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

[Dietmar Maurer]

applied

On 4/22/21 4:01 PM, Wolfgang Bumiller wrote:
> Signed-off-by: Wolfgang Bumiller <w.bumiller at 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());
> +}