ErrorKind: Provide many more ErrorKinds, motivated by Unix errnos

Rationale for the mappings etc. is extensively discussed in the MR
  #79965

Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>

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 +138,37 @@ 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; often, too many levels of symbolic links.
+    ///
+    /// There was a loop (or excessively long chain) resolving a filesystem 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,
@@ -158,6 +198,62 @@ 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::new`.
+    #[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.
@@ -213,19 +309,39 @@ impl ErrorKind {
             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 (e.g. symbolic link loop)",
+            NotSeekable => "seek on unseekable file",
             TimedOut => "timed out",
+            TooManyLinks => "too many links",
             Uncategorized => "uncategorized error",
             UnexpectedEof => "unexpected end of file",
             Unsupported => "unsupported",

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

@@ -135,20 +135,40 @@ pub use libc::signal;
 pub fn decode_error_kind(errno: i32) -> ErrorKind {
     use ErrorKind::*;
     match errno as libc::c_int {
+        libc::E2BIG => ArgumentListTooLong,
         libc::EADDRINUSE => AddrInUse,
         libc::EADDRNOTAVAIL => AddrNotAvailable,
+        libc::EBUSY => ResourceBusy,
         libc::ECONNABORTED => ConnectionAborted,
         libc::ECONNREFUSED => ConnectionRefused,
         libc::ECONNRESET => ConnectionReset,
+        libc::EDEADLK => Deadlock,
+        libc::EDQUOT => FilesystemQuotaExceeded,
         libc::EEXIST => AlreadyExists,
+        libc::EFBIG => FileTooLarge,
+        libc::EHOSTUNREACH => HostUnreachable,
         libc::EINTR => Interrupted,
         libc::EINVAL => InvalidInput,
+        libc::EISDIR => IsADirectory,
+        libc::ELOOP => FilesystemLoop,
         libc::ENOENT => NotFound,
         libc::ENOMEM => OutOfMemory,
+        libc::ENOSPC => StorageFull,
         libc::ENOSYS => Unsupported,
+        libc::EMLINK => TooManyLinks,
+        libc::ENAMETOOLONG => FilenameTooLong,
+        libc::ENETDOWN => NetworkDown,
+        libc::ENETUNREACH => NetworkUnreachable,
         libc::ENOTCONN => NotConnected,
+        libc::ENOTDIR => NotADirectory,
+        libc::ENOTEMPTY => DirectoryNotEmpty,
         libc::EPIPE => BrokenPipe,
+        libc::EROFS => ReadOnlyFilesystem,
+        libc::ESPIPE => NotSeekable,
+        libc::ESTALE => StaleNetworkFileHandle,
         libc::ETIMEDOUT => TimedOut,
+        libc::ETXTBSY => ExecutableFileBusy,
+        libc::EXDEV => CrossesDevices,
 
         libc::EACCES | libc::EPERM => PermissionDenied,
 

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

@@ -90,6 +90,24 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
         | c::ERROR_RUNLEVEL_SWITCH_TIMEOUT
         | c::ERROR_RUNLEVEL_SWITCH_AGENT_TIMEOUT => return TimedOut,
         c::ERROR_CALL_NOT_IMPLEMENTED => return Unsupported,
+        | c::ERROR_RUNLEVEL_SWITCH_AGENT_TIMEOUT => return TimedOut,
+        c::ERROR_CALL_NOT_IMPLEMENTED => return Unsupported,
+        c::ERROR_HOST_UNREACHABLE => return HostUnreachable,
+        c::ERROR_NETWORK_UNREACHABLE => return NetworkUnreachable,
+        c::ERROR_DIRECTORY => return NotADirectory,
+        c::ERROR_DIRECTORY_NOT_SUPPORTED => return IsADirectory,
+        c::ERROR_DIR_NOT_EMPTY => return DirectoryNotEmpty,
+        c::ERROR_WRITE_PROTECT => return ReadOnlyFilesystem,
+        c::ERROR_DISK_FULL
+        | c::ERROR_HANDLE_DISK_FULL => return StorageFull,
+        c::ERROR_SEEK_ON_DEVICE => return NotSeekable,
+        c::ERROR_DISK_QUOTA_EXCEEDED => return FilesystemQuotaExceeded,
+        c::ERROR_FILE_TOO_LARGE => return FileTooLarge,
+        c::ERROR_BUSY => return ResourceBusy,
+        c::ERROR_POSSIBLE_DEADLOCK => return Deadlock,
+        c::ERROR_NOT_SAME_DEVICE => return CrossesDevices,
+        c::ERROR_TOO_MANY_LINKS => return TooManyLinks,
+        c::ERROR_FILENAME_EXCED_RANGE => return FilenameTooLong,
         _ => {}
     }
 
@@ -104,6 +122,9 @@ pub fn decode_error_kind(errno: i32) -> ErrorKind {
         c::WSAENOTCONN => NotConnected,
         c::WSAEWOULDBLOCK => WouldBlock,
         c::WSAETIMEDOUT => TimedOut,
+        c::WSAEHOSTUNREACH => HostUnreachable,
+        c::WSAENETDOWN => NetworkDown,
+        c::WSAENETUNREACH => NetworkUnreachable,
 
         _ => Uncategorized,
     }