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#[macro_use]
extern crate error_chain;
extern crate integer_encoding;
use std::io::prelude::*;
use std::io::SeekFrom;
use std::path::Path;
use std::fs::File;
use integer_encoding::FixedInt;
use std::fs::OpenOptions;
mod errors {
// Create the Error, ErrorKind, ResultExt, and Result types
error_chain! {
foreign_links { Fmt(::std::fmt::Error);
Io(::std::io::Error) #[cfg(unix)]; }
}
}
pub use errors::*;
// Abstract access to SLEEP content
pub trait SleepStorage {
fn get_magic(&self) -> u32;
fn get_algorithm(&self) -> Option<String>;
fn get_entry_size(&self) -> u16;
fn read(&mut self, index: u64) -> Result<Vec<u8>>;
fn write(&mut self, index: u64, data: &[u8]) -> Result<()>;
fn length(&self) -> Result<u64>;
}
#[derive(Debug)]
pub struct SleepFile {
file: File,
magic: u32,
entry_size: u16,
// Option isn't necessary here... idiomatic?
algorithm_name: Option<String>,
}
impl SleepFile {
// TODO: 'from' pre-existing File
pub fn open(path: &Path, writable: bool) -> Result<SleepFile> {
let mut f = OpenOptions::new()
.read(true)
.write(writable)
.create(false)
.open(path)?;
let mut header = [0; 32];
f.read_exact(&mut header)?;
let version: u8 = header[4];
if version != 0 {
return Err("Invalid SLEEP header: version must be 0".into());
}
let algo_len: u8 = header[7];
if algo_len > 24 {
return Err("Invalid SLEEP header: can't have algo_len > 24".into());
}
let algorithm_name = if algo_len == 0 { None } else {
Some(String::from_utf8_lossy(&header[8..(8+(algo_len as usize))]).into_owned())
};
Ok(SleepFile {
file: f,
magic: u32::from_be(FixedInt::decode_fixed(&header[0..4])),
entry_size: u16::from_be(FixedInt::decode_fixed(&header[5..7])),
algorithm_name: algorithm_name,
})
}
pub fn create(path: &Path, magic: u32, entry_size: u16, algo: Option<String>) -> Result<SleepFile> {
// This function will *not* allow overwriting an existing file.
let mut header = [0; 32];
u32::to_be(magic).encode_fixed(&mut header[0..4]);
header[4] = 0; // version
u16::to_be(entry_size).encode_fixed(&mut header[5..7]);
if let Some(name) = algo.clone() {
let name = name.as_bytes();
let algo_len = name.len();
if algo_len > 24 {
return Err("Algorithm name must be 24 bytes at most".into());
}
header[7] = algo_len as u8;
header[8..(8+algo_len)].clone_from_slice(name);
} else {
header[7] = 0;
};
let mut f = OpenOptions::new()
.read(true)
.write(true)
.create_new(true)
.open(path)?;
f.write_all(&header)?;
Ok(SleepFile {
file: f,
magic: magic,
entry_size: entry_size,
algorithm_name: algo,
})
}
}
impl SleepStorage for SleepFile {
fn get_magic(&self) -> u32 { self.magic }
fn get_algorithm(&self) -> Option<String> { self.algorithm_name.clone() }
fn get_entry_size(&self) -> u16 { self.entry_size }
fn read(&mut self, index: u64) -> Result<Vec<u8>> {
let entry_size = self.entry_size as usize;
if index + 1 > self.length()? {
return Err("Tried to read beyond end of SLEEP file".into());
}
let mut entry = vec![0; entry_size];
self.file.seek(SeekFrom::Start(32 + (entry_size as u64) * index))?;
self.file.read_exact(&mut entry)?;
Ok(entry)
}
fn write(&mut self, index: u64, data: &[u8]) -> Result<()> {
// TODO: need to extend file seek beyond end?
if data.len() != self.entry_size as usize {
return Err("Tried to write mis-sized data".into());
}
self.file.seek(SeekFrom::Start(32 + (self.entry_size as u64) * index))?;
self.file.write_all(&data)?;
Ok(())
}
fn length(&self) -> Result<u64> {
let length = self.file.metadata()?.len();
if length < 32 || (length - 32) % (self.entry_size as u64) != 0 {
return Err("Bad SLEEP file: missing header or not multiple of entry_size".into());
}
return Ok((length - 32) / (self.entry_size as u64))
}
}
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