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
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
use std::env;
use std::ffi::{CString, OsStr};
use std::fs::{self, File, OpenOptions};
use std::io;
use std::os::unix::ffi::OsStrExt;
use std::os::unix::fs::{MetadataExt, OpenOptionsExt};
use std::path::Path;
use crate::util;

#[cfg(not(target_os = "redox"))]
use libc::{c_char, c_int, link, rename, unlink};

#[cfg(not(target_os = "redox"))]
#[inline(always)]
pub fn cvt_err(result: c_int) -> io::Result<c_int> {
    if result == -1 {
        Err(io::Error::last_os_error())
    } else {
        Ok(result)
    }
}

#[cfg(target_os = "redox")]
#[inline(always)]
pub fn cvt_err(result: Result<usize, syscall::Error>) -> io::Result<usize> {
    result.map_err(|err| io::Error::from_raw_os_error(err.errno))
}

// Stolen from std.
pub fn cstr(path: &Path) -> io::Result<CString> {
    CString::new(path.as_os_str().as_bytes())
        .map_err(|_| io::Error::new(io::ErrorKind::InvalidInput, "path contained a null"))
}

pub fn create_named(world_accessible: bool, path: &Path, open_options: &mut OpenOptions) -> io::Result<File> {
    open_options
        .read(true)
        .write(true)
        .create_new(true)
        .mode(if world_accessible { 0o666 } else { 0o600 })
        .open(path)
}

fn create_unlinked(path: &Path) -> io::Result<File> {
    let tmp;
    // shadow this to decrease the lifetime. It can't live longer than `tmp`.
    let mut path = path;
    if !path.is_absolute() {
        let cur_dir = env::current_dir()?;
        tmp = cur_dir.join(path);
        path = &tmp;
    }

    let f = create_named(false, path, &mut OpenOptions::new())?;
    // don't care whether the path has already been unlinked,
    // but perhaps there are some IO error conditions we should send up?
    let _ = fs::remove_file(path);
    Ok(f)
}

#[cfg(target_os = "linux")]
pub fn create(dir: &Path) -> io::Result<File> {
    use libc::{EISDIR, ENOENT, EOPNOTSUPP, O_EXCL, O_TMPFILE};
    OpenOptions::new()
        .read(true)
        .write(true)
        .custom_flags(O_TMPFILE | O_EXCL) // do not mix with `create_new(true)`
        .open(dir)
        .or_else(|e| {
            match e.raw_os_error() {
                // These are the three "not supported" error codes for O_TMPFILE.
                Some(EOPNOTSUPP) | Some(EISDIR) | Some(ENOENT) => create_unix(dir),
                _ => Err(e),
            }
        })
}

#[cfg(not(target_os = "linux"))]
pub fn create(dir: &Path) -> io::Result<File> {
    create_unix(dir)
}

fn create_unix(dir: &Path) -> io::Result<File> {
    util::create_helper(
        dir,
        false,
        OsStr::new(".tmp"),
        OsStr::new(""),
        crate::NUM_RAND_CHARS,
        |_world_accessible, path| create_unlinked(&path),
    )
}

pub fn reopen(file: &File, path: &Path) -> io::Result<File> {
    let new_file = OpenOptions::new().read(true).write(true).open(path)?;
    let old_meta = file.metadata()?;
    let new_meta = new_file.metadata()?;
    if old_meta.dev() != new_meta.dev() || old_meta.ino() != new_meta.ino() {
        return Err(io::Error::new(
            io::ErrorKind::NotFound,
            "original tempfile has been replaced",
        ));
    }
    Ok(new_file)
}

#[cfg(not(target_os = "redox"))]
pub fn persist(old_path: &Path, new_path: &Path, overwrite: bool) -> io::Result<()> {
    unsafe {
        let old_path = cstr(old_path)?;
        let new_path = cstr(new_path)?;
        if overwrite {
            cvt_err(rename(
                old_path.as_ptr() as *const c_char,
                new_path.as_ptr() as *const c_char,
            ))?;
        } else {
            cvt_err(link(
                old_path.as_ptr() as *const c_char,
                new_path.as_ptr() as *const c_char,
            ))?;
            // Ignore unlink errors. Can we do better?
            // On recent linux, we can use renameat2 to do this atomically.
            let _ = unlink(old_path.as_ptr() as *const c_char);
        }
        Ok(())
    }
}

#[cfg(target_os = "redox")]
pub fn persist(old_path: &Path, new_path: &Path, overwrite: bool) -> io::Result<()> {
    // XXX implement when possible
    Err(io::Error::from_raw_os_error(syscall::ENOSYS))
}

pub fn keep(_: &Path) -> io::Result<()> {
    Ok(())
}