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