security/selinux/ss/ebitmap.h

   1 /*
   2  * An extensible bitmap is a bitmap that supports an
   3  * arbitrary number of bits.  Extensible bitmaps are
   4  * used to represent sets of values, such as types,
   5  * roles, categories, and classes.
   6  *
   7  * Each extensible bitmap is implemented as a linked
   8  * list of bitmap nodes, where each bitmap node has
   9  * an explicitly specified starting bit position within
  10  * the total bitmap.
  11  *
  12  * Author : Stephen Smalley, <sds@epoch.ncsc.mil>
  13  */
  14 #ifndef _SS_EBITMAP_H_
  15 #define _SS_EBITMAP_H_
  16
  17 #define MAPTYPE u64                     /* portion of bitmap in each node */
  18 #define MAPSIZE (sizeof(MAPTYPE) * 8)   /* number of bits in node bitmap */
  19 #define MAPBIT  1ULL                    /* a bit in the node bitmap */
  20
  21 struct ebitmap_node {
  22         u32 startbit;           /* starting position in the total bitmap */
  23         MAPTYPE map;            /* this node's portion of the bitmap */
  24         struct ebitmap_node *next;
  25 };
  26
  27 struct ebitmap {
  28         struct ebitmap_node *node;      /* first node in the bitmap */
  29         u32 highbit;    /* highest position in the total bitmap */
  30 };
  31
  32 #define ebitmap_length(e) ((e)->highbit)
  33 #define ebitmap_startbit(e) ((e)->node ? (e)->node->startbit : 0)
  34
  35 static inline unsigned int ebitmap_start(struct ebitmap *e,
  36                                          struct ebitmap_node **n)
  37 {
  38         *n = e->node;
  39         return ebitmap_startbit(e);
  40 }
  41
  42 static inline void ebitmap_init(struct ebitmap *e)
  43 {
  44         memset(e, 0, sizeof(*e));
  45 }
  46
  47 static inline unsigned int ebitmap_next(struct ebitmap_node **n,
  48                                         unsigned int bit)
  49 {
  50         if ((bit == ((*n)->startbit + MAPSIZE - 1)) &&
  51             (*n)->next) {
  52                 *n = (*n)->next;
  53                 return (*n)->startbit;
  54         }
  55
  56         return (bit+1);
  57 }
  58
  59 static inline int ebitmap_node_get_bit(struct ebitmap_node * n,
  60                                        unsigned int bit)
  61 {
  62         if (n->map & (MAPBIT << (bit - n->startbit)))
  63                 return 1;
  64         return 0;
  65 }
  66
  67 #define ebitmap_for_each_bit(e, n, bit) \
  68         for (bit = ebitmap_start(e, &n); bit < ebitmap_length(e); bit = ebitmap_next(&n, bit)) \
  69
  70 int ebitmap_cmp(struct ebitmap *e1, struct ebitmap *e2);
  71 int ebitmap_cpy(struct ebitmap *dst, struct ebitmap *src);
  72 int ebitmap_contains(struct ebitmap *e1, struct ebitmap *e2);
  73 int ebitmap_get_bit(struct ebitmap *e, unsigned long bit);
  74 int ebitmap_set_bit(struct ebitmap *e, unsigned long bit, int value);
  75 void ebitmap_destroy(struct ebitmap *e);
  76 int ebitmap_read(struct ebitmap *e, void *fp);
  77
  78 #endif  /* _SS_EBITMAP_H_ */