widget/LSBUtils.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  *
   3  * This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #include "LSBUtils.h"
   8
   9 #include <fstream>
  10 #include <string>
  11 #include <string_view>
  12 #include <unistd.h>
  13 #include "base/process_util.h"
  14 #include "mozilla/FileUtils.h"
  15 #include "mozilla/Result.h"
  16 #include "mozilla/ResultVariant.h"
  17 #include "mozilla/ipc/LaunchError.h"
  18
  19 namespace mozilla::widget::lsb {
  20
  21 static const char gLsbReleasePath[] = "/usr/bin/lsb_release";
  22 static const char gEtcOsReleasePath[] = "/etc/os-release";
  23 static const char gUsrOsReleasePath[] = "/usr/lib/os-release";
  24
  25 // See https://www.freedesktop.org/software/systemd/man/latest/os-release.html
  26 bool ExtractAndSetValue(nsACString& aContainer, std::string_view& aValue) {
  27   // We assume the value is well formed and doesn't contain escape characters.
  28   if (aValue.size() > 1 && (aValue.front() == '"' || aValue.front() == '\'')) {
  29     // We assume the quote is properly balanced.
  30     aValue = aValue.substr(1, aValue.size() - 2);
  31   }
  32   aContainer.Assign(aValue.data(), aValue.size());
  33   return !aValue.empty();
  34 }
  35
  36 bool GetOSRelease(nsACString& aDistributor, nsACString& aDescription,
  37                   nsACString& aRelease, nsACString& aCodename) {
  38   std::ifstream stream(gEtcOsReleasePath);
  39   if (stream.fail()) {
  40     stream.open(gUsrOsReleasePath);
  41     if (stream.fail()) {
  42       return false;
  43     }
  44   }
  45   bool seen_id = false, seen_pretty_name = false, seen_version_id = false;
  46   std::string rawline;
  47   nsAutoCString name;
  48   while (std::getline(stream, rawline)) {
  49     std::string_view line(rawline);
  50     size_t pos = line.find('=');
  51     if (pos != std::string_view::npos) {
  52       auto key = line.substr(0, pos);
  53       auto value = line.substr(pos + 1);
  54       if (key == "ID") {
  55         if (ExtractAndSetValue(aDistributor, value)) {
  56           // Capitalize the first letter of the id. This mimics what
  57           // lsb_release does on Debian and derivatives. On RH derivatives,
  58           // ID tends to be capitalized already.
  59           char* c = aDistributor.BeginWriting();
  60           if (*c >= 'a' && *c <= 'z') {
  61             *c -= ('a' - 'A');
  62           }
  63           seen_id = true;
  64         }
  65       } else if (key == "NAME") {
  66         ExtractAndSetValue(name, value);
  67       } else if (key == "PRETTY_NAME") {
  68         if (ExtractAndSetValue(aDescription, value)) seen_pretty_name = true;
  69       } else if (key == "VERSION_ID") {
  70         if (ExtractAndSetValue(aRelease, value)) seen_version_id = true;
  71       } else if (key == "VERSION_CODENAME") {
  72         ExtractAndSetValue(aCodename, value);
  73       }
  74     }
  75   }
  76   // If NAME is set and only differs from ID in case, use NAME.
  77   if (seen_id && !name.IsEmpty() && name.EqualsIgnoreCase(aDistributor)) {
  78     aDistributor = name;
  79   }
  80   // Only consider our work done if we've seen at least ID, PRETTY_NAME and
  81   // VERSION_ID.
  82   return seen_id && seen_pretty_name && seen_version_id;
  83 }
  84
  85 bool GetLSBRelease(nsACString& aDistributor, nsACString& aDescription,
  86                    nsACString& aRelease, nsACString& aCodename) {
  87   // Nowadays, /etc/os-release is more likely to be available than
  88   // /usr/bin/lsb_release. Relying on the former also avoids forking.
  89   if (GetOSRelease(aDistributor, aDescription, aRelease, aCodename)) {
  90     return true;
  91   }
  92
  93   if (access(gLsbReleasePath, R_OK) != 0) return false;
  94
  95   int pipefd[2];
  96   if (pipe(pipefd) == -1) {
  97     NS_WARNING("pipe() failed!");
  98     return false;
  99   }
 100
 101   std::vector<std::string> argv = {gLsbReleasePath, "-idrc"};
 102
 103   base::LaunchOptions options;
 104   options.fds_to_remap.push_back({pipefd[1], STDOUT_FILENO});
 105   options.wait = true;
 106
 107   base::ProcessHandle process;
 108   Result<Ok, ipc::LaunchError> err =
 109       base::LaunchApp(argv, std::move(options), &process);
 110   close(pipefd[1]);
 111   if (err.isErr()) {
 112     NS_WARNING("Failed to spawn lsb_release!");
 113     close(pipefd[0]);
 114     return false;
 115   }
 116
 117   ScopedCloseFile stream(fdopen(pipefd[0], "r"));
 118   if (!stream) {
 119     NS_WARNING("Could not wrap fd!");
 120     close(pipefd[0]);
 121     return false;
 122   }
 123
 124   char dist[256], desc[256], release[256], codename[256];
 125   if (fscanf(stream.get(),
 126              "Distributor ID:\t%255[^\n]\n"
 127              "Description:\t%255[^\n]\n"
 128              "Release:\t%255[^\n]\n"
 129              "Codename:\t%255[^\n]\n",
 130              dist, desc, release, codename) != 4) {
 131     NS_WARNING("Failed to parse lsb_release!");
 132     return false;
 133   }
 134
 135   aDistributor.Assign(dist);
 136   aDescription.Assign(desc);
 137   aRelease.Assign(release);
 138   aCodename.Assign(codename);
 139   return true;
 140 }
 141
 142 }  // namespace mozilla::widget::lsb