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    data_root().map(|r| r.join(game_id))
31}
32
33/// `<data dir>/gasm`: saves live in subdirectories, `keymap.txt` next to them.
34pub fn data_root() -> Option<PathBuf> {
35    let base = if cfg!(target_os = "macos") {
36        std::env::var_os("HOME").map(|h| PathBuf::from(h).join("Library/Application Support"))
37    } else if cfg!(windows) {
38        std::env::var_os("APPDATA").map(PathBuf::from)
39    } else {
40        std::env::var_os("XDG_DATA_HOME")
41            .map(PathBuf::from)
42            .or_else(|| std::env::var_os("HOME").map(|h| PathBuf::from(h).join(".local/share")))
43    };
44    base.map(|b| b.join("gasm"))
45}
46
47impl Storage {
48    pub fn memory() -> Storage {
49        Storage { dir: None, values: HashMap::new() }
50    }
51
52    /// Open (creating if needed) a directory-backed store and load its values.
53    pub fn open(dir: PathBuf) -> Result<Storage, String> {
54        std::fs::create_dir_all(&dir).map_err(|e| format!("{}: {e}", dir.display()))?;
55        let mut values = HashMap::new();
56        for entry in std::fs::read_dir(&dir).map_err(|e| e.to_string())?.flatten() {
57            let name = entry.file_name().to_string_lossy().into_owned();
58            if valid_key(&name) && entry.path().is_file() {
59                if let Ok(v) = std::fs::read(entry.path()) {
60                    values.insert(name, v);
61                }
62            }
63        }
64        Ok(Storage { dir: Some(dir), values })
65    }
66
67    pub fn location(&self) -> String {
68        self.dir.as_ref().map_or("memory".into(), |d| d.display().to_string())
69    }
70
71    pub fn get(&self, key: &str) -> Option<&[u8]> {
72        self.values.get(key).map(Vec::as_slice)
73    }
74
75    pub fn set(&mut self, key: &str, value: &[u8]) -> Result<(), String> {
76        if !valid_key(key) {
77            return Err(format!("invalid key {key:?}"));
78        }
79        if value.len() > MAX_VALUE {
80            return Err(format!("value for {key:?} is {} bytes (max {MAX_VALUE})", value.len()));
81        }
82        let used: usize = self.values.iter().filter(|(k, _)| k.as_str() != key).map(|(k, v)| k.len() + v.len()).sum();
83        if used + key.len() + value.len() > QUOTA {
84            return Err(format!("storage quota of {QUOTA} bytes exceeded"));
85        }
86        if let Some(dir) = &self.dir {
87            let tmp = dir.join(format!(".{key}.tmp"));
88            std::fs::write(&tmp, value).map_err(|e| e.to_string())?;
89            std::fs::rename(&tmp, dir.join(key)).map_err(|e| e.to_string())?;
90        }
91        self.values.insert(key.to_owned(), value.to_vec());
92        Ok(())
93    }
94
95    pub fn delete(&mut self, key: &str) -> bool {
96        if self.values.remove(key).is_none() {
97            return false;
98        }
99        if let Some(dir) = &self.dir {
100            let _ = std::fs::remove_file(dir.join(key));
101        }
102        true
103    }
104}
gasm_host/storage.rs

gasm_host/
storage.rs
