1 | //===-- Implementation of getenv ------------------------------------------===// |
2 | // |
3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
4 | // See https://llvm.org/LICENSE.txt for license information. |
5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
6 | // |
7 | //===----------------------------------------------------------------------===// |
8 | |
9 | #include "src/stdlib/getenv.h" |
10 | #include "config/app.h" |
11 | #include "src/__support/CPP/string_view.h" |
12 | #include "src/__support/common.h" |
13 | #include "src/__support/macros/config.h" |
14 | |
15 | #include <stddef.h> // For size_t. |
16 | |
17 | namespace LIBC_NAMESPACE_DECL { |
18 | |
19 | LLVM_LIBC_FUNCTION(char *, getenv, (const char *name)) { |
20 | char **env_ptr = reinterpret_cast<char **>(LIBC_NAMESPACE::app.env_ptr); |
21 | |
22 | if (name == nullptr || env_ptr == nullptr) |
23 | return nullptr; |
24 | |
25 | LIBC_NAMESPACE::cpp::string_view env_var_name(name); |
26 | if (env_var_name.size() == 0) |
27 | return nullptr; |
28 | for (char **env = env_ptr; *env != nullptr; env++) { |
29 | LIBC_NAMESPACE::cpp::string_view cur(*env); |
30 | if (!cur.starts_with(env_var_name)) |
31 | continue; |
32 | |
33 | if (cur[env_var_name.size()] != '=') |
34 | continue; |
35 | |
36 | // Remove the name and the equals sign. |
37 | cur.remove_prefix(env_var_name.size() + 1); |
38 | // We know that data is null terminated, so this is safe. |
39 | return const_cast<char *>(cur.data()); |
40 | } |
41 | |
42 | return nullptr; |
43 | } |
44 | |
45 | } // namespace LIBC_NAMESPACE_DECL |
46 | |