microsoft/openvmm
Publicmirrored from https://github.com/microsoft/openvmmAvailable
flowey/flowey_cli/src/var_db/single_json_file.rs
89lines · modecode
| 1 | // Copyright (c) Microsoft Corporation. |
| 2 | // Licensed under the MIT License. |
| 3 | |
| 4 | //! A dead simple runtime variable db, backed by a single JSON file. |
| 5 | |
| 6 | use anyhow::Context; |
| 7 | use fs_err::File; |
| 8 | use serde::Deserialize; |
| 9 | use serde::Serialize; |
| 10 | use std::collections::BTreeMap; |
| 11 | use std::io::Seek; |
| 12 | use std::io::Write; |
| 13 | use std::path::Path; |
| 14 | |
| 15 | /// On-disk format for the var db |
| 16 | #[derive(Serialize, Deserialize)] |
| 17 | #[serde(transparent)] |
| 18 | struct VarDb { |
| 19 | vars: BTreeMap<String, (bool, serde_json::Value)>, |
| 20 | } |
| 21 | |
| 22 | /// Implements [`flowey_core::node::RuntimeVarDb`] backed by a JSON file. |
| 23 | pub struct SingleJsonFileVarDb { |
| 24 | file: File, |
| 25 | } |
| 26 | |
| 27 | impl SingleJsonFileVarDb { |
| 28 | pub fn new(backing_file: impl AsRef<Path>) -> anyhow::Result<Self> { |
| 29 | let backing_file = backing_file.as_ref(); |
| 30 | let exists = backing_file.exists(); |
| 31 | let mut file = fs_err::OpenOptions::new() |
| 32 | .read(true) |
| 33 | .write(true) |
| 34 | .create(true) |
| 35 | .open(backing_file) |
| 36 | .context("failed to open/create database file")?; |
| 37 | |
| 38 | // seed the database file with an empty json map |
| 39 | if !exists { |
| 40 | eprintln!( |
| 41 | "seeding new empty database file: {}", |
| 42 | backing_file.display() |
| 43 | ); |
| 44 | file.write_all(b"{}")?; |
| 45 | } |
| 46 | |
| 47 | Ok(Self { file }) |
| 48 | } |
| 49 | |
| 50 | fn load_db(&mut self) -> VarDb { |
| 51 | self.file.rewind().unwrap(); |
| 52 | serde_json::from_reader(&self.file).expect("corrupt runtime variable db") |
| 53 | } |
| 54 | } |
| 55 | |
| 56 | impl flowey_core::node::RuntimeVarDb for SingleJsonFileVarDb { |
| 57 | fn try_get_var(&mut self, var_name: &str) -> Option<Vec<u8>> { |
| 58 | let db = self.load_db(); |
| 59 | let (is_secret, val) = db.vars.get(var_name)?; |
| 60 | let val = val.to_string(); |
| 61 | if *is_secret { |
| 62 | log::debug!("[db] read var: {} = <secret>", var_name); |
| 63 | } else { |
| 64 | log::debug!("[db] read var: {} = {}", var_name, val); |
| 65 | } |
| 66 | Some(val.into()) |
| 67 | } |
| 68 | |
| 69 | fn set_var(&mut self, var_name: &str, is_secret: bool, value: Vec<u8>) { |
| 70 | if is_secret { |
| 71 | log::debug!("[db] set var: {} = <secret>", var_name) |
| 72 | } else { |
| 73 | log::debug!( |
| 74 | "[db] set var: {} = {}", |
| 75 | var_name, |
| 76 | String::from_utf8_lossy(&value) |
| 77 | ) |
| 78 | }; |
| 79 | let mut db = self.load_db(); |
| 80 | let existing = db.vars.insert( |
| 81 | var_name.into(), |
| 82 | (is_secret, serde_json::from_slice(&value).unwrap()), |
| 83 | ); |
| 84 | assert!(existing.is_none()); // all vars are one-time-write |
| 85 | self.file.set_len(0).unwrap(); |
| 86 | self.file.rewind().unwrap(); |
| 87 | serde_json::to_writer(&self.file, &db).expect("failed to write to db JSON"); |
| 88 | } |
| 89 | } |
| 90 | |