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 CaDirectoryEntry {
  17     start: u64,
  18     end: u64,
  19     pub filename: OsString,
  20     pub entry: CaFormatEntry,
  21 }
  22
  23 // This one needs Read+Seek
  24 pub struct Decoder<'a, R: Read + Seek> {
  25     inner: SequentialDecoder<'a, R>,
  26     root_start: u64,
  27     root_end: u64,
  28 }
  29
  30 const HEADER_SIZE: u64 = std::mem::size_of::<CaFormatHeader>() as u64;
  31
  32 impl <'a, R: Read + Seek> Decoder<'a, R> {
  33
  34     pub fn new(reader: &'a mut R) -> Result<Self, Error> {
  35
  36         let root_end = reader.seek(SeekFrom::End(0))?;
  37
  38         Ok(Self {
  39             inner: SequentialDecoder::new(reader, CA_FORMAT_DEFAULT),
  40             root_start: 0,
  41             root_end: root_end,
  42         })
  43     }
  44
  45     pub fn root(&self) -> CaDirectoryEntry {
  46         CaDirectoryEntry {
  47             start: self.root_start,
  48             end: self.root_end,
  49             filename: OsString::new(), // Empty
  50             entry: CaFormatEntry {
  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<F>(
  66         &mut self,
  67         dir: &CaDirectoryEntry,
  68         path: &Path,
  69         callback: F,
  70     ) -> Result<(), Error>
  71         where F: Fn(&Path) -> Result<(), Error>
  72     {
  73         let start = dir.start;
  74
  75         self.seek(SeekFrom::Start(start))?;
  76
  77         self.inner.restore(path, &callback)?;
  78
  79         Ok(())
  80     }
  81
  82     fn read_directory_entry(&mut self, start: u64, end: u64) -> Result<CaDirectoryEntry, Error> {
  83
  84         self.seek(SeekFrom::Start(start))?;
  85
  86         let head: CaFormatHeader = self.inner.read_item()?;
  87
  88         if head.htype != CA_FORMAT_FILENAME {
  89             bail!("wrong filename header type for object [{}..{}]", start, end);
  90         }
  91
  92         let entry_start = start + head.size;
  93
  94         let filename = self.inner.read_filename(head.size)?;
  95
  96         let head: CaFormatHeader = self.inner.read_item()?;
  97         check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
  98         let entry: CaFormatEntry = self.inner.read_item()?;
  99
 100         Ok(CaDirectoryEntry {
 101             start: entry_start,
 102             end: end,
 103             filename: filename,
 104             entry,
 105         })
 106     }
 107
 108     pub fn list_dir(&mut self, dir: &CaDirectoryEntry) -> Result<Vec<CaDirectoryEntry>, Error> {
 109
 110         const GOODBYE_ITEM_SIZE: u64 = std::mem::size_of::<CaFormatGoodbyeItem>() as u64;
 111
 112         let start = dir.start;
 113         let end = dir.end;
 114
 115         //println!("list_dir1: {} {}", start, end);
 116
 117         if (end - start) < (HEADER_SIZE + GOODBYE_ITEM_SIZE) {
 118             bail!("detected short object [{}..{}]", start, end);
 119         }
 120
 121         self.seek(SeekFrom::Start(end - GOODBYE_ITEM_SIZE))?;
 122
 123         let item: CaFormatGoodbyeItem = self.inner.read_item()?;
 124
 125         if item.hash != CA_FORMAT_GOODBYE_TAIL_MARKER {
 126             bail!("missing goodbye tail marker for object [{}..{}]", start, end);
 127         }
 128
 129         let goodbye_table_size = item.size;
 130         if goodbye_table_size < (HEADER_SIZE + GOODBYE_ITEM_SIZE) {
 131             bail!("short goodbye table size for object [{}..{}]", start, end);
 132
 133         }
 134         let goodbye_inner_size = goodbye_table_size - HEADER_SIZE - GOODBYE_ITEM_SIZE;
 135         if (goodbye_inner_size % GOODBYE_ITEM_SIZE) != 0 {
 136             bail!("wrong goodbye inner table size for entry [{}..{}]", start, end);
 137         }
 138
 139         let goodbye_start = end - goodbye_table_size;
 140
 141         if item.offset != (goodbye_start - start) {
 142             println!("DEBUG: {} {}", u64::from_le(item.offset), goodbye_start - start);
 143             bail!("wrong offset in goodbye tail marker for entry [{}..{}]", start, end);
 144         }
 145
 146         self.seek(SeekFrom::Start(goodbye_start))?;
 147         let head: CaFormatHeader = self.inner.read_item()?;
 148
 149         if head.htype != CA_FORMAT_GOODBYE {
 150             bail!("wrong goodbye table header type for entry [{}..{}]", start, end);
 151         }
 152
 153         if head.size != goodbye_table_size {
 154             bail!("wrong goodbye table size for entry [{}..{}]", start, end);
 155         }
 156
 157         let mut range_list = Vec::new();
 158
 159         for i in 0..goodbye_inner_size/GOODBYE_ITEM_SIZE {
 160             let item: CaFormatGoodbyeItem = self.inner.read_item()?;
 161
 162             if item.offset > (goodbye_start - start) {
 163                 bail!("goodbye entry {} offset out of range [{}..{}] {} {} {}",
 164                       i, start, end, item.offset, goodbye_start, start);
 165             }
 166             let item_start = goodbye_start - item.offset;
 167             let item_end = item_start + item.size;
 168             if item_end > goodbye_start {
 169                 bail!("goodbye entry {} end out of range [{}..{}]",
 170                       i, start, end);
 171             }
 172
 173             range_list.push((item_start, item_end));
 174         }
 175
 176         let mut result = vec![];
 177
 178         for (item_start, item_end) in range_list {
 179             let entry = self.read_directory_entry(item_start, item_end)?;
 180             //println!("ENTRY: {} {} {:?}", item_start, item_end, entry.filename);
 181             result.push(entry);
 182         }
 183
 184         Ok(result)
 185     }
 186
 187     pub fn print_filenames<W: std::io::Write>(
 188         &mut self,
 189         output: &mut W,
 190         prefix: &mut PathBuf,
 191         dir: &CaDirectoryEntry,
 192     ) -> Result<(), Error> {
 193
 194         let mut list = self.list_dir(dir)?;
 195
 196         list.sort_unstable_by(|a, b| a.filename.cmp(&b.filename));
 197
 198         for item in &list {
 199
 200             prefix.push(item.filename.clone());
 201
 202             let mode = item.entry.mode as u32;
 203
 204             let ifmt = mode & libc::S_IFMT;
 205
 206             writeln!(output, "{:?}", prefix)?;
 207
 208             if ifmt == libc::S_IFDIR {
 209                 self.print_filenames(output, prefix, item)?;
 210             } else if ifmt == libc::S_IFREG {
 211             } else if ifmt == libc::S_IFLNK {
 212             } else if ifmt == libc::S_IFBLK {
 213             } else if ifmt == libc::S_IFCHR {
 214             } else {
 215                 bail!("unknown item mode/type for {:?}", prefix);
 216             }
 217
 218             prefix.pop();
 219         }
 220
 221         Ok(())
 222     }
 223 }