llvm-project

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//===-- Implementation of getenv ------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "src/stdlib/getenv.h"
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#include "config/linux/app.h"
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#include "src/__support/CPP/string_view.h"
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#include "src/__support/common.h"
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#include <stddef.h> // For size_t.
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namespace LIBC_NAMESPACE {
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LLVM_LIBC_FUNCTION(char *, getenv, (const char *name)) {
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  char **env_ptr = reinterpret_cast<char **>(LIBC_NAMESPACE::app.env_ptr);
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  if (name == nullptr || env_ptr == nullptr)
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    return nullptr;
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  LIBC_NAMESPACE::cpp::string_view env_var_name(name);
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  if (env_var_name.size() == 0)
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    return nullptr;
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  for (char **env = env_ptr; *env != nullptr; env++) {
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    LIBC_NAMESPACE::cpp::string_view cur(*env);
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    if (!cur.starts_with(env_var_name))
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      continue;
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    if (cur[env_var_name.size()] != '=')
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      continue;
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    // Remove the name and the equals sign.
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    cur.remove_prefix(env_var_name.size() + 1);
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    // We know that data is null terminated, so this is safe.
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    return const_cast<char *>(cur.data());
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  }
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  return nullptr;
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}
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} // namespace LIBC_NAMESPACE
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