com32/lib/syslinux/pxe_get_cached.c

   1 /* ----------------------------------------------------------------------- *
   2  *
   3  *   Copyright 2007-2008 H. Peter Anvin - All Rights Reserved
   4  *
   5  *   Permission is hereby granted, free of charge, to any person
   6  *   obtaining a copy of this software and associated documentation
   7  *   files (the "Software"), to deal in the Software without
   8  *   restriction, including without limitation the rights to use,
   9  *   copy, modify, merge, publish, distribute, sublicense, and/or
  10  *   sell copies of the Software, and to permit persons to whom
  11  *   the Software is furnished to do so, subject to the following
  12  *   conditions:
  13  *
  14  *   The above copyright notice and this permission notice shall
  15  *   be included in all copies or substantial portions of the Software.
  16  *
  17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
  19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
  21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
  22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  24  *   OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  * ----------------------------------------------------------------------- */
  27
  28 /*
  29  * pxe_get_cached.c
  30  *
  31  * PXE call "get cached info"
  32  */
  33
  34 #include <stdlib.h>
  35 #include <stdint.h>
  36 #include <string.h>
  37 #include <com32.h>
  38
  39 #include <syslinux/pxe.h>
  40
  41 /* Returns the status code from PXE (0 on success),
  42    or -1 on invocation failure */
  43 int pxe_get_cached_info(int level, void **buf, size_t * len)
  44 {
  45     const int max_dhcp_packet = 2048;
  46     com32sys_t regs;
  47     t_PXENV_GET_CACHED_INFO *gci;
  48     void *bbuf, *nbuf;
  49     int err;
  50
  51     gci = lmalloc(sizeof *gci + max_dhcp_packet);
  52     if (!gci)
  53         return -1;
  54
  55     memset(&regs, 0, sizeof regs);
  56     regs.eax.w[0] = 0x0009;
  57     regs.ebx.w[0] = PXENV_GET_CACHED_INFO;
  58     regs.es = SEG(gci);
  59     /* regs.edi.w[0] = OFFS(gci); */
  60
  61     bbuf = &gci[1];
  62
  63     gci->Status = PXENV_STATUS_FAILURE;
  64     gci->PacketType = level;
  65     gci->BufferSize = gci->BufferLimit = max_dhcp_packet;
  66     gci->Buffer.seg = SEG(bbuf);
  67     gci->Buffer.offs = OFFS(bbuf);
  68
  69     __intcall(0x22, &regs, &regs);
  70
  71     if (regs.eflags.l & EFLAGS_CF) {
  72         err = -1;
  73         goto exit;
  74     }
  75
  76     if (gci->Status) {
  77         err = gci->Status;
  78         goto exit;
  79     }
  80
  81     nbuf = malloc(gci->BufferSize);
  82     if (!nbuf) {
  83         err = -1;
  84         goto exit;
  85     }
  86
  87     memcpy(nbuf, bbuf, gci->BufferSize);
  88
  89     *buf = nbuf;
  90     *len = gci->BufferSize;
  91     err = 0;
  92
  93 exit:
  94     lfree(gci);
  95     return err;
  96 }