osutil.cpp

   1 #include "osutil.hpp"
   2
   3 #include "iobuffer.hpp"
   4
   5 #include <regex>
   6
   7 #include <boost/algorithm/string/classification.hpp>
   8 #include <boost/algorithm/string/split.hpp>
   9
  10 #include <pwd.h>
  11 #include <sys/stat.h>
  12 #include <sys/types.h>
  13
  14 #include <gflags/gflags.h>
  15 namespace gflags {
  16 }
  17
  18 DEFINE_string(config_dir, "", "path to support/config files");
  19
  20 #include <sys/utsname.h>
  21 #include <unistd.h>
  22
  23 #include <netdb.h>
  24 #include <sys/socket.h>
  25 #include <sys/types.h>
  26
  27 #include <glog/logging.h>
  28
  29 namespace osutil {
  30
  31 fs::path get_config_dir()
  32 {
  33   if (!FLAGS_config_dir.empty()) {
  34     return FLAGS_config_dir;
  35   }
  36   else {
  37     return get_exe_path().parent_path();
  38
  39     // Maybe work from some installed location...
  40     // if ends in /bin, switch to /share or /etc
  41
  42     // auto path = get_exe_path().parent_path();
  43     // if (fs::is_directory(path) && (path.filename() == "bin")) {
  44     //   auto share = path;
  45     //   share.replace_filename("share");
  46     //   if (fs::exists(share) && fs::is_directory(share))
  47     //   path = share;
  48     // }
  49   }
  50 }
  51
  52 fs::path get_exe_path()
  53 {
  54   // The std::experimental::filesystem::read_symlink() as shipped with
  55   // GCC 7.2.1 20170915 included with Fedora 27 is unusable when lstat
  56   // returns st_size of zero, as happens with /proc/self/exe.
  57
  58   // This problem has been corrected in later versions, but this code
  59   // should work on everything POSIX.
  60
  61   auto constexpr exe = "/proc/self/exe";
  62
  63   auto constexpr max_link = 4 * 1024;
  64   char buf[max_link];
  65
  66   auto const len{::readlink(exe, buf, max_link)};
  67
  68   PCHECK(len != -1) << "readlink";
  69   if (len == max_link) {
  70     LOG(FATAL) << exe << " link too long";
  71   }
  72   buf[len] = '\0';
  73   return fs::path(buf);
  74 }
  75
  76 fs::path get_home_dir()
  77 {
  78   auto const homedir_ev{getenv("HOME")};
  79   if (homedir_ev) {
  80     return homedir_ev;
  81   }
  82   else {
  83     errno = 0; // See GETPWNAM(3)
  84     passwd* pw;
  85     PCHECK(pw = getpwuid(getuid()));
  86     return pw->pw_dir;
  87   }
  88 }
  89
  90 std::string get_hostname()
  91 {
  92   utsname un;
  93   PCHECK(uname(&un) == 0);
  94
  95   auto node = std::string(un.nodename);
  96
  97   // auto labels{std::vector<std::string>{}};
  98   // boost::algorithm::split(labels, node,
  99   //                         boost::algorithm::is_any_of("."));
 100   // if (labels.size() < 2) {
 101   //   node += ".digilicious.com";
 102   // }
 103
 104   return node;
 105 }
 106
 107 uint16_t get_port(char const* const service, char const* const proto)
 108 {
 109   char*      ep = nullptr;
 110   auto const service_no{strtoul(service, &ep, 10)};
 111   if (ep && (*ep == '\0')) {
 112     CHECK_LE(service_no, std::numeric_limits<uint16_t>::max());
 113     return static_cast<uint16_t>(service_no);
 114   }
 115
 116   iobuffer<char> str_buf{1024}; // suggested by getservbyname_r(3)
 117
 118   auto     result_buf{servent{}};
 119   servent* result_ptr = nullptr;
 120   while (getservbyname_r(service, proto, &result_buf, str_buf.data(),
 121                          str_buf.size(), &result_ptr)
 122          == ERANGE) {
 123     CHECK_LT(str_buf.size(), 64 * 1024); // ridiculous
 124     str_buf.resize(str_buf.size() * 2);
 125   }
 126   if (result_ptr == nullptr) {
 127     LOG(FATAL) << "service " << service << " unknown";
 128   }
 129   return ntohs(result_buf.s_port);
 130 }
 131
 132 std::vector<fs::path> list_directory(
 133     fs::path const& path,
 134     // pattern should be std::string_view see p0506r0:
 135     // <http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0506r0.pdf>
 136     // maybe C++20?
 137     std::string const& pattern)
 138 {
 139   std::vector<fs::path> ret;
 140
 141   auto const traits = std::regex_constants::ECMAScript
 142 #if defined(__APPLE__) || defined(_WIN32)
 143                       | std::regex_constants::icase
 144 #endif
 145       ;
 146
 147   std::regex const pattern_regex(pattern, traits);
 148
 149   auto const di = fs::directory_iterator(path);
 150   for (auto const& it : di) {
 151     auto const  it_filename = it.path().filename().string();
 152     std::smatch matches;
 153     if (std::regex_match(it_filename, matches, pattern_regex)) {
 154       ret.push_back(it.path());
 155     }
 156   }
 157
 158   return ret;
 159 }
 160
 161 } // namespace osutil