+
+ dnl On most platforms, the default multithreading logic in OpenSSL 1.0.x uses
+ dnl a threadid that is based on the address of errno. We need to double-check
+ dnl that &errno is, in fact, different for each thread before using that
+ dnl default.
+ AC_CACHE_CHECK([if OpenSSL can use &errno as a THREADID],
+ [ac_cv_openssl_use_errno_threadid], [
+ ac_cv_openssl_use_errno_threadid=no
+
+ save_CFLAGS=$CFLAGS
+ save_LIBS=$LIBS
+
+ CFLAGS=`$apr_config --cflags --cppflags --includes`
+ LIBS=`$apr_config --link-ld`
+
+ AC_RUN_IFELSE([
+ AC_LANG_PROGRAM([[
+ #include <stdlib.h>
+
+ #include "apr_pools.h"
+ #include "apr_thread_cond.h"
+ #include "apr_thread_proc.h"
+
+ #define NUM_THREADS 10
+
+ struct thread_data {
+ apr_thread_mutex_t *mutex;
+ apr_thread_cond_t *cv;
+ int *init_count;
+ void *errno_addr;
+ };
+
+ /**
+ * Thread entry point. Waits for all the threads to be started, then
+ * records the address of errno into the thread_data.
+ */
+ void * APR_THREAD_FUNC tmain(apr_thread_t *thread, void *data)
+ {
+ struct thread_data *tdata = data;
+
+ /* The only point of this barrier is to make sure that all threads
+ * are started before we record &errno, hopefully preventing any
+ * false negatives in case a platform "recycles" threads. */
+ apr_thread_mutex_lock(tdata->mutex);
+ ++(*tdata->init_count);
+
+ if (*tdata->init_count == NUM_THREADS) {
+ apr_thread_cond_broadcast(tdata->cv);
+ } else {
+ while (*tdata->init_count != NUM_THREADS) {
+ apr_thread_cond_wait(tdata->cv, tdata->mutex);
+ }
+ }
+ apr_thread_mutex_unlock(tdata->mutex);
+
+ tdata->errno_addr = &errno;
+ return NULL;
+ }
+ ]], [[
+ int ret = 0;
+ apr_status_t status;
+ int i;
+ int j;
+
+ apr_pool_t *pool;
+ apr_thread_mutex_t *mutex;
+ apr_thread_cond_t *cv;
+ int init_count = 0;
+
+ struct thread_data tdata[NUM_THREADS] = { 0 };
+ apr_thread_t *threads[NUM_THREADS] = { 0 };
+
+ if (apr_initialize() != APR_SUCCESS) {
+ exit(1);
+ }
+
+ /* Set up the shared APR primitives. */
+ if ((apr_pool_create(&pool, NULL) != APR_SUCCESS)
+ || (apr_thread_mutex_create(&mutex, 0, pool) != APR_SUCCESS)
+ || (apr_thread_cond_create(&cv, pool) != APR_SUCCESS)) {
+ ret = 2;
+ goto out;
+ }
+
+ /* Start every thread. */
+ for (i = 0; i < NUM_THREADS; ++i) {
+ tdata[i].mutex = mutex;
+ tdata[i].cv = cv;
+ tdata[i].init_count = &init_count;
+
+ status = apr_thread_create(&threads[i], NULL, tmain, &tdata[i],
+ pool);
+ if (status != APR_SUCCESS) {
+ ret = 3;
+ goto out;
+ }
+ }
+
+ /* Wait for them to finish (they'll record and exit after every one
+ * has been started). */
+ for (i = 0; i < NUM_THREADS; ++i) {
+ apr_thread_join(&status, threads[i]);
+ if (status != APR_SUCCESS) {
+ ret = 4;
+ goto out;
+ }
+ }
+
+ /* Check that no addresses were duplicated. */
+ for (i = 0; i < NUM_THREADS - 1; ++i) {
+ for (j = i + 1; j < NUM_THREADS; ++j) {
+ if (tdata[i].errno_addr == tdata[j].errno_addr) {
+ ret = 5;
+ goto out;
+ }
+ }
+ }
+
+ out:
+ apr_terminate();
+ exit(ret);
+ ]])
+ ], [
+ ac_cv_openssl_use_errno_threadid=yes
+ ], [
+ ac_cv_openssl_use_errno_threadid=no
+ ], [
+ dnl Assume the worst when cross-compiling; users can override via either
+ dnl cachevars or the config header if necessary.
+ ac_cv_openssl_use_errno_threadid=no
+ ])
+
+ CFLAGS=$save_CFLAGS
+ LIBS=$save_LIBS
+ ])
+ if test "x$ac_cv_openssl_use_errno_threadid" = "xyes"; then
+ AC_DEFINE(AP_OPENSSL_USE_ERRNO_THREADID, 1,
+ [Define if OpenSSL can use an errno-based threadid callback on this platform])