sys/src/cmd/tapefs/tpfs.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include "tapefs.h"
   4
   5 /*
   6  * File system for tp tapes.  dectape versions have 192
   7  * entries, magtape have 496.  This treats the same
   8  * by ignoring entries with bad header checksums
   9  */
  10
  11 struct tp {
  12         unsigned char   name[32];
  13         unsigned char   mode[2];
  14         unsigned char   uid[1];
  15         unsigned char   gid[1];
  16         unsigned char   unused[1];
  17         unsigned char   size[3];
  18         unsigned char   tmod[4];
  19         unsigned char   taddress[2];
  20         unsigned char   unused2[16];
  21         unsigned char   checksum[2];
  22 } dir[496+8];
  23
  24 char    buffer[8192];
  25 int     tapefile;
  26
  27 void
  28 populate(char *name)
  29 {
  30         int i, isabs, badcksum, goodcksum;
  31         struct tp *tpp;
  32         Fileinf f;
  33
  34         replete = 1;
  35         tapefile = open(name, OREAD);
  36         if (tapefile<0)
  37                 error("Can't open argument file");
  38         read(tapefile, dir, sizeof dir);
  39         badcksum = goodcksum = 0;
  40         for (i=0, tpp=&dir[8]; i<496; i++, tpp++) {
  41                 unsigned char *sp = (unsigned char *)tpp;
  42                 int j, cksum = 0;
  43                 for (j=0; j<32; j++, sp+=2)
  44                         cksum += sp[0] + (sp[1]<<8);
  45                 cksum &= 0xFFFF;
  46                 if (cksum!=0) {
  47                         badcksum++;
  48                         continue;
  49                 }
  50                 goodcksum++;
  51                 if (tpp->name[0]=='\0')
  52                         continue;
  53                 f.addr = tpp->taddress[0] + (tpp->taddress[1]<<8);
  54                 if (f.addr==0)
  55                         continue;
  56                 f.size = (tpp->size[0]<<16) + (tpp->size[1]<<0) + (tpp->size[2]<<8);
  57                 f.mdate = (tpp->tmod[2]<<0) + (tpp->tmod[3]<<8)
  58                      +(tpp->tmod[0]<<16) + (tpp->tmod[1]<<24);
  59                 f.mode = tpp->mode[0]&0777;
  60                 f.uid = tpp->uid[0];
  61                 f.gid = tpp->gid[0];
  62                 isabs = tpp->name[0]=='/';
  63                 f.name = (char *)tpp->name+isabs;
  64                 poppath(f, 1);
  65         }
  66         fprint(2, "%d bad checksums, %d good\n", badcksum, goodcksum);
  67 }
  68
  69 void
  70 popdir(Ram *r)
  71 {
  72         USED(r);
  73 }
  74
  75 void
  76 dotrunc(Ram *r)
  77 {
  78         USED(r);
  79 }
  80
  81 void
  82 docreate(Ram *r)
  83 {
  84         USED(r);
  85 }
  86
  87 char *
  88 doread(Ram *r, vlong off, long cnt)
  89 {
  90         if (cnt>sizeof(buffer))
  91                 print("count too big\n");
  92         seek(tapefile, 512*r->addr+off, 0);
  93         read(tapefile, buffer, cnt);
  94         return buffer;
  95 }
  96
  97 void
  98 dowrite(Ram *r, char *buf, long off, long cnt)
  99 {
 100         USED(r); USED(buf); USED(off); USED(cnt);
 101 }
 102
 103 int
 104 dopermw(Ram *r)
 105 {
 106         USED(r);
 107         return 0;
 108 }