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 #ifdef FAT
  43 int
  44 readsect4(ulong drive, ulong lba, void *buf)
  45 {
  46         int i;
  47
  48         lba *= Sectsz/512;
  49         for(i = 0; i<Sectsz/512; i++){
  50                 if(readsect(drive, lba++, buf))
  51                         return -1;
  52                 buf = (uchar*)buf + 512;
  53         }
  54         return 0;
  55 }
  56 #define readsect readsect4
  57 #endif
  58
  59 void
  60 unload(void)
  61 {
  62 }
  63
  64 int
  65 read(void *f, void *data, int len)
  66 {
  67         Extend *ex = f;
  68
  69         if(ex->len > 0 && ex->rp >= ex->ep)
  70                 if(readsect(ex->drive, ex->lba++, ex->rp = ex->buf))
  71                         return -1;
  72         if(ex->len < len)
  73                 len = ex->len;
  74         if(len > (ex->ep - ex->rp))
  75                 len = ex->ep - ex->rp;
  76         memmove(data, ex->rp, len);
  77         ex->rp += len;
  78         ex->len -= len;
  79         return len;
  80 }
  81
  82 void
  83 close(void *f)
  84 {
  85         Extend *ex = f;
  86
  87         ex->drive = 0;
  88         ex->lba = 0;
  89         ex->len = 0;
  90         ex->rp = ex->ep = ex->buf + Sectsz;
  91 }
  92
  93 static int
  94 isowalk(Extend *ex, int drive, char *path)
  95 {
  96         char name[Maxpath], c, *end;
  97         int i;
  98         Dir d;
  99
 100         close(ex);
 101         ex->drive = drive;
 102
 103         /* find pvd */
 104         for(i=0x10; i<0x1000; i++){
 105                 if(readsect(drive, i, ex->buf))
 106                         return -1;
 107                 if(*ex->buf == 1)
 108                         break;
 109         }
 110         ex->lba = *((ulong*)(ex->buf + 156 + 2));
 111         ex->len = *((ulong*)(ex->buf + 156 + 10));
 112
 113         for(;;){
 114                 if(readn(ex, &d, Dirsz) != Dirsz)
 115                         break;
 116                 if(d.dirlen == 0)
 117                         break;
 118                 if(readn(ex, name, d.namelen) != d.namelen)
 119                         break;
 120                 i = d.dirlen - (Dirsz + d.namelen);
 121                 while(i-- > 0)
 122                         read(ex, &c, 1);
 123                 for(i=0; i<d.namelen; i++){
 124                         c = name[i];
 125                         if(c >= 'A' && c <= 'Z'){
 126                                 c -= 'A';
 127                                 c += 'a';
 128                         }
 129                         name[i] = c;
 130                 }
 131                 name[i] = 0;
 132                 while(*path == '/')
 133                         path++;
 134                 if((end = strchr(path, '/')) == 0)
 135                         end = path + strlen(path);
 136                 i = end - path;
 137                 if(d.namelen == i && memcmp(name, path, i) == 0){
 138                         ex->rp = ex->ep;
 139                         ex->lba = *((ulong*)d.lba);
 140                         ex->len = *((ulong*)d.len);
 141                         if(*end == 0)
 142                                 return 0;
 143                         else if(d.flags[0] & 2){
 144                                 path = end;
 145                                 continue;
 146                         }
 147                         break;
 148                 }
 149         }
 150         close(ex);
 151         return -1;
 152 }
 153
 154 void
 155 start(void *sp)
 156 {
 157         char path[Maxpath], *kern;
 158         int drive;
 159         Extend ex;
 160         void *f;
 161
 162         /* drive passed in DL */
 163         drive = ((ushort*)sp)[5] & 0xFF;
 164
 165 #ifndef FAT
 166         /*
 167          * load full bootblock as only the frist 2K get
 168          * loaded from bios. the code is specially arranged
 169          * to have all the important routines in the first
 170          * 2K of the 9bootiso image. (strings have been
 171          * placed in l.s to make sure they will be < 2K)
 172          */
 173         if(isowalk(&ex, drive, bootname)){
 174                 print(bootname);
 175                 putc('?');
 176                 halt();
 177         }
 178         readn(&ex, origin, ex.len);
 179         close(&ex);
 180 #endif
 181
 182         if(isowalk(f = &ex, drive, "/cfg/plan9.ini")){
 183                 print("no config\n");
 184                 f = 0;
 185         }
 186         for(;;){
 187                 kern = configure(f, path); f = 0;
 188                 if(isowalk(&ex, drive, kern)){
 189                         print("not found\n");
 190                         continue;
 191                 }
 192                 print(bootkern(&ex));
 193                 print("\n");
 194         }
 195 }
 196