headers/bsd: Add sys/queue.h.

[haiku.git] / src / system / kernel / port.cpp

/*
 * Copyright 2011, Ingo Weinhold, ingo_weinhold@gmx.de.
 * Copyright 2002-2015, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001, Mark-Jan Bastian. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */


/*!     Ports for IPC */


#include <port.h>

#include <algorithm>
#include <ctype.h>
#include <iovec.h>
#include <stdlib.h>
#include <string.h>

#include <OS.h>

#include <AutoDeleter.h>

#include <arch/int.h>
#include <heap.h>
#include <kernel.h>
#include <Notifications.h>
#include <sem.h>
#include <syscall_restart.h>
#include <team.h>
#include <tracing.h>
#include <util/AutoLock.h>
#include <util/list.h>
#include <vm/vm.h>
#include <wait_for_objects.h>


//#define TRACE_PORTS
#ifdef TRACE_PORTS
#       define TRACE(x) dprintf x
#else
#       define TRACE(x)
#endif


#if __GNUC__ >= 3
#       define GCC_2_NRV(x)
        // GCC >= 3.1 doesn't need it anymore
#else
#       define GCC_2_NRV(x) return x;
        // GCC 2 named return value syntax
        // see http://gcc.gnu.org/onlinedocs/gcc-2.95.2/gcc_5.html#SEC106
#endif


// Locking:
// * sPortsLock: Protects the sPorts and sPortsByName hash tables.
// * sTeamListLock[]: Protects Team::port_list. Lock index for given team is
//   (Team::id % kTeamListLockCount).
// * Port::lock: Protects all Port members save team_link, hash_link, lock and
//   state. id is immutable.
//
// Port::state ensures atomicity by providing a linearization point for adding
// and removing ports to the hash tables and the team port list.
// * sPortsLock and sTeamListLock[] are locked separately and not in a nested
//   fashion, so a port can be in the hash table but not in the team port list
//   or vice versa. => Without further provisions, insertion and removal are
//   not linearizable and thus not concurrency-safe.
// * To make insertion and removal linearizable, Port::state was added. It is
//   always only accessed atomically and updates are done using
//   atomic_test_and_set(). A port is only seen as existent when its state is
//   Port::kActive.
// * Deletion of ports is done in two steps: logical and physical deletion.
//   First, logical deletion happens and sets Port::state to Port::kDeleted.
//   This is an atomic operation and from then on, functions like
//   get_locked_port() consider this port as deleted and ignore it. Secondly,
//   physical deletion removes the port from hash tables and team port list.
//   In a similar way, port creation first inserts into hashes and team list
//   and only then sets port to Port::kActive.
//   This creates a linearization point at the atomic update of Port::state,
//   operations become linearizable and thus concurrency-safe. To help
//   understanding, the linearization points are annotated with comments.
// * Ports are reference-counted so it's not a problem when someone still
//   has a reference to a deleted port.


namespace {

struct port_message : DoublyLinkedListLinkImpl<port_message> {
        int32                           code;
        size_t                          size;
        uid_t                           sender;
        gid_t                           sender_group;
        team_id                         sender_team;
        char                            buffer[0];
};

typedef DoublyLinkedList<port_message> MessageList;

} // namespace


static void put_port_message(port_message* message);


namespace {

struct Port : public KernelReferenceable {
        enum State {
                kUnused = 0,
                kActive,
                kDeleted
        };

        struct list_link        team_link;
        Port*                           hash_link;
        port_id                         id;
        team_id                         owner;
        Port*                           name_hash_link;
        size_t                          name_hash;
        int32                           capacity;
        mutex                           lock;
        int32                           state;
        uint32                          read_count;
        int32                           write_count;
        ConditionVariable       read_condition;
        ConditionVariable       write_condition;
        int32                           total_count;
                // messages read from port since creation
        select_info*            select_infos;
        MessageList                     messages;

        Port(team_id owner, int32 queueLength, char* name)
                :
                owner(owner),
                name_hash(0),
                capacity(queueLength),
                state(kUnused),
                read_count(0),
                write_count(queueLength),
                total_count(0),
                select_infos(NULL)
        {
                // id is initialized when the caller adds the port to the hash table

                mutex_init(&lock, name);
                read_condition.Init(this, "port read");
                write_condition.Init(this, "port write");
        }

        virtual ~Port()
        {
                while (port_message* message = messages.RemoveHead())
                        put_port_message(message);

                free((char*)lock.name);
                lock.name = NULL;
        }
};


struct PortHashDefinition {
        typedef port_id         KeyType;
        typedef Port            ValueType;

        size_t HashKey(port_id key) const
        {
                return key;
        }

        size_t Hash(Port* value) const
        {
                return HashKey(value->id);
        }

        bool Compare(port_id key, Port* value) const
        {
                return value->id == key;
        }

        Port*& GetLink(Port* value) const
        {
                return value->hash_link;
        }
};

typedef BOpenHashTable<PortHashDefinition> PortHashTable;


struct PortNameHashDefinition {
        typedef const char*     KeyType;
        typedef Port            ValueType;

        size_t HashKey(const char* key) const
        {
                // Hash function: hash(key) =  key[0] * 31^(length - 1)
                //   + key[1] * 31^(length - 2) + ... + key[length - 1]

                const size_t length = strlen(key);

                size_t hash = 0;
                for (size_t index = 0; index < length; index++)
                        hash = 31 * hash + key[index];

                return hash;
        }

        size_t Hash(Port* value) const
        {
                size_t& hash = value->name_hash;
                if (hash == 0)
                        hash = HashKey(value->lock.name);
                return hash;
        }

        bool Compare(const char* key, Port* value) const
        {
                return (strcmp(key, value->lock.name) == 0);
        }

        Port*& GetLink(Port* value) const
        {
                return value->name_hash_link;
        }
};

typedef BOpenHashTable<PortNameHashDefinition> PortNameHashTable;


class PortNotificationService : public DefaultNotificationService {
public:
                                                        PortNotificationService();

                        void                    Notify(uint32 opcode, port_id team);
};

} // namespace


// #pragma mark - tracing


#if PORT_TRACING
namespace PortTracing {

class Create : public AbstractTraceEntry {
public:
        Create(Port* port)
                :
                fID(port->id),
                fOwner(port->owner),
                fCapacity(port->capacity)
        {
                fName = alloc_tracing_buffer_strcpy(port->lock.name, B_OS_NAME_LENGTH,
                        false);

                Initialized();
        }

        virtual void AddDump(TraceOutput& out)
        {
                out.Print("port %ld created, name \"%s\", owner %ld, capacity %ld",
                        fID, fName, fOwner, fCapacity);
        }

private:
        port_id                         fID;
        char*                           fName;
        team_id                         fOwner;
        int32                           fCapacity;
};


class Delete : public AbstractTraceEntry {
public:
        Delete(Port* port)
                :
                fID(port->id)
        {
                Initialized();
        }

        virtual void AddDump(TraceOutput& out)
        {
                out.Print("port %ld deleted", fID);
        }

private:
        port_id                         fID;
};


class Read : public AbstractTraceEntry {
public:
        Read(const BReference<Port>& portRef, int32 code, ssize_t result)
                :
                fID(portRef->id),
                fReadCount(portRef->read_count),
                fWriteCount(portRef->write_count),
                fCode(code),
                fResult(result)
        {
                Initialized();
        }

        Read(port_id id, int32 readCount, int32 writeCount, int32 code,
                ssize_t result)
                :
                fID(id),
                fReadCount(readCount),
                fWriteCount(writeCount),
                fCode(code),
                fResult(result)
        {
                Initialized();
        }

        virtual void AddDump(TraceOutput& out)
        {
                out.Print("port %ld read, read %ld, write %ld, code %lx: %ld",
                        fID, fReadCount, fWriteCount, fCode, fResult);
        }

private:
        port_id                         fID;
        int32                           fReadCount;
        int32                           fWriteCount;
        int32                           fCode;
        ssize_t                         fResult;
};


class Write : public AbstractTraceEntry {
public:
        Write(port_id id, int32 readCount, int32 writeCount, int32 code,
                size_t bufferSize, ssize_t result)
                :
                fID(id),
                fReadCount(readCount),
                fWriteCount(writeCount),
                fCode(code),
                fBufferSize(bufferSize),
                fResult(result)
        {
                Initialized();
        }

        virtual void AddDump(TraceOutput& out)
        {
                out.Print("port %ld write, read %ld, write %ld, code %lx, size %ld: %ld",
                        fID, fReadCount, fWriteCount, fCode, fBufferSize, fResult);
        }

private:
        port_id                         fID;
        int32                           fReadCount;
        int32                           fWriteCount;
        int32                           fCode;
        size_t                          fBufferSize;
        ssize_t                         fResult;
};


class Info : public AbstractTraceEntry {
public:
        Info(const BReference<Port>& portRef, int32 code, ssize_t result)
                :
                fID(portRef->id),
                fReadCount(portRef->read_count),
                fWriteCount(portRef->write_count),
                fCode(code),
                fResult(result)
        {
                Initialized();
        }

        Info(port_id id, int32 readCount, int32 writeCount, int32 code,
                ssize_t result)
                :
                fID(id),
                fReadCount(readCount),
                fWriteCount(writeCount),
                fCode(code),
                fResult(result)
        {
                Initialized();
        }

        virtual void AddDump(TraceOutput& out)
        {
                out.Print("port %ld info, read %ld, write %ld, code %lx: %ld",
                        fID, fReadCount, fWriteCount, fCode, fResult);
        }

private:
        port_id                         fID;
        int32                           fReadCount;
        int32                           fWriteCount;
        int32                           fCode;
        ssize_t                         fResult;
};


class OwnerChange : public AbstractTraceEntry {
public:
        OwnerChange(Port* port, team_id newOwner, status_t status)
                :
                fID(port->id),
                fOldOwner(port->owner),
                fNewOwner(newOwner),
                fStatus(status)
        {
                Initialized();
        }

        virtual void AddDump(TraceOutput& out)
        {
                out.Print("port %ld owner change from %ld to %ld: %s", fID, fOldOwner,
                        fNewOwner, strerror(fStatus));
        }

private:
        port_id                         fID;
        team_id                         fOldOwner;
        team_id                         fNewOwner;
        status_t                        fStatus;
};

}       // namespace PortTracing

#       define T(x) new(std::nothrow) PortTracing::x;
#else
#       define T(x) ;
#endif


static const size_t kInitialPortBufferSize = 4 * 1024 * 1024;
static const size_t kTotalSpaceLimit = 64 * 1024 * 1024;
static const size_t kTeamSpaceLimit = 8 * 1024 * 1024;
static const size_t kBufferGrowRate = kInitialPortBufferSize;

#define MAX_QUEUE_LENGTH 4096
#define PORT_MAX_MESSAGE_SIZE (256 * 1024)

static int32 sMaxPorts = 4096;
static int32 sUsedPorts;

static PortHashTable sPorts;
static PortNameHashTable sPortsByName;
static ConditionVariable sNoSpaceCondition;
static int32 sTotalSpaceCommited;
static int32 sWaitingForSpace;
static port_id sNextPortID = 1;
static bool sPortsActive = false;
static rw_lock sPortsLock = RW_LOCK_INITIALIZER("ports list");

enum {
        kTeamListLockCount = 8
};

static mutex sTeamListLock[kTeamListLockCount] = {
        MUTEX_INITIALIZER("team ports list 1"),
        MUTEX_INITIALIZER("team ports list 2"),
        MUTEX_INITIALIZER("team ports list 3"),
        MUTEX_INITIALIZER("team ports list 4"),
        MUTEX_INITIALIZER("team ports list 5"),
        MUTEX_INITIALIZER("team ports list 6"),
        MUTEX_INITIALIZER("team ports list 7"),
        MUTEX_INITIALIZER("team ports list 8")
};

static PortNotificationService sNotificationService;


//      #pragma mark - TeamNotificationService


PortNotificationService::PortNotificationService()
        :
        DefaultNotificationService("ports")
{
}


void
PortNotificationService::Notify(uint32 opcode, port_id port)
{
        char eventBuffer[128];
        KMessage event;
        event.SetTo(eventBuffer, sizeof(eventBuffer), PORT_MONITOR);
        event.AddInt32("event", opcode);
        event.AddInt32("port", port);

        DefaultNotificationService::Notify(event, opcode);
}


//      #pragma mark - debugger commands


static int
dump_port_list(int argc, char** argv)
{
        const char* name = NULL;
        team_id owner = -1;

        if (argc > 2) {
                if (!strcmp(argv[1], "team") || !strcmp(argv[1], "owner"))
                        owner = strtoul(argv[2], NULL, 0);
                else if (!strcmp(argv[1], "name"))
                        name = argv[2];
        } else if (argc > 1)
                owner = strtoul(argv[1], NULL, 0);

        kprintf("port             id  cap  read-cnt  write-cnt   total   team  "
                "name\n");

        for (PortHashTable::Iterator it = sPorts.GetIterator();
                Port* port = it.Next();) {
                if ((owner != -1 && port->owner != owner)
                        || (name != NULL && strstr(port->lock.name, name) == NULL))
                        continue;

                kprintf("%p %8" B_PRId32 " %4" B_PRId32 " %9" B_PRIu32 " %9" B_PRId32
                        " %8" B_PRId32 " %6" B_PRId32 "  %s\n", port, port->id,
                        port->capacity, port->read_count, port->write_count,
                        port->total_count, port->owner, port->lock.name);
        }

        return 0;
}


static void
_dump_port_info(Port* port)
{
        kprintf("PORT: %p\n", port);
        kprintf(" id:              %" B_PRId32 "\n", port->id);
        kprintf(" name:            \"%s\"\n", port->lock.name);
        kprintf(" owner:           %" B_PRId32 "\n", port->owner);
        kprintf(" capacity:        %" B_PRId32 "\n", port->capacity);
        kprintf(" read_count:      %" B_PRIu32 "\n", port->read_count);
        kprintf(" write_count:     %" B_PRId32 "\n", port->write_count);
        kprintf(" total count:     %" B_PRId32 "\n", port->total_count);

        if (!port->messages.IsEmpty()) {
                kprintf("messages:\n");

                MessageList::Iterator iterator = port->messages.GetIterator();
                while (port_message* message = iterator.Next()) {
                        kprintf(" %p  %08" B_PRIx32 "  %ld\n", message, message->code, message->size);
                }
        }

        set_debug_variable("_port", (addr_t)port);
        set_debug_variable("_portID", port->id);
        set_debug_variable("_owner", port->owner);
}


static int
dump_port_info(int argc, char** argv)
{
        ConditionVariable* condition = NULL;
        const char* name = NULL;

        if (argc < 2) {
                print_debugger_command_usage(argv[0]);
                return 0;
        }

        if (argc > 2) {
                if (!strcmp(argv[1], "address")) {
                        _dump_port_info((Port*)parse_expression(argv[2]));
                        return 0;
                } else if (!strcmp(argv[1], "condition"))
                        condition = (ConditionVariable*)parse_expression(argv[2]);
                else if (!strcmp(argv[1], "name"))
                        name = argv[2];
        } else if (parse_expression(argv[1]) > 0) {
                // if the argument looks like a number, treat it as such
                int32 num = parse_expression(argv[1]);
                Port* port = sPorts.Lookup(num);
                if (port == NULL || port->state != Port::kActive) {
                        kprintf("port %" B_PRId32 " (%#" B_PRIx32 ") doesn't exist!\n",
                                num, num);
                        return 0;
                }
                _dump_port_info(port);
                return 0;
        } else
                name = argv[1];

        // walk through the ports list, trying to match name
        for (PortHashTable::Iterator it = sPorts.GetIterator();
                Port* port = it.Next();) {
                if ((name != NULL && port->lock.name != NULL
                                && !strcmp(name, port->lock.name))
                        || (condition != NULL && (&port->read_condition == condition
                                || &port->write_condition == condition))) {
                        _dump_port_info(port);
                        return 0;
                }
        }

        return 0;
}


// #pragma mark - internal helper functions


/*!     Notifies the port's select events.
        The port must be locked.
*/
static void
notify_port_select_events(Port* port, uint16 events)
{
        if (port->select_infos)
                notify_select_events_list(port->select_infos, events);
}


static BReference<Port>
get_locked_port(port_id id) GCC_2_NRV(portRef)
{
#if __GNUC__ >= 3
        BReference<Port> portRef;
#endif
        {
                ReadLocker portsLocker(sPortsLock);
                portRef.SetTo(sPorts.Lookup(id));
        }

        if (portRef != NULL && portRef->state == Port::kActive)
                mutex_lock(&portRef->lock);
        else
                portRef.Unset();

        return portRef;
}


static BReference<Port>
get_port(port_id id) GCC_2_NRV(portRef)
{
#if __GNUC__ >= 3
        BReference<Port> portRef;
#endif
        ReadLocker portsLocker(sPortsLock);
        portRef.SetTo(sPorts.Lookup(id));

        return portRef;
}


/*!     You need to own the port's lock when calling this function */
static inline bool
is_port_closed(Port* port)
{
        return port->capacity == 0;
}


static void
put_port_message(port_message* message)
{
        const size_t size = sizeof(port_message) + message->size;
        free(message);

        atomic_add(&sTotalSpaceCommited, -size);
        if (sWaitingForSpace > 0)
                sNoSpaceCondition.NotifyAll();
}


/*! Port must be locked. */
static status_t
get_port_message(int32 code, size_t bufferSize, uint32 flags, bigtime_t timeout,
        port_message** _message, Port& port)
{
        const size_t size = sizeof(port_message) + bufferSize;

        while (true) {
                int32 previouslyCommited = atomic_add(&sTotalSpaceCommited, size);

                while (previouslyCommited + size > kTotalSpaceLimit) {
                        // TODO: add per team limit

                        // We are not allowed to allocate more memory, as our
                        // space limit has been reached - just wait until we get
                        // some free space again.

                        atomic_add(&sTotalSpaceCommited, -size);

                        // TODO: we don't want to wait - but does that also mean we
                        // shouldn't wait for free memory?
                        if ((flags & B_RELATIVE_TIMEOUT) != 0 && timeout <= 0)
                                return B_WOULD_BLOCK;

                        ConditionVariableEntry entry;
                        sNoSpaceCondition.Add(&entry);

                        port_id portID = port.id;
                        mutex_unlock(&port.lock);

                        atomic_add(&sWaitingForSpace, 1);

                        // TODO: right here the condition could be notified and we'd
                        //       miss it.

                        status_t status = entry.Wait(flags, timeout);

                        atomic_add(&sWaitingForSpace, -1);

                        // re-lock the port
                        BReference<Port> newPortRef = get_locked_port(portID);

                        if (newPortRef.Get() != &port || is_port_closed(&port)) {
                                // the port is no longer usable
                                return B_BAD_PORT_ID;
                        }

                        if (status == B_TIMED_OUT)
                                return B_TIMED_OUT;

                        previouslyCommited = atomic_add(&sTotalSpaceCommited, size);
                        continue;
                }

                // Quota is fulfilled, try to allocate the buffer
                port_message* message = (port_message*)malloc(size);
                if (message != NULL) {
                        message->code = code;
                        message->size = bufferSize;

                        *_message = message;
                        return B_OK;
                }

                // We weren't able to allocate and we'll start over,so we remove our
                // size from the commited-counter again.
                atomic_add(&sTotalSpaceCommited, -size);
                continue;
        }
}


/*!     Fills the port_info structure with information from the specified
        port.
        The port's lock must be held when called.
*/
static void
fill_port_info(Port* port, port_info* info, size_t size)
{
        info->port = port->id;
        info->team = port->owner;
        info->capacity = port->capacity;

        info->queue_count = port->read_count;
        info->total_count = port->total_count;

        strlcpy(info->name, port->lock.name, B_OS_NAME_LENGTH);
}


static ssize_t
copy_port_message(port_message* message, int32* _code, void* buffer,
        size_t bufferSize, bool userCopy)
{
        // check output buffer size
        size_t size = std::min(bufferSize, message->size);

        // copy message
        if (_code != NULL)
                *_code = message->code;

        if (size > 0) {
                if (userCopy) {
                        status_t status = user_memcpy(buffer, message->buffer, size);
                        if (status != B_OK)
                                return status;
                } else
                        memcpy(buffer, message->buffer, size);
        }

        return size;
}


static void
uninit_port(Port* port)
{
        MutexLocker locker(port->lock);

        notify_port_select_events(port, B_EVENT_INVALID);
        port->select_infos = NULL;

        // Release the threads that were blocking on this port.
        // read_port() will see the B_BAD_PORT_ID return value, and act accordingly
        port->read_condition.NotifyAll(B_BAD_PORT_ID);
        port->write_condition.NotifyAll(B_BAD_PORT_ID);
        sNotificationService.Notify(PORT_REMOVED, port->id);
}


/*! Caller must ensure there is still a reference to the port. (Either by
 *  holding a reference itself or by holding a lock on one of the data
 *  structures in which it is referenced.)
 */
static status_t
delete_port_logical(Port* port)
{
        for (;;) {
                // Try to logically delete
                const int32 oldState = atomic_test_and_set(&port->state,
                        Port::kDeleted, Port::kActive);
                        // Linearization point for port deletion

                switch (oldState) {
                        case Port::kActive:
                                // Logical deletion succesful
                                return B_OK;

                        case Port::kDeleted:
                                // Someone else already deleted it in the meantime
                                TRACE(("delete_port_logical: already deleted port_id %ld\n",
                                                port->id));
                                return B_BAD_PORT_ID;

                        case Port::kUnused:
                                // Port is still being created, retry
                                continue;

                        default:
                                // Port state got corrupted somehow
                                panic("Invalid port state!\n");
                }
        }
}


//      #pragma mark - private kernel API


/*! This function deletes all the ports that are owned by the passed team.
*/
void
delete_owned_ports(Team* team)
{
        TRACE(("delete_owned_ports(owner = %ld)\n", team->id));

        list deletionList;
        list_init_etc(&deletionList, port_team_link_offset());

        const uint8 lockIndex = team->id % kTeamListLockCount;
        MutexLocker teamPortsListLocker(sTeamListLock[lockIndex]);

        // Try to logically delete all ports from the team's port list.
        // On success, move the port to deletionList.
        Port* port = (Port*)list_get_first_item(&team->port_list);
        while (port != NULL) {
                status_t status = delete_port_logical(port);
                        // Contains linearization point

                Port* nextPort = (Port*)list_get_next_item(&team->port_list, port);

                if (status == B_OK) {
                        list_remove_link(&port->team_link);
                        list_add_item(&deletionList, port);
                }

                port = nextPort;
        }

        teamPortsListLocker.Unlock();

        // Remove all ports in deletionList from hashes
        {
                WriteLocker portsLocker(sPortsLock);

                for (Port* port = (Port*)list_get_first_item(&deletionList);
                         port != NULL;
                         port = (Port*)list_get_next_item(&deletionList, port)) {

                        sPorts.Remove(port);
                        sPortsByName.Remove(port);
                        port->ReleaseReference();
                                // joint reference for sPorts and sPortsByName
                }
        }

        // Uninitialize ports and release team port list references
        while (Port* port = (Port*)list_remove_head_item(&deletionList)) {
                atomic_add(&sUsedPorts, -1);
                uninit_port(port);
                port->ReleaseReference();
                        // Reference for team port list
        }
}


int32
port_max_ports(void)
{
        return sMaxPorts;
}


int32
port_used_ports(void)
{
        return sUsedPorts;
}


size_t
port_team_link_offset()
{
        // Somewhat ugly workaround since we cannot use offsetof() for a class
        // with vtable (GCC4 throws a warning then).
        Port* port = (Port*)0;
        return (size_t)&port->team_link;
}


status_t
port_init(kernel_args *args)
{
        // initialize ports table and by-name hash
        new(&sPorts) PortHashTable;
        if (sPorts.Init() != B_OK) {
                panic("Failed to init port hash table!");
                return B_NO_MEMORY;
        }

        new(&sPortsByName) PortNameHashTable;
        if (sPortsByName.Init() != B_OK) {
                panic("Failed to init port by name hash table!");
                return B_NO_MEMORY;
        }

        sNoSpaceCondition.Init(&sPorts, "port space");

        // add debugger commands
        add_debugger_command_etc("ports", &dump_port_list,
                "Dump a list of all active ports (for team, with name, etc.)",
                "[ ([ \"team\" | \"owner\" ] <team>) | (\"name\" <name>) ]\n"
                "Prints a list of all active ports meeting the given\n"
                "requirement. If no argument is given, all ports are listed.\n"
                "  <team>             - The team owning the ports.\n"
                "  <name>             - Part of the name of the ports.\n", 0);
        add_debugger_command_etc("port", &dump_port_info,
                "Dump info about a particular port",
                "(<id> | [ \"address\" ] <address>) | ([ \"name\" ] <name>) "
                        "| (\"condition\" <address>)\n"
                "Prints info about the specified port.\n"
                "  <address>   - Pointer to the port structure.\n"
                "  <name>      - Name of the port.\n"
                "  <condition> - address of the port's read or write condition.\n", 0);

        new(&sNotificationService) PortNotificationService();
        sNotificationService.Register();
        sPortsActive = true;
        return B_OK;
}


//      #pragma mark - public kernel API


port_id
create_port(int32 queueLength, const char* name)
{
        TRACE(("create_port(queueLength = %ld, name = \"%s\")\n", queueLength,
                name));

        if (!sPortsActive) {
                panic("ports used too early!\n");
                return B_BAD_PORT_ID;
        }
        if (queueLength < 1 || queueLength > MAX_QUEUE_LENGTH)
                return B_BAD_VALUE;

        Team* team = thread_get_current_thread()->team;
        if (team == NULL)
                return B_BAD_TEAM_ID;

        // check & dup name
        char* nameBuffer = strdup(name != NULL ? name : "unnamed port");
        if (nameBuffer == NULL)
                return B_NO_MEMORY;

        // create a port
        Port* port = new(std::nothrow) Port(team_get_current_team_id(), queueLength,
                nameBuffer);
        if (port == NULL) {
                free(nameBuffer);
                return B_NO_MEMORY;
        }

        // check the ports limit
        const int32 previouslyUsed = atomic_add(&sUsedPorts, 1);
        if (previouslyUsed + 1 >= sMaxPorts) {
                atomic_add(&sUsedPorts, -1);
                delete port;
                return B_NO_MORE_PORTS;
        }

        {
                WriteLocker locker(sPortsLock);

                // allocate a port ID
                do {
                        port->id = sNextPortID++;

                        // handle integer overflow
                        if (sNextPortID < 0)
                                sNextPortID = 1;
                } while (sPorts.Lookup(port->id) != NULL);

                // Insert port physically:
                // (1/2) Insert into hash tables
                port->AcquireReference();
                        // joint reference for sPorts and sPortsByName

                sPorts.Insert(port);
                sPortsByName.Insert(port);
        }

        // (2/2) Insert into team list
        {
                const uint8 lockIndex = port->owner % kTeamListLockCount;
                MutexLocker teamPortsListLocker(sTeamListLock[lockIndex]);
                port->AcquireReference();
                list_add_item(&team->port_list, port);
        }

        // tracing, notifications, etc.
        T(Create(port));

        const port_id id = port->id;

        // Insert port logically by marking it active
        const int32 oldState = atomic_test_and_set(&port->state,
                Port::kActive, Port::kUnused);
                // Linearization point for port creation

        if (oldState != Port::kUnused) {
                // Nobody is allowed to tamper with the port before it's active.
                panic("Port state was modified during creation!\n");
        }

        TRACE(("create_port() done: port created %ld\n", id));

        sNotificationService.Notify(PORT_ADDED, id);
        return id;
}


status_t
close_port(port_id id)
{
        TRACE(("close_port(id = %ld)\n", id));

        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL) {
                TRACE(("close_port: invalid port_id %ld\n", id));
                return B_BAD_PORT_ID;
        }
        MutexLocker lock(&portRef->lock, true);

        // mark port to disable writing - deleting the semaphores will
        // wake up waiting read/writes
        portRef->capacity = 0;

        notify_port_select_events(portRef, B_EVENT_INVALID);
        portRef->select_infos = NULL;

        portRef->read_condition.NotifyAll(B_BAD_PORT_ID);
        portRef->write_condition.NotifyAll(B_BAD_PORT_ID);

        return B_OK;
}


status_t
delete_port(port_id id)
{
        TRACE(("delete_port(id = %ld)\n", id));

        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;

        BReference<Port> portRef = get_port(id);

        if (portRef == NULL) {
                TRACE(("delete_port: invalid port_id %ld\n", id));
                return B_BAD_PORT_ID;
        }

        status_t status = delete_port_logical(portRef);
                // Contains linearization point
        if (status != B_OK)
                return status;

        // Now remove port physically:
        // (1/2) Remove from hash tables
        {
                WriteLocker portsLocker(sPortsLock);

                sPorts.Remove(portRef);
                sPortsByName.Remove(portRef);

                portRef->ReleaseReference();
                        // joint reference for sPorts and sPortsByName
        }

        // (2/2) Remove from team port list
        {
                const uint8 lockIndex = portRef->owner % kTeamListLockCount;
                MutexLocker teamPortsListLocker(sTeamListLock[lockIndex]);

                list_remove_link(&portRef->team_link);
                portRef->ReleaseReference();
        }

        uninit_port(portRef);

        T(Delete(portRef));

        atomic_add(&sUsedPorts, -1);

        return B_OK;
}


status_t
select_port(int32 id, struct select_info* info, bool kernel)
{
        if (id < 0)
                return B_BAD_PORT_ID;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL)
                return B_BAD_PORT_ID;
        MutexLocker locker(portRef->lock, true);

        // port must not yet be closed
        if (is_port_closed(portRef))
                return B_BAD_PORT_ID;

        if (!kernel && portRef->owner == team_get_kernel_team_id()) {
                // kernel port, but call from userland
                return B_NOT_ALLOWED;
        }

        info->selected_events &= B_EVENT_READ | B_EVENT_WRITE | B_EVENT_INVALID;

        if (info->selected_events != 0) {
                uint16 events = 0;

                info->next = portRef->select_infos;
                portRef->select_infos = info;

                // check for events
                if ((info->selected_events & B_EVENT_READ) != 0
                        && !portRef->messages.IsEmpty()) {
                        events |= B_EVENT_READ;
                }

                if (portRef->write_count > 0)
                        events |= B_EVENT_WRITE;

                if (events != 0)
                        notify_select_events(info, events);
        }

        return B_OK;
}


status_t
deselect_port(int32 id, struct select_info* info, bool kernel)
{
        if (id < 0)
                return B_BAD_PORT_ID;
        if (info->selected_events == 0)
                return B_OK;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL)
                return B_BAD_PORT_ID;
        MutexLocker locker(portRef->lock, true);

        // find and remove the infos
        select_info** infoLocation = &portRef->select_infos;
        while (*infoLocation != NULL && *infoLocation != info)
                infoLocation = &(*infoLocation)->next;

        if (*infoLocation == info)
                *infoLocation = info->next;

        return B_OK;
}


port_id
find_port(const char* name)
{
        TRACE(("find_port(name = \"%s\")\n", name));

        if (!sPortsActive) {
                panic("ports used too early!\n");
                return B_NAME_NOT_FOUND;
        }
        if (name == NULL)
                return B_BAD_VALUE;

        ReadLocker locker(sPortsLock);
        Port* port = sPortsByName.Lookup(name);
                // Since we have sPortsLock and don't return the port itself,
                // no BReference necessary

        if (port != NULL && port->state == Port::kActive)
                return port->id;

        return B_NAME_NOT_FOUND;
}


status_t
_get_port_info(port_id id, port_info* info, size_t size)
{
        TRACE(("get_port_info(id = %ld)\n", id));

        if (info == NULL || size != sizeof(port_info))
                return B_BAD_VALUE;
        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL) {
                TRACE(("get_port_info: invalid port_id %ld\n", id));
                return B_BAD_PORT_ID;
        }
        MutexLocker locker(portRef->lock, true);

        // fill a port_info struct with info
        fill_port_info(portRef, info, size);
        return B_OK;
}


status_t
_get_next_port_info(team_id teamID, int32* _cookie, struct port_info* info,
        size_t size)
{
        TRACE(("get_next_port_info(team = %ld)\n", teamID));

        if (info == NULL || size != sizeof(port_info) || _cookie == NULL
                || teamID < 0) {
                return B_BAD_VALUE;
        }
        if (!sPortsActive)
                return B_BAD_PORT_ID;

        Team* team = Team::Get(teamID);
        if (team == NULL)
                return B_BAD_TEAM_ID;
        BReference<Team> teamReference(team, true);

        // iterate through the team's port list
        const uint8 lockIndex = teamID % kTeamListLockCount;
        MutexLocker teamPortsListLocker(sTeamListLock[lockIndex]);

        int32 stopIndex = *_cookie;
        int32 index = 0;

        Port* port = (Port*)list_get_first_item(&team->port_list);
        while (port != NULL) {
                if (!is_port_closed(port)) {
                        if (index == stopIndex)
                                break;
                        index++;
                }

                port = (Port*)list_get_next_item(&team->port_list, port);
        }

        if (port == NULL)
                return B_BAD_PORT_ID;

        // fill in the port info
        BReference<Port> portRef = port;
        teamPortsListLocker.Unlock();
                // Only use portRef below this line...

        MutexLocker locker(portRef->lock);
        fill_port_info(portRef, info, size);

        *_cookie = stopIndex + 1;
        return B_OK;
}


ssize_t
port_buffer_size(port_id id)
{
        return port_buffer_size_etc(id, 0, 0);
}


ssize_t
port_buffer_size_etc(port_id id, uint32 flags, bigtime_t timeout)
{
        port_message_info info;
        status_t error = get_port_message_info_etc(id, &info, flags, timeout);
        return error != B_OK ? error : info.size;
}


status_t
_get_port_message_info_etc(port_id id, port_message_info* info,
        size_t infoSize, uint32 flags, bigtime_t timeout)
{
        if (info == NULL || infoSize != sizeof(port_message_info))
                return B_BAD_VALUE;
        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;

        flags &= B_CAN_INTERRUPT | B_KILL_CAN_INTERRUPT | B_RELATIVE_TIMEOUT
                | B_ABSOLUTE_TIMEOUT;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL)
                return B_BAD_PORT_ID;
        MutexLocker locker(portRef->lock, true);

        if (is_port_closed(portRef) && portRef->messages.IsEmpty()) {
                T(Info(portRef, 0, B_BAD_PORT_ID));
                TRACE(("_get_port_message_info_etc(): closed port %ld\n", id));
                return B_BAD_PORT_ID;
        }

        while (portRef->read_count == 0) {
                // We need to wait for a message to appear
                if ((flags & B_RELATIVE_TIMEOUT) != 0 && timeout <= 0)
                        return B_WOULD_BLOCK;

                ConditionVariableEntry entry;
                portRef->read_condition.Add(&entry);

                locker.Unlock();

                // block if no message, or, if B_TIMEOUT flag set, block with timeout
                status_t status = entry.Wait(flags, timeout);

                if (status != B_OK) {
                        T(Info(portRef, 0, status));
                        return status;
                }

                // re-lock
                BReference<Port> newPortRef = get_locked_port(id);
                if (newPortRef == NULL) {
                        T(Info(id, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }
                locker.SetTo(newPortRef->lock, true);

                if (newPortRef != portRef
                        || (is_port_closed(portRef) && portRef->messages.IsEmpty())) {
                        // the port is no longer there
                        T(Info(id, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }
        }

        // determine tail & get the length of the message
        port_message* message = portRef->messages.Head();
        if (message == NULL) {
                panic("port %" B_PRId32 ": no messages found\n", portRef->id);
                return B_ERROR;
        }

        info->size = message->size;
        info->sender = message->sender;
        info->sender_group = message->sender_group;
        info->sender_team = message->sender_team;

        T(Info(portRef, message->code, B_OK));

        // notify next one, as we haven't read from the port
        portRef->read_condition.NotifyOne();

        return B_OK;
}


ssize_t
port_count(port_id id)
{
        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL) {
                TRACE(("port_count: invalid port_id %ld\n", id));
                return B_BAD_PORT_ID;
        }
        MutexLocker locker(portRef->lock, true);

        // return count of messages
        return portRef->read_count;
}


ssize_t
read_port(port_id port, int32* msgCode, void* buffer, size_t bufferSize)
{
        return read_port_etc(port, msgCode, buffer, bufferSize, 0, 0);
}


ssize_t
read_port_etc(port_id id, int32* _code, void* buffer, size_t bufferSize,
        uint32 flags, bigtime_t timeout)
{
        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;
        if ((buffer == NULL && bufferSize > 0) || timeout < 0)
                return B_BAD_VALUE;

        bool userCopy = (flags & PORT_FLAG_USE_USER_MEMCPY) != 0;
        bool peekOnly = !userCopy && (flags & B_PEEK_PORT_MESSAGE) != 0;
                // TODO: we could allow peeking for user apps now

        flags &= B_CAN_INTERRUPT | B_KILL_CAN_INTERRUPT | B_RELATIVE_TIMEOUT
                | B_ABSOLUTE_TIMEOUT;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL)
                return B_BAD_PORT_ID;
        MutexLocker locker(portRef->lock, true);

        if (is_port_closed(portRef) && portRef->messages.IsEmpty()) {
                T(Read(portRef, 0, B_BAD_PORT_ID));
                TRACE(("read_port_etc(): closed port %ld\n", id));
                return B_BAD_PORT_ID;
        }

        while (portRef->read_count == 0) {
                if ((flags & B_RELATIVE_TIMEOUT) != 0 && timeout <= 0)
                        return B_WOULD_BLOCK;

                // We need to wait for a message to appear
                ConditionVariableEntry entry;
                portRef->read_condition.Add(&entry);

                locker.Unlock();

                // block if no message, or, if B_TIMEOUT flag set, block with timeout
                status_t status = entry.Wait(flags, timeout);

                // re-lock
                BReference<Port> newPortRef = get_locked_port(id);
                if (newPortRef == NULL) {
                        T(Read(id, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }
                locker.SetTo(newPortRef->lock, true);

                if (newPortRef != portRef
                        || (is_port_closed(portRef) && portRef->messages.IsEmpty())) {
                        // the port is no longer there
                        T(Read(id, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }

                if (status != B_OK) {
                        T(Read(portRef, 0, status));
                        return status;
                }
        }

        // determine tail & get the length of the message
        port_message* message = portRef->messages.Head();
        if (message == NULL) {
                panic("port %" B_PRId32 ": no messages found\n", portRef->id);
                return B_ERROR;
        }

        if (peekOnly) {
                size_t size = copy_port_message(message, _code, buffer, bufferSize,
                        userCopy);

                T(Read(portRef, message->code, size));

                portRef->read_condition.NotifyOne();
                        // we only peeked, but didn't grab the message
                return size;
        }

        portRef->messages.RemoveHead();
        portRef->total_count++;
        portRef->write_count++;
        portRef->read_count--;

        notify_port_select_events(portRef, B_EVENT_WRITE);
        portRef->write_condition.NotifyOne();
                // make one spot in queue available again for write

        T(Read(portRef, message->code, std::min(bufferSize, message->size)));

        locker.Unlock();

        size_t size = copy_port_message(message, _code, buffer, bufferSize,
                userCopy);

        put_port_message(message);
        return size;
}


status_t
write_port(port_id id, int32 msgCode, const void* buffer, size_t bufferSize)
{
        iovec vec = { (void*)buffer, bufferSize };

        return writev_port_etc(id, msgCode, &vec, 1, bufferSize, 0, 0);
}


status_t
write_port_etc(port_id id, int32 msgCode, const void* buffer,
        size_t bufferSize, uint32 flags, bigtime_t timeout)
{
        iovec vec = { (void*)buffer, bufferSize };

        return writev_port_etc(id, msgCode, &vec, 1, bufferSize, flags, timeout);
}


status_t
writev_port_etc(port_id id, int32 msgCode, const iovec* msgVecs,
        size_t vecCount, size_t bufferSize, uint32 flags, bigtime_t timeout)
{
        if (!sPortsActive || id < 0)
                return B_BAD_PORT_ID;
        if (bufferSize > PORT_MAX_MESSAGE_SIZE)
                return B_BAD_VALUE;

        // mask irrelevant flags (for acquire_sem() usage)
        flags &= B_CAN_INTERRUPT | B_KILL_CAN_INTERRUPT | B_RELATIVE_TIMEOUT
                | B_ABSOLUTE_TIMEOUT;
        if ((flags & B_RELATIVE_TIMEOUT) != 0
                && timeout != B_INFINITE_TIMEOUT && timeout > 0) {
                // Make the timeout absolute, since we have more than one step where
                // we might have to wait
                flags = (flags & ~B_RELATIVE_TIMEOUT) | B_ABSOLUTE_TIMEOUT;
                timeout += system_time();
        }

        bool userCopy = (flags & PORT_FLAG_USE_USER_MEMCPY) > 0;

        status_t status;
        port_message* message = NULL;

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL) {
                TRACE(("write_port_etc: invalid port_id %ld\n", id));
                return B_BAD_PORT_ID;
        }
        MutexLocker locker(portRef->lock, true);

        if (is_port_closed(portRef)) {
                TRACE(("write_port_etc: port %ld closed\n", id));
                return B_BAD_PORT_ID;
        }

        if (portRef->write_count <= 0) {
                if ((flags & B_RELATIVE_TIMEOUT) != 0 && timeout <= 0)
                        return B_WOULD_BLOCK;

                portRef->write_count--;

                // We need to block in order to wait for a free message slot
                ConditionVariableEntry entry;
                portRef->write_condition.Add(&entry);

                locker.Unlock();

                status = entry.Wait(flags, timeout);

                // re-lock
                BReference<Port> newPortRef = get_locked_port(id);
                if (newPortRef == NULL) {
                        T(Write(id, 0, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }
                locker.SetTo(newPortRef->lock, true);

                if (newPortRef != portRef || is_port_closed(portRef)) {
                        // the port is no longer there
                        T(Write(id, 0, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }

                if (status != B_OK)
                        goto error;
        } else
                portRef->write_count--;

        status = get_port_message(msgCode, bufferSize, flags, timeout,
                &message, *portRef);
        if (status != B_OK) {
                if (status == B_BAD_PORT_ID) {
                        // the port had to be unlocked and is now no longer there
                        T(Write(id, 0, 0, 0, 0, B_BAD_PORT_ID));
                        return B_BAD_PORT_ID;
                }

                goto error;
        }

        // sender credentials
        message->sender = geteuid();
        message->sender_group = getegid();
        message->sender_team = team_get_current_team_id();

        if (bufferSize > 0) {
                size_t offset = 0;
                for (uint32 i = 0; i < vecCount; i++) {
                        size_t bytes = msgVecs[i].iov_len;
                        if (bytes > bufferSize)
                                bytes = bufferSize;

                        if (userCopy) {
                                status_t status = user_memcpy(message->buffer + offset,
                                        msgVecs[i].iov_base, bytes);
                                if (status != B_OK) {
                                        put_port_message(message);
                                        goto error;
                                }
                        } else
                                memcpy(message->buffer + offset, msgVecs[i].iov_base, bytes);

                        bufferSize -= bytes;
                        if (bufferSize == 0)
                                break;

                        offset += bytes;
                }
        }

        portRef->messages.Add(message);
        portRef->read_count++;

        T(Write(id, portRef->read_count, portRef->write_count, message->code,
                message->size, B_OK));

        notify_port_select_events(portRef, B_EVENT_READ);
        portRef->read_condition.NotifyOne();
        return B_OK;

error:
        // Give up our slot in the queue again, and let someone else
        // try and fail
        T(Write(id, portRef->read_count, portRef->write_count, 0, 0, status));
        portRef->write_count++;
        notify_port_select_events(portRef, B_EVENT_WRITE);
        portRef->write_condition.NotifyOne();

        return status;
}


status_t
set_port_owner(port_id id, team_id newTeamID)
{
        TRACE(("set_port_owner(id = %ld, team = %ld)\n", id, newTeamID));

        if (id < 0)
                return B_BAD_PORT_ID;

        // get the new team
        Team* team = Team::Get(newTeamID);
        if (team == NULL)
                return B_BAD_TEAM_ID;
        BReference<Team> teamReference(team, true);

        // get the port
        BReference<Port> portRef = get_locked_port(id);
        if (portRef == NULL) {
                TRACE(("set_port_owner: invalid port_id %ld\n", id));
                return B_BAD_PORT_ID;
        }
        MutexLocker locker(portRef->lock, true);

        // transfer ownership to other team
        if (team->id != portRef->owner) {
                uint8 firstLockIndex  = portRef->owner % kTeamListLockCount;
                uint8 secondLockIndex = team->id % kTeamListLockCount;

                // Avoid deadlocks: always lock lower index first
                if (secondLockIndex < firstLockIndex) {
                        uint8 temp = secondLockIndex;
                        secondLockIndex = firstLockIndex;
                        firstLockIndex = temp;
                }

                MutexLocker oldTeamPortsListLocker(sTeamListLock[firstLockIndex]);
                MutexLocker newTeamPortsListLocker;
                if (firstLockIndex != secondLockIndex) {
                        newTeamPortsListLocker.SetTo(sTeamListLock[secondLockIndex],
                                        false);
                }

                // Now that we have locked the team port lists, check the state again
                if (portRef->state == Port::kActive) {
                        list_remove_link(&portRef->team_link);
                        list_add_item(&team->port_list, portRef.Get());
                        portRef->owner = team->id;
                } else {
                        // Port was already deleted. We haven't changed anything yet so
                        // we can cancel the operation.
                        return B_BAD_PORT_ID;
                }
        }

        T(OwnerChange(portRef, team->id, B_OK));
        return B_OK;
}


//      #pragma mark - syscalls


port_id
_user_create_port(int32 queueLength, const char *userName)
{
        char name[B_OS_NAME_LENGTH];

        if (userName == NULL)
                return create_port(queueLength, NULL);

        if (!IS_USER_ADDRESS(userName)
                || user_strlcpy(name, userName, B_OS_NAME_LENGTH) < B_OK)
                return B_BAD_ADDRESS;

        return create_port(queueLength, name);
}


status_t
_user_close_port(port_id id)
{
        return close_port(id);
}


status_t
_user_delete_port(port_id id)
{
        return delete_port(id);
}


port_id
_user_find_port(const char *userName)
{
        char name[B_OS_NAME_LENGTH];

        if (userName == NULL)
                return B_BAD_VALUE;
        if (!IS_USER_ADDRESS(userName)
                || user_strlcpy(name, userName, B_OS_NAME_LENGTH) < B_OK)
                return B_BAD_ADDRESS;

        return find_port(name);
}


status_t
_user_get_port_info(port_id id, struct port_info *userInfo)
{
        struct port_info info;
        status_t status;

        if (userInfo == NULL)
                return B_BAD_VALUE;
        if (!IS_USER_ADDRESS(userInfo))
                return B_BAD_ADDRESS;

        status = get_port_info(id, &info);

        // copy back to user space
        if (status == B_OK
                && user_memcpy(userInfo, &info, sizeof(struct port_info)) < B_OK)
                return B_BAD_ADDRESS;

        return status;
}


status_t
_user_get_next_port_info(team_id team, int32 *userCookie,
        struct port_info *userInfo)
{
        struct port_info info;
        status_t status;
        int32 cookie;

        if (userCookie == NULL || userInfo == NULL)
                return B_BAD_VALUE;
        if (!IS_USER_ADDRESS(userCookie) || !IS_USER_ADDRESS(userInfo)
                || user_memcpy(&cookie, userCookie, sizeof(int32)) < B_OK)
                return B_BAD_ADDRESS;

        status = get_next_port_info(team, &cookie, &info);

        // copy back to user space
        if (user_memcpy(userCookie, &cookie, sizeof(int32)) < B_OK
                || (status == B_OK && user_memcpy(userInfo, &info,
                                sizeof(struct port_info)) < B_OK))
                return B_BAD_ADDRESS;

        return status;
}


ssize_t
_user_port_buffer_size_etc(port_id port, uint32 flags, bigtime_t timeout)
{
        syscall_restart_handle_timeout_pre(flags, timeout);

        status_t status = port_buffer_size_etc(port, flags | B_CAN_INTERRUPT,
                timeout);

        return syscall_restart_handle_timeout_post(status, timeout);
}


ssize_t
_user_port_count(port_id port)
{
        return port_count(port);
}


status_t
_user_set_port_owner(port_id port, team_id team)
{
        return set_port_owner(port, team);
}


ssize_t
_user_read_port_etc(port_id port, int32 *userCode, void *userBuffer,
        size_t bufferSize, uint32 flags, bigtime_t timeout)
{
        int32 messageCode;
        ssize_t bytesRead;

        syscall_restart_handle_timeout_pre(flags, timeout);

        if (userBuffer == NULL && bufferSize != 0)
                return B_BAD_VALUE;
        if ((userCode != NULL && !IS_USER_ADDRESS(userCode))
                || (userBuffer != NULL && !IS_USER_ADDRESS(userBuffer)))
                return B_BAD_ADDRESS;

        bytesRead = read_port_etc(port, &messageCode, userBuffer, bufferSize,
                flags | PORT_FLAG_USE_USER_MEMCPY | B_CAN_INTERRUPT, timeout);

        if (bytesRead >= 0 && userCode != NULL
                && user_memcpy(userCode, &messageCode, sizeof(int32)) < B_OK)
                return B_BAD_ADDRESS;

        return syscall_restart_handle_timeout_post(bytesRead, timeout);
}


status_t
_user_write_port_etc(port_id port, int32 messageCode, const void *userBuffer,
        size_t bufferSize, uint32 flags, bigtime_t timeout)
{
        iovec vec = { (void *)userBuffer, bufferSize };

        syscall_restart_handle_timeout_pre(flags, timeout);

        if (userBuffer == NULL && bufferSize != 0)
                return B_BAD_VALUE;
        if (userBuffer != NULL && !IS_USER_ADDRESS(userBuffer))
                return B_BAD_ADDRESS;

        status_t status = writev_port_etc(port, messageCode, &vec, 1, bufferSize,
                flags | PORT_FLAG_USE_USER_MEMCPY | B_CAN_INTERRUPT, timeout);

        return syscall_restart_handle_timeout_post(status, timeout);
}


status_t
_user_writev_port_etc(port_id port, int32 messageCode, const iovec *userVecs,
        size_t vecCount, size_t bufferSize, uint32 flags, bigtime_t timeout)
{
        syscall_restart_handle_timeout_pre(flags, timeout);

        if (userVecs == NULL && bufferSize != 0)
                return B_BAD_VALUE;
        if (userVecs != NULL && !IS_USER_ADDRESS(userVecs))
                return B_BAD_ADDRESS;

        iovec *vecs = NULL;
        if (userVecs && vecCount != 0) {
                vecs = (iovec*)malloc(sizeof(iovec) * vecCount);
                if (vecs == NULL)
                        return B_NO_MEMORY;

                if (user_memcpy(vecs, userVecs, sizeof(iovec) * vecCount) < B_OK) {
                        free(vecs);
                        return B_BAD_ADDRESS;
                }
        }

        status_t status = writev_port_etc(port, messageCode, vecs, vecCount,
                bufferSize, flags | PORT_FLAG_USE_USER_MEMCPY | B_CAN_INTERRUPT,
                timeout);

        free(vecs);
        return syscall_restart_handle_timeout_post(status, timeout);
}


status_t
_user_get_port_message_info_etc(port_id port, port_message_info *userInfo,
        size_t infoSize, uint32 flags, bigtime_t timeout)
{
        if (userInfo == NULL || infoSize != sizeof(port_message_info))
                return B_BAD_VALUE;

        syscall_restart_handle_timeout_pre(flags, timeout);

        port_message_info info;
        status_t error = _get_port_message_info_etc(port, &info, sizeof(info),
                flags | B_CAN_INTERRUPT, timeout);

        // copy info to userland
        if (error == B_OK && (!IS_USER_ADDRESS(userInfo)
                        || user_memcpy(userInfo, &info, sizeof(info)) != B_OK)) {
                error = B_BAD_ADDRESS;
        }

        return syscall_restart_handle_timeout_post(error, timeout);
}