[pbs-devel] [PATCH v2 backup 12/27] add 'config file format' to tools::config

[Wolfgang Bumiller <w.bumiller@proxmox.com>]

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
---
* Replaces the serde-based parser from v1. Outside API stays similar (with
  `from_str`, `from_property_string`, `to_bytes` ...
* Added a very simple testcase.

 src/tools.rs        |   1 +
 src/tools/config.rs | 171 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 172 insertions(+)
 create mode 100644 src/tools/config.rs

diff --git a/src/tools.rs b/src/tools.rs
index 890db826..25323881 100644
--- a/src/tools.rs
+++ b/src/tools.rs
@@ -23,6 +23,7 @@ pub mod async_io;
 pub mod borrow;
 pub mod cert;
 pub mod compression;
+pub mod config;
 pub mod cpio;
 pub mod daemon;
 pub mod disks;
diff --git a/src/tools/config.rs b/src/tools/config.rs
new file mode 100644
index 00000000..499bd187
--- /dev/null
+++ b/src/tools/config.rs
@@ -0,0 +1,171 @@
+//! Our 'key: value' config format.
+
+use std::io::Write;
+
+use anyhow::{bail, format_err, Error};
+use serde::{Deserialize, Serialize};
+use serde_json::Value;
+
+use proxmox::api::schema::{
+    parse_property_string, parse_simple_value, verify_json_object, ObjectSchemaType, Schema,
+};
+
+type Object = serde_json::Map<String, Value>;
+
+fn object_schema(schema: &'static Schema) -> Result<&'static dyn ObjectSchemaType, Error> {
+    Ok(match schema {
+        Schema::Object(schema) => schema,
+        Schema::AllOf(schema) => schema,
+        _ => bail!("invalid schema for config, must be an object schema"),
+    })
+}
+
+/// Parse a full string representing a config file.
+pub fn from_str<T: for<'de> Deserialize<'de>>(
+    input: &str,
+    schema: &'static Schema,
+) -> Result<T, Error> {
+    Ok(serde_json::from_value(value_from_str(input, schema)?)?)
+}
+
+/// Parse a full string representing a config file.
+pub fn value_from_str(input: &str, schema: &'static Schema) -> Result<Value, Error> {
+    let schema = object_schema(schema)?;
+
+    let mut config = Object::new();
+
+    for (lineno, line) in input.lines().enumerate() {
+        let line = line.trim();
+        if line.starts_with('#') || line.is_empty() {
+            continue;
+        }
+
+        parse_line(&mut config, line, schema)
+            .map_err(|err| format_err!("line {}: {}", lineno, err))?;
+    }
+
+    Ok(Value::Object(config))
+}
+
+/// Parse a single `key: value` line from a config file.
+fn parse_line(
+    config: &mut Object,
+    line: &str,
+    schema: &'static dyn ObjectSchemaType,
+) -> Result<(), Error> {
+    if line.starts_with('#') || line.is_empty() {
+        return Ok(());
+    }
+
+    let colon = line
+        .find(':')
+        .ok_or_else(|| format_err!("missing colon to separate key from value"))?;
+    if colon == 0 {
+        bail!("empty key not allowed");
+    }
+
+    let key = &line[..colon];
+    let value = line[(colon + 1)..].trim_start();
+
+    parse_key_value(config, key, value, schema)
+}
+
+/// Lookup the key in the schema, parse the value and insert it into the config object.
+fn parse_key_value(
+    config: &mut Object,
+    key: &str,
+    value: &str,
+    schema: &'static dyn ObjectSchemaType,
+) -> Result<(), Error> {
+    let schema = match schema.lookup(key) {
+        Some((_optional, schema)) => Some(schema),
+        None if schema.additional_properties() => None,
+        None => bail!(
+            "invalid key '{}' and schema does not allow additional properties",
+            key
+        ),
+    };
+
+    let value = parse_value(value, schema)?;
+    config.insert(key.to_owned(), value);
+    Ok(())
+}
+
+/// For this we can just reuse the schema's "parse_simple_value".
+///
+/// "Additional" properties (`None` schema) will simply become strings.
+///
+/// Note that this does not handle Object or Array types at all, so if we want to support them
+/// natively without going over a `String` type, we can add this here.
+fn parse_value(value: &str, schema: Option<&'static Schema>) -> Result<Value, Error> {
+    match schema {
+        None => Ok(Value::String(value.to_owned())),
+        Some(schema) => parse_simple_value(value, schema),
+    }
+}
+
+/// Parse a string as a property string into a deserializable type. This is just a short wrapper
+/// around deserializing the s
+pub fn from_property_string<T>(input: &str, schema: &'static Schema) -> Result<T, Error>
+where
+    T: for<'de> Deserialize<'de>,
+{
+    Ok(serde_json::from_value(parse_property_string(
+        input, schema,
+    )?)?)
+}
+
+/// Serialize a data structure using a 'key: value' config file format.
+pub fn to_bytes<T: Serialize>(value: &T, schema: &'static Schema) -> Result<Vec<u8>, Error> {
+    value_to_bytes(&serde_json::to_value(value)?, schema)
+}
+
+/// Serialize a json value using a 'key: value' config file format.
+pub fn value_to_bytes(value: &Value, schema: &'static Schema) -> Result<Vec<u8>, Error> {
+    let schema = object_schema(schema)?;
+
+    verify_json_object(value, schema)?;
+
+    let object = value
+        .as_object()
+        .ok_or_else(|| format_err!("value must be an object"))?;
+
+    let mut out = Vec::new();
+    object_to_writer(&mut out, object)?;
+    Ok(out)
+}
+
+/// Note: the object must have already been verified at this point.
+fn object_to_writer(output: &mut dyn Write, object: &Object) -> Result<(), Error> {
+    for (key, value) in object.iter() {
+        match value {
+            Value::Null => continue, // delete this entry
+            Value::Bool(v) => writeln!(output, "{}: {}", key, v)?,
+            Value::String(v) => writeln!(output, "{}: {}", key, v)?,
+            Value::Number(v) => writeln!(output, "{}: {}", key, v)?,
+            Value::Array(_) => bail!("arrays are not supported in config files"),
+            Value::Object(_) => bail!("complex objects are not supported in config files"),
+        }
+    }
+    Ok(())
+}
+
+#[test]
+fn test() {
+    // let's just reuse some schema we actually have available:
+    use crate::config::node::NodeConfig;
+
+    const NODE_CONFIG: &str = "\
+        acme: account=pebble\n\
+        acmedomain0: test1.invalid.local,plugin=power\n\
+        acmedomain1: test2.invalid.local\n\
+    ";
+
+    let data: NodeConfig = from_str(NODE_CONFIG, &NodeConfig::API_SCHEMA)
+        .expect("failed to parse simple node config");
+
+    let config = to_bytes(&data, &NodeConfig::API_SCHEMA)
+        .expect("failed to serialize node config");
+
+    assert_eq!(config, NODE_CONFIG.as_bytes());
+}
-- 
2.20.1