catar/decoder.rs: start implementing sequential decoder, cleanups
And use [derive(Endian)] for endian conversion.
This commit is contained in:
Dietmar Maurer
parent
ad827b3f44
commit
b6ebfb8dab
@ -3,12 +3,13 @@
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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 endian_trait::Endian;
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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::path::{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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@ -58,6 +59,127 @@ impl <'a, R: Read + Seek> CaTarDecoder<'a, R> {
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}
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}
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fn read_item<T: Endian>(&mut self) -> Result<T, Error> {
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let mut result: T = unsafe { std::mem::uninitialized() };
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let buffer = unsafe { std::slice::from_raw_parts_mut(
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&mut result as *mut T as *mut u8,
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std::mem::size_of::<T>()
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)};
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self.reader.read_exact(buffer)?;
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Ok(result.from_le())
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}
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fn read_symlink(&mut self, size: u64) -> Result<PathBuf, Error> {
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if size < (HEADER_SIZE + 2) {
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bail!("dectected short symlink target.");
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}
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let target_len = size - HEADER_SIZE;
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if target_len > (libc::PATH_MAX as u64) {
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bail!("symlink target too long ({}).", target_len);
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}
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let mut buffer = vec![0u8; target_len as usize];
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self.reader.read_exact(&mut buffer)?;
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let last_byte = buffer.pop().unwrap();
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if last_byte != 0u8 {
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bail!("symlink target not nul terminated.");
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}
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Ok(PathBuf::from(std::ffi::OsString::from_vec(buffer)))
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}
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fn read_filename(&mut self, size: u64) -> Result<OsString, Error> {
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if size < (HEADER_SIZE + 2) {
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bail!("dectected short filename");
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}
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let name_len = size - HEADER_SIZE;
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if name_len > ((libc::FILENAME_MAX as u64) + 1) {
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bail!("filename too long ({}).", name_len);
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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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let last_byte = buffer.pop().unwrap();
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if last_byte != 0u8 {
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bail!("filename entry not nul terminated.");
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}
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Ok(std::ffi::OsString::from_vec(buffer))
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}
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pub fn restore<F: Fn(&Path) -> Result<(), Error>>(
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&mut self,
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dir: &CaDirectoryEntry,
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callback: F,
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) -> Result<(), Error> {
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let start = dir.start;
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let end = dir.end;
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self.reader.seek(SeekFrom::Start(start))?;
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let mut path = PathBuf::from(".");
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self.restore_sequential(&mut path, &callback)
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}
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pub fn restore_sequential<F: Fn(&Path) -> Result<(), Error>>(
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&mut self,
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path: &mut PathBuf,
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callback: &F,
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) -> Result<(), Error> {
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// read ENTRY first
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let head: CaFormatHeader = self.read_item()?;
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check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
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let entry: CaFormatEntry = self.read_item()?;
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let is_dir = ((entry.mode as u32) & libc::S_IFMT) == libc::S_IFDIR;
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loop {
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let head: CaFormatHeader = self.read_item()?;
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match head.htype {
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CA_FORMAT_SYMLINK => {
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let target = self.read_symlink(head.size)?;
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println!("TARGET: {:?}", target);
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}
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CA_FORMAT_FILENAME => {
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if !is_dir { bail!("onyl directoriy entries may contain file names."); }
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let name = self.read_filename(head.size)?;
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path.push(name);
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println!("NAME: {:?}", path);
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self.restore_sequential(path, callback)?;
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path.pop();
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}
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CA_FORMAT_PAYLOAD => {
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println!("Skip Payload");
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if head.size < HEADER_SIZE { bail!("detected short payload"); }
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self.reader.seek(SeekFrom::Current((head.size - HEADER_SIZE) as i64))?;
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return Ok(());
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}
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CA_FORMAT_GOODBYE => {
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println!("Skip Goodbye");
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if head.size < HEADER_SIZE { bail!("detected short goodbye table"); }
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self.reader.seek(SeekFrom::Current((head.size - HEADER_SIZE) as i64))?;
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return Ok(());
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}
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_ => {
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bail!("got unknown header type {:016x}", head.htype);
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}
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}
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}
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Ok(())
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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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@ -73,46 +195,11 @@ impl <'a, R: Read + Seek> CaTarDecoder<'a, R> {
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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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let filename = self.read_filename(name_len)?;
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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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let head: CaFormatHeader = self.read_item()?;
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check_ca_header::<CaFormatEntry>(&head, CA_FORMAT_ENTRY)?;
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let entry: CaFormatEntry = self.read_item()?;
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Ok(CaDirectoryEntry {
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start: entry_start,
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@ -6,6 +6,7 @@
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//! `CaFormatHeader`, followed by the item data.
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use failure::*;
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use endian_trait::Endian;
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use siphasher::sip::SipHasher24;
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@ -20,6 +21,7 @@ pub const CA_FORMAT_GOODBYE_TAIL_MARKER: u64 = 0x57446fa533702943;
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pub const CA_FORMAT_FEATURE_FLAGS_MAX: u64 = 0xb000_0001_ffef_fe26; // fixme: ?
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#[derive(Endian)]
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#[repr(C)]
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pub struct CaFormatHeader {
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/// The size of the item, including the size of `CaFormatHeader`.
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@ -28,6 +30,7 @@ pub struct CaFormatHeader {
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pub htype: u64,
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}
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#[derive(Endian)]
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#[repr(C)]
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pub struct CaFormatEntry {
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pub feature_flags: u64,
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@ -38,6 +41,7 @@ pub struct CaFormatEntry {
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pub mtime: u64,
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}
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#[derive(Endian)]
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#[repr(C)]
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pub struct CaFormatGoodbyeItem {
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/// The offset from the start of the GOODBYE object to the start
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@ -78,3 +82,14 @@ pub fn compute_goodbye_hash(name: &[u8]) -> u64 {
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hasher.write(name);
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hasher.finish()
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}
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pub fn check_ca_header<T>(head: &CaFormatHeader, htype: u64) -> Result<(), Error> {
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if head.htype != htype {
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bail!("got wrong header type ({:016x} != {:016x}", head.htype, htype);
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}
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if head.size != (std::mem::size_of::<T>() + std::mem::size_of::<CaFormatHeader>()) as u64 {
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bail!("got wrong header size for type {:016x}", htype);
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}
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Ok(())
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}
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