🔧 Support <include>

Implemented by iterating over the `Vec<Element>`, inspired by work by @elmarco , although this version doesn't have all the same features and validations as dbus2#23

src/config.rs

@@ -1,4 +1,7 @@
-use std::{collections::HashSet, path::PathBuf};
+use std::{
+    collections::HashSet,
+    path::{Path, PathBuf},
+};
 
 use anyhow::{Error, Result};
 use serde::Deserialize;
@@ -90,6 +93,7 @@ impl TryFrom<Document> for Config {
                     bc.auth.insert(s);
                 }
                 Element::Fork => bc.fork = true,
+                Element::Include(_) => { /* no-op */ }
                 Element::KeepUmask => bc.keep_umask = true,
                 Element::Limit => {
                     warn!("warning: busd does not implement `<limit>`");
@@ -142,6 +146,11 @@ impl Config {
         let doc: Document = quick_xml::de::from_str(s)?;
         Self::try_from(doc)
     }
+
+    pub fn read_file(file_path: impl AsRef<Path>) -> Result<Self> {
+        let doc = Document::read_file(file_path)?;
+        Self::try_from(doc)
+    }
 }
 
 #[derive(Clone, Debug, Deserialize, PartialEq)]

src/config/xml.rs

@@ -1,6 +1,13 @@
-use std::path::PathBuf;
+use std::{
+    env::current_dir,
+    fs::read_to_string,
+    path::{Path, PathBuf},
+    str::FromStr,
+};
 
+use anyhow::{Error, Result};
 use serde::Deserialize;
+use tracing::{error, warn};
 
 use super::{BusType, MessageType};
 
@@ -14,6 +21,92 @@ use super::{BusType, MessageType};
 pub struct Document {
     #[serde(rename = "$value", default)]
     pub busconfig: Vec<Element>,
+    file_path: Option<PathBuf>,
+}
+impl FromStr for Document {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        quick_xml::de::from_str(s).map_err(Error::msg)
+    }
+}
+impl Document {
+    pub fn read_file(file_path: impl AsRef<Path>) -> Result<Document> {
+        let text = read_to_string(file_path.as_ref())?;
+        let mut doc = Document::from_str(&text)?;
+        doc.file_path = Some(file_path.as_ref().to_path_buf());
+        doc.resolve_includes()
+    }
+
+    fn resolve_includes(self) -> Result<Document> {
+        // TODO: implement protection against circular `<include>` references
+        let base_path = self.base_path()?;
+        let Document {
+            busconfig,
+            file_path,
+        } = self;
+
+        let mut doc = Document {
+            busconfig: vec![],
+            file_path: None,
+        };
+
+        for el in busconfig {
+            match el {
+                Element::Include(include) => {
+                    let ignore_missing = include.ignore_missing == IncludeOption::Yes;
+                    let file_path = match resolve_include_path(&base_path, &include.file_path) {
+                        Ok(ok) => ok,
+                        Err(err) => {
+                            let msg = format!(
+                                "'{}' should be a valid file path",
+                                include.file_path.display()
+                            );
+                            if ignore_missing {
+                                warn!(msg);
+                                continue;
+                            }
+                            error!(msg);
+                            return Err(err);
+                        }
+                    };
+                    let mut included = match Document::read_file(&file_path) {
+                        Ok(ok) => ok,
+                        Err(err) => {
+                            let msg = format!(
+                                "'{}' should contain valid XML",
+                                include.file_path.display()
+                            );
+                            if ignore_missing {
+                                warn!(msg);
+                                continue;
+                            }
+                            error!(msg);
+                            return Err(err);
+                        }
+                    };
+                    doc.busconfig.append(&mut included.busconfig);
+                }
+                _ => doc.busconfig.push(el),
+            }
+        }
+
+        doc.file_path = file_path;
+        Ok(doc)
+    }
+
+    fn base_path(&self) -> Result<PathBuf> {
+        match &self.file_path {
+            Some(some) => Ok(some
+                .parent()
+                .ok_or_else(|| Error::msg("`<include>` path should contain a file name"))?
+                .to_path_buf()),
+            None => {
+                warn!("ad-hoc document with unknown file path, using current working directory");
+                current_dir().map_err(Error::msg)
+            }
+        }
+    }
 }
 
 #[derive(Clone, Debug, Deserialize, PartialEq)]
@@ -22,9 +115,9 @@ pub enum Element {
     AllowAnonymous,
     Auth(String),
     Fork,
+    Include(IncludeElement),
+    // TODO: support `<includedir>`
     KeepUmask,
-    // TODO: support `<include ignore_missing=(yes|no) if_selinux_enabled=(yes|no)
-    // selinux_root_relative=(yes|no)>` TODO: support `<includedir>`
     Listen(String),
     Limit,
     Pidfile(PathBuf),
@@ -43,6 +136,29 @@ pub enum Element {
     User(String),
 }
 
+#[derive(Clone, Debug, Default, Deserialize, PartialEq)]
+pub struct IncludeElement {
+    #[serde(default, rename = "@ignore_missing")]
+    ignore_missing: IncludeOption,
+
+    // TODO: implement SELinux
+    #[serde(default, rename = "@if_selinux_enabled")]
+    if_selinux_enable: IncludeOption,
+    #[serde(default, rename = "@selinux_root_relative")]
+    selinux_root_relative: IncludeOption,
+
+    #[serde(rename = "$value")]
+    file_path: PathBuf,
+}
+
+#[derive(Clone, Debug, Default, Deserialize, PartialEq)]
+#[serde(rename_all = "lowercase")]
+pub enum IncludeOption {
+    #[default]
+    No,
+    Yes,
+}
+
 #[derive(Clone, Debug, Deserialize, PartialEq)]
 #[serde(rename_all = "snake_case")]
 pub enum PolicyContext {
@@ -137,3 +253,19 @@ pub struct TypeElement {
     #[serde(rename = "$text")]
     pub r#type: BusType,
 }
+
+fn resolve_include_path(
+    base_path: impl AsRef<Path>,
+    include_path: impl AsRef<Path>,
+) -> Result<PathBuf> {
+    let p = include_path.as_ref();
+    if p.is_absolute() {
+        return p.canonicalize().map_err(Error::msg);
+    }
+
+    base_path
+        .as_ref()
+        .join(p)
+        .canonicalize()
+        .map_err(Error::msg)
+}

tests/config.rs

@@ -0,0 +1,51 @@
+use std::collections::HashSet;
+
+use busd::config::{Access, Config, Name, Operation, OwnOperation, Policy};
+
+#[test]
+fn config_read_file_with_includes_ok() {
+    let got = Config::read_file("./tests/fixture.conf")
+        .expect("should read and parse ./tests/fixture.conf");
+
+    assert_eq!(
+        got,
+        Config {
+            auth: HashSet::from_iter(vec![String::from("ANONYMOUS"), String::from("EXTERNAL"),]),
+            listen: HashSet::from_iter(vec![
+                String::from("unix:path=/tmp/foo"),
+                String::from("tcp:host=localhost,port=1234"),
+            ]),
+            policies: vec![
+                Policy::DefaultContext(vec![
+                    (
+                        Access::Allow,
+                        Operation::Own(OwnOperation {
+                            own: Some(Name::Any)
+                        })
+                    ),
+                    (
+                        Access::Deny,
+                        Operation::Own(OwnOperation {
+                            own: Some(Name::Any)
+                        })
+                    ),
+                ]),
+                Policy::MandatoryContext(vec![
+                    (
+                        Access::Deny,
+                        Operation::Own(OwnOperation {
+                            own: Some(Name::Any)
+                        })
+                    ),
+                    (
+                        Access::Allow,
+                        Operation::Own(OwnOperation {
+                            own: Some(Name::Any)
+                        })
+                    ),
+                ],),
+            ],
+            ..Default::default()
+        }
+    );
+}

tests/fixture.conf

@@ -0,0 +1,12 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+    <auth>ANONYMOUS</auth>
+    <listen>unix:path=/tmp/foo</listen>
+    <policy context="default">
+        <allow own="*"/>
+        <deny own="*"/>
+    </policy>
+    <include>./fixture_included.conf</include>
+    <include ignore_missing="yes">./fixture_missing.conf</include>
+</busconfig>

tests/fixture_included.conf

@@ -0,0 +1,10 @@
+<!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-Bus Bus Configuration 1.0//EN"
+    "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
+<busconfig>
+    <auth>EXTERNAL</auth>
+    <listen>tcp:host=localhost,port=1234</listen>
+    <policy context="mandatory">
+        <deny own="*"/>
+        <allow own="*"/>
+    </policy>
+</busconfig>