sys/src/boot/pc/iso.c

   1 #include <u.h>
   2 #include "fns.h"
   3
   4 enum {
   5         Sectsz = 0x800,
   6         Maxpath = 256,
   7         Dirsz = 33,
   8 };
   9
  10 typedef struct Extend Extend;
  11 typedef struct Dir Dir;
  12
  13 struct Extend
  14 {
  15         int drive;
  16         ulong lba;
  17         ulong len;
  18         uchar *rp;
  19         uchar *ep;
  20         uchar buf[Sectsz];
  21 };
  22
  23 struct Dir
  24 {
  25         uchar dirlen;
  26         uchar extlen;
  27
  28         uchar lba[8];
  29         uchar len[8];
  30
  31         uchar date[7];
  32
  33         uchar flags[3];
  34
  35         uchar seq[4];
  36
  37         uchar namelen;
  38 };
  39
  40 int readsect(ulong drive, ulong lba, void *buf);
  41
  42 void
  43 unload(void)
  44 {
  45 }
  46
  47 int
  48 read(void *f, void *data, int len)
  49 {
  50         Extend *ex = f;
  51
  52         if(ex->len > 0 && ex->rp >= ex->ep)
  53                 if(readsect(ex->drive, ex->lba++, ex->rp = ex->buf))
  54                         return -1;
  55         if(ex->len < len)
  56                 len = ex->len;
  57         if(len > (ex->ep - ex->rp))
  58                 len = ex->ep - ex->rp;
  59         memmove(data, ex->rp, len);
  60         ex->rp += len;
  61         ex->len -= len;
  62         return len;
  63 }
  64
  65 void
  66 close(void *f)
  67 {
  68         Extend *ex = f;
  69
  70         ex->drive = 0;
  71         ex->lba = 0;
  72         ex->len = 0;
  73         ex->rp = ex->ep = ex->buf + Sectsz;
  74 }
  75
  76 static int
  77 isowalk(Extend *ex, int drive, char *path)
  78 {
  79         char name[Maxpath], c, *end;
  80         int i;
  81         Dir d;
  82
  83         close(ex);
  84         ex->drive = drive;
  85
  86         /* find pvd */
  87         for(i=0x10; i<0x1000; i++){
  88                 if(readsect(drive, i, ex->buf))
  89                         return -1;
  90                 if(*ex->buf == 1)
  91                         break;
  92         }
  93         ex->lba = *((ulong*)(ex->buf + 156 + 2));
  94         ex->len = *((ulong*)(ex->buf + 156 + 10));
  95
  96         for(;;){
  97                 if(readn(ex, &d, Dirsz) != Dirsz)
  98                         break;
  99                 if(d.dirlen == 0)
 100                         break;
 101                 if(readn(ex, name, d.namelen) != d.namelen)
 102                         break;
 103                 i = d.dirlen - (Dirsz + d.namelen);
 104                 while(i-- > 0)
 105                         read(ex, &c, 1);
 106                 for(i=0; i<d.namelen; i++){
 107                         c = name[i];
 108                         if(c >= 'A' && c <= 'Z'){
 109                                 c -= 'A';
 110                                 c += 'a';
 111                         }
 112                         name[i] = c;
 113                 }
 114                 name[i] = 0;
 115                 while(*path == '/')
 116                         path++;
 117                 if((end = strchr(path, '/')) == 0)
 118                         end = path + strlen(path);
 119                 i = end - path;
 120                 if(d.namelen == i && memcmp(name, path, i) == 0){
 121                         ex->rp = ex->ep;
 122                         ex->lba = *((ulong*)d.lba);
 123                         ex->len = *((ulong*)d.len);
 124                         if(*end == 0)
 125                                 return 0;
 126                         else if(d.flags[0] & 2){
 127                                 path = end;
 128                                 continue;
 129                         }
 130                         break;
 131                 }
 132         }
 133         close(ex);
 134         return -1;
 135 }
 136
 137 void
 138 start(void *sp)
 139 {
 140         char path[Maxpath], *kern;
 141         int drive;
 142         Extend ex;
 143         void *f;
 144
 145         /* drive passed in DL */
 146         drive = ((ushort*)sp)[5] & 0xFF;
 147
 148         /*
 149          * load full bootblock as only the frist 2K get
 150          * loaded from bios. the code is specially arranged
 151          * to have all the important routines in the first
 152          * 2K of the 9bootiso image. (strings have been
 153          * placed in l.s to make sure they will be < 2K)
 154          */
 155         if(isowalk(&ex, drive, bootname)){
 156                 print(bootname);
 157                 putc('?');
 158                 halt();
 159         }
 160         readn(&ex, origin, ex.len);
 161         close(&ex);
 162
 163         if(isowalk(f = &ex, drive, "/cfg/plan9.ini")){
 164                 print("no config\r\n");
 165                 f = 0;
 166         }
 167         for(;;){
 168                 kern = configure(f, path); f = 0;
 169                 if(isowalk(&ex, drive, kern)){
 170                         print("not found\r\n");
 171                         continue;
 172                 }
 173                 print(bootkern(&ex));
 174                 print(crnl);
 175         }
 176 }
 177