Add root syspath and hwmon functionality

src/hwmon.rs

@@ -0,0 +1,179 @@
+use std::path::{Path, PathBuf};
+use std::convert::AsRef;
+use std::io::Result as IoResult;
+
+const HWMON_DIR_PATH: &'static str = "sys/class/hwmon/";
+
+/// Attribute representation.
+/// Attribute files are usually in the format `<type><number>_<item>`.
+#[derive(Clone, Copy)]
+pub struct HwMonAttribute {
+   inner: HwMonAttributeInner,
+}
+
+#[derive(Clone, Copy)]
+enum HwMonAttributeInner {
+    Name,
+    Standard {
+        ty: HwMonAttributeType,
+        number: u64,
+        item: HwMonAttributeItem,
+    },
+    Uevent,
+}
+
+/// Attribute type in the format `<type><number>_<item>`
+#[derive(Clone, Copy)]
+pub enum HwMonAttributeType {
+    /// Voltage
+    In,
+    /// Temperature
+    Temp,
+    /// Fan
+    Fan,
+    /// Current
+    Curr,
+}
+
+impl HwMonAttributeType {
+    fn to_attr_str(&self) -> &str {
+        match self {
+            Self::In => "in",
+            Self::Temp => "out",
+            Self::Fan => "fan",
+            Self::Curr => "curr",
+        }
+    }
+}
+
+/// Attribute item in the format `<type><number>_<item>`
+#[derive(Clone, Copy)]
+pub enum HwMonAttributeItem {
+    /// Input
+    Input,
+    /// Minimum
+    Min,
+    /// Maximum
+    Max,
+}
+
+impl HwMonAttributeItem {
+    fn to_attr_str(&self) -> &str {
+        match self {
+            Self::Input => "input",
+            Self::Min => "min",
+            Self::Max => "max",
+        }
+    }
+}
+
+impl HwMonAttribute {
+    /// `name` attribute
+    pub const fn name() -> Self {
+        Self {
+            inner: HwMonAttributeInner::Name
+        }
+    }
+    
+    /// Custom attribute in standard format
+    pub const fn new(ty: HwMonAttributeType, number: u64, item: HwMonAttributeItem) -> Self {
+        Self {
+            inner: HwMonAttributeInner::Standard { ty, number, item }
+        }
+    }
+    
+    /// `uevent` attribute
+    pub const fn uevent() -> Self {
+        Self {
+            inner: HwMonAttributeInner::Uevent
+        }
+    }
+    
+    fn to_attr_str(&self) -> String {
+        match self.inner {
+            HwMonAttributeInner::Name => "name".to_string(),
+            HwMonAttributeInner::Standard { ty, number, item } => format!("{}{}_{}", ty.to_attr_str(), number, item.to_attr_str()),
+            HwMonAttributeInner::Uevent => "uevent".to_string(),
+        }
+    }
+}
+/// hwmon<number>/ directory
+pub struct HwMonPath {
+    path: PathBuf
+}
+
+impl HwMonPath {
+    pub(crate) fn all(root: impl AsRef<Path>) -> IoResult<impl Iterator<Item=IoResult<Self>>> {
+        let hwmon_dir_path = root.as_ref().join(HWMON_DIR_PATH);
+        hwmon_dir_path.read_dir()
+            .map(
+                |iter| iter.filter_map(
+                    |entry| entry.map(
+                        |entry| if crate::os_str_util::starts_with(&entry.file_name(), "hwmon".as_ref()) {
+                            Some(Self {
+                                path: entry.path(),
+                            })
+                        } else {
+                            None
+                        }).transpose()))
+    }
+    
+    /// Get a hwmon entry by index. 
+    /// This does not check if it exists.
+    pub(crate) fn entry(root: &crate::SysPath, i: u64) -> Self {
+        Self {
+            path: root.as_ref().join(HWMON_DIR_PATH).join(format!("hwmon{}", i)),
+        }
+    }
+    
+    /// Get a hwmon entry by name, if it exists
+    pub(crate) fn name(root: &crate::SysPath, name: &str) -> IoResult<Option<Self>> {
+        for entry in Self::all(root)? {
+            let entry = entry?;
+            if entry.attribute(HwMonAttribute::name())? == name {
+                return Ok(Some(entry))
+            }
+        }
+        Ok(None)
+    }
+    
+    /// Get a hwmon attribute (file contents) by attribute filename.
+    /// It is recommended to use HwMon.attribute unless the attribute has a non-standard name
+    pub fn attribute_str(&self, name: &str) -> IoResult<String> {
+        std::fs::read_to_string(self.path.join(name))
+    }
+    
+    /// Get a hwmon attribute (file contents)
+    pub fn attribute(&self, attr: HwMonAttribute) -> IoResult<String> {
+        self.attribute_str(&attr.to_attr_str())
+    }
+    
+    /// Get the path to a hwmon attribute.
+    /// Use `HwMonPath.as_ref().join(attribute_str)` for non-standard attributes
+    pub fn path_to(&self, attr: HwMonAttribute) -> PathBuf {
+        self.path.join(&attr.to_attr_str())
+    }
+}
+
+impl AsRef<Path> for HwMonPath {
+    fn as_ref(&self) -> &Path {
+        self.path.as_path()
+    }
+}
+
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn hwmon_all() -> std::io::Result<()> {
+        let sys = crate::SysPath::default();
+        let all_hwmon: Vec<_> = HwMonPath::all(sys)?.collect();
+        assert!(!all_hwmon.is_empty());
+        for hwmon in all_hwmon.into_iter() {
+            assert!(hwmon?.attribute(HwMonAttribute::name())? != "");
+        }
+        Ok(())
+    }
+}

src/lib.rs

@@ -1,6 +1,16 @@
-pub fn add(left: usize, right: usize) -> usize {
-    left + right
-}
+#![warn(missing_docs)]
+//! Utility library for manipulating files in the Linux sysfs
+//!
+
+pub(crate) const DEFAULT_ROOT: &'static str = "/";
+
+mod hwmon;
+pub use hwmon::{HwMonPath, HwMonAttribute, HwMonAttributeType, HwMonAttributeItem};
+
+mod syspath;
+pub use syspath::SysPath;
+
+pub(crate) mod os_str_util;
 
 #[cfg(test)]
 mod tests {
@@ -8,7 +18,7 @@ mod tests {
 
     #[test]
     fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+        SysPath::default();
+        SysPath::path("/");
     }
 }

src/os_str_util.rs

@@ -0,0 +1,12 @@
+use std::ffi::OsStr;
+use std::os::unix::ffi::OsStrExt;
+
+pub fn starts_with(src: &OsStr, contains: &OsStr) -> bool {
+    let src_bytes = src.as_bytes();
+    for (index, byte) in contains.as_bytes().iter().enumerate() {
+        if src_bytes[index] != *byte {
+            return false;
+        }
+    }
+    true
+}

src/syspath.rs

@@ -0,0 +1,47 @@
+use std::path::{Path, PathBuf};
+use std::convert::AsRef;
+
+/// sysfs root
+pub struct SysPath {
+    root: PathBuf,
+}
+
+impl SysPath {
+    /// Initialize with a custom root.
+    /// Use SysPath::default() to use the default root `/`.
+    pub fn path(root: impl AsRef<Path>) -> Self {
+        Self {
+            root: root.as_ref().to_path_buf()
+        }
+    }
+    
+    /// Find a hardware monitor entry by name
+    pub fn hwmon_by_name(&self, name: &str) -> std::io::Result<crate::HwMonPath> {
+        match crate::HwMonPath::name(self, name) {
+            Ok(None) => Err(std::io::Error::from_raw_os_error(std::io::ErrorKind::NotFound as _)),
+            Ok(Some(x)) => Ok(x),
+            Err(e) => Err(e)
+        }
+    }
+    
+    /// Find a hardware monitor entry by index
+    pub fn hwmon_by_index(&self, index: u64) -> std::io::Result<crate::HwMonPath> {
+        let entry = crate::HwMonPath::entry(self, index);
+        entry.attribute(crate::HwMonAttribute::name())?;
+        Ok(entry)
+    }
+}
+
+impl std::default::Default for SysPath {
+    fn default() -> Self {
+        Self {
+            root: PathBuf::from(crate::DEFAULT_ROOT)
+        }
+    }
+}
+
+impl AsRef<Path> for SysPath {
+    fn as_ref(&self) -> &Path {
+        self.root.as_path()
+    }
+}