drivers/fbd/rule.c

   1 #include <minix/drivers.h>
   2 #include <minix/ioctl.h>
   3 #include <sys/ioc_fbd.h>
   4
   5 #include "action.h"
   6 #include "rule.h"
   7
   8 static struct fbd_rule rules[MAX_RULES];
   9 static struct fbd_rule *matches[MAX_RULES];
  10 static int nr_matches;
  11
  12 /*===========================================================================*
  13  *                              rule_ctl                                     *
  14  *===========================================================================*/
  15 int rule_ctl(int request, endpoint_t endpt, cp_grant_id_t grant)
  16 {
  17         /* Handle an I/O control request regarding rules. */
  18         fbd_rulenum_t i;
  19         int r;
  20
  21         /* Note that any of the safecopy calls may fail if the ioctl is
  22          * improperly defined in userland; never panic if they fail!
  23          */
  24         switch (request) {
  25         case FBDCADDRULE:
  26                 /* Find a free rule slot. */
  27                 for (i = 1; i <= MAX_RULES; i++)
  28                         if (rules[i-1].num == 0)
  29                                 break;
  30
  31                 if (i == MAX_RULES+1)
  32                         return ENOMEM;
  33
  34                 /* Copy in the rule. */
  35                 if ((r = sys_safecopyfrom(endpt, grant, 0,
  36                                 (vir_bytes) &rules[i-1], sizeof(rules[0]))) != OK)
  37                         return r;
  38
  39                 /* Mark the rule as active, and return its number. */
  40                 rules[i-1].num = i;
  41
  42                 return i;
  43
  44         case FBDCDELRULE:
  45                 /* Copy in the given rule number. */
  46                 if ((r = sys_safecopyfrom(endpt, grant, 0, (vir_bytes) &i,
  47                                 sizeof(i))) != OK)
  48                         return r;
  49
  50                 /* Fail if the given rule number is not valid or in use.
  51                  * Allow the caller to determine the maximum rule number.
  52                  */
  53                 if (i <= 0 || i > MAX_RULES) return EINVAL;
  54
  55                 if (rules[i-1].num != i) return ENOENT;
  56
  57                 /* Mark the rule as not active. */
  58                 rules[i-1].num = 0;
  59
  60                 return OK;
  61
  62         case FBDCGETRULE:
  63                 /* Copy in just the rule number from the given structure. */
  64                 if ((r = sys_safecopyfrom(endpt, grant,
  65                                 offsetof(struct fbd_rule, num), (vir_bytes) &i,
  66                                 sizeof(i))) != OK)
  67                         return r;
  68
  69                 /* Fail if the given rule number is not valid or in use.
  70                  * Allow the caller to determine the maximum rule number.
  71                  */
  72                 if (i <= 0 || i > MAX_RULES) return EINVAL;
  73
  74                 if (rules[i-1].num != i) return ENOENT;
  75
  76                 /* Copy out the entire rule as is. */
  77                 return sys_safecopyto(endpt, grant, 0, (vir_bytes) &rules[i-1],
  78                                 sizeof(rules[0]));
  79
  80         default:
  81                 return EINVAL;
  82         }
  83 }
  84
  85 /*===========================================================================*
  86  *                              rule_match                                   *
  87  *===========================================================================*/
  88 static int rule_match(struct fbd_rule *rule, u64_t pos, size_t size, int flag)
  89 {
  90         /* Check whether the given rule matches the given parameters. As side
  91          * effect, update counters in the rule as appropriate.
  92          */
  93
  94         /* Ranges must overlap (start < pos+size && end > pos). */
  95         if (rule->start >= pos + size ||
  96                         (rule->end != 0 && rule->end <= pos))
  97                 return FALSE;
  98
  99         /* Flags must match. */
 100         if (!(rule->flags & flag)) return FALSE;
 101
 102         /* This is a match, but is it supposed to trigger yet? */
 103         if (rule->skip > 0) {
 104                 rule->skip--;
 105
 106                 return FALSE;
 107         }
 108
 109         return TRUE;
 110 }
 111
 112 /*===========================================================================*
 113  *                              rule_find                                    *
 114  *===========================================================================*/
 115 int rule_find(u64_t pos, size_t size, int flag)
 116 {
 117         /* Find all matching rules, and return a hook mask. */
 118         struct fbd_rule *rule;
 119         int i, hooks;
 120
 121         nr_matches = 0;
 122         hooks = 0;
 123
 124         for (i = 0; i < MAX_RULES; i++) {
 125                 rule = &rules[i];
 126
 127                 if (rule->num == 0) continue;
 128
 129                 if (!rule_match(rule, pos, size, flag))
 130                         continue;
 131
 132                 matches[nr_matches++] = rule;
 133
 134                 /* If the rule has a limited lifetime, update it now. */
 135                 if (rule->count > 0) {
 136                         rule->count--;
 137
 138                         /* Disable the rule from future matching. */
 139                         if (rule->count == 0)
 140                                 rule->num = 0;
 141                 }
 142
 143                 hooks |= action_mask(rule);
 144         }
 145
 146         return hooks;
 147 }
 148
 149 /*===========================================================================*
 150  *                              rule_pre_hook                                *
 151  *===========================================================================*/
 152 void rule_pre_hook(iovec_t *iov, unsigned *count, size_t *size,
 153         u64_t *pos)
 154 {
 155         int i;
 156
 157         for (i = 0; i < nr_matches; i++)
 158                 if (action_mask(matches[i]) & PRE_HOOK)
 159                         action_pre_hook(matches[i], iov, count, size, pos);
 160 }
 161
 162 /*===========================================================================*
 163  *                              rule_io_hook                                 *
 164  *===========================================================================*/
 165 void rule_io_hook(char *buf, size_t size, u64_t pos, int flag)
 166 {
 167         int i;
 168
 169         for (i = 0; i < nr_matches; i++)
 170                 if (action_mask(matches[i]) & IO_HOOK)
 171                         action_io_hook(matches[i], buf, size, pos, flag);
 172 }
 173
 174 /*===========================================================================*
 175  *                              rule_post_hook                               *
 176  *===========================================================================*/
 177 void rule_post_hook(size_t osize, int *result)
 178 {
 179         int i;
 180
 181         for (i = 0; i < nr_matches; i++)
 182                 if (action_mask(matches[i]) & POST_HOOK)
 183                         action_post_hook(matches[i], osize, result);
 184 }