minix/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
  17 /*===========================================================================*
  18  *                              do_safememset                                *
  19  *===========================================================================*/
  20 int do_safememset(struct proc *caller, message *m_ptr) {
  21         /* Implementation of the do_safememset() kernel call */
  22
  23         /* Extract parameters */
  24         endpoint_t dst_endpt = m_ptr->SMS_DST;
  25         endpoint_t caller_endpt = caller->p_endpoint;
  26         cp_grant_id_t grantid = m_ptr->SMS_GID;
  27         vir_bytes g_offset = m_ptr->SMS_OFFSET;
  28         int pattern = m_ptr->SMS_PATTERN;
  29         size_t len = (size_t)m_ptr->SMS_BYTES;
  30
  31         struct proc *dst_p;
  32         endpoint_t new_granter;
  33         static vir_bytes v_offset;
  34         int r;
  35
  36         if (dst_endpt == NONE || caller_endpt == NONE)
  37                 return EFAULT;
  38
  39         if (!(dst_p = endpoint_lookup(dst_endpt)))
  40                 return EINVAL;
  41
  42         if (!(priv(dst_p) && priv(dst_p)->s_grant_table)) {
  43                 printf("safememset: dst %d has no grant table\n", dst_endpt);
  44                 return EINVAL;
  45         }
  46
  47         /* Verify permission exists, memset always requires CPF_WRITE */
  48         r = verify_grant(dst_endpt, caller_endpt, grantid, len, CPF_WRITE,
  49                          g_offset, &v_offset, &new_granter, NULL);
  50
  51         if (r != OK) {
  52                 printf("safememset: grant %d verify failed %d", grantid, r);
  53                 return r;
  54         }
  55
  56         return vm_memset(caller, new_granter, v_offset, pattern, len);
  57 }