f2a7f83595
Add support for getenv as defined by the Open Group's "System Interface & Header" in https://pubs.opengroup.org/onlinepubs/7908799/xsh/getenv.html getenv requires a standard way of accessing the environment, so a pointer to the environment is added to the startup in crt1. Consquently, this function is not usable on top of other libcs. Added starts_with method to StringView. getenv function uses it. Co-authored-by: Jeff Bailey <jeffbailey@google.com> Reviewed By: sivachandra, rtenneti Differential Revision: https://reviews.llvm.org/D119403
43 lines
1.2 KiB
C++
43 lines
1.2 KiB
C++
//===-- 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/StringView.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 __llvm_libc {
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LLVM_LIBC_FUNCTION(char *, getenv, (const char *name)) {
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char **env_ptr = reinterpret_cast<char **>(__llvm_libc::app.envPtr);
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if (name == nullptr || env_ptr == nullptr)
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return nullptr;
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__llvm_libc::cpp::StringView 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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__llvm_libc::cpp::StringView 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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return const_cast<char *>(
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cur.remove_prefix(env_var_name.size() + 1).data());
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}
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return nullptr;
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}
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} // namespace __llvm_libc
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