gecko-dev/security/nss/lib/ssl/sslmutex.h

/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef __SSLMUTEX_H_
#define __SSLMUTEX_H_ 1

/* What SSL really wants is portable process-shared unnamed mutexes in
 * shared memory, that have the property that if the process that holds
 * them dies, they are released automatically, and that (unlike fcntl
 * record locking) lock to the thread, not to the process.
 * NSPR doesn't provide that.
 * Windows has mutexes that meet that description, but they're not portable.
 * POSIX mutexes are not automatically released when the holder dies,
 * and other processes/threads cannot release the mutex on behalf of the
 * dead holder.
 * POSIX semaphores can be used to accomplish this on systems that implement
 * process-shared unnamed POSIX semaphores, because a watchdog thread can
 * discover and release semaphores that were held by a dead process.
 * On systems that do not support process-shared POSIX unnamed semaphores,
 * they can be emulated using pipes.
 * The performance cost of doing that is not yet measured.
 *
 * So, this API looks a lot like POSIX pthread mutexes.
 */

#include "prtypes.h"
#include "prlock.h"

#if defined(NETBSD)
#include <sys/param.h> /* for __NetBSD_Version__ */
#endif

#if defined(WIN32)

#include <wtypes.h>

typedef struct {
    PRBool isMultiProcess;
#ifdef WINNT
    /* on WINNT we need both the PRLock and the Win32 mutex for fibers */
    struct {
#else
    union {
#endif
        PRLock *sslLock;
        HANDLE sslMutx;
    } u;
} sslMutex;

typedef int sslPID;

#elif defined(LINUX) || defined(AIX) || defined(BEOS) || defined(BSDI) || \
    (defined(NETBSD) && __NetBSD_Version__ < 500000000) || defined(OPENBSD) || defined(__GLIBC__)

#include <sys/types.h>
#include "prtypes.h"

typedef struct {
    PRBool isMultiProcess;
    union {
        PRLock *sslLock;
        struct {
            int mPipes[3];
            PRInt32 nWaiters;
        } pipeStr;
    } u;
} sslMutex;
typedef pid_t sslPID;

/* other types of unix, except OS X */
#elif defined(XP_UNIX) && !defined(DARWIN)

#include <sys/types.h> /* for pid_t */
#include <semaphore.h> /* for sem_t, and sem_* functions */

typedef struct {
    PRBool isMultiProcess;
    union {
        PRLock *sslLock;
        sem_t sem;
    } u;
} sslMutex;

typedef pid_t sslPID;

#else /* no support for cross-process locking */

/* what platform is this ?? */

typedef struct {
    PRBool isMultiProcess;
    union {
        PRLock *sslLock;
        /* include cross-process locking mechanism here */
    } u;
} sslMutex;

#ifdef DARWIN
typedef pid_t sslPID;
#else
typedef int sslPID;
#endif

#endif

#include "seccomon.h"

SEC_BEGIN_PROTOS

extern SECStatus sslMutex_Init(sslMutex *sem, int shared);

/* If processLocal is set to true, then just free resources which are *only* associated
 * with the current process. Leave any shared resources (including the state of
 * shared memory) intact. */
extern SECStatus sslMutex_Destroy(sslMutex *sem, PRBool processLocal);

extern SECStatus sslMutex_Unlock(sslMutex *sem);

extern SECStatus sslMutex_Lock(sslMutex *sem);

#ifdef WINNT

extern SECStatus sslMutex_2LevelInit(sslMutex *sem);

#endif

SEC_END_PROTOS

#endif