1 files changed, 72 insertions, 1 deletions

diff --git a/widget/LSBUtils.cpp b/widget/LSBUtils.cpp
index bcadddef12..520d50e5cc 100644
--- a/widget/LSBUtils.cpp
+++ b/widget/LSBUtils.cpp
@@ -6,6 +6,9 @@
 
 #include "LSBUtils.h"
 
+#include <fstream>
+#include <string>
+#include <string_view>
 #include <unistd.h>
 #include "base/process_util.h"
 #include "mozilla/FileUtils.h"
@@ -15,10 +18,78 @@
 
 namespace mozilla::widget::lsb {
 
-static const char* gLsbReleasePath = "/usr/bin/lsb_release";
+static const char gLsbReleasePath[] = "/usr/bin/lsb_release";
+static const char gEtcOsReleasePath[] = "/etc/os-release";
+static const char gUsrOsReleasePath[] = "/usr/lib/os-release";
+
+// See https://www.freedesktop.org/software/systemd/man/latest/os-release.html
+bool ExtractAndSetValue(nsACString& aContainer, std::string_view& aValue) {
+  // We assume the value is well formed and doesn't contain escape characters.
+  if (aValue.size() > 1 && (aValue.front() == '"' || aValue.front() == '\'')) {
+    // We assume the quote is properly balanced.
+    aValue = aValue.substr(1, aValue.size() - 2);
+  }
+  aContainer.Assign(aValue.data(), aValue.size());
+  return !aValue.empty();
+}
+
+bool GetOSRelease(nsACString& aDistributor, nsACString& aDescription,
+                  nsACString& aRelease, nsACString& aCodename) {
+  std::ifstream stream(gEtcOsReleasePath);
+  if (stream.fail()) {
+    stream.open(gUsrOsReleasePath);
+    if (stream.fail()) {
+      return false;
+    }
+  }
+  bool seen_id = false, seen_pretty_name = false, seen_version_id = false;
+  std::string rawline;
+  nsAutoCString name;
+  while (std::getline(stream, rawline)) {
+    std::string_view line(rawline);
+    size_t pos = line.find('=');
+    if (pos != std::string_view::npos) {
+      auto key = line.substr(0, pos);
+      auto value = line.substr(pos + 1);
+      if (key == "ID") {
+        if (ExtractAndSetValue(aDistributor, value)) {
+          // Capitalize the first letter of the id. This mimics what
+          // lsb_release does on Debian and derivatives. On RH derivatives,
+          // ID tends to be capitalized already.
+          char* c = aDistributor.BeginWriting();
+          if (*c >= 'a' && *c <= 'z') {
+            *c -= ('a' - 'A');
+          }
+          seen_id = true;
+        }
+      } else if (key == "NAME") {
+        ExtractAndSetValue(name, value);
+      } else if (key == "PRETTY_NAME") {
+        if (ExtractAndSetValue(aDescription, value)) seen_pretty_name = true;
+      } else if (key == "VERSION_ID") {
+        if (ExtractAndSetValue(aRelease, value)) seen_version_id = true;
+      } else if (key == "VERSION_CODENAME") {
+        ExtractAndSetValue(aCodename, value);
+      }
+    }
+  }
+  // If NAME is set and only differs from ID in case, use NAME.
+  if (seen_id && !name.IsEmpty() && name.EqualsIgnoreCase(aDistributor)) {
+    aDistributor = name;
+  }
+  // Only consider our work done if we've seen at least ID, PRETTY_NAME and
+  // VERSION_ID.
+  return seen_id && seen_pretty_name && seen_version_id;
+}
 
 bool GetLSBRelease(nsACString& aDistributor, nsACString& aDescription,
                    nsACString& aRelease, nsACString& aCodename) {
+  // Nowadays, /etc/os-release is more likely to be available than
+  // /usr/bin/lsb_release. Relying on the former also avoids forking.
+  if (GetOSRelease(aDistributor, aDescription, aRelease, aCodename)) {
+    return true;
+  }
+
   if (access(gLsbReleasePath, R_OK) != 0) return false;
 
   int pipefd[2];