Add ability to set user/group/mode on exported sysfs gpio entries

In systems where gpio-utils is being used to export entries, it is
useful to be able to setup permissions in this same system.

Signed-off-by: Paul Osborne <[email protected]>

Author: posborne

Cargo.lock

@@ -1,11 +1,11 @@
 [package]
 name = "gpio-utils"
-version = "0.1.2"
+version = "0.2.0"
 authors = ["Paul Osborne <[email protected]>"]
 license = "MIT/Apache-2.0"
 readme = "README.md"
 homepage = "https://github.com/rust-embedded/gpio-utils"
-keywords = ["gpio", "linux", "sysfs_gpoi", "cli", "command-line"]
+keywords = ["gpio", "linux", "sysfs_gpio", "cli", "command-line"]
 description = """
 Command-line utilities for interacting with GPIOs under Linux
 
@@ -15,21 +15,16 @@ Rust applications or any other applications.
 
 [dependencies]
 clap = "2.2"
+error-chain = "0.12"
 sysfs_gpio = "0.5.2"
 toml = "0.4"
 glob = "0.2"
-log = "0.3"
-env_logger = "0.3"
+log = "0.4"
+env_logger = "0.5"
+nix = "0.11"
 serde_derive = "1.0"
 serde = "1.0"
-
-[dependencies.clippy]
-version = "0.0"
-optional = true
-
-[features]
-default = []
-lints = ["clippy"]
+users = "0.8"
 
 [[bin]]
 name = "gpio"

Cargo.toml

@@ -29,6 +29,7 @@ cargo install gpio-utils
 - [x] Ability to get/set gpio values by pin number or name (including temporary
       export if necessary)
 - [x] Ability to block awaiting pin state change (with timeout)
+- [x] Ability to set exported GPIO permissions
 
 ## System Integration
 
@@ -66,14 +67,19 @@ how you can configure your GPIOs.
 #    be reversed.
 # - `export`: Default: `true`.  If true, this GPIO will be automatically
 #    exported when `gpio export-all` is run (e.g. by an init script).
-#
+# - `user`: User that should own the exported GPIO
+# - `group`: Group that should own the exported GPIO
+# - `mode`: Mode for exported directory
 
 [[pins]]
 num = 73                 # required
 names = ["reset_button"] # required (may have multiple)
 direction = "in"         # default: in
 active_low = false       # default: false (really means invert logic)
 export = true            # default: true
+user = "root"            # default: (OS Default - root)
+group = "gpio"           # default: (OS Default - root)
+mode = 0o664             # default: (OS Default - 0o644)
 
 [[pins]]
 num = 37

README.md

@@ -53,6 +53,9 @@ pub struct PinConfig {
     pub export: bool,
     #[serde(default)]
     pub active_low: bool,
+    pub user: Option<String>,
+    pub group: Option<String>,
+    pub mode: Option<u32>,
 }
 
 fn default_direction()-> sysfs_gpio::Direction {

src/config.rs

@@ -0,0 +1,23 @@
+// Copyright (c) 2018, The gpio-utils Authors.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/license/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.
+
+use sysfs_gpio::Error as GpioError;
+use nix::Error as NixError;
+use std::io::Error as IoError;
+
+error_chain! {
+    types {
+        Error, ErrorKind, ResultExt, Result;
+    }
+
+    foreign_links {
+        Gpio(GpioError);
+        Nix(NixError);
+        Io(IoError);
+    }
+}

src/error.rs

@@ -8,10 +8,14 @@
 
 use std::path;
 use std::os::unix::fs as unix_fs;
+use std::os::unix::fs::PermissionsExt;
 use std::fs;
 use std::io::ErrorKind;
 use config::PinConfig;
+use nix::unistd::{chown, Gid, Uid};
 use sysfs_gpio;
+use users::{get_user_by_name, get_group_by_name};
+use error::*;
 
 /// Unexport the pin specified in the provided config
 ///
@@ -26,7 +30,7 @@ use sysfs_gpio;
 /// without an error as the desired end state is achieved.
 pub fn unexport(pin_config: &PinConfig,
                 symlink_root: Option<&str>)
-                -> Result<(), sysfs_gpio::Error> {
+                -> Result<()> {
     if let Some(symroot) = symlink_root {
         // create symlink for each name
         for name in &pin_config.names {
@@ -48,7 +52,7 @@ pub fn unexport(pin_config: &PinConfig,
     match pin.unexport() {
         Ok(_) => Ok(()),
         Err(sysfs_gpio::Error::Io(ref e)) if e.kind() == ErrorKind::InvalidInput => Ok(()),
-        Err(e) => Err(e)
+        Err(e) => Err(e.into())
     }
 }
 
@@ -63,10 +67,34 @@ pub fn unexport(pin_config: &PinConfig,
 ///
 /// If the GPIO is already exported, this function will continue
 /// without an error as the desired end state is achieved.
-pub fn export(pin_config: &PinConfig, symlink_root: Option<&str>) -> Result<(), sysfs_gpio::Error> {
+pub fn export(pin_config: &PinConfig, symlink_root: Option<&str>) -> Result<()> {
     let pin = pin_config.get_pin();
     try!(pin.export());
 
+    // change user, group, mode for files in gpio directory
+    for entry in fs::read_dir(format!("/sys/class/gpio/gpio{}", &pin_config.num))? {
+        let e = entry?;
+        let metadata = e.metadata()?;
+
+        let user = pin_config.user.as_ref().and_then(|username| get_user_by_name(username));
+        let group = pin_config.group.as_ref().and_then(|groupname| get_group_by_name(groupname));
+
+        if metadata.is_file() {
+            if user.is_some() && group.is_some() {
+                chown(e.path().as_path(),
+                      user.as_ref().map(|u| Uid::from_raw(u.uid())),
+                      group.as_ref().map(|g| Gid::from_raw(g.gid())))?;
+            }
+
+            if let Some(mode) = pin_config.mode {
+                let mut permissions = metadata.permissions();
+                permissions.set_mode(mode);
+                fs::set_permissions(e.path().as_path(), permissions)?;
+            }
+        }
+    }
+
+
     // if there is a symlink root provided, create symlink
     if let Some(symroot) = symlink_root {
         // create root directory if not exists

src/export.rs

@@ -6,13 +6,19 @@
 // option.  This file may not be copied, modified, or distributed
 // except according to those terms.
 
-extern crate sysfs_gpio;
-extern crate toml;
+#[macro_use]
+extern crate error_chain;
 extern crate glob;
 extern crate log;
+extern crate nix;
 extern crate serde;
-#[macro_use] extern crate serde_derive;
+#[macro_use]
+extern crate serde_derive;
+extern crate sysfs_gpio;
+extern crate toml;
+extern crate users;
 
+pub mod error;
 pub mod options;
 pub mod config;
 pub mod commands;

src/lib.rs

@@ -17,7 +17,7 @@ use gpio_utils::config::{self, GpioConfig};
 use std::process::exit;
 
 fn main() {
-    env_logger::init().unwrap();
+    env_logger::init();
 
     let matches = App::new("GPIO Utils")
         .version(env!("CARGO_PKG_VERSION"))