More ErrorKinds for common errnos

library/std/src/fs.rs

@@ -880,8 +880,7 @@ impl OpenOptions {
     /// This function will return an error under a number of different
     /// circumstances. Some of these error conditions are listed here, together
     /// with their [`io::ErrorKind`]. The mapping to [`io::ErrorKind`]s is not
-    /// part of the compatibility contract of the function, especially the
-    /// [`Other`] kind might change to more specific kinds in the future.
+    /// part of the compatibility contract of the function.
     ///
     /// * [`NotFound`]: The specified file does not exist and neither `create`
     ///   or `create_new` is set.
@@ -895,9 +894,11 @@ impl OpenOptions {
     ///   exists.
     /// * [`InvalidInput`]: Invalid combinations of open options (truncate
     ///   without write access, no access mode set, etc.).
-    /// * [`Other`]: One of the directory components of the specified file path
+    ///
+    /// The following errors don't match any existing [`io::ErrorKind`] at the moment:
+    /// * One of the directory components of the specified file path
     ///   was not, in fact, a directory.
-    /// * [`Other`]: Filesystem-level errors: full disk, write permission
+    /// * Filesystem-level errors: full disk, write permission
     ///   requested on a read-only file system, exceeded disk quota, too many
     ///   open files, too long filename, too many symbolic links in the
     ///   specified path (Unix-like systems only), etc.
@@ -913,7 +914,6 @@ impl OpenOptions {
     /// [`AlreadyExists`]: io::ErrorKind::AlreadyExists
     /// [`InvalidInput`]: io::ErrorKind::InvalidInput
     /// [`NotFound`]: io::ErrorKind::NotFound
-    /// [`Other`]: io::ErrorKind::Other
     /// [`PermissionDenied`]: io::ErrorKind::PermissionDenied
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn open<P: AsRef<Path>>(&self, path: P) -> io::Result<File> {
@@ -2190,7 +2190,7 @@ impl DirBuilder {
             Some(p) => self.create_dir_all(p)?,
             None => {
                 return Err(io::Error::new_const(
-                    io::ErrorKind::Other,
+                    io::ErrorKind::Uncategorized,
                     &"failed to create whole tree",
                 ));
             }

library/std/src/fs/tests.rs

@@ -1329,7 +1329,8 @@ fn metadata_access_times() {
         match (a.created(), b.created()) {
             (Ok(t1), Ok(t2)) => assert!(t1 <= t2),
             (Err(e1), Err(e2))
-                if e1.kind() == ErrorKind::Other && e2.kind() == ErrorKind::Other
+                if e1.kind() == ErrorKind::Uncategorized
+                    && e2.kind() == ErrorKind::Uncategorized
                     || e1.kind() == ErrorKind::Unsupported
                         && e2.kind() == ErrorKind::Unsupported => {}
             (a, b) => {

library/std/src/io/error.rs

@@ -105,6 +105,12 @@ pub enum ErrorKind {
     /// The connection was reset by the remote server.
     #[stable(feature = "rust1", since = "1.0.0")]
     ConnectionReset,
+    /// The remote host is not reachable.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    HostUnreachable,
+    /// The network containing the remote host is not reachable.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    NetworkUnreachable,
     /// The connection was aborted (terminated) by the remote server.
     #[stable(feature = "rust1", since = "1.0.0")]
     ConnectionAborted,
@@ -119,6 +125,9 @@ pub enum ErrorKind {
     /// local.
     #[stable(feature = "rust1", since = "1.0.0")]
     AddrNotAvailable,
+    /// The system's networking is down.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    NetworkDown,
     /// The operation failed because a pipe was closed.
     #[stable(feature = "rust1", since = "1.0.0")]
     BrokenPipe,
@@ -129,6 +138,38 @@ pub enum ErrorKind {
     /// requested to not occur.
     #[stable(feature = "rust1", since = "1.0.0")]
     WouldBlock,
+    /// A filesystem object is, unexpectedly, not a directory.
+    ///
+    /// For example, a filesystem path was specified where one of the intermediate directory
+    /// components was, in fact, a plain file.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    NotADirectory,
+    /// The filesystem object is, unexpectedly, a directory.
+    ///
+    /// A directory was specified when a non-directory was expected.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    IsADirectory,
+    /// A non-empty directory was specified where an empty directory was expected.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    DirectoryNotEmpty,
+    /// The filesystem or storage medium is read-only, but a write operation was attempted.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    ReadOnlyFilesystem,
+    /// Loop in the filesystem or IO subsystem; often, too many levels of symbolic links.
+    ///
+    /// There was a loop (or excessively long chain) resolving a filesystem object
+    /// or file IO object.
+    ///
+    /// On Unix this is usually the result of a symbolic link loop; or, of exceeding the
+    /// system-specific limit on the depth of symlink traversal.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    FilesystemLoop,
+    /// Stale network file handle.
+    ///
+    /// With some network filesystems, notably NFS, an open file (or directory) can be invalidated
+    /// by problems with the network or server.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    StaleNetworkFileHandle,
     /// A parameter was incorrect.
     #[stable(feature = "rust1", since = "1.0.0")]
     InvalidInput,
@@ -158,19 +199,67 @@ pub enum ErrorKind {
     /// [`Ok(0)`]: Ok
     #[stable(feature = "rust1", since = "1.0.0")]
     WriteZero,
+    /// The underlying storage (typically, a filesystem) is full.
+    ///
+    /// This does not include out of quota errors.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    StorageFull,
+    /// Seek on unseekable file.
+    ///
+    /// Seeking was attempted on an open file handle which is not suitable for seeking - for
+    /// example, on Unix, a named pipe opened with `File::open`.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    NotSeekable,
+    /// Filesystem quota was exceeded.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    FilesystemQuotaExceeded,
+    /// File larger than allowed or supported.
+    ///
+    /// This might arise from a hard limit of the underlying filesystem or file access API, or from
+    /// an administratively imposed resource limitation.  Simple disk full, and out of quota, have
+    /// their own errors.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    FileTooLarge,
+    /// Resource is busy.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    ResourceBusy,
+    /// Executable file is busy.
+    ///
+    /// An attempt was made to write to a file which is also in use as a running program.  (Not all
+    /// operating systems detect this situation.)
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    ExecutableFileBusy,
+    /// Deadlock (avoided).
+    ///
+    /// A file locking operation would result in deadlock.  This situation is typically detected, if
+    /// at all, on a best-effort basis.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    Deadlock,
+    /// Cross-device or cross-filesystem (hard) link or rename.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    CrossesDevices,
+    /// Too many (hard) links to the same filesystem object.
+    ///
+    /// The filesystem does not support making so many hardlinks to the same file.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    TooManyLinks,
+    /// Filename too long.
+    ///
+    /// The limit might be from the underlying filesystem or API, or an administratively imposed
+    /// resource limit.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    FilenameTooLong,
+    /// Program argument list too long.
+    ///
+    /// When trying to run an external program, a system or process limit on the size of the
+    /// arguments would have been exceeded.
+    #[unstable(feature = "io_error_more", issue = "86442")]
+    ArgumentListTooLong,
     /// This operation was interrupted.
     ///
     /// Interrupted operations can typically be retried.
     #[stable(feature = "rust1", since = "1.0.0")]
     Interrupted,
-    /// Any I/O error not part of this list.
-    ///
-    /// Errors that are `Other` now may move to a different or a new
-    /// [`ErrorKind`] variant in the future. It is not recommended to match
-    /// an error against `Other` and to expect any additional characteristics,
-    /// e.g., a specific [`Error::raw_os_error`] return value.
-    #[stable(feature = "rust1", since = "1.0.0")]
-    Other,
 
     /// An error returned when an operation could not be completed because an
     /// "end of file" was reached prematurely.
@@ -180,6 +269,18 @@ pub enum ErrorKind {
     /// read.
     #[stable(feature = "read_exact", since = "1.6.0")]
     UnexpectedEof,
+    /// A custom error that does not fall under any other I/O error kind.
+    ///
+    /// This can be used to construct your own [`Error`]s that do not match any
+    /// [`ErrorKind`].
+    ///
+    /// This [`ErrorKind`] is not used by the standard library.
+    ///
+    /// Errors from the standard library that do not fall under any of the I/O
+    /// error kinds cannot be `match`ed on, and will only match a wildcard (`_`) pattern.
+    /// New [`ErrorKind`]s might be added in the future for some of those.
+    #[stable(feature = "rust1", since = "1.0.0")]
+    Other,
 
     /// This operation is unsupported on this platform.
     ///
@@ -191,31 +292,62 @@ pub enum ErrorKind {
     /// to allocate enough memory.
     #[stable(feature = "out_of_memory_error", since = "1.54.0")]
     OutOfMemory,
+
+    /// Any I/O error from the standard library that's not part of this list.
+    ///
+    /// Errors that are `Uncategorized` now may move to a different or a new
+    /// [`ErrorKind`] variant in the future. It is not recommended to match
+    /// an error against `Uncategorized`; use a wildcard match (`_`) instead.
+    #[unstable(feature = "io_error_uncategorized", issue = "none")]
+    #[doc(hidden)]
+    Uncategorized,
 }
 
 impl ErrorKind {
     pub(crate) fn as_str(&self) -> &'static str {
+        use ErrorKind::*;
         match *self {
-            ErrorKind::NotFound => "entity not found",
-            ErrorKind::PermissionDenied => "permission denied",
-            ErrorKind::ConnectionRefused => "connection refused",
-            ErrorKind::ConnectionReset => "connection reset",
-            ErrorKind::ConnectionAborted => "connection aborted",
-            ErrorKind::NotConnected => "not connected",
-            ErrorKind::AddrInUse => "address in use",
-            ErrorKind::AddrNotAvailable => "address not available",
-            ErrorKind::BrokenPipe => "broken pipe",
-            ErrorKind::AlreadyExists => "entity already exists",
-            ErrorKind::WouldBlock => "operation would block",
-            ErrorKind::InvalidInput => "invalid input parameter",
-            ErrorKind::InvalidData => "invalid data",
-            ErrorKind::TimedOut => "timed out",
-            ErrorKind::WriteZero => "write zero",
-            ErrorKind::Interrupted => "operation interrupted",
-            ErrorKind::Other => "other os error",
-            ErrorKind::UnexpectedEof => "unexpected end of file",
-            ErrorKind::Unsupported => "unsupported",
-            ErrorKind::OutOfMemory => "out of memory",
+            AddrInUse => "address in use",
+            AddrNotAvailable => "address not available",
+            AlreadyExists => "entity already exists",
+            ArgumentListTooLong => "argument list too long",
+            BrokenPipe => "broken pipe",
+            ResourceBusy => "resource busy",
+            ConnectionAborted => "connection aborted",
+            ConnectionRefused => "connection refused",
+            ConnectionReset => "connection reset",
+            CrossesDevices => "cross-device link or rename",
+            Deadlock => "deadlock",
+            DirectoryNotEmpty => "directory not empty",
+            ExecutableFileBusy => "executable file busy",
+            FilenameTooLong => "filename too long",
+            FilesystemQuotaExceeded => "filesystem quota exceeded",
+            FileTooLarge => "file too large",
+            HostUnreachable => "host unreachable",
+            Interrupted => "operation interrupted",
+            InvalidData => "invalid data",
+            InvalidInput => "invalid input parameter",
+            IsADirectory => "is a directory",
+            NetworkDown => "network down",
+            NetworkUnreachable => "network unreachable",
+            NotADirectory => "not a directory",
+            StorageFull => "no storage space",
+            NotConnected => "not connected",
+            NotFound => "entity not found",
+            Other => "other error",
+            OutOfMemory => "out of memory",
+            PermissionDenied => "permission denied",
+            ReadOnlyFilesystem => "read-only filesystem or storage medium",
+            StaleNetworkFileHandle => "stale network file handle",
+            FilesystemLoop => "filesystem loop or indirection limit (e.g. symlink loop)",
+            NotSeekable => "seek on unseekable file",
+            TimedOut => "timed out",
+            TooManyLinks => "too many links",
+            Uncategorized => "uncategorized error",
+            UnexpectedEof => "unexpected end of file",
+            Unsupported => "unsupported",
+            WouldBlock => "operation would block",
+            WriteZero => "write zero",
         }
     }
 }
@@ -538,7 +670,7 @@ impl Error {
     /// }
     ///
     /// fn main() {
-    ///     // Will print "Other".
+    ///     // Will print "Uncategorized".
     ///     print_error(Error::last_os_error());
     ///     // Will print "AddrInUse".
     ///     print_error(Error::new(ErrorKind::AddrInUse, "oh no!"));

library/std/src/io/mod.rs

@@ -1592,7 +1592,7 @@ pub trait Write {
                 if output.error.is_err() {
                     output.error
                 } else {
-                    Err(Error::new_const(ErrorKind::Other, &"formatter error"))
+                    Err(Error::new_const(ErrorKind::Uncategorized, &"formatter error"))
                 }
             }
         }

library/std/src/net/tcp/tests.rs

@@ -342,7 +342,7 @@ fn double_bind() {
             Err(e) => {
                 assert!(
                     e.kind() == ErrorKind::ConnectionRefused
-                        || e.kind() == ErrorKind::Other
+                        || e.kind() == ErrorKind::Uncategorized
                         || e.kind() == ErrorKind::AddrInUse,
                     "unknown error: {} {:?}",
                     e,

library/std/src/os/wasi/fs.rs

@@ -532,5 +532,6 @@ pub fn symlink_path<P: AsRef<Path>, U: AsRef<Path>>(old_path: P, new_path: U) ->
 }
 
 fn osstr2str(f: &OsStr) -> io::Result<&str> {
-    f.to_str().ok_or_else(|| io::Error::new_const(io::ErrorKind::Other, &"input must be utf-8"))
+    f.to_str()
+        .ok_or_else(|| io::Error::new_const(io::ErrorKind::Uncategorized, &"input must be utf-8"))
 }

library/std/src/process.rs

@@ -1658,8 +1658,7 @@ impl Child {
     /// Forces the child process to exit. If the child has already exited, an [`InvalidInput`]
     /// error is returned.
     ///
-    /// The mapping to [`ErrorKind`]s is not part of the compatibility contract of the function,
-    /// especially the [`Other`] kind might change to more specific kinds in the future.
+    /// The mapping to [`ErrorKind`]s is not part of the compatibility contract of the function.
     ///
     /// This is equivalent to sending a SIGKILL on Unix platforms.
     ///
@@ -1680,7 +1679,6 @@ impl Child {
     ///
     /// [`ErrorKind`]: io::ErrorKind
     /// [`InvalidInput`]: io::ErrorKind::InvalidInput
-    /// [`Other`]: io::ErrorKind::Other
     #[stable(feature = "process", since = "1.0.0")]
     pub fn kill(&mut self) -> io::Result<()> {
         self.handle.kill()

library/std/src/sys/hermit/mod.rs

@@ -149,7 +149,7 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
         x if x == 1 as i32 => ErrorKind::PermissionDenied,
         x if x == 32 as i32 => ErrorKind::BrokenPipe,
         x if x == 110 as i32 => ErrorKind::TimedOut,
-        _ => ErrorKind::Other,
+        _ => ErrorKind::Uncategorized,
     }
 }