kernel/system/do_copy.c

   1 /* The kernel call implemented in this file:
   2  *   m_type:    SYS_VIRCOPY, SYS_PHYSCOPY
   3  *
   4  * The parameters for this kernel call are:
   5  *    m5_c1:    CP_SRC_SPACE            source virtual segment
   6  *    m5_l1:    CP_SRC_ADDR             source offset within segment
   7  *    m5_i1:    CP_SRC_PROC_NR          source process number
   8  *    m5_c2:    CP_DST_SPACE            destination virtual segment
   9  *    m5_l2:    CP_DST_ADDR             destination offset within segment
  10  *    m5_i2:    CP_DST_PROC_NR          destination process number
  11  *    m5_l3:    CP_NR_BYTES             number of bytes to copy
  12  */
  13
  14 #include "../system.h"
  15 #include <minix/type.h>
  16
  17 #if (USE_VIRCOPY || USE_PHYSCOPY)
  18
  19 /*===========================================================================*
  20  *                              do_copy                                      *
  21  *===========================================================================*/
  22 PUBLIC int do_copy(m_ptr)
  23 register message *m_ptr;        /* pointer to request message */
  24 {
  25 /* Handle sys_vircopy() and sys_physcopy().  Copy data using virtual or
  26  * physical addressing. Although a single handler function is used, there
  27  * are two different kernel calls so that permissions can be checked.
  28  */
  29   struct vir_addr vir_addr[2];  /* virtual source and destination address */
  30   phys_bytes bytes;             /* number of bytes to copy */
  31   int i;
  32
  33   if (m_ptr->m_source != 0 && m_ptr->m_source != 1 &&
  34         m_ptr->m_source != 2 && m_ptr->m_source != 3)
  35   {
  36         static int first=1;
  37         if (first)
  38         {
  39                 first= 0;
  40                 kprintf(
  41 "do_copy: got request from %d (source %d, seg %d, destination %d, seg %d)\n",
  42                         m_ptr->m_source,
  43                         m_ptr->CP_SRC_ENDPT,
  44                         m_ptr->CP_SRC_SPACE,
  45                         m_ptr->CP_DST_ENDPT,
  46                         m_ptr->CP_DST_SPACE);
  47         }
  48   }
  49
  50   /* Dismember the command message. */
  51   vir_addr[_SRC_].proc_nr_e = m_ptr->CP_SRC_ENDPT;
  52   vir_addr[_SRC_].segment = m_ptr->CP_SRC_SPACE;
  53   vir_addr[_SRC_].offset = (vir_bytes) m_ptr->CP_SRC_ADDR;
  54   vir_addr[_DST_].proc_nr_e = m_ptr->CP_DST_ENDPT;
  55   vir_addr[_DST_].segment = m_ptr->CP_DST_SPACE;
  56   vir_addr[_DST_].offset = (vir_bytes) m_ptr->CP_DST_ADDR;
  57   bytes = (phys_bytes) m_ptr->CP_NR_BYTES;
  58
  59   /* Now do some checks for both the source and destination virtual address.
  60    * This is done once for _SRC_, then once for _DST_.
  61    */
  62   for (i=_SRC_; i<=_DST_; i++) {
  63         int p;
  64       /* Check if process number was given implictly with SELF and is valid. */
  65       if (vir_addr[i].proc_nr_e == SELF)
  66         vir_addr[i].proc_nr_e = m_ptr->m_source;
  67       if (vir_addr[i].segment != PHYS_SEG &&
  68         ! isokendpt(vir_addr[i].proc_nr_e, &p))
  69           return(EINVAL);
  70
  71       /* Check if physical addressing is used without SYS_PHYSCOPY. */
  72       if ((vir_addr[i].segment & PHYS_SEG) &&
  73           m_ptr->m_type != SYS_PHYSCOPY) return(EPERM);
  74   }
  75
  76   /* Check for overflow. This would happen for 64K segments and 16-bit
  77    * vir_bytes. Especially copying by the PM on do_fork() is affected.
  78    */
  79   if (bytes != (vir_bytes) bytes) return(E2BIG);
  80
  81   /* Now try to make the actual virtual copy. */
  82   return( virtual_copy(&vir_addr[_SRC_], &vir_addr[_DST_], bytes) );
  83 }
  84 #endif /* (USE_VIRCOPY || USE_PHYSCOPY) */
  85