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// Copyright 2019 The TCMalloc Authors
//
// 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
//
// https://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.
#include "tcmalloc/internal/environment.h"
#include <string.h>
GOOGLE_MALLOC_SECTION_BEGIN
namespace tcmalloc {
namespace tcmalloc_internal {
// POSIX provides the **environ array which contains environment variables in a
// linear array, terminated by a NULL string. This array is only perturbed when
// the environment is changed (which is inherently unsafe) so it's safe to
// return a const pointer into it.
// e.g. { "SHELL=/bin/bash", "MY_ENV_VAR=1", "" }
extern "C" char** environ;
const char* thread_safe_getenv(const char* env_var) {
int var_len = strlen(env_var);
char** envv = environ;
if (!envv) {
return nullptr;
}
for (; *envv != nullptr; envv++)
if (strncmp(*envv, env_var, var_len) == 0 && (*envv)[var_len] == '=')
return *envv + var_len + 1; // skip over the '='
return nullptr;
}
} // namespace tcmalloc_internal
} // namespace tcmalloc
GOOGLE_MALLOC_SECTION_END
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