blob: 7397b790be537d85cb4c187e62d39fc680bfc2af (
plain) (
blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
|
/*
* This source code is released into the public domain.
*/
module;
#include <cstdint>
#include <expected>
#include <string>
#include <system_error>
#include <vector>
#include <unistd.h>
export module nihil:getenv;
namespace nihil {
/*
* Find a variable by the given name in the environment by calling getenv_r().
*/
export auto getenv(std::string_view varname)
-> std::expected<std::string, std::error_code>
{
// Start with a buffer of this size, and double it every iteration.
constexpr auto bufinc = std::size_t{1024};
auto cvarname = std::string(varname);
auto buf = std::vector<char>(bufinc);
for (;;) {
auto const ret = ::getenv_r(cvarname.c_str(),
buf.data(), buf.size());
if (ret == 0)
return {std::string(buf.data())};
if (ret == -1 && errno == ERANGE) {
buf.resize(buf.size() * 2);
continue;
}
return std::unexpected(std::make_error_code(std::errc(errno)));
}
}
} // namespace nihil
|
