/*

 * Copyright 2016-2026 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the Apache License 2.0 (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

/* We need to use the OPENSSL_fork_*() deprecated APIs */

#define OPENSSL_SUPPRESS_DEPRECATED

#if !defined(__GNUC__) || !defined(__ATOMIC_ACQ_REL) || defined(BROKEN_CLANG_ATOMICS) || defined(OPENSSL_NO_STDIO)

/*

 * we only enable REPORT_RWLOCK_CONTENTION on clang/gcc when we have

 * atomics available.  We do this because we need to use an atomic to track

 * when we can close the log file.  We could use the CRYPTO_atomic_ api

 * but that requires lock creation which gets us into a bad recursive loop

 * when we try to initialize the file pointer

 */

#ifdef REPORT_RWLOCK_CONTENTION

#warning "RWLOCK CONTENTION REPORTING NOT SUPPORTED, Disabling"

#undef REPORT_RWLOCK_CONTENTION

#endif

#endif

#ifdef REPORT_RWLOCK_CONTENTION

#define _GNU_SOURCE

#include <execinfo.h>

#include <unistd.h>

#endif

#include <openssl/crypto.h>

#include <crypto/cryptlib.h>

#include <crypto/sparse_array.h>

#include "internal/cryptlib.h"

#include "internal/threads_common.h"

#include "internal/rcu.h"

#ifdef REPORT_RWLOCK_CONTENTION

#include <fcntl.h>

#include <stdbool.h>

#include <sys/syscall.h>

#include <sys/uio.h>

#include "internal/time.h"

#endif

#include "rcu_internal.h"

#if defined(__SANITIZE_THREAD__)

#define TSAN_FAKE_UNLOCK(x)          \

    __tsan_mutex_pre_unlock((x), 0); \

    __tsan_mutex_post_unlock((x), 0)

#define TSAN_FAKE_LOCK(x)          \

    __tsan_mutex_pre_lock((x), 0); \

    __tsan_mutex_post_lock((x), 0, 0)

#else

#define TSAN_FAKE_UNLOCK(x)

#define TSAN_FAKE_LOCK(x)

#endif

#if defined(__sun)

#include <atomic.h>

#endif

#if defined(__apple_build_version__) && __apple_build_version__ < 6000000

/*

 * OS/X 10.7 and 10.8 had a weird version of clang which has __ATOMIC_ACQUIRE and

 * __ATOMIC_ACQ_REL but which expects only one parameter for __atomic_is_lock_free()

 * rather than two which has signature __atomic_is_lock_free(sizeof(_Atomic(T))).

 * All of this makes impossible to use __atomic_is_lock_free here.

 *

 * See: https://github.com/llvm/llvm-project/commit/a4c2602b714e6c6edb98164550a5ae829b2de760

 */

#define BROKEN_CLANG_ATOMICS

#endif

#if defined(OPENSSL_THREADS) && !defined(CRYPTO_TDEBUG) && !defined(OPENSSL_SYS_WINDOWS)

#if defined(OPENSSL_SYS_UNIX)

#include <sys/types.h>

#include <unistd.h>

#endif

#include <assert.h>

/*

 * The Non-Stop KLT thread model currently seems broken in its rwlock

 * implementation

 * Likewise is there a problem with the glibc implementation on riscv.

 */

#if defined(PTHREAD_RWLOCK_INITIALIZER) && !defined(_KLT_MODEL_) && !defined(_PUT_MODEL_) \

    && !defined(__riscv)

#define USE_RWLOCK

#endif

/*

 * For all GNU/clang atomic builtins, we also need fallbacks, to cover all

 * other compilers.

 * Unfortunately, we can't do that with some "generic type", because there's no

 * guarantee that the chosen generic type is large enough to cover all cases.

 * Therefore, we implement fallbacks for each applicable type, with composed

 * names that include the type they handle.

 *

 * (an anecdote: we previously tried to use |void *| as the generic type, with

 * the thought that the pointer itself is the largest type.  However, this is

 * not true on 32-bit pointer platforms, as a |uint64_t| is twice as large)

 *

 * All applicable ATOMIC_ macros take the intended type as first parameter, so

 * they can map to the correct fallback function.  In the GNU/clang case, that

 * parameter is simply ignored.

 */

/*

 * Internal types used with the ATOMIC_ macros, to make it possible to compose

 * fallback function names.

 */

typedef void *pvoid;

#if defined(__GNUC__) && defined(__ATOMIC_ACQUIRE) && !defined(BROKEN_CLANG_ATOMICS) \

    && !defined(USE_ATOMIC_FALLBACKS)

#define ATOMIC_LOAD_N(t, p, o) __atomic_load_n(p, o)

#define ATOMIC_STORE_N(t, p, v, o) __atomic_store_n(p, v, o)

#define ATOMIC_STORE(t, p, v, o) __atomic_store(p, v, o)

#define ATOMIC_ADD_FETCH(p, v, o) __atomic_add_fetch(p, v, o)

#define ATOMIC_SUB_FETCH(p, v, o) __atomic_sub_fetch(p, v, o)

#else

static pthread_mutex_t atomic_sim_lock = PTHREAD_MUTEX_INITIALIZER;

#define IMPL_fallback_atomic_load_n(t)                    \

    static ossl_inline t fallback_atomic_load_n_##t(t *p) \

    {                                                     \

        t ret;                                            \

                                                          \

        pthread_mutex_lock(&atomic_sim_lock);             \

        ret = *p;                                         \

        pthread_mutex_unlock(&atomic_sim_lock);           \

        return ret;                                       \

    }

IMPL_fallback_atomic_load_n(uint32_t)

    IMPL_fallback_atomic_load_n(uint64_t)

        IMPL_fallback_atomic_load_n(pvoid)

#define ATOMIC_LOAD_N(t, p, o) fallback_atomic_load_n_##t(p)

#define IMPL_fallback_atomic_store_n(t)                         \

    static ossl_inline t fallback_atomic_store_n_##t(t *p, t v) \

    {                                                           \

        t ret;                                                  \

                                                                \

        pthread_mutex_lock(&atomic_sim_lock);                   \

        ret = *p;                                               \

        *p = v;                                                 \

        pthread_mutex_unlock(&atomic_sim_lock);                 \

        return ret;                                             \

    }

            IMPL_fallback_atomic_store_n(uint32_t)

#define ATOMIC_STORE_N(t, p, v, o) fallback_atomic_store_n_##t(p, v)

#define IMPL_fallback_atomic_store(t)                             \

    static ossl_inline void fallback_atomic_store_##t(t *p, t *v) \

    {                                                             \

        pthread_mutex_lock(&atomic_sim_lock);                     \

        *p = *v;                                                  \

        pthread_mutex_unlock(&atomic_sim_lock);                   \

    }

                IMPL_fallback_atomic_store(pvoid)

#define ATOMIC_STORE(t, p, v, o) fallback_atomic_store_##t(p, v)

    /*

     * The fallbacks that follow don't need any per type implementation, as

     * they are designed for uint64_t only.  If there comes a time when multiple

     * types need to be covered, it's relatively easy to refactor them the same

     * way as the fallbacks above.

     */

    static ossl_inline uint64_t fallback_atomic_add_fetch(uint64_t *p, uint64_t v)

{

    uint64_t ret;

    pthread_mutex_lock(&atomic_sim_lock);

    *p += v;

    ret = *p;

    pthread_mutex_unlock(&atomic_sim_lock);

    return ret;

}

#define ATOMIC_ADD_FETCH(p, v, o) fallback_atomic_add_fetch(p, v)

static ossl_inline uint64_t fallback_atomic_sub_fetch(uint64_t *p, uint64_t v)

{

    uint64_t ret;

    pthread_mutex_lock(&atomic_sim_lock);

    *p -= v;

    ret = *p;

    pthread_mutex_unlock(&atomic_sim_lock);

    return ret;

}

#define ATOMIC_SUB_FETCH(p, v, o) fallback_atomic_sub_fetch(p, v)

#endif

/*

 * This is the core of an rcu lock. It tracks the readers and writers for the

 * current quiescence point for a given lock. Users is the 64 bit value that

 * stores the READERS/ID as defined above

 *

 */

struct rcu_qp {

    uint64_t users;

};

struct thread_qp {

    struct rcu_qp *qp;

    unsigned int depth;

    CRYPTO_RCU_LOCK *lock;

};

#define MAX_QPS 10

/*

 * This is the per thread tracking data

 * that is assigned to each thread participating

 * in an rcu qp

 *

 * qp points to the qp that it last acquired

 *

 */

struct rcu_thr_data {

    struct thread_qp thread_qps[MAX_QPS];

};

/*

 * This is the internal version of a CRYPTO_RCU_LOCK

 * it is cast from CRYPTO_RCU_LOCK

 */

struct rcu_lock_st {

    /* Callbacks to call for next ossl_synchronize_rcu */

    struct rcu_cb_item *cb_items;

    /* The context we are being created against */

    OSSL_LIB_CTX *ctx;

    /* Array of quiescent points for synchronization */

    struct rcu_qp *qp_group;

    /* rcu generation counter for in-order retirement */

    uint32_t id_ctr;

    /* Number of elements in qp_group array */

    uint32_t group_count;

    /* Index of the current qp in the qp_group array */

    uint32_t reader_idx;

    /* value of the next id_ctr value to be retired */

    uint32_t next_to_retire;

    /* index of the next free rcu_qp in the qp_group */

    uint32_t current_alloc_idx;

    /* number of qp's in qp_group array currently being retired */

    uint32_t writers_alloced;

    /* lock protecting write side operations */

    pthread_mutex_t write_lock;

    /* lock protecting updates to writers_alloced/current_alloc_idx */

    pthread_mutex_t alloc_lock;

    /* signal to wake threads waiting on alloc_lock */

    pthread_cond_t alloc_signal;

    /* lock to enforce in-order retirement */

    pthread_mutex_t prior_lock;

    /* signal to wake threads waiting on prior_lock */

    pthread_cond_t prior_signal;

};

/* Read side acquisition of the current qp */

static struct rcu_qp *get_hold_current_qp(struct rcu_lock_st *lock)

{

    uint32_t qp_idx;

    /* get the current qp index */

    for (;;) {

        qp_idx = ATOMIC_LOAD_N(uint32_t, &lock->reader_idx, __ATOMIC_RELAXED);

        /*

         * Notes on use of __ATOMIC_ACQUIRE

         * We need to ensure the following:

         * 1) That subsequent operations aren't optimized by hoisting them above

         * this operation.  Specifically, we don't want the below re-load of

         * qp_idx to get optimized away

         * 2) We want to ensure that any updating of reader_idx on the write side

         * of the lock is flushed from a local cpu cache so that we see any

         * updates prior to the load.  This is a non-issue on cache coherent

         * systems like x86, but is relevant on other arches

         */

        ATOMIC_ADD_FETCH(&lock->qp_group[qp_idx].users, (uint64_t)1,

            __ATOMIC_ACQUIRE);

        /* if the idx hasn't changed, we're good, else try again */

        if (qp_idx == ATOMIC_LOAD_N(uint32_t, &lock->reader_idx, __ATOMIC_ACQUIRE))

            break;

        ATOMIC_SUB_FETCH(&lock->qp_group[qp_idx].users, (uint64_t)1,

            __ATOMIC_RELAXED);

    }

    return &lock->qp_group[qp_idx];

}

static void ossl_rcu_free_local_data(void *arg)

{

    OSSL_LIB_CTX *ctx = arg;

    struct rcu_thr_data *data = CRYPTO_THREAD_get_local_ex(CRYPTO_THREAD_LOCAL_RCU_KEY, ctx);

    CRYPTO_THREAD_set_local_ex(CRYPTO_THREAD_LOCAL_RCU_KEY, ctx, NULL);

    OPENSSL_free(data);

}

int ossl_rcu_read_lock(CRYPTO_RCU_LOCK *lock)

{

    struct rcu_thr_data *data;

    int i, available_qp = -1;

    /*

     * we're going to access current_qp here so ask the

     * processor to fetch it

     */

    data = CRYPTO_THREAD_get_local_ex(CRYPTO_THREAD_LOCAL_RCU_KEY, lock->ctx);

    if (data == NULL) {

        data = OPENSSL_zalloc(sizeof(*data));

        if (data == NULL)

            return 0;

        if (!CRYPTO_THREAD_set_local_ex(CRYPTO_THREAD_LOCAL_RCU_KEY, lock->ctx, data)) {

            OPENSSL_free(data);

            return 0;

        }

        if (!ossl_init_thread_start(NULL, lock->ctx, ossl_rcu_free_local_data)) {

            OPENSSL_free(data);

            CRYPTO_THREAD_set_local_ex(CRYPTO_THREAD_LOCAL_RCU_KEY, lock->ctx, NULL);

            return 0;

        }

    }

    for (i = 0; i < MAX_QPS; i++) {

        if (data->thread_qps[i].qp == NULL && available_qp == -1)

            available_qp = i;

        /* If we have a hold on this lock already, we're good */

        if (data->thread_qps[i].lock == lock) {

            data->thread_qps[i].depth++;

            return 1;

        }

    }

    /*

     * if we get here, then we don't have a hold on this lock yet

     */

    assert(available_qp != -1);

    data->thread_qps[available_qp].qp = get_hold_current_qp(lock);

    data->thread_qps[available_qp].depth = 1;

    data->thread_qps[available_qp].lock = lock;

    return 1;

}

void ossl_rcu_read_unlock(CRYPTO_RCU_LOCK *lock)

{

    int i;

    struct rcu_thr_data *data = CRYPTO_THREAD_get_local_ex(CRYPTO_THREAD_LOCAL_RCU_KEY, lock->ctx);

    uint64_t ret;

    assert(data != NULL);

    for (i = 0; i < MAX_QPS; i++) {

        if (data->thread_qps[i].lock == lock) {

            /*

             * we have to use __ATOMIC_RELEASE here

             * to ensure that all preceding read instructions complete

             * before the decrement is visible to ossl_synchronize_rcu

             */

            data->thread_qps[i].depth--;

            if (data->thread_qps[i].depth == 0) {

                ret = ATOMIC_SUB_FETCH(&data->thread_qps[i].qp->users,

                    (uint64_t)1, __ATOMIC_RELEASE);

                OPENSSL_assert(ret != UINT64_MAX);

                data->thread_qps[i].qp = NULL;

                data->thread_qps[i].lock = NULL;

            }

            return;

        }

    }

    /*

     * If we get here, we're trying to unlock a lock that we never acquired -

     * that's fatal.

     */

    assert(0);

}

/*

 * Write side allocation routine to get the current qp

 * and replace it with a new one

 */

static struct rcu_qp *update_qp(CRYPTO_RCU_LOCK *lock, uint32_t *curr_id)

{

    uint32_t current_idx;

    pthread_mutex_lock(&lock->alloc_lock);

    /*

     * we need at least one qp to be available with one

     * left over, so that readers can start working on

     * one that isn't yet being waited on

     */

    while (lock->group_count - lock->writers_alloced < 2)

        /* we have to wait for one to be free */

        pthread_cond_wait(&lock->alloc_signal, &lock->alloc_lock);

    current_idx = lock->current_alloc_idx;

    /* Allocate the qp */

    lock->writers_alloced++;

    /* increment the allocation index */

    lock->current_alloc_idx = (lock->current_alloc_idx + 1) % lock->group_count;

    *curr_id = lock->id_ctr;

    lock->id_ctr++;

    /*

     * make the current state of everything visible by this release

     * when get_hold_current_qp acquires the next qp

     */

    ATOMIC_STORE_N(uint32_t, &lock->reader_idx, lock->current_alloc_idx,

        __ATOMIC_RELEASE);

    /*

     * this should make sure that the new value of reader_idx is visible in

     * get_hold_current_qp, directly after incrementing the users count

     */

    ATOMIC_ADD_FETCH(&lock->qp_group[current_idx].users, (uint64_t)0,

        __ATOMIC_RELEASE);

    /* wake up any waiters */

    pthread_cond_signal(&lock->alloc_signal);

    pthread_mutex_unlock(&lock->alloc_lock);

    return &lock->qp_group[current_idx];

}

static void retire_qp(CRYPTO_RCU_LOCK *lock, struct rcu_qp *qp)

{

    pthread_mutex_lock(&lock->alloc_lock);

    lock->writers_alloced--;

    pthread_cond_signal(&lock->alloc_signal);

    pthread_mutex_unlock(&lock->alloc_lock);

}

static struct rcu_qp *allocate_new_qp_group(CRYPTO_RCU_LOCK *lock,

    uint32_t count)

{

    struct rcu_qp *new = OPENSSL_calloc(count, sizeof(*new));

    lock->group_count = count;

    return new;

}

void ossl_rcu_write_lock(CRYPTO_RCU_LOCK *lock)

{

    pthread_mutex_lock(&lock->write_lock);

    TSAN_FAKE_UNLOCK(&lock->write_lock);

}

void ossl_rcu_write_unlock(CRYPTO_RCU_LOCK *lock)

{

    TSAN_FAKE_LOCK(&lock->write_lock);

    pthread_mutex_unlock(&lock->write_lock);

}

void ossl_synchronize_rcu(CRYPTO_RCU_LOCK *lock)

{

    struct rcu_qp *qp;

    uint64_t count;

    uint32_t curr_id;

    struct rcu_cb_item *cb_items, *tmpcb;

    pthread_mutex_lock(&lock->write_lock);

    cb_items = lock->cb_items;

    lock->cb_items = NULL;

    pthread_mutex_unlock(&lock->write_lock);

    qp = update_qp(lock, &curr_id);

    /* retire in order */

    pthread_mutex_lock(&lock->prior_lock);

    while (lock->next_to_retire != curr_id)

        pthread_cond_wait(&lock->prior_signal, &lock->prior_lock);

    /*

     * wait for the reader count to reach zero

     * Note the use of __ATOMIC_ACQUIRE here to ensure that any

     * prior __ATOMIC_RELEASE write operation in ossl_rcu_read_unlock

     * is visible prior to our read

     * however this is likely just necessary to silence a tsan warning

     * because the read side should not do any write operation

     * outside the atomic itself

     */

    do {

        count = ATOMIC_LOAD_N(uint64_t, &qp->users, __ATOMIC_ACQUIRE);

    } while (count != (uint64_t)0);

    lock->next_to_retire++;

    pthread_cond_broadcast(&lock->prior_signal);

    pthread_mutex_unlock(&lock->prior_lock);

    retire_qp(lock, qp);

    /* handle any callbacks that we have */

    while (cb_items != NULL) {

        tmpcb = cb_items;

        cb_items = cb_items->next;

        tmpcb->fn(tmpcb->data);

        OPENSSL_free(tmpcb);

    }

}

CRYPTO_RCU_CB_ITEM *ossl_rcu_cb_item_new(void)

{

    return OPENSSL_zalloc(sizeof(CRYPTO_RCU_CB_ITEM));

}

void ossl_rcu_cb_item_free(CRYPTO_RCU_CB_ITEM *item)

{

    OPENSSL_free(item);

}

/*

 * Note: This call assumes its made under the protection of

 * ossl_rcu_write_lock

 */

void ossl_rcu_call(CRYPTO_RCU_LOCK *lock, CRYPTO_RCU_CB_ITEM *item,

    rcu_cb_fn cb, void *data)

{

    item->fn = cb;

    item->data = data;

    item->next = lock->cb_items;

    lock->cb_items = item;

}

void *ossl_rcu_uptr_deref(void **p)

{

    return ATOMIC_LOAD_N(pvoid, p, __ATOMIC_ACQUIRE);

}

void ossl_rcu_assign_uptr(void **p, void **v)

{

    ATOMIC_STORE(pvoid, p, v, __ATOMIC_RELEASE);

}

CRYPTO_RCU_LOCK *ossl_rcu_lock_new(int num_writers, OSSL_LIB_CTX *ctx)

{

    struct rcu_lock_st *new;

    pthread_mutex_t *mutexes[3] = { NULL };

    pthread_cond_t *conds[2] = { NULL };

    int i;

    /*

     * We need a minimum of 2 qp's

     */

    if (num_writers < 2)

        num_writers = 2;

    ctx = ossl_lib_ctx_get_concrete(ctx);

    if (ctx == NULL)

        return 0;

    new = OPENSSL_zalloc(sizeof(*new));

    if (new == NULL)

        return NULL;

    new->ctx = ctx;

    i = 0;

    mutexes[i] = pthread_mutex_init(&new->write_lock, NULL) == 0 ? &new->write_lock : NULL;

    if (mutexes[i++] == NULL)

        goto err;

    mutexes[i] = pthread_mutex_init(&new->prior_lock, NULL) == 0 ? &new->prior_lock : NULL;

    if (mutexes[i++] == NULL)

        goto err;

    mutexes[i] = pthread_mutex_init(&new->alloc_lock, NULL) == 0 ? &new->alloc_lock : NULL;

    if (mutexes[i++] == NULL)

        goto err;

    conds[i - 3] = pthread_cond_init(&new->prior_signal, NULL) == 0 ? &new->prior_signal : NULL;

    if (conds[i - 3] == NULL)

        goto err;

    i++;

    conds[i - 3] = pthread_cond_init(&new->alloc_signal, NULL) == 0 ? &new->alloc_signal : NULL;

    if (conds[i - 3] == NULL)

        goto err;

    i++;

    new->qp_group = allocate_new_qp_group(new, num_writers);

    if (new->qp_group == NULL)

        goto err;

    return new;

err:

    for (i = 0; i < 3; i++)

        if (mutexes[i] != NULL)

            pthread_mutex_destroy(mutexes[i]);

    for (i = 0; i < 2; i++)

        if (conds[i] != NULL)

            pthread_cond_destroy(conds[i]);

    OPENSSL_free(new->qp_group);

    OPENSSL_free(new);

    return NULL;

}

void ossl_rcu_lock_free(CRYPTO_RCU_LOCK *lock)

{

    struct rcu_lock_st *rlock = (struct rcu_lock_st *)lock;

    if (lock == NULL)

        return;

    /* make sure we're synchronized */

    ossl_synchronize_rcu(rlock);

    OPENSSL_free(rlock->qp_group);

    /*

     * Some targets (BSD) allocate heap when initializing

     * a mutex or condition, to prevent leaks, those need

     * to be destroyed here

     */

    pthread_mutex_destroy(&rlock->write_lock);

    pthread_mutex_destroy(&rlock->prior_lock);

    pthread_mutex_destroy(&rlock->alloc_lock);

    pthread_cond_destroy(&rlock->prior_signal);

    pthread_cond_destroy(&rlock->alloc_signal);

    /* There should only be a single qp left now */

    OPENSSL_free(rlock);

}

#ifdef REPORT_RWLOCK_CONTENTION

/*

 * Normally we would use a BIO here to do this, but we create locks during

 * library initialization, and creating a bio too early, creates a recursive set

 * of stack calls that leads us to call CRYPTO_thread_run_once while currently

 * executing the init routine for various run_once functions, which leads to

 * deadlock.  Avoid that by just using a FILE pointer.  Also note that we

 * directly use a pthread_mutex_t to protect access from multiple threads

 * to the contention log file.  We do this because we want to avoid use

 * of the CRYPTO_THREAD api so as to prevent recursive blocking reports.

 */

static CRYPTO_ONCE init_contention_data_flag = CRYPTO_ONCE_STATIC_INIT;

pthread_mutex_t log_lock = PTHREAD_MUTEX_INITIALIZER;

CRYPTO_THREAD_LOCAL thread_contention_data;

struct stack_info {

    unsigned int nptrs;

    int write;

    OSSL_TIME start;

    OSSL_TIME duration;

    char **strings;

};

#define STACKS_COUNT 32

#define BT_BUF_SIZE 1024

struct stack_traces {

    int fd;

    int lock_depth;

    size_t idx;

    struct stack_info stacks[STACKS_COUNT];

};

/* The glibc gettid() definition presents only since 2.30. */

static ossl_inline pid_t get_tid(void)

{

#ifdef OPENSSL_SYS_MACOSX

    /*

     * MACOS has the gettid call, but it does something completely different

     * here than on other unixes.  Specifically it returns the uid of the calling thread

     * (if set), or -1.  We need to use a MACOS specific call to get the thread id here

     */

    uint64_t tid;

    pthread_threadid_np(NULL, &tid);

    return (pid_t)tid;

#else

    return syscall(SYS_gettid);

#endif

}

#ifdef FIPS_MODULE

#define FIPS_SFX "-fips"

#else

#define FIPS_SFX ""

#endif

static void *init_contention_data(void)

{

    struct stack_traces *traces;

    char fname_fmt[] = "lock-contention-log" FIPS_SFX ".%d.txt";

    char fname[sizeof(fname_fmt) + sizeof(int) * 3];

    traces = OPENSSL_zalloc(sizeof(struct stack_traces));

    snprintf(fname, sizeof(fname), fname_fmt, get_tid());

    traces->fd = open(fname, O_WRONLY | O_APPEND | O_CLOEXEC | O_CREAT, 0600);

    return traces;

}

static void destroy_contention_data(void *data)

{

    struct stack_traces *st = data;

    close(st->fd);

    OPENSSL_free(data);

}

static void init_contention_data_once(void)

{

    /*

     * Create a thread local key here to store our list of stack traces

     * to be printed when we unlock the lock we are holding

     */

    CRYPTO_THREAD_init_local(&thread_contention_data, destroy_contention_data);

    return;

}

static struct stack_traces *get_stack_traces(bool init)

{

    struct stack_traces *traces = CRYPTO_THREAD_get_local(&thread_contention_data);

    if (!traces && init) {

        traces = init_contention_data();

        CRYPTO_THREAD_set_local(&thread_contention_data, traces);

    }

    return traces;

}

static void print_stack_traces(struct stack_traces *traces)

{

    unsigned int j;

    struct iovec *iov;

    int iovcnt;

    while (traces != NULL && traces->idx >= 1) {

        traces->idx--;

        dprintf(traces->fd,

            "lock blocked on %s for %zu usec at time %zu tid %d\n",

            traces->stacks[traces->idx].write == 1 ? "WRITE" : "READ",

            ossl_time2us(traces->stacks[traces->idx].duration),

            ossl_time2us(traces->stacks[traces->idx].start),

            get_tid());

        if (traces->stacks[traces->idx].strings != NULL) {

            static const char lf = '\n';

            iovcnt = traces->stacks[traces->idx].nptrs * 2 + 1;

            iov = alloca(iovcnt * sizeof(*iov));

            for (j = 0; j < traces->stacks[traces->idx].nptrs; j++) {

                iov[2 * j].iov_base = traces->stacks[traces->idx].strings[j];

                iov[2 * j].iov_len = strlen(traces->stacks[traces->idx].strings[j]);

                iov[2 * j + 1].iov_base = (char *)&lf;

                iov[2 * j + 1].iov_len = 1;

            }

            iov[traces->stacks[traces->idx].nptrs * 2].iov_base = (char *)&lf;

            iov[traces->stacks[traces->idx].nptrs * 2].iov_len = 1;

        } else {

            static const char no_bt[] = "No stack trace available\n\n";

            iovcnt = 1;

            iov = alloca(iovcnt * sizeof(*iov));

            iov[0].iov_base = (char *)no_bt;

            iov[0].iov_len = sizeof(no_bt) - 1;

        }

        writev(traces->fd, iov, iovcnt);

        free(traces->stacks[traces->idx].strings);

    }

}

static ossl_inline void ossl_init_rwlock_contention_data(void)

{

    CRYPTO_THREAD_run_once(&init_contention_data_flag, init_contention_data_once);

}

static int record_lock_contention(pthread_rwlock_t *lock,

    struct stack_traces *traces, bool write)

{

    void *buffer[BT_BUF_SIZE];

    OSSL_TIME start, end;

    int ret;

    start = ossl_time_now();

    ret = (write ? pthread_rwlock_wrlock : pthread_rwlock_rdlock)(lock);

    if (ret)

        return ret;

    end = ossl_time_now();

    traces->stacks[traces->idx].nptrs = backtrace(buffer, BT_BUF_SIZE);

    traces->stacks[traces->idx].strings = backtrace_symbols(buffer,

        traces->stacks[traces->idx].nptrs);

    traces->stacks[traces->idx].duration = ossl_time_subtract(end, start);

    traces->stacks[traces->idx].start = start;

    traces->stacks[traces->idx].write = write;

    traces->idx++;

    if (traces->idx >= STACKS_COUNT) {

        fprintf(stderr, "STACK RECORD OVERFLOW!\n");

        print_stack_traces(traces);

    }

    return 0;

}

static ossl_inline int ossl_rwlock_rdlock(pthread_rwlock_t *lock)

{

    struct stack_traces *traces = get_stack_traces(true);

    if (ossl_unlikely(traces == NULL))

        return ENOMEM;

    traces->lock_depth++;

    if (pthread_rwlock_tryrdlock(lock)) {

        int ret = record_lock_contention(lock, traces, false);

        if (ret)

            traces->lock_depth--;

        return ret;

    }

    return 0;

}

static ossl_inline int ossl_rwlock_wrlock(pthread_rwlock_t *lock)

{

    struct stack_traces *traces = get_stack_traces(true);

    if (ossl_unlikely(traces == NULL))

        return ENOMEM;

    traces->lock_depth++;

    if (pthread_rwlock_trywrlock(lock)) {

        int ret = record_lock_contention(lock, traces, true);

        if (ret)

            traces->lock_depth--;

        return ret;

    }

    return 0;

}

static ossl_inline int ossl_rwlock_unlock(pthread_rwlock_t *lock)

{

    int ret;

    ret = pthread_rwlock_unlock(lock);

    if (ret)

        return ret;

    {

        struct stack_traces *traces = get_stack_traces(false);

        if (traces != NULL) {

            traces->lock_depth--;

            assert(traces->lock_depth >= 0);

            if (traces->lock_depth == 0)

                print_stack_traces(traces);

        }

    }

    return 0;

}

#else /* !REPORT_RWLOCK_CONTENTION */

#if defined(USE_RWLOCK)

static ossl_inline void ossl_init_rwlock_contention_data(void)

{

}

static ossl_inline int ossl_rwlock_rdlock(pthread_rwlock_t *rwlock)

{

    return pthread_rwlock_rdlock(rwlock);

}

static ossl_inline int ossl_rwlock_wrlock(pthread_rwlock_t *rwlock)

{

    return pthread_rwlock_wrlock(rwlock);

}

static ossl_inline int ossl_rwlock_unlock(pthread_rwlock_t *rwlock)

{

    return pthread_rwlock_unlock(rwlock);

}

#endif /* USE_RWLOCK */

#endif /* REPORT_RWLOCK_CONTENTION */

CRYPTO_RWLOCK *CRYPTO_THREAD_lock_new(void)

{

#ifdef USE_RWLOCK

    CRYPTO_RWLOCK *lock;

    ossl_init_rwlock_contention_data();

    if ((lock = OPENSSL_zalloc(sizeof(pthread_rwlock_t))) == NULL)

        /* Don't set error, to avoid recursion blowup. */

        return NULL;

    if (pthread_rwlock_init(lock, NULL) != 0) {

        OPENSSL_free(lock);

        return NULL;

    }

#else

    pthread_mutexattr_t attr;

    CRYPTO_RWLOCK *lock;

    if ((lock = OPENSSL_zalloc(sizeof(pthread_mutex_t))) == NULL)

        /* Don't set error, to avoid recursion blowup. */

        return NULL;

    /*

     * We don't use recursive mutexes, but try to catch errors if we do.

     */

    pthread_mutexattr_init(&attr);

#if !defined(__TANDEM) && !defined(_SPT_MODEL_)

#if !defined(NDEBUG) && !defined(OPENSSL_NO_MUTEX_ERRORCHECK)

    pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_ERRORCHECK);

#endif

#else

    /* The SPT Thread Library does not define MUTEX attributes. */

#endif

    if (pthread_mutex_init(lock, &attr) != 0) {

        pthread_mutexattr_destroy(&attr);

        OPENSSL_free(lock);

        return NULL;

    }

    pthread_mutexattr_destroy(&attr);

#endif

    return lock;

}

__owur int CRYPTO_THREAD_read_lock(CRYPTO_RWLOCK *lock)

{

#ifdef USE_RWLOCK

    if (!ossl_assert(ossl_rwlock_rdlock(lock) == 0))

        return 0;

#else

    if (pthread_mutex_lock(lock) != 0) {

        assert(errno != EDEADLK && errno != EBUSY);

        return 0;

    }

#endif

    return 1;

}

__owur int CRYPTO_THREAD_write_lock(CRYPTO_RWLOCK *lock)

{

#ifdef USE_RWLOCK

    if (!ossl_assert(ossl_rwlock_wrlock(lock) == 0))

        return 0;

#else

    if (pthread_mutex_lock(lock) != 0) {

        assert(errno != EDEADLK && errno != EBUSY);

        return 0;

    }

#endif

    return 1;

}

int CRYPTO_THREAD_unlock(CRYPTO_RWLOCK *lock)

{

#ifdef USE_RWLOCK

    if (ossl_rwlock_unlock(lock) != 0)

        return 0;

#else

    if (pthread_mutex_unlock(lock) != 0) {

        assert(errno != EPERM);

        return 0;

    }

#endif

    return 1;

}

void CRYPTO_THREAD_lock_free(CRYPTO_RWLOCK *lock)

{

    if (lock == NULL)

        return;

#ifdef USE_RWLOCK

    pthread_rwlock_destroy(lock);

#else

    pthread_mutex_destroy(lock);

#endif

    OPENSSL_free(lock);

    return;

}

int CRYPTO_THREAD_run_once(CRYPTO_ONCE *once, void (*init)(void))

{

    if (ossl_unlikely(pthread_once(once, init) != 0))

        return 0;

    return 1;

}

int CRYPTO_THREAD_init_local(CRYPTO_THREAD_LOCAL *key, void (*cleanup)(void *))

{

    if (pthread_key_create(key, cleanup) != 0)

        return 0;

    return 1;

}

void *CRYPTO_THREAD_get_local(CRYPTO_THREAD_LOCAL *key)

{

    return pthread_getspecific(*key);

}

int CRYPTO_THREAD_set_local(CRYPTO_THREAD_LOCAL *key, void *val)

{

    if (pthread_setspecific(*key, val) != 0)

        return 0;

    return 1;

}

int CRYPTO_THREAD_cleanup_local(CRYPTO_THREAD_LOCAL *key)

{

    if (pthread_key_delete(*key) != 0)

        return 0;

    return 1;

}

CRYPTO_THREAD_ID CRYPTO_THREAD_get_current_id(void)

{

    return pthread_self();

}

int CRYPTO_THREAD_compare_id(CRYPTO_THREAD_ID a, CRYPTO_THREAD_ID b)

{

    return pthread_equal(a, b);

}

int CRYPTO_atomic_add(int *val, int amount, int *ret, CRYPTO_RWLOCK *lock)

{

#if defined(__GNUC__) && defined(__ATOMIC_ACQ_REL) && !defined(BROKEN_CLANG_ATOMICS)

    if (__atomic_is_lock_free(sizeof(*val), val)) {

        *ret = __atomic_add_fetch(val, amount, __ATOMIC_ACQ_REL);

        return 1;

    }

#elif defined(__sun) && (defined(__SunOS_5_10) || defined(__SunOS_5_11))

    /* This will work for all future Solaris versions. */

    if (ret != NULL) {

        *ret = atomic_add_int_nv((volatile unsigned int *)val, amount);

        return 1;

    }

#endif

    if (lock == NULL || !CRYPTO_THREAD_write_lock(lock))

        return 0;

    *val += amount;

    *ret = *val;