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minix/servers/ipc/shm.c
Ben Gras d343041caa VM: make mapping types explicit 
Introduce explicit abstractions for different mapping types,
handling the instantiation, forking, pagefaults and freeing of
anonymous memory, direct physical mappings, shared memory and
physically contiguous anonymous memory as separate types, making
region.c more generic.

Also some other genericification like merging the 3 munmap cases
into one.

COW and SMAP safemap code is still implicit in region.c.
2012-10-12 14:52:01 +02:00

349 lines
8.4 KiB
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#include "inc.h"
#define MAX_SHM_NR 1024
struct shm_struct {
key_t key;
int id;
struct shmid_ds shmid_ds;
vir_bytes page;
int vm_id;
};
static struct shm_struct shm_list[MAX_SHM_NR];
static int shm_list_nr = 0;
static struct shm_struct *shm_find_key(key_t key)
{
int i;
if (key == IPC_PRIVATE)
return NULL;
for (i = 0; i < shm_list_nr; i++)
if (shm_list[i].key == key)
return shm_list+i;
return NULL;
}
static struct shm_struct *shm_find_id(int id)
{
int i;
for (i = 0; i < shm_list_nr; i++)
if (shm_list[i].id == id)
return shm_list+i;
return NULL;
}
/*===========================================================================*
* do_shmget *
*===========================================================================*/
int do_shmget(message *m)
{
struct shm_struct *shm;
long key, size, old_size;
int flag;
int id;
key = m->SHMGET_KEY;
old_size = size = m->SHMGET_SIZE;
flag = m->SHMGET_FLAG;
if ((shm = shm_find_key(key))) {
if (!check_perm(&shm->shmid_ds.shm_perm, who_e, flag))
return EACCES;
if ((flag & IPC_CREAT) && (flag & IPC_EXCL))
return EEXIST;
if (size && shm->shmid_ds.shm_segsz < size)
return EINVAL;
id = shm->id;
} else { /* no key found */
if (!(flag & IPC_CREAT))
return ENOENT;
if (size <= 0)
return EINVAL;
/* round up to a multiple of PAGE_SIZE */
if (size % I386_PAGE_SIZE)
size += I386_PAGE_SIZE - size % I386_PAGE_SIZE;
if (size <= 0)
return EINVAL;
if (shm_list_nr == MAX_SHM_NR)
return ENOMEM;
/* TODO: shmmni should be changed... */
if (identifier == SHMMNI)
return ENOSPC;
shm = &shm_list[shm_list_nr];
memset(shm, 0, sizeof(struct shm_struct));
shm->page = (vir_bytes) minix_mmap(0, size,
PROT_READ|PROT_WRITE, MAP_ANON, -1, 0);
if (shm->page == (vir_bytes) MAP_FAILED)
return ENOMEM;
shm->vm_id = vm_getphys(SELF_E, (void *) shm->page);
memset((void *)shm->page, 0, size);
shm->shmid_ds.shm_perm.cuid =
shm->shmid_ds.shm_perm.uid = getnuid(who_e);
shm->shmid_ds.shm_perm.cgid =
shm->shmid_ds.shm_perm.gid = getngid(who_e);
shm->shmid_ds.shm_perm.mode = flag & 0777;
shm->shmid_ds.shm_segsz = old_size;
shm->shmid_ds.shm_atime = 0;
shm->shmid_ds.shm_dtime = 0;
shm->shmid_ds.shm_ctime = time(NULL);
shm->shmid_ds.shm_cpid = getnpid(who_e);
shm->shmid_ds.shm_lpid = 0;
shm->shmid_ds.shm_nattch = 0;
shm->id = id = identifier++;
shm->key = key;
shm_list_nr++;
}
m->SHMGET_RETID = id;
return OK;
}
/*===========================================================================*
* do_shmat *
*===========================================================================*/
int do_shmat(message *m)
{
int id, flag;
vir_bytes addr;
void *ret;
struct shm_struct *shm;
id = m->SHMAT_ID;
addr = (vir_bytes) m->SHMAT_ADDR;
flag = m->SHMAT_FLAG;
if (addr && (addr % I386_PAGE_SIZE)) {
if (flag & SHM_RND)
addr -= (addr % I386_PAGE_SIZE);
else
return EINVAL;
}
if (!(shm = shm_find_id(id)))
return EINVAL;
if (flag & SHM_RDONLY)
flag = 0444;
else
flag = 0666;
if (!check_perm(&shm->shmid_ds.shm_perm, who_e, flag))
return EACCES;
ret = vm_remap(who_e, SELF_E, (void *)addr, (void *)shm->page,
shm->shmid_ds.shm_segsz);
if (ret == MAP_FAILED)
return ENOMEM;
shm->shmid_ds.shm_atime = time(NULL);
shm->shmid_ds.shm_lpid = getnpid(who_e);
/* nattach is updated lazily */
m->SHMAT_RETADDR = (long) ret;
return OK;
}
/*===========================================================================*
* update_refcount_and_destroy *
*===========================================================================*/
void update_refcount_and_destroy(void)
{
int i, j;
for (i = 0, j = 0; i < shm_list_nr; i++) {
u8_t rc;
rc = vm_getrefcount(SELF_E, (void *) shm_list[i].page);
if (rc == (u8_t) -1) {
printf("IPC: can't find physical region.\n");
continue;
}
shm_list[i].shmid_ds.shm_nattch = rc - 1;
if (shm_list[i].shmid_ds.shm_nattch ||
!(shm_list[i].shmid_ds.shm_perm.mode & SHM_DEST)) {
if (i != j)
shm_list[j] = shm_list[i];
j++;
} else {
int size = shm_list[i].shmid_ds.shm_segsz;
if (size % I386_PAGE_SIZE)
size += I386_PAGE_SIZE - size % I386_PAGE_SIZE;
minix_munmap((void *)shm_list[i].page, size);
}
}
shm_list_nr = j;
}
/*===========================================================================*
* do_shmdt *
*===========================================================================*/
int do_shmdt(message *m)
{
vir_bytes addr;
phys_bytes vm_id;
int i;
addr = m->SHMDT_ADDR;
if ((vm_id = vm_getphys(who_e, (void *) addr)) == 0)
return EINVAL;
for (i = 0; i < shm_list_nr; i++) {
if (shm_list[i].vm_id == vm_id) {
struct shm_struct *shm = &shm_list[i];
shm->shmid_ds.shm_atime = time(NULL);
shm->shmid_ds.shm_lpid = getnpid(who_e);
/* nattch is updated lazily */
vm_unmap(who_e, (void *) addr);
break;
}
}
if (i == shm_list_nr)
printf("IPC: do_shmdt impossible error! could not find id %lu to unmap\n",
vm_id);
update_refcount_and_destroy();
return OK;
}
/*===========================================================================*
* do_shmctl *
*===========================================================================*/
int do_shmctl(message *m)
{
int id = m->SHMCTL_ID;
int cmd = m->SHMCTL_CMD;
struct shmid_ds *ds = (struct shmid_ds *)m->SHMCTL_BUF;
struct shmid_ds tmp_ds;
struct shm_struct *shm = NULL;
struct shminfo sinfo;
struct shm_info s_info;
uid_t uid;
int r, i;
if (cmd == IPC_STAT)
update_refcount_and_destroy();
if ((cmd == IPC_STAT ||
cmd == IPC_SET ||
cmd == IPC_RMID) &&
!(shm = shm_find_id(id)))
return EINVAL;
switch (cmd) {
case IPC_STAT:
if (!ds)
return EFAULT;
/* check whether it has read permission */
if (!check_perm(&shm->shmid_ds.shm_perm, who_e, 0444))
return EACCES;
r = sys_datacopy(SELF_E, (vir_bytes)&shm->shmid_ds,
who_e, (vir_bytes)ds, sizeof(struct shmid_ds));
if (r != OK)
return EFAULT;
break;
case IPC_SET:
uid = getnuid(who_e);
if (uid != shm->shmid_ds.shm_perm.cuid &&
uid != shm->shmid_ds.shm_perm.uid &&
uid != 0)
return EPERM;
r = sys_datacopy(who_e, (vir_bytes)ds,
SELF_E, (vir_bytes)&tmp_ds, sizeof(struct shmid_ds));
if (r != OK)
return EFAULT;
shm->shmid_ds.shm_perm.uid = tmp_ds.shm_perm.uid;
shm->shmid_ds.shm_perm.gid = tmp_ds.shm_perm.gid;
shm->shmid_ds.shm_perm.mode &= ~0777;
shm->shmid_ds.shm_perm.mode |= tmp_ds.shm_perm.mode & 0666;
shm->shmid_ds.shm_ctime = time(NULL);
break;
case IPC_RMID:
uid = getnuid(who_e);
if (uid != shm->shmid_ds.shm_perm.cuid &&
uid != shm->shmid_ds.shm_perm.uid &&
uid != 0)
return EPERM;
shm->shmid_ds.shm_perm.mode |= SHM_DEST;
/* destroy if possible */
update_refcount_and_destroy();
break;
case IPC_INFO:
if (!ds)
return EFAULT;
sinfo.shmmax = (unsigned long) -1;
sinfo.shmmin = 1;
sinfo.shmmni = MAX_SHM_NR;
sinfo.shmseg = (unsigned long) -1;
sinfo.shmall = (unsigned long) -1;
r = sys_datacopy(SELF_E, (vir_bytes)&sinfo,
who_e, (vir_bytes)ds, sizeof(struct shminfo));
if (r != OK)
return EFAULT;
m->SHMCTL_RET = shm_list_nr - 1;
if (m->SHMCTL_RET < 0)
m->SHMCTL_RET = 0;
break;
case SHM_INFO:
if (!ds)
return EFAULT;
s_info.used_ids = shm_list_nr;
s_info.shm_tot = 0;
for (i = 0; i < shm_list_nr; i++)
s_info.shm_tot +=
shm_list[i].shmid_ds.shm_segsz/I386_PAGE_SIZE;
s_info.shm_rss = s_info.shm_tot;
s_info.shm_swp = 0;
s_info.swap_attempts = 0;
s_info.swap_successes = 0;
r = sys_datacopy(SELF_E, (vir_bytes)&s_info,
who_e, (vir_bytes)ds, sizeof(struct shm_info));
if (r != OK)
return EFAULT;
m->SHMCTL_RET = shm_list_nr - 1;
if (m->SHMCTL_RET < 0)
m->SHMCTL_RET = 0;
break;
case SHM_STAT:
if (id < 0 || id >= shm_list_nr)
return EINVAL;
shm = &shm_list[id];
r = sys_datacopy(SELF_E, (vir_bytes)&shm->shmid_ds,
who_e, (vir_bytes)ds, sizeof(struct shmid_ds));
if (r != OK)
return EFAULT;
m->SHMCTL_RET = shm->id;
break;
default:
return EINVAL;
}
return OK;
}
#if 0
static void list_shm_ds(void)
{
int i;
printf("key\tid\tpage\n");
for (i = 0; i < shm_list_nr; i++)
printf("%ld\t%d\t%lx\n",
shm_list[i].key,
shm_list[i].id,
shm_list[i].page);
}
#endif
/*===========================================================================*
* is_shm_nil *
*===========================================================================*/
int is_shm_nil(void)
{
return (shm_list_nr == 0);
}
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