Untitled

struct group_info init_groups = { .usage = ATOMIC_INIT(2) };struct group_info *groups_alloc(int gidsetsize){struct group_info *group_info;int nblocks;int i;nblocks = (gidsetsize + NGROUPS_PER_BLOCK - 1) / NGROUPS_PER_BLOCK;/* Make sure we always allocate at least one indirect block pointer */nblocks = nblocks ? : 1;group_info = kmalloc(sizeof(*group_info) + nblocks*sizeof(gid_t *), GFP_USER);if (!group_info)return NULL;group_info->ngroups = gidsetsize;group_info->nblocks = nblocks;atomic_set(&group_info->usage, 1);if (gidsetsize <= NGROUPS_SMALL)group_info->blocks[0] = group_info->small_block;else {for (i = 0; i < nblocks; i++) {gid_t *b;b = (void *)__get_free_page(GFP_USER);if (!b)goto out_undo_partial_alloc;group_info->blocks[i] = b;}}return group_info;out_undo_partial_alloc:while (--i >= 0) {free_page((unsigned long)group_info->blocks[i]);}kfree(group_info);return NULL;}EXPORT_SYMBOL(groups_alloc);void groups_free(struct group_info *group_info){if (group_info->blocks[0] != group_info->small_block) {int i;for (i = 0; i < group_info->nblocks; i++)free_page((unsigned long)group_info->blocks[i]);}kfree(group_info);}EXPORT_SYMBOL(groups_free);/* export the group_info to a user-space array */static int groups_to_user(gid_t __user *grouplist,const struct group_info *group_info){int i;unsigned int count = group_info->ngroups;for (i = 0; i < group_info->nblocks; i++) {unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);unsigned int len = cp_count * sizeof(*grouplist);if (copy_to_user(grouplist, group_info->blocks[i], len))return -EFAULT;grouplist += NGROUPS_PER_BLOCK;count -= cp_count;}return 0;}/* fill a group_info from a user-space array - it must be allocated already */static int groups_from_user(struct group_info *group_info,gid_t __user *grouplist){int i;unsigned int count = group_info->ngroups;for (i = 0; i < group_info->nblocks; i++) {unsigned int cp_count = min(NGROUPS_PER_BLOCK, count);unsigned int len = cp_count * sizeof(*grouplist);if (copy_from_user(group_info->blocks[i], grouplist, len))return -EFAULT;grouplist += NGROUPS_PER_BLOCK;count -= cp_count;}return 0;}/* a simple Shell sort */static void groups_sort(struct group_info *group_info){int base, max, stride;int gidsetsize =Sponsored Links