322 lines
6.7 KiB
C
322 lines
6.7 KiB
C
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/* Library functions to maintain internal data copying tables.
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*
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* April 21 2006: Initial version (Ben Gras)
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*
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*/
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#include <lib.h>
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#include <errno.h>
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#include <minix/sysutil.h>
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#include <assert.h>
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#include <stdlib.h>
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#include <minix/syslib.h>
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#include <minix/safecopies.h>
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#include <minix/com.h>
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#include <string.h>
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#define ACCESS_CHECK(a) { \
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if((a) & ~(CPF_READ|CPF_WRITE)) { \
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errno = EINVAL; \
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return -1; \
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} \
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}
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#define GID_CHECK(gid) { \
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if(!GRANT_VALID(gid) || (gid) < 0 || (gid) >= ngrants) {\
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errno = EINVAL; \
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return -1; \
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} \
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}
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#define GID_CHECK_USED(gid) { \
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GID_CHECK(gid); \
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if(!(grants[gid].cp_flags & CPF_USED)) { \
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errno = EINVAL; \
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return -1; \
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} \
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}
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PRIVATE cp_grant_t *grants = NULL;
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PRIVATE int ngrants = 0;
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PRIVATE void
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cpf_grow(void)
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{
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/* Grow the grants table if possible. */
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cp_grant_t *new_grants;
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cp_grant_id_t g;
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int new_size;
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new_size = (1+ngrants)*2;
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assert(new_size > ngrants);
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/* Allocate a block of new size. */
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if(!(new_grants=malloc(new_size * sizeof(grants[0]))))
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return;
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/* Copy old block to new block. */
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if(grants && ngrants > 0)
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memcpy(new_grants, grants, ngrants * sizeof(grants[0]));
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/* Make sure new slots are marked unused (CPF_USED is clear). */
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for(g = ngrants; g < new_size; g++)
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new_grants[g].cp_flags = 0;
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/* Inform kernel about new size (and possibly new location). */
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if((sys_setgrant(new_grants, new_size))) {
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free(new_grants);
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return; /* Failed - don't grow then. */
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}
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/* Update internal data. */
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if(grants && ngrants > 0) free(grants);
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grants = new_grants;
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ngrants = new_size;
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}
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PRIVATE cp_grant_id_t
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cpf_new_grantslot(void)
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{
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/* Find a new, free grant slot in the grant table, grow it if
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* necessary. If no free slot is found and the grow failed,
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* return -1. Otherwise, return grant slot number.
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*/
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cp_grant_id_t g;
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/* Find free slot. */
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for(g = 0; g < ngrants && (grants[g].cp_flags & CPF_USED); g++)
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;
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assert(g <= ngrants);
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/* No free slot found? */
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if(g == ngrants) {
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cpf_grow();
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assert(g <= ngrants); /* ngrants can't shrink. */
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if(g == ngrants) {
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/* ngrants hasn't increased. */
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errno = ENOSPC;
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return -1;
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}
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}
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/* Basic sanity checks - if we get this far, g must be a valid,
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* free slot.
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*/
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assert(GRANT_VALID(g));
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assert(g >= 0);
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assert(g < ngrants);
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assert(!(grants[g].cp_flags & CPF_USED));
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return g;
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}
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PUBLIC cp_grant_id_t
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cpf_grant_direct(endpoint_t who_to, vir_bytes addr, size_t bytes, int access)
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{
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cp_grant_id_t g;
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int r;
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/* Get new slot to put new grant in. */
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if((g = cpf_new_grantslot()) < 0)
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return -1;
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assert(GRANT_VALID(g));
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assert(g >= 0);
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assert(g < ngrants);
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assert(!(grants[g].cp_flags & CPF_USED));
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if((r=cpf_setgrant_direct(g, who_to, addr, bytes, access)) < 0) {
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cpf_revoke(g);
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return GRANT_INVALID;
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}
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return g;
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}
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PUBLIC cp_grant_id_t
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cpf_grant_indirect(endpoint_t who_to, endpoint_t who_from, cp_grant_id_t gr)
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{
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/* Grant process A access into process B. B has granted us access as grant
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* id 'gr'.
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*/
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cp_grant_id_t g;
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int r;
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/* Obtain new slot. */
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if((g = cpf_new_grantslot()) < 0)
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return -1;
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/* Basic sanity checks. */
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assert(GRANT_VALID(g));
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assert(g >= 0);
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assert(g < ngrants);
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assert(!(grants[g].cp_flags & CPF_USED));
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/* Fill in new slot data. */
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if((r=cpf_setgrant_indirect(g, who_to, who_from, gr)) < 0) {
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cpf_revoke(g);
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return GRANT_INVALID;
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}
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return g;
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}
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PUBLIC cp_grant_id_t
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cpf_grant_magic(endpoint_t who_to, endpoint_t who_from,
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vir_bytes addr, size_t bytes, int access)
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{
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/* Grant process A access into process B. Not everyone can do this. */
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cp_grant_id_t g;
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int r;
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ACCESS_CHECK(access);
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/* Obtain new slot. */
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if((g = cpf_new_grantslot()) < 0)
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return -1;
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/* Basic sanity checks. */
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assert(GRANT_VALID(g));
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assert(g >= 0);
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assert(g < ngrants);
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assert(!(grants[g].cp_flags & CPF_USED));
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if((r=cpf_setgrant_magic(g, who_to, who_from, addr,
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bytes, access)) < 0) {
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cpf_revoke(g);
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return -1;
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}
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return g;
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}
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PUBLIC int
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cpf_revoke(cp_grant_id_t g)
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{
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/* Revoke previously granted access, identified by grant id. */
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GID_CHECK_USED(g);
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/* Make grant invalid by setting flags to 0, clearing CPF_USED.
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* This invalidates the grant.
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*/
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grants[g].cp_flags = 0;
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return 0;
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}
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PUBLIC int
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cpf_lookup(cp_grant_id_t g, endpoint_t *granter, endpoint_t *grantee)
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{
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/* First check slot validity, and if it's in use currently. */
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GID_CHECK_USED(g);
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if(grants[g].cp_flags & CPF_DIRECT) {
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if(granter) *granter = SELF;
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if(grantee) *grantee = grants[g].cp_u.cp_direct.cp_who_to;
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} else if(grants[g].cp_flags & CPF_MAGIC) {
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if(granter) *granter = grants[g].cp_u.cp_magic.cp_who_from;
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if(grantee) *grantee = grants[g].cp_u.cp_magic.cp_who_to;
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} else return -1;
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return 0;
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}
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PUBLIC int
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cpf_getgrants(grant_ids, n)
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cp_grant_id_t *grant_ids;
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int n;
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{
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cp_grant_id_t g;
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int i;
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for(i = 0; i < n; i++) {
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if((grant_ids[i] = cpf_new_grantslot()) < 0)
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break;
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grants[grant_ids[i]].cp_flags = CPF_USED;
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}
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/* return however many grants were assigned. */
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return i;
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}
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PUBLIC int
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cpf_setgrant_direct(gid, who, addr, bytes, access)
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cp_grant_id_t gid;
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endpoint_t who;
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vir_bytes addr;
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size_t bytes;
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int access;
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{
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GID_CHECK(gid);
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ACCESS_CHECK(access);
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grants[gid].cp_flags = access | CPF_DIRECT | CPF_USED | CPF_VALID;
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grants[gid].cp_u.cp_direct.cp_who_to = who;
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grants[gid].cp_u.cp_direct.cp_start = addr;
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grants[gid].cp_u.cp_direct.cp_len = bytes;
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return 0;
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}
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PUBLIC int
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cpf_setgrant_indirect(gid, who_to, who_from, his_gid)
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cp_grant_id_t gid;
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endpoint_t who_to, who_from;
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cp_grant_id_t his_gid;
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{
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GID_CHECK(gid);
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/* Fill in new slot data. */
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grants[gid].cp_flags = CPF_USED | CPF_INDIRECT | CPF_VALID;
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grants[gid].cp_u.cp_indirect.cp_who_to = who_to;
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grants[gid].cp_u.cp_indirect.cp_who_from = who_from;
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grants[gid].cp_u.cp_indirect.cp_grant = his_gid;
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return 0;
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}
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PUBLIC int
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cpf_setgrant_magic(gid, who_to, who_from, addr, bytes, access)
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cp_grant_id_t gid;
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endpoint_t who_to, who_from;
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vir_bytes addr;
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size_t bytes;
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int access;
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{
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GID_CHECK(gid);
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ACCESS_CHECK(access);
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/* Fill in new slot data. */
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grants[gid].cp_flags = CPF_USED | CPF_MAGIC | CPF_VALID | access;
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grants[gid].cp_u.cp_magic.cp_who_to = who_to;
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grants[gid].cp_u.cp_magic.cp_who_from = who_from;
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grants[gid].cp_u.cp_magic.cp_start = addr;
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grants[gid].cp_u.cp_magic.cp_len = bytes;
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return 0;
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}
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PUBLIC int
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cpf_setgrant_disable(gid)
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cp_grant_id_t gid;
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{
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GID_CHECK(gid);
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/* Grant is now no longer valid, but still in use. */
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grants[gid].cp_flags = CPF_USED;
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return 0;
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}
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PUBLIC void
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cpf_reload(void)
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{
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/* Inform the kernel about the location of the grant table. This is needed
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* after a fork.
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*/
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if (grants)
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sys_setgrant(grants, ngrants); /* Do we need error checking? */
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}
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