gasm_host/
storage.rs

1//! gasm:storage for the native runner: one directory per game, one file per key.
2//!
3//! Windowed runs persist under the OS data directory (`--storage-dir` overrides);
4//! headless runs use an in-memory store unless a directory is given, so tests
5//! stay reproducible. Writes go to a temp file and are renamed into place.
6
7use std::collections::HashMap;
8use std::path::PathBuf;
9
10pub const MAX_KEY: usize = 128;
11pub const MAX_VALUE: usize = 1 << 20;
12pub const QUOTA: usize = 16 << 20;
13
14pub struct Storage {
15    dir: Option<PathBuf>,
16    values: HashMap<String, Vec<u8>>,
17}
18
19pub fn valid_key(k: &str) -> bool {
20    !k.is_empty()
21        && k.len() <= MAX_KEY
22        && k.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'.' || b == b'_' || b == b'-')
23        && k != "."
24        && k != ".."
25}
26
27/// Default location: <data dir>/gasm/<game id>, e.g.
28/// ~/Library/Application Support/gasm/sumo on macOS.
29pub fn default_dir(game_id: &str) -> Option<PathBuf> {
30    let base = if cfg!(target_os = "macos") {
31        std::env::var_os("HOME").map(|h| PathBuf::from(h).join("Library/Application Support"))
32    } else if cfg!(windows) {
33        std::env::var_os("APPDATA").map(PathBuf::from)
34    } else {
35        std::env::var_os("XDG_DATA_HOME")
36            .map(PathBuf::from)
37            .or_else(|| std::env::var_os("HOME").map(|h| PathBuf::from(h).join(".local/share")))
38    };
39    base.map(|b| b.join("gasm").join(game_id))
40}
41
42impl Storage {
43    pub fn memory() -> Storage {
44        Storage { dir: None, values: HashMap::new() }
45    }
46
47    /// Open (creating if needed) a directory-backed store and load its values.
48    pub fn open(dir: PathBuf) -> Result<Storage, String> {
49        std::fs::create_dir_all(&dir).map_err(|e| format!("{}: {e}", dir.display()))?;
50        let mut values = HashMap::new();
51        for entry in std::fs::read_dir(&dir).map_err(|e| e.to_string())?.flatten() {
52            let name = entry.file_name().to_string_lossy().into_owned();
53            if valid_key(&name) && entry.path().is_file() {
54                if let Ok(v) = std::fs::read(entry.path()) {
55                    values.insert(name, v);
56                }
57            }
58        }
59        Ok(Storage { dir: Some(dir), values })
60    }
61
62    pub fn location(&self) -> String {
63        self.dir.as_ref().map_or("memory".into(), |d| d.display().to_string())
64    }
65
66    pub fn get(&self, key: &str) -> Option<&[u8]> {
67        self.values.get(key).map(Vec::as_slice)
68    }
69
70    pub fn set(&mut self, key: &str, value: &[u8]) -> Result<(), String> {
71        if !valid_key(key) {
72            return Err(format!("invalid key {key:?}"));
73        }
74        if value.len() > MAX_VALUE {
75            return Err(format!("value for {key:?} is {} bytes (max {MAX_VALUE})", value.len()));
76        }
77        let used: usize = self.values.iter().filter(|(k, _)| k.as_str() != key).map(|(k, v)| k.len() + v.len()).sum();
78        if used + key.len() + value.len() > QUOTA {
79            return Err(format!("storage quota of {QUOTA} bytes exceeded"));
80        }
81        if let Some(dir) = &self.dir {
82            let tmp = dir.join(format!(".{key}.tmp"));
83            std::fs::write(&tmp, value).map_err(|e| e.to_string())?;
84            std::fs::rename(&tmp, dir.join(key)).map_err(|e| e.to_string())?;
85        }
86        self.values.insert(key.to_owned(), value.to_vec());
87        Ok(())
88    }
89
90    pub fn delete(&mut self, key: &str) -> bool {
91        if self.values.remove(key).is_none() {
92            return false;
93        }
94        if let Some(dir) = &self.dir {
95            let _ = std::fs::remove_file(dir.join(key));
96        }
97        true
98    }
99}
gasm_host/storage.rs

gasm_host/
storage.rs
