catar/decoder.rs: start implementation
This commit is contained in:
Dietmar Maurer
@ -1,3 +1,253 @@
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//! *catar* format decoder.
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//!
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//! This module contain the code to decode *catar* archive files.
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use failure::*;
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use super::format_definition::*;
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use crate::tools;
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use std::io::{Read, Seek, SeekFrom};
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use std::path::PathBuf;
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use std::os::unix::ffi::{OsStrExt, OsStringExt};
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use std::ffi::{OsStr, OsString};
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pub struct CaDirectoryEntry {
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start: u64,
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end: u64,
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pub filename: OsString,
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pub entry: CaFormatEntry,
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}
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// This one needs Read+Seek (we may want one without Seek?)
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pub struct CaTarDecoder<'a, R: Read + Seek> {
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reader: &'a mut R,
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root_start: u64,
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root_end: u64,
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}
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const HEADER_SIZE: u64 = std::mem::size_of::<CaFormatHeader>() as u64;
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impl <'a, R: Read + Seek> CaTarDecoder<'a, R> {
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pub fn new(reader: &'a mut R) -> Result<Self, Error> {
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let root_end = reader.seek(SeekFrom::End(0))?;
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Ok(Self {
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reader: reader,
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root_start: 0,
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root_end: root_end,
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})
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}
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pub fn root(&self) -> CaDirectoryEntry {
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CaDirectoryEntry {
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start: self.root_start,
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end: self.root_end,
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filename: OsString::new(), // Empty
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entry: CaFormatEntry {
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feature_flags: 0,
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mode: 0,
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flags: 0,
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uid: 0,
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gid: 0,
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mtime: 0,
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}
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}
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}
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fn read_directory_entry(&mut self, start: u64, end: u64) -> Result<CaDirectoryEntry, Error> {
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self.reader.seek(SeekFrom::Start(start))?;
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let mut buffer = [0u8; HEADER_SIZE as usize];
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self.reader.read_exact(&mut buffer)?;
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let head = tools::map_struct::<CaFormatHeader>(&buffer)?;
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if u64::from_le(head.htype) != CA_FORMAT_FILENAME {
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bail!("wrong filename header type for object [{}..{}]", start, end);
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}
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let mut name_len = u64::from_le(head.size);
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let entry_start = start + name_len;
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if name_len < (HEADER_SIZE + 2) {
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bail!("filename size too short for object [{}..{}]", start, end);
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}
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name_len -= HEADER_SIZE;
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if name_len > ((libc::FILENAME_MAX as u64) + 1) {
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bail!("filename too long for object [{}..{}]", start, end);
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}
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let mut buffer = vec![0u8; name_len as usize];
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self.reader.read_exact(&mut buffer)?;
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// fixme: check nul termination
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let last_byte = buffer.pop().unwrap();
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if last_byte != 0u8 {
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bail!("filename entry not nul terminated, object [{}..{}]", start, end);
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}
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let filename = std::ffi::OsString::from_vec(buffer);
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let mut buffer = [0u8; HEADER_SIZE as usize];
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self.reader.read_exact(&mut buffer)?;
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let head = tools::map_struct::<CaFormatHeader>(&buffer)?;
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if u64::from_le(head.htype) != CA_FORMAT_ENTRY {
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bail!("wrong entry header type for object [{}..{}]", start, end);
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}
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const ENTRY_SIZE: u64 = std::mem::size_of::<CaFormatEntry>() as u64;
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let mut entry_len = u64::from_le(head.size);
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if entry_len != (HEADER_SIZE + ENTRY_SIZE) {
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bail!("wrong entry header size for object [{}..{}]", start, end);
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}
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entry_len -= HEADER_SIZE;
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let mut buffer = [0u8; ENTRY_SIZE as usize];
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self.reader.read_exact(&mut buffer)?;
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let entry = tools::map_struct::<CaFormatEntry>(&buffer)?;
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Ok(CaDirectoryEntry {
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start: entry_start,
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end: end,
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filename: filename,
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entry: CaFormatEntry {
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feature_flags: u64::from_le(entry.feature_flags),
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mode: u64::from_le(entry.mode),
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flags: u64::from_le(entry.flags),
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uid: u64::from_le(entry.uid),
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gid: u64::from_le(entry.gid),
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mtime: u64::from_le(entry.mtime),
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},
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})
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}
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pub fn list_dir(&mut self, dir: &CaDirectoryEntry) -> Result<Vec<CaDirectoryEntry>, Error> {
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const GOODBYE_ITEM_SIZE: u64 = std::mem::size_of::<CaFormatGoodbyeItem>() as u64;
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let start = dir.start;
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let end = dir.end;
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//println!("list_dir1: {} {}", start, end);
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if (end - start) < (HEADER_SIZE + GOODBYE_ITEM_SIZE) {
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bail!("detected short object [{}..{}]", start, end);
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}
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self.reader.seek(SeekFrom::Start(end - GOODBYE_ITEM_SIZE))?;
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let mut buffer = [0u8; GOODBYE_ITEM_SIZE as usize];
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self.reader.read_exact(&mut buffer)?;
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let item = tools::map_struct::<CaFormatGoodbyeItem>(&buffer)?;
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if u64::from_le(item.hash) != CA_FORMAT_GOODBYE_TAIL_MARKER {
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bail!("missing goodbye tail marker for object [{}..{}]", start, end);
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}
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let goodbye_table_size = u64::from_le(item.size);
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if goodbye_table_size < (HEADER_SIZE + GOODBYE_ITEM_SIZE) {
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bail!("short goodbye table size for object [{}..{}]", start, end);
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}
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let goodbye_inner_size = goodbye_table_size - HEADER_SIZE - GOODBYE_ITEM_SIZE;
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if (goodbye_inner_size % GOODBYE_ITEM_SIZE) != 0 {
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bail!("wrong goodbye inner table size for entry [{}..{}]", start, end);
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}
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let goodbye_start = end - goodbye_table_size;
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if u64::from_le(item.offset) != (goodbye_start - start) {
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println!("DEBUG: {} {}", u64::from_le(item.offset), goodbye_start - start);
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bail!("wrong offset in goodbye tail marker for entry [{}..{}]", start, end);
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}
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self.reader.seek(SeekFrom::Start(goodbye_start))?;
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let mut buffer = [0u8; HEADER_SIZE as usize];
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self.reader.read_exact(&mut buffer)?;
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let head = tools::map_struct::<CaFormatHeader>(&buffer)?;
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if u64::from_le(head.htype) != CA_FORMAT_GOODBYE {
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bail!("wrong goodbye table header type for entry [{}..{}]", start, end);
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}
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if u64::from_le(head.size) != goodbye_table_size {
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bail!("wrong goodbye table size for entry [{}..{}]", start, end);
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}
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let mut buffer = [0u8; GOODBYE_ITEM_SIZE as usize];
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let mut range_list = Vec::new();
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for i in 0..goodbye_inner_size/GOODBYE_ITEM_SIZE {
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self.reader.read_exact(&mut buffer)?;
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let item = tools::map_struct::<CaFormatGoodbyeItem>(&buffer)?;
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let item_offset = u64::from_le(item.offset);
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if item_offset > (goodbye_start - start) {
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bail!("goodbye entry {} offset out of range [{}..{}] {} {} {}",
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i, start, end, item_offset, goodbye_start, start);
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}
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let item_start = goodbye_start - item_offset;
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let item_hash = u64::from_le(item.hash);
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let item_end = item_start + u64::from_le(item.size);
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if item_end > goodbye_start {
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bail!("goodbye entry {} end out of range [{}..{}]",
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i, start, end);
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}
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range_list.push((item_start, item_end));
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}
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let mut result = vec![];
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for (item_start, item_end) in range_list {
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let entry = self.read_directory_entry(item_start, item_end)?;
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//println!("ENTRY: {} {} {:?}", item_start, item_end, entry.filename);
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result.push(entry);
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}
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Ok(result)
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}
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pub fn print_filenames<W: std::io::Write>(
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&mut self,
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output: &mut W,
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prefix: &mut PathBuf,
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dir: &CaDirectoryEntry,
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) -> Result<(), Error> {
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let mut list = self.list_dir(dir)?;
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list.sort_unstable_by(|a, b| a.filename.cmp(&b.filename));
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for item in &list {
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prefix.push(item.filename.clone());
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let mode = item.entry.mode as u32;
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let osstr: &OsStr = prefix.as_ref();
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output.write(osstr.as_bytes())?;
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output.write(b"\n")?;
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if (mode & libc::S_IFMT) == libc::S_IFDIR {
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self.print_filenames(output, prefix, item)?;
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} else if (mode & libc::S_IFMT) == libc::S_IFREG {
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} else if (mode & libc::S_IFMT) == libc::S_IFLNK {
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} else {
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bail!("unknown item mode/type for {:?}", prefix);
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}
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prefix.pop();
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}
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Ok(())
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}
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}
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