gpxe/src/arch/i386/core/aout_loader.c

   1 /* a.out */
   2 struct exec {
   3         unsigned long      a_midmag;    /* flags<<26 | mid<<16 | magic */
   4         unsigned long      a_text;      /* text segment size */
   5         unsigned long      a_data;      /* initialized data size */
   6         unsigned long      a_bss;       /* uninitialized data size */
   7         unsigned long      a_syms;      /* symbol table size */
   8         unsigned long      a_entry;     /* entry point */
   9         unsigned long      a_trsize;    /* text relocation size */
  10         unsigned long      a_drsize;    /* data relocation size */
  11 };
  12
  13 struct aout_state {
  14         struct exec head;
  15         unsigned long curaddr;
  16         int segment;                    /* current segment number, -1 for none */
  17         unsigned long loc;              /* start offset of current block */
  18         unsigned long skip;             /* padding to be skipped to current segment */
  19         unsigned long toread;           /* remaining data to be read in the segment */
  20 };
  21
  22 static struct aout_state astate;
  23
  24 static sector_t aout_download(unsigned char *data, unsigned int len, int eof);
  25 static inline os_download_t aout_probe(unsigned char *data, unsigned int len)
  26 {
  27         unsigned long start, mid, end, istart, iend;
  28         if (len < sizeof(astate.head)) {
  29                 return 0;
  30         }
  31         memcpy(&astate.head, data, sizeof(astate.head));
  32         if ((astate.head.a_midmag & 0xffff) != 0x010BL) {
  33                 return 0;
  34         }
  35
  36         printf("(a.out");
  37         aout_freebsd_probe();
  38         printf(")... ");
  39         /* Check the aout image */
  40         start  = astate.head.a_entry;
  41         mid    = (((start + astate.head.a_text) + 4095) & ~4095) + astate.head.a_data;
  42         end    = ((mid + 4095) & ~4095) + astate.head.a_bss;
  43         istart = 4096;
  44         iend   = istart + (mid - start);
  45         if (!prep_segment(start, mid, end, istart, iend))
  46                 return dead_download;
  47         astate.segment = -1;
  48         astate.loc = 0;
  49         astate.skip = 0;
  50         astate.toread = 0;
  51         return aout_download;
  52 }
  53
  54 static sector_t aout_download(unsigned char *data, unsigned int len, int eof)
  55 {
  56         unsigned int offset;    /* working offset in the current data block */
  57
  58         offset = 0;
  59
  60 #ifdef AOUT_LYNX_KDI
  61         astate.segment++;
  62         if (astate.segment == 0) {
  63                 astate.curaddr = 0x100000;
  64                 astate.head.a_entry = astate.curaddr + 0x20;
  65         }
  66         memcpy(phys_to_virt(astate.curaddr), data, len);
  67         astate.curaddr += len;
  68         return 0;
  69 #endif
  70
  71         do {
  72                 if (astate.segment != -1) {
  73                         if (astate.skip) {
  74                                 if (astate.skip >= len - offset) {
  75                                         astate.skip -= len - offset;
  76                                         break;
  77                                 }
  78                                 offset += astate.skip;
  79                                 astate.skip = 0;
  80                         }
  81
  82                         if (astate.toread) {
  83                                 if (astate.toread >= len - offset) {
  84                                         memcpy(phys_to_virt(astate.curaddr), data+offset,
  85                                                 len - offset);
  86                                         astate.curaddr += len - offset;
  87                                         astate.toread -= len - offset;
  88                                         break;
  89                                 }
  90                                 memcpy(phys_to_virt(astate.curaddr), data+offset, astate.toread);
  91                                 offset += astate.toread;
  92                                 astate.toread = 0;
  93                         }
  94                 }
  95
  96                 /* Data left, but current segment finished - look for the next
  97                  * segment.  This is quite simple for a.out files.  */
  98                 astate.segment++;
  99                 switch (astate.segment) {
 100                 case 0:
 101                         /* read text */
 102                         astate.curaddr = astate.head.a_entry;
 103                         astate.skip = 4096;
 104                         astate.toread = astate.head.a_text;
 105                         break;
 106                 case 1:
 107                         /* read data */
 108                         /* skip and curaddr may be wrong, but I couldn't find
 109                          * examples where this failed.  There is no reasonable
 110                          * documentation for a.out available.  */
 111                         astate.skip = ((astate.curaddr + 4095) & ~4095) - astate.curaddr;
 112                         astate.curaddr = (astate.curaddr + 4095) & ~4095;
 113                         astate.toread = astate.head.a_data;
 114                         break;
 115                 case 2:
 116                         /* initialize bss and start kernel */
 117                         astate.curaddr = (astate.curaddr + 4095) & ~4095;
 118                         astate.skip = 0;
 119                         astate.toread = 0;
 120                         memset(phys_to_virt(astate.curaddr), '\0', astate.head.a_bss);
 121                         goto aout_startkernel;
 122                 default:
 123                         break;
 124                 }
 125         } while (offset < len);
 126
 127         astate.loc += len;
 128
 129         if (eof) {
 130                 unsigned long entry;
 131
 132 aout_startkernel:
 133                 entry = astate.head.a_entry;
 134                 done(1);
 135
 136                 aout_freebsd_boot();
 137 #ifdef AOUT_LYNX_KDI
 138                 xstart32(entry);
 139 #endif
 140                 printf("unexpected a.out variant\n");
 141                 longjmp(restart_etherboot, -2);
 142         }
 143         return 0;
 144 }