Implement ionice

Cargo.toml

@@ -33,6 +33,7 @@ feat_common_core = [
   "dmesg",
   "fsfreeze",
   "hexdump",
+  "ionice",
   "last",
   "lscpu",
   "lsipc",
@@ -106,6 +107,7 @@ ctrlaltdel = { optional = true, version = "0.0.1", package = "uu_ctrlaltdel", pa
 dmesg = { optional = true, version = "0.0.1", package = "uu_dmesg", path = "src/uu/dmesg" }
 fsfreeze = { optional = true, version = "0.0.1", package = "uu_fsfreeze", path = "src/uu/fsfreeze" }
 hexdump = { optional = true, version = "0.0.1", package = "uu_hexdump", path = "src/uu/hexdump" }
+ionice = { optional = true, version = "0.0.1", package = "uu_ionice", path = "src/uu/ionice" }
 last = { optional = true, version = "0.0.1", package = "uu_last", path = "src/uu/last" }
 lscpu = { optional = true, version = "0.0.1", package = "uu_lscpu", path = "src/uu/lscpu" }
 lsipc = { optional = true, version = "0.0.1", package = "uu_lsipc", path = "src/uu/lsipc" }

src/uu/ionice/Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "uu_ionice"
+version = "0.0.1"
+edition = "2021"
+description = "ionice ~ (uutils) Show or change the I/O-scheduling class and priority of a process"
+
+[lib]
+path = "src/ionice.rs"
+
+[[bin]]
+name = "ionice"
+path = "src/main.rs"
+
+[dependencies]
+clap = { workspace = true }
+libc = { workspace = true }
+thiserror = { workspace = true }
+uucore = { workspace = true }

src/uu/ionice/ionice.md

@@ -0,0 +1,10 @@
+# ionice
+
+```
+ionice [options] -p <pid>...
+ionice [options] -P <pgid>...
+ionice [options] -u <uid>...
+ionice [options] <command>
+```
+
+Show or change the I/O-scheduling class and priority of a process

src/uu/ionice/src/errors.rs

@@ -0,0 +1,107 @@
+// This file is part of the uutils util-linux package.
+//
+// For the full copyright and license information, please view the LICENSE
+// file that was distributed with this source code.
+// spell-checker:ignore (words) ERANGE ioprio pgid strerror
+
+use std::fmt;
+use std::io;
+
+use uucore::error::{strip_errno, UError};
+
+/// Which option a numeric argument came from. Supplies the middle of the
+/// "invalid ... argument" message.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum NumericArg {
+    Class,
+    ClassData,
+    Pid,
+    Pgid,
+    Uid,
+}
+
+impl fmt::Display for NumericArg {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(match self {
+            Self::Class => "class",
+            Self::ClassData => "class data",
+            Self::Pid => "PID",
+            Self::Pgid => "PGID",
+            Self::Uid => "UID",
+        })
+    }
+}
+
+/// Trailing detail on a numeric argument error: nothing when the text was
+/// merely malformed, strerror(ERANGE) when it did not fit in an i32, and the
+/// bounds themselves when it fell outside a range ionice(1) documents.
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) enum NumericDetail {
+    Malformed,
+    Overflow,
+    OutOfRange { low: i32, high: i32 },
+}
+
+impl fmt::Display for NumericDetail {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Malformed => Ok(()),
+            Self::Overflow => {
+                let range = io::Error::from_raw_os_error(libc::ERANGE);
+                write!(f, ": {}", strip_errno(&range))
+            }
+            Self::OutOfRange { low, high } => write!(f, ": must be {low}-{high}"),
+        }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub(crate) enum IoniceError {
+    #[error("invalid {arg} argument: '{value}'{detail}")]
+    InvalidNumber {
+        arg: NumericArg,
+        value: String,
+        detail: NumericDetail,
+    },
+
+    #[error("unknown scheduling class: '{0}'")]
+    UnknownClass(String),
+
+    #[error("can handle only one of pid, pgid or uid at once")]
+    ConflictingIdKinds,
+
+    // The hint is built here rather than left to UError::usage(), which spells
+    // out execution_phrase() - the whole multicall binary path - instead of the
+    // utility name.
+    #[error(
+        "bad usage\nTry '{} --help' for more information.",
+        uucore::util_name()
+    )]
+    BadUsage,
+
+    #[error("ioprio_get failed: {}", strip_errno(.0))]
+    GetFailed(io::Error),
+
+    #[error("ioprio_set failed: {}", strip_errno(.0))]
+    SetFailed(io::Error),
+}
+
+impl IoniceError {
+    pub(crate) fn invalid_number(arg: NumericArg, value: &str, detail: NumericDetail) -> Self {
+        Self::InvalidNumber {
+            arg,
+            value: value.to_owned(),
+            detail,
+        }
+    }
+}
+
+impl UError for IoniceError {
+    fn code(&self) -> i32 {
+        1
+    }
+
+    fn usage(&self) -> bool {
+        false
+    }
+}