treefile: Support multiple includes

I'm working on having Silverblue inherit from Fedora CoreOS.  But
conceptually it also inherits from (parts of) Workstation.
It is just easier if we support multiple inheritance, then I don't
need to think too hard about how to make it a single inheritance chain.

Closes: #1870
Approved by: jlebon

docs/manual/treefile.md

@@ -216,11 +216,13 @@ It supports the following parameters:
    are provided, then `postprocess-script` will be executed after all
    other `postprocess`.
 
- * `include`: string, optional: Path to another treefile which will be
+ * `include`: string or array of string, optional: Path(s) to treefiles which will be
    used as an inheritance base.  The semantics for inheritance are:
    Non-array values in child values override parent values.  Array
    values are concatenated.  Filenames will be resolved relative to
-   the including treefile.
+   the including treefile.  Since rpm-ostree 2019.5, this value may
+   also be an array of strings.  Including the same file multiple times
+   is an error.
 
  * `container`: boolean, optional: Defaults to `false`.  If `true`, then
    rpm-ostree will not do any special handling of kernel, initrd or the

rust/src/treefile.rs

@@ -21,7 +21,7 @@
  * */
 
 use c_utf8::CUtf8Buf;
-use failure::Fallible;
+use failure::{Fallible, bail};
 use openat;
 use serde_derive::{Deserialize, Serialize};
 use serde_json;
@@ -30,6 +30,8 @@ use std::collections::{HashMap, BTreeMap};
 use std::io::prelude::*;
 use std::path::Path;
 use std::{collections, fs, io};
+use std::os::unix::fs::MetadataExt;
+use std::collections::btree_map::Entry;
 
 use crate::utils;
 
@@ -213,14 +215,28 @@ fn load_passwd_file<P: AsRef<Path>>(
     return Ok(None);
 }
 
+type IncludeMap = collections::BTreeMap<(u64, u64), String>;
+
 /// Given a treefile filename and an architecture, parse it and also
 /// open its external files.
 fn treefile_parse<P: AsRef<Path>>(
     filename: P,
     basearch: Option<&str>,
+    seen_includes: &mut IncludeMap,
 ) -> Fallible<ConfigAndExternals> {
     let filename = filename.as_ref();
-    let mut f = io::BufReader::new(utils::open_file(filename)?);
+    let f = utils::open_file(filename)?;
+    let meta = f.metadata()?;
+    let devino = (meta.dev(), meta.ino());
+    match seen_includes.entry(devino) {
+        Entry::Occupied(_) => {
+            bail!("Include loop detected; {} was already included", filename.to_str().unwrap())
+        },
+        Entry::Vacant(e) => {
+            e.insert(filename.to_str().unwrap().to_string());
+        }
+    };
+    let mut f = io::BufReader::new(f);
     let basename = filename
         .file_name()
         .map(|s| s.to_string_lossy())
@@ -379,11 +395,16 @@ fn treefile_parse_recurse<P: AsRef<Path>>(
     filename: P,
     basearch: Option<&str>,
     depth: u32,
+    seen_includes: &mut IncludeMap,
 ) -> Fallible<ConfigAndExternals> {
     let filename = filename.as_ref();
-    let mut parsed = treefile_parse(filename, basearch)?;
+    let mut parsed = treefile_parse(filename, basearch, seen_includes)?;
-    let include_path = parsed.config.include.take();
+    let include = parsed.config.include.take().unwrap_or_else(|| Include::Multiple(Vec::new()));
-    if let &Some(ref include_path) = &include_path {
+    let includes = match include {
+        Include::Single(v) => vec![v],
+        Include::Multiple(v) => v,
+    };
+    for include_path in includes.iter() {
         if depth == INCLUDE_MAXDEPTH {
             return Err(io::Error::new(
                 io::ErrorKind::InvalidInput,
@@ -393,7 +414,7 @@ fn treefile_parse_recurse<P: AsRef<Path>>(
         }
         let parent = filename.parent().unwrap();
         let include_path = parent.join(include_path);
-        let mut included = treefile_parse_recurse(include_path, basearch, depth + 1)?;
+        let mut included = treefile_parse_recurse(include_path, basearch, depth + 1, seen_includes)?;
         treefile_merge(&mut parsed.config, &mut included.config);
         treefile_merge_externals(&mut parsed.externals, &mut included.externals);
     }
@@ -419,7 +440,8 @@ impl Treefile {
         basearch: Option<&str>,
         workdir: openat::Dir,
     ) -> Fallible<Box<Treefile>> {
-        let mut parsed = treefile_parse_recurse(filename, basearch, 0)?;
+        let mut seen_includes = collections::BTreeMap::new();
+        let mut parsed = treefile_parse_recurse(filename, basearch, 0, &mut seen_includes)?;
         parsed.config = parsed.config.substitute_vars()?;
         Treefile::validate_config(&parsed.config)?;
         let dfd = openat::Dir::open(filename.parent().unwrap())?;
@@ -612,6 +634,13 @@ struct Rojig {
     description: Option<String>,
 }
 
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(untagged)]
+enum Include {
+    Single(String),
+    Multiple(Vec<String>)
+}
+
 // Because of how we handle includes, *everything* here has to be
 // Option<T>.  The defaults live in the code (e.g. machineid-compat defaults
 // to `true`).
@@ -634,7 +663,7 @@ struct TreeComposeConfig {
     #[serde(rename = "gpg-key")]
     gpg_key: Option<String>,
     #[serde(skip_serializing_if = "Option::is_none")]
-    include: Option<String>,
+    include: Option<Include>,
 
     // Core content
     #[serde(skip_serializing_if = "Option::is_none")]

tests/compose-tests/test-misc-tweaks.sh

@@ -6,15 +6,20 @@ dn=$(cd $(dirname $0) && pwd)
 . ${dn}/libcomposetest.sh
 
 prepare_compose_test "misc-tweaks"
-# No docs
+# No docs, also test multi includes
-pysetjsonmember "documentation" "False"
+cat >composedata/documentation.yaml <<'EOF'
+documentation: false
+EOF
+cat > composedata/recommends.yaml <<'EOF'
+recommends: false
+EOF
+pysetjsonmember "include" '["documentation.yaml", "recommends.yaml"]'
 # Note this overrides:
 # $ rpm -q systemd
 # systemd-238-8.git0e0aa59.fc28.x86_64
 # $ rpm -qlv systemd|grep -F 'system/default.target '
 # lrwxrwxrwx    1 root    root                       16 May 11 06:59 /usr/lib/systemd/system/default.target -> graphical.target
 pysetjsonmember "default_target" '"multi-user.target"'
-pysetjsonmember "recommends" 'False'
 pysetjsonmember "units" '["tuned.service"]'
 # And test adding/removing files
 pysetjsonmember "add-files" '[["foo.txt", "/usr/etc/foo.txt"],