kernel/system/do_safememset.c

   1 /* The kernel call implemented in this file:
   2  *   m_type:    SYS_SAFEMEMSET
   3  *
   4  * The parameters for this kernel call are:
   5  *      SMS_DST         dst endpoint
   6  *      SMS_GID         grant id
   7  *      SMS_OFFSET      offset within grant
   8  *      SMS_PATTERN     memset pattern byte
   9  *      SMS_BYTES       bytes from offset
  10  */
  11 #include <assert.h>
  12
  13 #include <minix/safecopies.h>
  14
  15 #include "kernel/system.h"
  16 #include "kernel.h"
  17
  18 /*===========================================================================*
  19  *                              do_safememset                                *
  20  *===========================================================================*/
  21 int do_safememset(struct proc *caller, message *m_ptr) {
  22         /* Implementation of the do_safememset() kernel call */
  23
  24         /* Extract parameters */
  25         endpoint_t dst_endpt = m_ptr->SMS_DST;
  26         endpoint_t caller_endpt = caller->p_endpoint;
  27         cp_grant_id_t grantid = m_ptr->SMS_GID;
  28         vir_bytes g_offset = m_ptr->SMS_OFFSET;
  29         int pattern = m_ptr->SMS_PATTERN;
  30         size_t len = (size_t)m_ptr->SMS_BYTES;
  31
  32         struct proc *dst_p;
  33         endpoint_t new_granter;
  34         static vir_bytes v_offset;
  35         int r;
  36
  37         if (dst_endpt == NONE || caller_endpt == NONE)
  38                 return EFAULT;
  39
  40         if (!(dst_p = endpoint_lookup(dst_endpt)))
  41                 return EINVAL;
  42
  43         if (!(priv(dst_p) && priv(dst_p)->s_grant_table)) {
  44                 printf("safememset: dst %d has no grant table\n", dst_endpt);
  45                 return EINVAL;
  46         }
  47
  48         /* Verify permission exists, memset always requires CPF_WRITE */
  49         r = verify_grant(dst_endpt, caller_endpt, grantid, len, CPF_WRITE,
  50                          g_offset, &v_offset, &new_granter);
  51
  52         if (r != OK) {
  53                 printf("safememset: grant %d verify failed %d", grantid, r);
  54                 return r;
  55         }
  56
  57         return vm_memset(caller, new_granter, v_offset, pattern, len);
  58 }