Index/src / corosio / src / host_name.cpp

src/corosio/src/host_name.cpp

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host_name.cpp
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boost::corosio::host_name() :29 6x 44.4% 11.1% 15.0%
Line Branch TLA Hits Source Code
1 //
2 // Copyright (c) 2026 Steve Gerbino
3 //
4 // Distributed under the Boost Software License, Version 1.0. (See accompanying
5 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
6 //
7 // Official repository: https://github.com/cppalliance/corosio
8 //
9
10 #include <boost/corosio/host_name.hpp>
11 #include <boost/corosio/detail/platform.hpp>
12
13 #include <stdexcept>
14 #include <string>
15
16 #if BOOST_COROSIO_POSIX
17 #include <cerrno>
18 #include <cstring>
19 #include <unistd.h>
20 #elif BOOST_COROSIO_HAS_IOCP
21 #include <windows.h>
22 #endif
23
24 namespace boost::corosio {
25
26 #if BOOST_COROSIO_POSIX
27
28 std::string
29 6x host_name()
30 {
31 // 256 exceeds POSIX's _POSIX_HOST_NAME_MAX floor of 255 and
32 // every mainstream OS's actual cap (Linux 64, macOS/BSD 255).
33 char buf[256];
34
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 6x if (::gethostname(buf, sizeof(buf)) != 0)
35 {
36 ✗ int e = errno;
37 ✗ throw std::runtime_error(
38 ✗ std::string("gethostname failed: ") + std::strerror(e));
39 }
40
41 // POSIX does not guarantee NUL termination on truncation.
42
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 6x if (std::memchr(buf, '\0', sizeof(buf)) == nullptr)
43 ✗ throw std::runtime_error("gethostname: hostname truncated");
44
45 6x return std::string(buf);
46 ✗ }
47
48 #elif BOOST_COROSIO_HAS_IOCP
49
50 std::string
51 host_name()
52 {
53 // Size query: returns ERROR_MORE_DATA and writes the required
54 // wide-char count (including the trailing NUL) into `size`.
55 DWORD size = 0;
56 BOOL ok = ::GetComputerNameExW(
57 ComputerNameDnsHostname, nullptr, &size);
58 DWORD err = ::GetLastError();
59 if (ok)
60 {
61 throw std::runtime_error(
62 "GetComputerNameExW (size query) unexpectedly succeeded");
63 }
64 if (err != ERROR_MORE_DATA)
65 {
66 throw std::runtime_error(
67 "GetComputerNameExW (size query) failed: error " +
68 std::to_string(err));
69 }
70
71 // On success, GetComputerNameExW rewrites `size` to the count
72 // without the NUL, so resize(size) below trims to the hostname.
73 std::wstring wide(size, L'\0');
74 if (!::GetComputerNameExW(
75 ComputerNameDnsHostname, wide.data(), &size))
76 {
77 throw std::runtime_error(
78 "GetComputerNameExW failed: error " +
79 std::to_string(::GetLastError()));
80 }
81 wide.resize(size);
82
83 int needed = ::WideCharToMultiByte(
84 CP_UTF8, 0, wide.data(), static_cast<int>(wide.size()),
85 nullptr, 0, nullptr, nullptr);
86 if (needed <= 0)
87 {
88 throw std::runtime_error(
89 "WideCharToMultiByte (size query) failed: error " +
90 std::to_string(::GetLastError()));
91 }
92
93 std::string out(static_cast<std::size_t>(needed), '\0');
94 int written = ::WideCharToMultiByte(
95 CP_UTF8, 0, wide.data(), static_cast<int>(wide.size()),
96 out.data(), needed, nullptr, nullptr);
97 if (written != needed)
98 {
99 throw std::runtime_error(
100 "WideCharToMultiByte failed: error " +
101 std::to_string(::GetLastError()));
102 }
103 return out;
104 }
105
106 #endif
107
108 } // namespace boost::corosio
109