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 #include <errno.h>
  19 #include <algorithm>
  20
  21 #include "io_stream.h"
  22 #include "compress.h"
  23 #include "archive.h"
  24 #include "archive_tar.h"
  25
  26 archive_tar_file::archive_tar_file (tar_state & newstate):read_something (false), state (newstate)
  27 {
  28 }
  29
  30 archive_tar_file::~archive_tar_file ()
  31 {
  32   if (read_something)
  33     state.header_read = 0;
  34 }
  35
  36 /* Virtual memebrs */
  37 ssize_t archive_tar_file::read (void *buffer, size_t len)
  38 {
  39   /* how many bytes do we want to give the user */
  40   int
  41     want = std::min (len, state.file_length - state.file_offset);
  42   /* how many do we need to read after that to line up the file pointer */
  43   int
  44     roundup = (512 - (want % 512)) % 512;
  45   read_something = true;
  46   if (want)
  47     {
  48       int need = want;
  49       char *p = (char *)buffer;
  50       while (need > 0)
  51         {
  52           ssize_t got = state.parent->read (p, need);
  53           if (got <= 0)
  54             {
  55               /* unexpected EOF or read error in the tar parent stream */
  56               /* the user can query the parent for the error */
  57               state.lasterr = EIO;
  58               return -1;
  59             }
  60           p += got;
  61           need -= got;
  62         }
  63
  64       char throwaway[512];
  65       p = &throwaway[0];
  66       while (roundup > 0)
  67         {
  68           ssize_t got2 = state.parent->read (p, roundup);
  69           if (got2 <= 0)
  70             {
  71               /* unexpected EOF or read error in the tar parent stream */
  72               /* the user can query the parent for the error */
  73               state.lasterr = EIO;
  74               return -1;
  75             }
  76           p += got2;
  77           roundup -= got2;
  78         }
  79
  80       state.file_offset += want;
  81       return want;
  82     }
  83   return 0;
  84 }
  85
  86 /* provide data to (double duh!) */
  87 ssize_t archive_tar_file::write (const void *buffer, size_t len)
  88 {
  89   /* write not supported */
  90   state.lasterr = EBADF;
  91   return -1;
  92 }
  93
  94 /* read data without removing it from the class's internal buffer */
  95 ssize_t archive_tar_file::peek (void *buffer, size_t len)
  96 {
  97   int
  98     want = std::min (len, state.file_length - state.file_offset);
  99   if (want)
 100     {
 101       ssize_t
 102         got = state.parent->peek (buffer, want);
 103       if (got == want)
 104         {
 105           return got;
 106         }
 107       else
 108         {
 109           /* unexpected EOF or read error in the tar parent stream */
 110           /* the user can query the parent for the error */
 111           state.lasterr = EIO;
 112           return -1;
 113         }
 114     }
 115   return 0;
 116 }
 117
 118 long
 119 archive_tar_file::tell ()
 120 {
 121   return state.file_offset;
 122 }
 123
 124 int
 125 archive_tar_file::seek (long where, io_stream_seek_t whence)
 126 {
 127   /* nothing needs seeking here yet. Implement when needed
 128    */
 129   state.lasterr = EINVAL;
 130   return -1;
 131 }
 132
 133 /* try guessing this one */
 134 int
 135 archive_tar_file::error ()
 136 {
 137   return state.lasterr;
 138 }
 139
 140 time_t
 141 archive_tar_file::get_mtime ()
 142 {
 143   unsigned long mtime;
 144   sscanf (state.tar_header.mtime, "%lo", &mtime);
 145   return (time_t) mtime;
 146 }
 147
 148 mode_t
 149 archive_tar_file::get_mode ()
 150 {
 151   unsigned long mode;
 152   sscanf (state.tar_header.mode, "%lo", &mode);
 153   return (mode_t) mode;
 154 }