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diff --git a/erts/emulator/sys/common/erl_osenv.h b/erts/emulator/sys/common/erl_osenv.h
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+++ b/erts/emulator/sys/common/erl_osenv.h
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+/*
+ * %CopyrightBegin%
+ *
+ * Copyright Ericsson AB 2017. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * %CopyrightEnd%
+ */
+
+/* This is a replacement for getenv(3) and friends, operating on instances so
+ * we can keep a common implementation for both the global and local (per-port)
+ * environments.
+ *
+ * The instances are not thread-safe on their own but unlike getenv(3) we're
+ * guaranteed to be the only user, so placing locks around all our accesses
+ * will suffice.
+ *
+ * Use erts_sys_rwlock_global_osenv to access the global environment. */
+
+#ifndef __ERL_OSENV_H__
+#define __ERL_OSENV_H__
+
+#ifdef HAVE_CONFIG_H
+#  include "config.h"
+#endif
+
+typedef struct __erts_osenv_data_t erts_osenv_data_t;
+
+typedef struct __erts_osenv_t {
+    struct __env_rbtnode_t *tree;
+    int variable_count;
+    int content_size;
+} erts_osenv_t;
+
+#include "sys.h"
+
+struct __erts_osenv_data_t {
+    Sint length;
+    void *data;
+};
+
+void erts_osenv_init(erts_osenv_t *env);
+void erts_osenv_clear(erts_osenv_t *env);
+
+/* @brief Merges \c with into \c env
+ *
+ * @param overwrite Whether to overwrite existing entries or keep them as they
+ * are. */
+void erts_osenv_merge(erts_osenv_t *env, const erts_osenv_t *with, int overwrite);
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+/* @brief Copies env[key] into \c value
+ *
+ * @return 1 on success, 0 if the key couldn't be found, and -1 if the input
+ * was invalid. */
+int erts_osenv_get_term(const erts_osenv_t *env, struct process *process,
+    Eterm key, Eterm *value);
+
+/* @brief Copies \c value into \c env[key]
+ *
+ * @return 1 on success, -1 if the input was invalid. */
+int erts_osenv_put_term(erts_osenv_t *env, Eterm key, Eterm value);
+
+/* @brief Removes \c env[key]
+ *
+ * @return 1 on success, 0 if the key couldn't be found, and -1 if the input
+ * was invalid. */
+int erts_osenv_unset_term(erts_osenv_t *env, Eterm key);
+
+/* @brief Copies env[key] into \c value
+ *
+ * @param value [in,out] The buffer to copy the value into, may be NULL if you
+ * only wish to query presence.
+ *
+ * @return 1 on success, 0 if the key couldn't be found, and -1 if if the value
+ * didn't fit into the buffer. */
+int erts_osenv_get_native(const erts_osenv_t *env, const erts_osenv_data_t *key,
+    erts_osenv_data_t *value);
+
+/* @brief Copies \c value into \c env[key]
+ *
+ * @return 1 on success, -1 on failure. */
+int erts_osenv_put_native(erts_osenv_t *env, const erts_osenv_data_t *key,
+    const erts_osenv_data_t *value);
+
+/* @brief Removes \c key from the env.
+ *
+ * @return 1 on success, 0 if the key couldn't be found. */
+int erts_osenv_unset_native(erts_osenv_t *env, const erts_osenv_data_t *key);
+
+/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
+
+typedef void (*erts_osenv_foreach_term_cb_t)(struct process *process,
+    void *state, Eterm key, Eterm value);
+
+typedef void (*erts_osenv_foreach_native_cb_t)(void *state,
+    const erts_osenv_data_t *key,
+    const erts_osenv_data_t *value);
+
+/* @brief Walks through all environment variables, calling \c callback for each
+ * one. It's unsafe to modify \c env within the callback. */
+void erts_osenv_foreach_term(const erts_osenv_t *env, struct process *process,
+    void *state, erts_osenv_foreach_term_cb_t callback);
+
+/* @copydoc erts_osenv_foreach_term */
+void erts_osenv_foreach_native(const erts_osenv_t *env, void *state,
+    erts_osenv_foreach_native_cb_t callback);
+
+#endif