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   nsAutoCString build_id;
  49   while (std::getline(stream, rawline)) {
  50     std::string_view line(rawline);
  51     size_t pos = line.find('=');
  52     if (pos != std::string_view::npos) {
  53       auto key = line.substr(0, pos);
  54       auto value = line.substr(pos + 1);
  55       if (key == "ID") {
  56         if (ExtractAndSetValue(aDistributor, value)) {
  57           // Capitalize the first letter of the id. This mimics what
  58           // lsb_release does on Debian and derivatives. On RH derivatives,
  59           // ID tends to be capitalized already.
  60           char* c = aDistributor.BeginWriting();
  61           if (*c >= 'a' && *c <= 'z') {
  62             *c -= ('a' - 'A');
  63           }
  64           seen_id = true;
  65         }
  66       } else if (key == "NAME") {
  67         ExtractAndSetValue(name, value);
  68       } else if (key == "PRETTY_NAME") {
  69         if (ExtractAndSetValue(aDescription, value)) seen_pretty_name = true;
  70       } else if (key == "VERSION_ID") {
  71         if (ExtractAndSetValue(aRelease, value)) seen_version_id = true;
  72       } else if (key == "BUILD_ID") {
  73         ExtractAndSetValue(build_id, value);
  74       } else if (key == "VERSION_CODENAME") {
  75         ExtractAndSetValue(aCodename, value);
  76       }
  77     }
  78   }
  79   // If NAME is set and only differs from ID in case, use NAME.
  80   if (seen_id && !name.IsEmpty() && name.EqualsIgnoreCase(aDistributor)) {
  81     aDistributor = name;
  82   }
  83   // If VERSION_ID is not set but BUILD_ID is, use BUILD_ID.
  84   if (!seen_version_id && !build_id.IsEmpty()) {
  85     aRelease = build_id;
  86     seen_version_id = true;
  87   }
  88   // Only consider our work done if we've seen at least ID, PRETTY_NAME and
  89   // VERSION_ID.
  90   return seen_id && seen_pretty_name && seen_version_id;
  91 }
  92
  93 bool GetLSBRelease(nsACString& aDistributor, nsACString& aDescription,
  94                    nsACString& aRelease, nsACString& aCodename) {
  95   // Nowadays, /etc/os-release is more likely to be available than
  96   // /usr/bin/lsb_release. Relying on the former also avoids forking.
  97   if (GetOSRelease(aDistributor, aDescription, aRelease, aCodename)) {
  98     return true;
  99   }
 100
 101   if (access(gLsbReleasePath, R_OK) != 0) return false;
 102
 103   int pipefd[2];
 104   if (pipe(pipefd) == -1) {
 105     NS_WARNING("pipe() failed!");
 106     return false;
 107   }
 108
 109   std::vector<std::string> argv = {gLsbReleasePath, "-idrc"};
 110
 111   base::LaunchOptions options;
 112   options.fds_to_remap.push_back({pipefd[1], STDOUT_FILENO});
 113   options.wait = true;
 114
 115   base::ProcessHandle process;
 116   Result<Ok, ipc::LaunchError> err =
 117       base::LaunchApp(argv, std::move(options), &process);
 118   close(pipefd[1]);
 119   if (err.isErr()) {
 120     NS_WARNING("Failed to spawn lsb_release!");
 121     close(pipefd[0]);
 122     return false;
 123   }
 124
 125   ScopedCloseFile stream(fdopen(pipefd[0], "r"));
 126   if (!stream) {
 127     NS_WARNING("Could not wrap fd!");
 128     close(pipefd[0]);
 129     return false;
 130   }
 131
 132   char dist[256], desc[256], release[256], codename[256];
 133   if (fscanf(stream.get(),
 134              "Distributor ID:\t%255[^\n]\n"
 135              "Description:\t%255[^\n]\n"
 136              "Release:\t%255[^\n]\n"
 137              "Codename:\t%255[^\n]\n",
 138              dist, desc, release, codename) != 4) {
 139     NS_WARNING("Failed to parse lsb_release!");
 140     return false;
 141   }
 142
 143   aDistributor.Assign(dist);
 144   aDescription.Assign(desc);
 145   aRelease.Assign(release);
 146   aCodename.Assign(codename);
 147   return true;
 148 }
 149
 150 }  // namespace mozilla::widget::lsb