1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99

use crate::db::DB;
use anyhow::anyhow;
use serde::{Deserialize, Serialize};
use std::os::unix::io::FromRawFd;

pub struct UnixFileLoader<'a>(pub &'a std::path::PathBuf);

impl<'a> UnixFileLoader<'a> {
    pub fn new(filename: &'a std::path::PathBuf) -> Self {
        Self(filename)
    }

    pub async fn load<T>(&self) -> T
    where
        T: DB + Serialize + for<'de> Deserialize<'de> + Default,
    {
        self.load_with_locking().await.unwrap_or_default()
    }

    async fn load_with_locking<T>(&self) -> Result<T, anyhow::Error>
    where
        T: DB + Serialize + for<'de> Deserialize<'de>,
    {
        unsafe {
            let fd = nix::libc::open(
                std::ffi::CString::from_vec_unchecked(self.0.to_str().unwrap().as_bytes().to_vec())
                    .as_ptr(),
                nix::libc::O_RDONLY,
            );
            if fd < 0 {
                return Err(anyhow!(std::ffi::CStr::from_ptr(nix::libc::strerror(
                    nix::errno::errno()
                ))
                .to_str()
                .unwrap()
                .to_string()));
            }

            if nix::libc::flock(fd, nix::libc::LOCK_EX) != 0 {
                return Err(anyhow!(std::ffi::CStr::from_ptr(nix::libc::strerror(
                    nix::errno::errno()
                ))
                .to_str()
                .unwrap()
                .to_string()));
            }

            Ok(ciborium::from_reader(std::fs::File::from_raw_fd(fd))?)
        }
    }

    pub async fn dump<T>(&self, mut db: T) -> Result<(), anyhow::Error>
    where
        T: DB + Serialize + for<'de> Deserialize<'de>,
    {
        unsafe {
            let fd = nix::libc::open(
                std::ffi::CString::from_vec_unchecked(self.0.to_str().unwrap().as_bytes().to_vec())
                    .as_ptr(),
                nix::libc::O_WRONLY | nix::libc::O_TRUNC | nix::libc::O_CREAT,
            );
            if fd < 0 {
                return Err(anyhow!(std::ffi::CStr::from_ptr(nix::libc::strerror(
                    nix::errno::errno()
                ))
                .to_str()
                .unwrap()
                .to_string()));
            }

            if nix::libc::flock(fd, nix::libc::LOCK_EX) != 0 {
                return Err(anyhow!(std::ffi::CStr::from_ptr(nix::libc::strerror(
                    nix::errno::errno()
                ))
                .to_str()
                .unwrap()
                .to_string()));
            }

            if nix::libc::chmod(
                std::ffi::CString::from_vec_unchecked(self.0.to_str().unwrap().as_bytes().to_vec())
                    .as_ptr(),
                nix::libc::S_IRUSR | nix::libc::S_IWUSR,
            ) != 0
            {
                return Err(anyhow!(std::ffi::CStr::from_ptr(nix::libc::strerror(
                    nix::errno::errno()
                ))
                .to_str()
                .unwrap()
                .to_string()));
            }

            db.update_recurrence().await?;

            Ok(ciborium::into_writer(&db, std::fs::File::from_raw_fd(fd))?)
        }
    }
}