--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/thirdparty/curl/docs/examples/opensslthreadlock.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,95 @@
+/***************************************************************************
+ *                                  _   _ ____  _
+ *  Project                     ___| | | |  _ \| |
+ *                             / __| | | | |_) | |
+ *                            | (__| |_| |  _ <| |___
+ *                             \___|\___/|_| \_\_____|
+ *
+ * Copyright (C) 1998 - 2017, Daniel Stenberg, <daniel@haxx.se>, et al.
+ *
+ * This software is licensed as described in the file COPYING, which
+ * you should have received as part of this distribution. The terms
+ * are also available at https://curl.haxx.se/docs/copyright.html.
+ *
+ * You may opt to use, copy, modify, merge, publish, distribute and/or sell
+ * copies of the Software, and permit persons to whom the Software is
+ * furnished to do so, under the terms of the COPYING file.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ***************************************************************************/
+/* <DESC>
+ * one way to set the necessary OpenSSL locking callbacks if you want to do
+ * multi-threaded transfers with HTTPS/FTPS with libcurl built to use OpenSSL.
+ * </DESC>
+ */
+/*
+ * This is not a complete stand-alone example.
+ *
+ * Author: Jeremy Brown
+ */
+
+#include <stdio.h>
+#include <pthread.h>
+#include <openssl/err.h>
+
+#define MUTEX_TYPE       pthread_mutex_t
+#define MUTEX_SETUP(x)   pthread_mutex_init(&(x), NULL)
+#define MUTEX_CLEANUP(x) pthread_mutex_destroy(&(x))
+#define MUTEX_LOCK(x)    pthread_mutex_lock(&(x))
+#define MUTEX_UNLOCK(x)  pthread_mutex_unlock(&(x))
+#define THREAD_ID        pthread_self()
+
+
+void handle_error(const char *file, int lineno, const char *msg)
+{
+  fprintf(stderr, "** %s:%d %s\n", file, lineno, msg);
+  ERR_print_errors_fp(stderr);
+  /* exit(-1); */
+}
+
+/* This array will store all of the mutexes available to OpenSSL. */
+static MUTEX_TYPE *mutex_buf = NULL;
+
+static void locking_function(int mode, int n, const char *file, int line)
+{
+  if(mode & CRYPTO_LOCK)
+    MUTEX_LOCK(mutex_buf[n]);
+  else
+    MUTEX_UNLOCK(mutex_buf[n]);
+}
+
+static unsigned long id_function(void)
+{
+  return ((unsigned long)THREAD_ID);
+}
+
+int thread_setup(void)
+{
+  int i;
+
+  mutex_buf = malloc(CRYPTO_num_locks() * sizeof(MUTEX_TYPE));
+  if(!mutex_buf)
+    return 0;
+  for(i = 0;  i < CRYPTO_num_locks();  i++)
+    MUTEX_SETUP(mutex_buf[i]);
+  CRYPTO_set_id_callback(id_function);
+  CRYPTO_set_locking_callback(locking_function);
+  return 1;
+}
+
+int thread_cleanup(void)
+{
+  int i;
+
+  if(!mutex_buf)
+    return 0;
+  CRYPTO_set_id_callback(NULL);
+  CRYPTO_set_locking_callback(NULL);
+  for(i = 0;  i < CRYPTO_num_locks();  i++)
+    MUTEX_CLEANUP(mutex_buf[i]);
+  free(mutex_buf);
+  mutex_buf = NULL;
+  return 1;
+}