1. struct group_info init_groups = { .usage = ATOMIC_INIT(2) };
  2. struct group_info *groups_alloc(int gidsetsize){
  3. struct group_info *group_info;
  4. int nblocks;
  5. int i;
  6.  
  7. nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;
  8. /* Make sure we always allocate at least one indirect block pointer */
  9. nblocks = nblocks ? : 1;
  10. group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);
  11. if (!group_info)
  12. return NULL;
  13. group_info->ngroups = gidsetsize;
  14. group_info->nblocks = nblocks;
  15. atomic_set(&group_info->usage, 1);
  16.  
  17. if (gidsetsize <= NGROUPS_SMALL)
  18. group_info->blocks[0] = group_info->small_block;
  19. else {
  20. for (i = 0; i < nblocks; i++) {
  21. gid_t *b;
  22. b = (void *)__get_free_page(GFP_USER);
  23. if (!b)
  24. goto out_undo_partial_alloc;
  25. group_info->blocks[i] = b;
  26. }
  27. }
  28. return group_info;
  29.  
  30. out_undo_partial_alloc:
  31. while (--i >= 0) {
  32. free_page((unsigned long)group_info->blocks[i]);
  33. }
  34. kfree(group_info);
  35. return NULL;
  36. }
  37.  
  38. EXPORT_SYMBOL(groups_alloc);
  39.  
  40. void groups_free(struct group_info *group_info)
  41. {
  42. if (group_info->blocks[0] != group_info->small_block) {
  43. int i;
  44. for (i = 0; i < group_info->nblocks; i++)
  45. free_page((unsigned long)group_info->blocks[i]);
  46. }
  47. kfree(group_info);
  48. }
  49.  
  50. EXPORT_SYMBOL(groups_free);
  51.  
  52. /* export the group_info to a user-space array */
  53. static int groups_to_user(gid_t __user *grouplist,
  54. const struct group_info *group_info)
  55. {
  56. int i;
  57. unsigned int count = group_info->ngroups;
  58.  
  59. for (i = 0; i < group_info->nblocks; i++) {
  60. unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
  61. unsigned int len = cp_count * sizeof(*grouplist);
  62.  
  63. if (copy_to_user(grouplist, group_info->blocks[i], len))
  64. return -EFAULT;
  65.  
  66. grouplist += NGROUPS_PER_BLOCK;
  67. count -= cp_count;
  68. }
  69. return 0;
  70. }
  71.  
  72. /* fill a group_info from a user-space array - it must be allocated already */
  73. static int groups_from_user(struct group_info *group_info,
  74. gid_t __user *grouplist)
  75. {
  76. int i;
  77. unsigned int count = group_info->ngroups;
  78.  
  79. for (i = 0; i < group_info->nblocks; i++) {
  80. unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);
  81. unsigned int len = cp_count * sizeof(*grouplist);
  82.  
  83. if (copy_from_user(group_info->blocks[i], grouplist, len))
  84. return -EFAULT;
  85.  
  86. grouplist += NGROUPS_PER_BLOCK;
  87. count -= cp_count;
  88. }
  89. return 0;
  90. }
  91.  
  92. /* a simple Shell sort */
  93. static void groups_sort(struct group_info *group_info)
  94. {
  95. int base, max, stride;
  96. int gidsetsize = group_info->ngroups;
  97.  
  98. for (stride = 1; stride < gidsetsize; stride = 3 * stride + 1)
  99. ; /* nothing */
  100. stride /= 3;
  101.  
  102. while (stride) {
  103. max = gidsetsize