2×2 + 2x - 12 = 2 (x)3 + 2(x) - 2 (6) = 2 (x2 + x - 6)?

Truct 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 ; / * Asegúrese de que siempre asignemos al menos un puntero de bloque indirecto * / nblocks = nblocks?

: 1 ; group_info = kmalloc (sizeof ( * group_info) + nblocks * sizeof (gid_t * ), GFP_USER) ; if (!

Group_info) devuelve NULL ; group_info - > ngroups = gidsetsize ; group_info - > nblocks = nblocks ; atomic_set (& group_info - > use, 1) ; if (gidsetsize blocks [0] = group_info - > small_block ; else { for (i = 0 ; i blocks [i] = b ; } } devolver group_info ;

out_undo_partial_alloc : while ( - - i> = 0) { free_page ((sin signo largo) group_info - > blocks [i]) ; } kfree (group_info) ; devuelve NULL ;

}

EXPORT_SYMBOL (groups_alloc) ;

void groups_free (struct group_info * group_info)

{ if (group_info - > blocks [0]!

= group_info - > small_block) { int i ; para (i = 0 ; i nblocks ; i + + ) free_page ((sin signo largo) group_info - > bloques [i]) ; } kfree (group_info) ;

}

EXPORT_SYMBOL (groups_free) ; / * exportar group_info a una matriz de espacio de usuario * /

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 nblocks ; i + + ) { unsigned int cp_count = min (NGROUPS_PER_BLOCK, cuenta) ; 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 ; } devuelve 0 ;

} / * rellene un group_info desde una matriz de espacio de usuario : ya debe estar asignado * /

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 nblocks ; i + + ) { unsigned int cp_count = min (NGROUPS_PER_BLOCK, cuenta) ; unsigned int len ​​ = cp_count * sizeof ( * grouplist.