src/pxar/decoder.rs

   1 //! *pxar* format decoder for seekable files
   2 //!
   3 //! This module contain the code to decode *pxar* archive files.
   4
   5 use failure::*;
   6
   7 use super::format_definition::*;
   8 use super::sequential_decoder::*;
   9
  10 use std::io::{Read, Seek, SeekFrom};
  11 use std::path::{Path, PathBuf};
  12
  13 use std::ffi::OsString;
  14
  15
  16 pub struct DirectoryEntry {
  17     start: u64,
  18     end: u64,
  19     pub filename: OsString,
  20     pub entry: PxarEntry,
  21 }
  22
  23 // This one needs Read+Seek
  24 pub struct Decoder<R: Read + Seek, F: Fn(&Path) -> Result<(), Error>> {
  25     inner: SequentialDecoder<R, F>,
  26     root_start: u64,
  27     root_end: u64,
  28 }
  29
  30 const HEADER_SIZE: u64 = std::mem::size_of::<PxarHeader>() as u64;
  31
  32 impl <R: Read + Seek, F: Fn(&Path) -> Result<(), Error>> Decoder<R, F> {
  33
  34     pub fn new(mut reader: R, callback: F) -> Result<Self, Error> {
  35
  36         let root_end = reader.seek(SeekFrom::End(0))?;
  37
  38         Ok(Self {
  39             inner: SequentialDecoder::new(reader, super::flags::DEFAULT, callback),
  40             root_start: 0,
  41             root_end: root_end,
  42         })
  43     }
  44
  45     pub fn root(&self) -> DirectoryEntry {
  46         DirectoryEntry {
  47             start: self.root_start,
  48             end: self.root_end,
  49             filename: OsString::new(), // Empty
  50             entry: PxarEntry {
  51                 mode: 0,
  52                 flags: 0,
  53                 uid: 0,
  54                 gid: 0,
  55                 mtime: 0,
  56             }
  57         }
  58     }
  59
  60     fn seek(&mut self, pos: SeekFrom) -> Result<u64, Error> {
  61         let pos = self.inner.get_reader_mut().seek(pos)?;
  62         Ok(pos)
  63     }
  64
  65     pub fn restore(
  66         &mut self,
  67         dir: &DirectoryEntry,
  68         path: &Path,
  69     ) -> Result<(), Error> {
  70         let start = dir.start;
  71
  72         self.seek(SeekFrom::Start(start))?;
  73
  74         self.inner.restore(path, &Vec::new())?;
  75
  76         Ok(())
  77     }
  78
  79     fn read_directory_entry(&mut self, start: u64, end: u64) -> Result<DirectoryEntry, Error> {
  80
  81         self.seek(SeekFrom::Start(start))?;
  82
  83         let head: PxarHeader = self.inner.read_item()?;
  84
  85         if head.htype != PXAR_FILENAME {
  86             bail!("wrong filename header type for object [{}..{}]", start, end);
  87         }
  88
  89         let entry_start = start + head.size;
  90
  91         let filename = self.inner.read_filename(head.size)?;
  92
  93         let head: PxarHeader = self.inner.read_item()?;
  94         check_ca_header::<PxarEntry>(&head, PXAR_ENTRY)?;
  95         let entry: PxarEntry = self.inner.read_item()?;
  96
  97         Ok(DirectoryEntry {
  98             start: entry_start,
  99             end: end,
 100             filename: filename,
 101             entry,
 102         })
 103     }
 104
 105     pub fn list_dir(&mut self, dir: &DirectoryEntry) -> Result<Vec<DirectoryEntry>, Error> {
 106
 107         const GOODBYE_ITEM_SIZE: u64 = std::mem::size_of::<PxarGoodbyeItem>() as u64;
 108
 109         let start = dir.start;
 110         let end = dir.end;
 111
 112         //println!("list_dir1: {} {}", start, end);
 113
 114         if (end - start) < (HEADER_SIZE + GOODBYE_ITEM_SIZE) {
 115             bail!("detected short object [{}..{}]", start, end);
 116         }
 117
 118         self.seek(SeekFrom::Start(end - GOODBYE_ITEM_SIZE))?;
 119
 120         let item: PxarGoodbyeItem = self.inner.read_item()?;
 121
 122         if item.hash != PXAR_GOODBYE_TAIL_MARKER {
 123             bail!("missing goodbye tail marker for object [{}..{}]", start, end);
 124         }
 125
 126         let goodbye_table_size = item.size;
 127         if goodbye_table_size < (HEADER_SIZE + GOODBYE_ITEM_SIZE) {
 128             bail!("short goodbye table size for object [{}..{}]", start, end);
 129
 130         }
 131         let goodbye_inner_size = goodbye_table_size - HEADER_SIZE - GOODBYE_ITEM_SIZE;
 132         if (goodbye_inner_size % GOODBYE_ITEM_SIZE) != 0 {
 133             bail!("wrong goodbye inner table size for entry [{}..{}]", start, end);
 134         }
 135
 136         let goodbye_start = end - goodbye_table_size;
 137
 138         if item.offset != (goodbye_start - start) {
 139             println!("DEBUG: {} {}", u64::from_le(item.offset), goodbye_start - start);
 140             bail!("wrong offset in goodbye tail marker for entry [{}..{}]", start, end);
 141         }
 142
 143         self.seek(SeekFrom::Start(goodbye_start))?;
 144         let head: PxarHeader = self.inner.read_item()?;
 145
 146         if head.htype != PXAR_GOODBYE {
 147             bail!("wrong goodbye table header type for entry [{}..{}]", start, end);
 148         }
 149
 150         if head.size != goodbye_table_size {
 151             bail!("wrong goodbye table size for entry [{}..{}]", start, end);
 152         }
 153
 154         let mut range_list = Vec::new();
 155
 156         for i in 0..goodbye_inner_size/GOODBYE_ITEM_SIZE {
 157             let item: PxarGoodbyeItem = self.inner.read_item()?;
 158
 159             if item.offset > (goodbye_start - start) {
 160                 bail!("goodbye entry {} offset out of range [{}..{}] {} {} {}",
 161                       i, start, end, item.offset, goodbye_start, start);
 162             }
 163             let item_start = goodbye_start - item.offset;
 164             let item_end = item_start + item.size;
 165             if item_end > goodbye_start {
 166                 bail!("goodbye entry {} end out of range [{}..{}]",
 167                       i, start, end);
 168             }
 169
 170             range_list.push((item_start, item_end));
 171         }
 172
 173         let mut result = vec![];
 174
 175         for (item_start, item_end) in range_list {
 176             let entry = self.read_directory_entry(item_start, item_end)?;
 177             //println!("ENTRY: {} {} {:?}", item_start, item_end, entry.filename);
 178             result.push(entry);
 179         }
 180
 181         Ok(result)
 182     }
 183
 184     pub fn print_filenames<W: std::io::Write>(
 185         &mut self,
 186         output: &mut W,
 187         prefix: &mut PathBuf,
 188         dir: &DirectoryEntry,
 189     ) -> Result<(), Error> {
 190
 191         let mut list = self.list_dir(dir)?;
 192
 193         list.sort_unstable_by(|a, b| a.filename.cmp(&b.filename));
 194
 195         for item in &list {
 196
 197             prefix.push(item.filename.clone());
 198
 199             let mode = item.entry.mode as u32;
 200
 201             let ifmt = mode & libc::S_IFMT;
 202
 203             writeln!(output, "{:?}", prefix)?;
 204
 205             if ifmt == libc::S_IFDIR {
 206                 self.print_filenames(output, prefix, item)?;
 207             } else if ifmt == libc::S_IFREG {
 208             } else if ifmt == libc::S_IFLNK {
 209             } else if ifmt == libc::S_IFBLK {
 210             } else if ifmt == libc::S_IFCHR {
 211             } else {
 212                 bail!("unknown item mode/type for {:?}", prefix);
 213             }
 214
 215             prefix.pop();
 216         }
 217
 218         Ok(())
 219     }
 220 }