Overhaul Nix's error types

For many of Nix's consumers it be convenient to easily convert a Nix
error into a std::io::Error.  That's currently not possible because of
the InvalidPath, InvalidUtf8, and UnsupportedOperation types that have
no equivalent in std::io::Error.

However, very few of Nix's public APIs actually return those unusual
errors.  So a more useful API would be for Nix's standard error type to
implement Into<std::io::Error>.

This commit makes Error a simple NewType around Errno.  For most
functions it's a drop-in replacement.  There are only three exceptions:

* clearenv now returns a bespoke error type.  It was the only Nix
  function whose error couldn't be cleanly mapped onto an Errno.

* sys::signal::signal now returns Error(Errno::ENOTSUP) instead of
  Error::UnsupportedOperation when the user passes an incompatible
  argument to `handler`.

* When a NixPath exceeds PATH_MAX, it will now return
  Error(Errno::ENAMETOOLONG) instead of Error::InvalidPath.

In the latter two cases there is now some abiguity about whether the
error code was generated by Nix or by the OS.  But I think the ambiguity
is worth it for the sake of being able to implement Into<io::Error>.

This commit also introduces Error::Sys() as a migration aid.  Previously
that as an enum variant.  Now it's a function, but it will work in many
of the same contexts as the original.

Fixes #1155

1 files changed, 17 insertions, 17 deletions

diff --git a/test/sys/test_ioctl.rs b/test/sys/test_ioctl.rs
index ddb86968..d65e43ac 100644
--- a/test/sys/test_ioctl.rs
+++ b/test/sys/test_ioctl.rs
@@ -167,15 +167,15 @@ mod linux_ioctls {
     use tempfile::tempfile;
     use libc::{TCGETS, TCSBRK, TCSETS, TIOCNXCL, termios};
 
-    use nix::Error::Sys;
-    use nix::errno::Errno::{ENOTTY, ENOSYS};
+    use nix::Error;
+    use nix::errno::Errno;
 
     ioctl_none_bad!(tiocnxcl, TIOCNXCL);
     #[test]
     fn test_ioctl_none_bad() {
         let file = tempfile().unwrap();
         let res = unsafe { tiocnxcl(file.as_raw_fd()) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 
     ioctl_read_bad!(tcgets, TCGETS, termios);
@@ -184,7 +184,7 @@ mod linux_ioctls {
         let file = tempfile().unwrap();
         let mut termios = unsafe { mem::zeroed() };
         let res = unsafe { tcgets(file.as_raw_fd(), &mut termios) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 
     ioctl_write_int_bad!(tcsbrk, TCSBRK);
@@ -192,7 +192,7 @@ mod linux_ioctls {
     fn test_ioctl_write_int_bad() {
         let file = tempfile().unwrap();
         let res = unsafe { tcsbrk(file.as_raw_fd(), 0) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 
     ioctl_write_ptr_bad!(tcsets, TCSETS, termios);
@@ -201,7 +201,7 @@ mod linux_ioctls {
         let file = tempfile().unwrap();
         let termios: termios = unsafe { mem::zeroed() };
         let res = unsafe { tcsets(file.as_raw_fd(), &termios) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 
     // FIXME: Find a suitable example for `ioctl_readwrite_bad`
@@ -212,7 +212,7 @@ mod linux_ioctls {
     fn test_ioctl_none() {
         let file = tempfile().unwrap();
         let res = unsafe { log_status(file.as_raw_fd()) };
-        assert!(res == Err(Sys(ENOTTY)) || res == Err(Sys(ENOSYS)));
+        assert!(res == Err(Error(Errno::ENOTTY)) || res == Err(Error(Errno::ENOSYS)));
     }
 
     #[repr(C)]
@@ -231,7 +231,7 @@ mod linux_ioctls {
         let file = tempfile().unwrap();
         let data: v4l2_audio = unsafe { mem::zeroed() };
         let res = unsafe { s_audio(file.as_raw_fd(), &data) };
-        assert!(res == Err(Sys(ENOTTY)) || res == Err(Sys(ENOSYS)));
+        assert!(res == Err(Error(Errno::ENOTTY)) || res == Err(Error(Errno::ENOSYS)));
     }
 
     // From linux/net/bluetooth/hci_sock.h
@@ -242,7 +242,7 @@ mod linux_ioctls {
     fn test_ioctl_write_int() {
         let file = tempfile().unwrap();
         let res = unsafe { hcidevup(file.as_raw_fd(), 0) };
-        assert!(res == Err(Sys(ENOTTY)) || res == Err(Sys(ENOSYS)));
+        assert!(res == Err(Error(Errno::ENOTTY)) || res == Err(Error(Errno::ENOSYS)));
     }
 
     // From linux/videodev2.h
@@ -252,7 +252,7 @@ mod linux_ioctls {
         let file = tempfile().unwrap();
         let mut data: v4l2_audio = unsafe { mem::zeroed() };
         let res = unsafe { g_audio(file.as_raw_fd(), &mut data) };
-        assert!(res == Err(Sys(ENOTTY)) || res == Err(Sys(ENOSYS)));
+        assert!(res == Err(Error(Errno::ENOTTY)) || res == Err(Error(Errno::ENOSYS)));
     }
 
     // From linux/videodev2.h
@@ -262,7 +262,7 @@ mod linux_ioctls {
         let file = tempfile().unwrap();
         let mut data: v4l2_audio = unsafe { mem::zeroed() };
         let res = unsafe { enum_audio(file.as_raw_fd(), &mut data) };
-        assert!(res == Err(Sys(ENOTTY)) || res == Err(Sys(ENOSYS)));
+        assert!(res == Err(Error(Errno::ENOTTY)) || res == Err(Error(Errno::ENOSYS)));
     }
 
     // FIXME: Find a suitable example for `ioctl_read_buf`.
@@ -288,7 +288,7 @@ mod linux_ioctls {
         let file = tempfile().unwrap();
         let data: [spi_ioc_transfer; 4] = unsafe { mem::zeroed() };
         let res = unsafe { spi_ioc_message(file.as_raw_fd(), &data[..]) };
-        assert!(res == Err(Sys(ENOTTY)) || res == Err(Sys(ENOSYS)));
+        assert!(res == Err(Error(Errno::ENOTTY)) || res == Err(Error(Errno::ENOSYS)));
     }
 
     // FIXME: Find a suitable example for `ioctl_readwrite_buf`.
@@ -302,8 +302,8 @@ mod freebsd_ioctls {
     use tempfile::tempfile;
     use libc::termios;
 
-    use nix::Error::Sys;
-    use nix::errno::Errno::ENOTTY;
+    use nix::Error;
+    use nix::errno::Errno;
 
     // From sys/sys/ttycom.h
     const TTY_IOC_MAGIC: u8 = b't';
@@ -316,7 +316,7 @@ mod freebsd_ioctls {
     fn test_ioctl_none() {
         let file = tempfile().unwrap();
         let res = unsafe { tiocnxcl(file.as_raw_fd()) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 
     ioctl_read!(tiocgeta, TTY_IOC_MAGIC, TTY_IOC_TYPE_GETA, termios);
@@ -325,7 +325,7 @@ mod freebsd_ioctls {
         let file = tempfile().unwrap();
         let mut termios = unsafe { mem::zeroed() };
         let res = unsafe { tiocgeta(file.as_raw_fd(), &mut termios) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 
     ioctl_write_ptr!(tiocseta, TTY_IOC_MAGIC, TTY_IOC_TYPE_SETA, termios);
@@ -334,6 +334,6 @@ mod freebsd_ioctls {
         let file = tempfile().unwrap();
         let termios: termios = unsafe { mem::zeroed() };
         let res = unsafe { tiocseta(file.as_raw_fd(), &termios) };
-        assert_eq!(res, Err(Sys(ENOTTY)));
+        assert_eq!(res, Err(Error(Errno::ENOTTY)));
     }
 }