feat(args): add --system flag for preloading from system directories

systeroid-core/src/sysctl/mod.rs

@@ -10,9 +10,19 @@ pub mod display;
 /// Kernel parameter.
 pub mod parameter;
 
-/// Default location to preload values.
+/// Default configuration file to preload values from.
 pub const DEFAULT_PRELOAD: &str = "/etc/sysctl.conf";
 
+/// Default system configuration files to preload values from.
+pub const SYSTEM_PRELOAD: &[&str] = &[
+    "/etc/sysctl.d",
+    "/run/sysctl.d",
+    "/usr/local/lib/sysctl.d",
+    "/usr/lib/sysctl.d",
+    "/lib/sysctl.d",
+    DEFAULT_PRELOAD,
+];
+
 /// Deprecated variables to skip while listing.
 /// <https://bugzilla.redhat.com/show_bug.cgi?id=152435>
 pub const DEPRECATED_VARIABLES: &[&str] = &["base_reachable_time", "retrans_time"];

systeroid-parser/src/lib.rs

@@ -5,6 +5,9 @@
 /// Export regex crate.
 pub use regex;
 
+/// Export globwalk crate.
+pub use globwalk;
+
 /// Document parser.
 pub mod parser;
 

systeroid/src/app.rs

@@ -7,7 +7,8 @@ use systeroid_core::error::Result;
 use systeroid_core::parsers::KERNEL_DOCS_PATH;
 use systeroid_core::regex::Regex;
 use systeroid_core::sysctl::controller::Sysctl;
-use systeroid_core::sysctl::DEPRECATED_VARIABLES;
+use systeroid_core::sysctl::{DEPRECATED_VARIABLES, SYSTEM_PRELOAD};
+use systeroid_parser::globwalk;
 use systeroid_parser::reader;
 
 /// Label for caching the kernel parameters.
@@ -181,4 +182,27 @@ impl<'a> App<'a> {
         }
         Ok(())
     }
+
+    /// Processes the parameters in files that are in predefined system directories.
+    pub fn preload_from_system(&mut self) -> Result<()> {
+        for preload_path in SYSTEM_PRELOAD
+            .iter()
+            .map(|v| PathBuf::from(v).join("*.conf"))
+        {
+            if let Ok(glob_walker) = globwalk::glob(preload_path.to_string_lossy()) {
+                for file in glob_walker.filter_map(|v| v.ok()) {
+                    println!("* Applying {} ...", file.path().display());
+                    let contents = reader::read_to_string(file.path())?;
+                    for parameter in contents.lines() {
+                        if let Err(e) = self.process_parameter(parameter.to_string(), false, false)
+                        {
+                            eprintln!("{}: {}", env!("CARGO_PKG_NAME"), e);
+                        }
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
 }

systeroid/src/args.rs

@@ -36,6 +36,8 @@ pub struct Args {
     pub no_pager: bool,
     /// Whether if files are given to preload values.
     pub preload_files: bool,
+    /// Whether if the values will be preloaded from system.
+    pub preload_system_files: bool,
     /// Pattern for matching the variables.
     pub pattern: Option<Regex>,
     /// Whether if the documentation should be shown.
@@ -62,6 +64,7 @@ impl Args {
         opts.optflag("b", "binary", "print only variable values without new line");
         opts.optflag("p", "load", "read values from file");
         opts.optflag("f", "", "alias of -p");
+        opts.optflag("S", "system", "read values from all system directories");
         opts.optopt(
             "r",
             "pattern",
@@ -100,6 +103,7 @@ impl Args {
         let required_args_present = !matches.free.is_empty()
             || display_all
             || preload_files
+            || matches.opt_present("S")
             || matches.opt_present("r")
             || matches.opt_present("E");
 
@@ -151,6 +155,7 @@ impl Args {
                 ignore_errors: matches.opt_present("e"),
                 no_pager: matches.opt_present("P"),
                 preload_files,
+                preload_system_files: matches.opt_present("S"),
                 pattern: matches
                     .opt_str("r")
                     .map(|v| Regex::new(&v).expect("invalid regex")),

systeroid/src/lib.rs

@@ -28,7 +28,9 @@ pub fn run(args: Args) -> Result<()> {
     let mut sysctl = Sysctl::init(config)?;
     let mut app = App::new(&mut sysctl)?;
 
-    if args.values.is_empty() {
+    if args.preload_system_files {
+        app.preload_from_system()?;
+    } else if args.values.is_empty() {
         app.display_parameters(args.pattern, args.display_deprecated)?;
     } else if args.explain_params {
         app.update_documentation(args.kernel_docs.as_ref())?;