1 // Copyright 2023 The Chromium Authors
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "base/posix/sysctl.h"
6
7 #include <sys/sysctl.h>
8
9 #include <initializer_list>
10 #include <string>
11
12 #include "base/check_op.h"
13 #include "base/functional/function_ref.h"
14 #include "base/numerics/safe_conversions.h"
15 #include "build/build_config.h"
16 #include "third_party/abseil-cpp/absl/types/optional.h"
17
18 namespace {
19
StringSysctlImpl(base::FunctionRef<int (char *,size_t *)> sysctl_func)20 absl::optional<std::string> StringSysctlImpl(
21 base::FunctionRef<int(char* /*out*/, size_t* /*out_len*/)> sysctl_func) {
22 size_t buf_len;
23 int result = sysctl_func(nullptr, &buf_len);
24 if (result < 0 || buf_len < 1) {
25 return absl::nullopt;
26 }
27
28 std::string value(buf_len - 1, '\0');
29 result = sysctl_func(&value[0], &buf_len);
30 if (result < 0) {
31 return absl::nullopt;
32 }
33 CHECK_LE(buf_len - 1, value.size());
34 CHECK_EQ(value[buf_len - 1], '\0');
35 value.resize(buf_len - 1);
36
37 return value;
38 }
39 } // namespace
40
41 namespace base {
42
StringSysctl(const std::initializer_list<int> & mib)43 absl::optional<std::string> StringSysctl(
44 const std::initializer_list<int>& mib) {
45 return StringSysctlImpl([mib](char* out, size_t* out_len) {
46 return sysctl(const_cast<int*>(std::data(mib)),
47 checked_cast<unsigned int>(std::size(mib)), out, out_len,
48 nullptr, 0);
49 });
50 }
51
52 #if !BUILDFLAG(IS_OPENBSD)
StringSysctlByName(const char * name)53 absl::optional<std::string> StringSysctlByName(const char* name) {
54 return StringSysctlImpl([name](char* out, size_t* out_len) {
55 return sysctlbyname(name, out, out_len, nullptr, 0);
56 });
57 }
58 #endif
59
60 } // namespace base
61