let ret = unsafe { libc::flock(file.as_raw_fd(), operation) };
+        if ret == -1 { Err(io::Error::last_os_error()) } else { Ok(Lock { _file: file }) }
+    }
+
+    pub fn error_unsupported(err: &io::Error) -> bool {
+        matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
+    }
+}
+
+// Note that we don't need a Drop impl to execute `flock(fd, LOCK_UN)`. A lock acquired by
+// `flock` is associated with the file descriptor and closing the file releases it
+// automatically.

compiler/rustc_data_structures/src/flock/unix.rs

@@ -0,0 +1,51 @@
+use std::fs::{File, OpenOptions};
+use std::io;
+use std::mem;
+use std::os::unix::prelude::*;
+use std::path::Path;
+
+#[derive(Debug)]
+pub struct Lock {
+    file: File,
+}
+
+impl Lock {
+    pub fn new(p: &Path, wait: bool, create: bool, exclusive: bool) -> io::Result<Lock> {
+        let file = OpenOptions::new()
+            .read(true)
+            .write(true)
+            .create(create)
+            .mode(libc::S_IRWXU as u32)
+            .open(p)?;
+
+        let lock_type = if exclusive { libc::F_WRLCK } else { libc::F_RDLCK };
+
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = lock_type as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        flock.l_start = 0;
+        flock.l_len = 0;
+
+        let cmd = if wait { libc::F_SETLKW } else { libc::F_SETLK };
+        let ret = unsafe { libc::fcntl(file.as_raw_fd(), cmd, &flock) };
+        if ret == -1 { Err(io::Error::last_os_error()) } else { Ok(Lock { file }) }
+    }
+
+    pub fn error_unsupported(err: &io::Error) -> bool {
+        matches!(err.raw_os_error(), Some(libc::ENOTSUP) | Some(libc::ENOSYS))
+    }
+}
+
+impl Drop for Lock {
+    fn drop(&mut self) {
+        let mut flock: libc::flock = unsafe { mem::zeroed() };
+        flock.l_type = libc::F_UNLCK as libc::c_short;
+        flock.l_whence = libc::SEEK_SET as libc::c_short;
+        flock.l_start = 0;
+        flock.l_len = 0;
+
+        unsafe {
+            libc::fcntl(self.file.as_raw_fd(), libc::F_SETLK, &flock);
+        }
+    }
+}

compiler/rustc_data_structures/src/flock/unsupported.rs

@@ -0,0 +1,16 @@
+use std::io;
+use std::path::Path;
+
+#[derive(Debug)]
+pub struct Lock(());
+
+impl Lock {
+    pub fn new(_p: &Path, _wait: bool, _create: bool, _exclusive: bool) -> io::Result<Lock> {
+        let msg = "file locks not supported on this platform";
+        Err(io::Error::new(io::ErrorKind::Other, msg))
+    }
+
+    pub fn error_unsupported(_err: &io::Error) -> bool {
+        true
+    }
+}