ipc/msg.c

Source file repositories/reference/linux-study-clean/ipc/msg.c

File Facts

System
Linux kernel
Corpus path
ipc/msg.c
Extension
.c
Size
33039 bytes
Lines
1377
Domain
Core OS
Bucket
IPC
Inferred role
Core OS: syscall or user/kernel boundary
Status
core implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
{
	return ksys_msgget(key, msgflg);
}

static inline unsigned long
copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
{
	switch (version) {
	case IPC_64:
		return copy_to_user(buf, in, sizeof(*in));
	case IPC_OLD:
	{
		struct msqid_ds out;

		memset(&out, 0, sizeof(out));

		ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);

		out.msg_stime		= in->msg_stime;
		out.msg_rtime		= in->msg_rtime;
		out.msg_ctime		= in->msg_ctime;

		if (in->msg_cbytes > USHRT_MAX)
			out.msg_cbytes	= USHRT_MAX;
		else
			out.msg_cbytes	= in->msg_cbytes;
		out.msg_lcbytes		= in->msg_cbytes;

		if (in->msg_qnum > USHRT_MAX)
			out.msg_qnum	= USHRT_MAX;
		else
			out.msg_qnum	= in->msg_qnum;

		if (in->msg_qbytes > USHRT_MAX)
			out.msg_qbytes	= USHRT_MAX;
		else
			out.msg_qbytes	= in->msg_qbytes;
		out.msg_lqbytes		= in->msg_qbytes;

		out.msg_lspid		= in->msg_lspid;
		out.msg_lrpid		= in->msg_lrpid;

		return copy_to_user(buf, &out, sizeof(out));
	}
	default:
		return -EINVAL;
	}
}

static inline unsigned long
copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
{
	switch (version) {
	case IPC_64:
		if (copy_from_user(out, buf, sizeof(*out)))
			return -EFAULT;
		return 0;
	case IPC_OLD:
	{
		struct msqid_ds tbuf_old;

		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
			return -EFAULT;

		out->msg_perm.uid	= tbuf_old.msg_perm.uid;
		out->msg_perm.gid	= tbuf_old.msg_perm.gid;
		out->msg_perm.mode	= tbuf_old.msg_perm.mode;

		if (tbuf_old.msg_qbytes == 0)
			out->msg_qbytes	= tbuf_old.msg_lqbytes;
		else
			out->msg_qbytes	= tbuf_old.msg_qbytes;

		return 0;
	}
	default:
		return -EINVAL;
	}
}

/*
 * This function handles some msgctl commands which require the rwsem
 * to be held in write mode.
 * NOTE: no locks must be held, the rwsem is taken inside this function.
 */
static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
			struct ipc64_perm *perm, int msg_qbytes)
{
	struct kern_ipc_perm *ipcp;

Annotation

Implementation Notes