Merge #26

26: Closes: #25 - manually implement errors r=posborne a=chris-ricketts

Wraps ioctl macros with another macro that maps the ioctl call to a particular `IoctlType`. That type and the underlying `nix::Error` are then stored in the `ErrorKind::Ioctl` variant. 

Plays nicely with the [anyhow](https://github.com/dtolnay/anyhow) error handling crate, which seems like a more mature version of `failure`. This can be seen in the [monitor example](https://github.com/chris-ricketts/gpio-cdev/blob/6179eea9d16025a9236a0d961ce932b8517fbda9/examples/monitor.rs#L30).

Co-authored-by: chris ricketts <[email protected]>

Author: bors[bot]

Cargo.toml

@@ -12,9 +12,9 @@ license = "MIT OR Apache-2.0"
 
 [dependencies]
 bitflags = "1.0"
-error-chain = "0.12"
 libc = "0.2"
 nix = "0.14"
 
 [dev-dependencies]
 quicli = "0.2"
+anyhow = "1.0"

examples/blinky.rs

@@ -15,6 +15,7 @@ use quicli::prelude::*;
 use std::thread::sleep;
 use std::time::{Duration, Instant};
 
+
 #[derive(Debug, StructOpt)]
 struct Cli {
     /// The gpiochip device (e.g. /dev/gpiochip0)
@@ -27,7 +28,7 @@ struct Cli {
     duration_ms: u64,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
 
     // NOTE: we set the default value to the desired state so

examples/driveoutput.rs

@@ -23,7 +23,7 @@ struct Cli {
     value: u8,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
 
     // NOTE: we set the default value to the desired state so

examples/gpioevents.rs

@@ -13,6 +13,7 @@ extern crate quicli;
 use gpio_cdev::*;
 use quicli::prelude::*;
 
+
 #[derive(Debug, StructOpt)]
 struct Cli {
     /// The gpiochip device (e.g. /dev/gpiochip0)
@@ -21,7 +22,7 @@ struct Cli {
     line: u32,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
     let line = chip.get_line(args.line)?;
 

examples/monitor.rs

@@ -8,12 +8,14 @@
 
 extern crate gpio_cdev;
 extern crate nix;
-#[macro_use] extern crate quicli;
+#[macro_use]
+extern crate quicli;
+extern crate anyhow;
 
 use gpio_cdev::*;
-use quicli::prelude::*;
 use nix::poll::*;
-use std::os::unix::io::{AsRawFd};
+use quicli::prelude::*;
+use std::os::unix::io::AsRawFd;
 
 type PollEventFlags = nix::poll::PollFlags;
 
@@ -25,27 +27,40 @@ struct Cli {
     lines: Vec<u32>,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> anyhow::Result<()> {
     let mut chip = Chip::new(args.chip)?;
 
     // Get event handles for each line to monitor.
-    let mut evt_handles: Vec<LineEventHandle> = args.lines.into_iter().map(|off| {
-        let line = chip.get_line(off).unwrap();
-        line.events(LineRequestFlags::INPUT, EventRequestFlags::BOTH_EDGES,
-                          "monitor").unwrap()
-    }).collect();
+    let mut evt_handles: Vec<LineEventHandle> = args
+        .lines
+        .into_iter()
+        .map(|off| {
+            let line = chip.get_line(off).unwrap();
+            line.events(
+                LineRequestFlags::INPUT,
+                EventRequestFlags::BOTH_EDGES,
+                "monitor",
+            )
+            .unwrap()
+        })
+        .collect();
 
     // Create a vector of file descriptors for polling
-    let mut pollfds: Vec<PollFd> = evt_handles.iter().map(|h| {
-        PollFd::new(h.as_raw_fd(), PollEventFlags::POLLIN | PollEventFlags::POLLPRI)
-    }).collect();
+    let mut pollfds: Vec<PollFd> = evt_handles
+        .iter()
+        .map(|h| {
+            PollFd::new(
+                h.as_raw_fd(),
+                PollEventFlags::POLLIN | PollEventFlags::POLLPRI,
+            )
+        })
+        .collect();
 
     loop {
         // poll for an event on any of the lines
         if poll(&mut pollfds, -1)? == 0 {
             println!("Timeout?!?");
-        }
-        else {
+        } else {
             for i in 0..pollfds.len() {
                 if let Some(revts) = pollfds[i].revents() {
                     let h = &mut evt_handles[i];
@@ -58,9 +73,8 @@ fn do_main(args: Cli) -> errors::Result<()> {
                         // to read the value of the bit.
                         let val = h.get_value()?;
                         println!("    {}", val);
-                    }
-                    else if revts.contains(PollEventFlags::POLLPRI) {
-                         println!("[{}] Got a POLLPRI", h.line().offset());
+                    } else if revts.contains(PollEventFlags::POLLPRI) {
+                        println!("[{}] Got a POLLPRI", h.line().offset());
                     }
                 }
             }
@@ -70,7 +84,7 @@ fn do_main(args: Cli) -> errors::Result<()> {
 
 main!(|args: Cli| {
     match do_main(args) {
-        Ok(()) => {},
+        Ok(()) => {}
         Err(e) => {
             println!("Error: {:?}", e);
         }

examples/multioutput.rs

@@ -28,7 +28,7 @@ struct Cli {
 // to set lines 0, 1, & 3 high
 //              2 & 4 low
 //
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
     let mut offsets = Vec::new();
     let mut values = Vec::new();

examples/multiread.rs

@@ -21,7 +21,7 @@ struct Cli {
     lines: Vec<u32>,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
     let ini_vals = vec![ 0; args.lines.len() ];
     let handle = chip

examples/readall.rs

@@ -19,9 +19,9 @@ struct Cli {
     chip: String,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
-    let ini_vals = vec![ 0; chip.num_lines() as usize ];
+    let ini_vals = vec![0; chip.num_lines() as usize];
     let handle = chip
         .get_all_lines()?
         .request(LineRequestFlags::INPUT, &ini_vals, "readall")?;

examples/readinput.rs

@@ -21,7 +21,7 @@ struct Cli {
     line: u32,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
     let handle = chip
         .get_line(args.line)?

examples/tit_for_tat.rs

@@ -15,6 +15,7 @@ use quicli::prelude::*;
 use std::thread::sleep;
 use std::time::Duration;
 
+
 #[derive(Debug, StructOpt)]
 struct Cli {
     /// The gpiochip device (e.g. /dev/gpiochip0)
@@ -27,7 +28,7 @@ struct Cli {
     sleeptime: u64,
 }
 
-fn do_main(args: Cli) -> errors::Result<()> {
+fn do_main(args: Cli) -> std::result::Result<(), errors::Error> {
     let mut chip = Chip::new(args.chip)?;
     let input = chip.get_line(args.inputline)?;
     let output = chip.get_line(args.outputline)?;

src/errors.rs

@@ -1,21 +1,101 @@
-// Copyright (c) 2018 The rust-gpio-cdev Project Developers.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-error_chain! {
-    types {
-        Error,
-        ErrorKind,
-        ResultExt,
-        Result;
-    }
-
-    foreign_links {
-        Nix(::nix::Error);
-        Io(::std::io::Error);
+use std::error::Error as StdError;
+use std::fmt;
+use std::io::Error as IOError;
+
+pub(crate) type Result<T> = std::result::Result<T, Error>;
+
+#[derive(Debug)]
+pub struct Error {
+    kind: ErrorKind,
+}
+
+#[derive(Debug)]
+pub enum IoctlKind {
+    ChipInfo,
+    LineInfo,
+    LineHandle,
+    LineEvent,
+    GetLine,
+    SetLine,
+}
+
+#[derive(Debug)]
+pub enum ErrorKind {
+    Event(nix::Error),
+    Io(IOError),
+    Ioctl { kind: IoctlKind, cause: nix::Error },
+    InvalidRequest(usize, usize),
+    Offset(u32),
+}
+
+pub(crate) fn ioctl_err(kind: IoctlKind, cause: nix::Error) -> Error {
+    Error {
+        kind: ErrorKind::Ioctl { kind, cause },
+    }
+}
+
+pub(crate) fn invalid_err(n_lines: usize, n_values: usize) -> Error {
+    Error {
+        kind: ErrorKind::InvalidRequest(n_lines, n_values),
+    }
+}
+
+pub(crate) fn offset_err(offset: u32) -> Error {
+    Error {
+        kind: ErrorKind::Offset(offset),
+    }
+}
+
+pub(crate) fn event_err(err: nix::Error) -> Error {
+    Error {
+        kind: ErrorKind::Event(err),
+    }
+}
+
+impl fmt::Display for IoctlKind {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            IoctlKind::ChipInfo => write!(f, "get chip info"),
+            IoctlKind::LineInfo => write!(f, "get line info"),
+            IoctlKind::LineHandle => write!(f, "get line handle"),
+            IoctlKind::LineEvent => write!(f, "get line event "),
+            IoctlKind::GetLine => write!(f, "get line value"),
+            IoctlKind::SetLine => write!(f, "set line value"),
+        }
+    }
+}
+
+impl fmt::Display for Error {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match &self.kind {
+            ErrorKind::Event(err) => write!(f, "Failed to read event: {}", err),
+            ErrorKind::Io(err) => err.fmt(f),
+            ErrorKind::Ioctl { cause, kind } => write!(f, "Ioctl to {} failed: {}", kind, cause),
+            ErrorKind::InvalidRequest(n_lines, n_values) => write!(
+                f,
+                "Invalid request: {} values requested to be set but only {} lines are open",
+                n_values, n_lines
+            ),
+            ErrorKind::Offset(offset) => write!(f, "Offset {} is out of range", offset),
+        }
+    }
+}
+
+impl StdError for Error {
+    fn source(&self) -> Option<&(dyn StdError + 'static)> {
+        match &self.kind {
+            ErrorKind::Event(err) => Some(err),
+            ErrorKind::Io(err) => Some(err),
+            ErrorKind::Ioctl { kind: _, cause } => Some(cause),
+            _ => None,
+        }
+    }
+}
+
+impl From<IOError> for Error {
+    fn from(err: IOError) -> Error {
+        Error {
+            kind: ErrorKind::Io(err),
+        }
     }
 }

src/ffi.rs

@@ -6,6 +6,7 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+use super::errors::IoctlKind;
 use libc;
 
 pub const GPIOHANDLES_MAX: usize = 64;
@@ -56,10 +57,52 @@ pub struct gpioevent_data {
     pub id: u32,
 }
 
-ioctl_read!(gpio_get_chipinfo_ioctl, 0xB4, 0x01, gpiochip_info);
-ioctl_readwrite!(gpio_get_lineinfo_ioctl, 0xB4, 0x02, gpioline_info);
-ioctl_readwrite!(gpio_get_linehandle_ioctl, 0xB4, 0x03, gpiohandle_request);
-ioctl_readwrite!(gpio_get_lineevent_ioctl, 0xB4, 0x04, gpioevent_request);
+macro_rules! wrap_ioctl {
+    ($ioctl_macro:ident!($name:ident, $ioty:expr, $nr:expr, $ty:ident), $ioctl_error_type:expr) => {
+        mod $name {
+            $ioctl_macro!($name, $ioty, $nr, super::$ty);
+        }
 
-ioctl_readwrite!(gpiohandle_get_line_values_ioctl, 0xB4, 0x08, gpiohandle_data);
-ioctl_readwrite!(gpiohandle_set_line_values_ioctl, 0xB4, 0x09, gpiohandle_data);
+        pub(crate) fn $name(fd: libc::c_int, data: &mut $ty) -> crate::errors::Result<libc::c_int> {
+            unsafe {
+                $name::$name(fd, data).map_err(|e| crate::errors::ioctl_err($ioctl_error_type, e))
+            }
+        }
+    };
+}
+
+wrap_ioctl!(
+    ioctl_read!(gpio_get_chipinfo_ioctl, 0xB4, 0x01, gpiochip_info),
+    IoctlKind::ChipInfo
+);
+wrap_ioctl!(
+    ioctl_readwrite!(gpio_get_lineinfo_ioctl, 0xB4, 0x02, gpioline_info),
+    IoctlKind::LineInfo
+);
+wrap_ioctl!(
+    ioctl_readwrite!(gpio_get_linehandle_ioctl, 0xB4, 0x03, gpiohandle_request),
+    IoctlKind::LineHandle
+);
+wrap_ioctl!(
+    ioctl_readwrite!(gpio_get_lineevent_ioctl, 0xB4, 0x04, gpioevent_request),
+    IoctlKind::LineEvent
+);
+
+wrap_ioctl!(
+    ioctl_readwrite!(
+        gpiohandle_get_line_values_ioctl,
+        0xB4,
+        0x08,
+        gpiohandle_data
+    ),
+    IoctlKind::GetLine
+);
+wrap_ioctl!(
+    ioctl_readwrite!(
+        gpiohandle_set_line_values_ioctl,
+        0xB4,
+        0x09,
+        gpiohandle_data
+    ),
+    IoctlKind::SetLine
+);