archive_tar_file.cc

   1 /*
   2  * Copyright (c) 2001, Robert Collins
   3  *
   4  *     This program is free software; you can redistribute it and/or modify
   5  *     it under the terms of the GNU General Public License as published by
   6  *     the Free Software Foundation; either version 2 of the License, or
   7  *     (at your option) any later version.
   8  *
   9  *     A copy of the GNU General Public License can be found at
  10  *     http://www.gnu.org/
  11  *
  12  * Written by Robert Collins <rbtcollins@hotmail.com>
  13  *
  14  */
  15
  16 /* An individual stream from a tar archive. */
  17
  18 #if 0
  19 static const char *cvsid = "\n%%% $Id$\n";
  20 #endif
  21
  22 #include <errno.h>
  23 #include <algorithm>
  24
  25 #include "zlib/zlib.h"
  26 #include "io_stream.h"
  27 #include "compress.h"
  28 #include "archive.h"
  29 #include "archive_tar.h"
  30 #include "log.h"
  31
  32 #include "port.h"
  33
  34 archive_tar_file::archive_tar_file (tar_state & newstate):state (newstate)
  35 {
  36 }
  37
  38 archive_tar_file::~archive_tar_file ()
  39 {
  40   state.header_read = 0;
  41   destroyed = 1;
  42 }
  43
  44 /* Virtual memebrs */
  45 ssize_t archive_tar_file::read (void *buffer, size_t len)
  46 {
  47   /* how many bytes do we want to give the user */
  48   int
  49     want = std::min (len, state.file_length - state.file_offset);
  50   /* how many do we need to read after that to line up the file pointer */
  51   int
  52     roundup = (512 - (want % 512)) % 512;
  53   if (want)
  54     {
  55       ssize_t
  56         got = state.parent->read (buffer, want);
  57       char
  58         throwaway[512];
  59       ssize_t
  60         got2 = state.parent->read (throwaway, roundup);
  61       if (got == want && got2 == roundup)
  62         {
  63           state.file_offset += got;
  64           return got;
  65         }
  66       else
  67         {
  68           /* unexpected EOF or read error in the tar parent stream */
  69           /* the user can query the parent for the error */
  70           state.lasterr = EIO;
  71           return EIO;
  72         }
  73     }
  74   return 0;
  75 }
  76
  77 /* provide data to (double duh!) */
  78 ssize_t archive_tar_file::write (const void *buffer, size_t len)
  79 {
  80   /* write not supported */
  81   return EBADF;
  82 }
  83
  84 /* read data without removing it from the class's internal buffer */
  85 ssize_t archive_tar_file::peek (void *buffer, size_t len)
  86 {
  87   int
  88     want = std::min (len, state.file_length - state.file_offset);
  89   if (want)
  90     {
  91       ssize_t
  92         got = state.parent->peek (buffer, want);
  93       if (got == want)
  94         {
  95           return got;
  96         }
  97       else
  98         {
  99           /* unexpected EOF or read error in the tar parent stream */
 100           /* the user can query the parent for the error */
 101           state.lasterr = EIO;
 102           return EIO;
 103         }
 104     }
 105   return 0;
 106 }
 107
 108 long
 109 archive_tar_file::tell ()
 110 {
 111   return state.file_offset;
 112 }
 113
 114 int
 115 archive_tar_file::seek (long where, io_stream_seek_t whence)
 116 {
 117   /* nothing needs seeking here yet. Implement when needed
 118    */
 119   return -1;
 120 }
 121
 122 /* try guessing this one */
 123 int
 124 archive_tar_file::error ()
 125 {
 126   return state.lasterr;
 127 }
 128
 129 int
 130 archive_tar_file::get_mtime ()
 131 {
 132   int mtime;
 133   sscanf (state.tar_header.mtime, "%o", &mtime);
 134   return mtime;
 135 }