libstdc++: Fix strings read from /etc/sysconfig/clock [PR108530]

In r13-5339-ge00d5cafbe1a77 I made std::chrono::current_zone() look for
DEFAULT_TIMEZONE in /etc/sysconfig/clock but that is the wrong variable.
Old Suse systems use TIMEZONE to determine which zone /etc/localtime is
a copy of, and old RHEL system use ZONE.

libstdc++-v3/ChangeLog:

	PR libstdc++/108530
	* src/c++20/tzdb.cc (current_zone): Look for TIMEZONE or ZONE in
	/etc/sysconfig/clock, not DEFAULT_TIMEZONE.

diff --git a/libstdc++-v3/src/c++20/tzdb.cc b/libstdc++-v3/src/c++20/tzdb.cc
index eb68111..c945f00 100644 (file)
--- a/libstdc++-v3/src/c++20/tzdb.cc
+++ b/libstdc++-v3/src/c++20/tzdb.cc
@@ -1667,21 +1667,23 @@ namespace std::chrono
     if (ifstream tzf{"/etc/sysconfig/clock"})
       {
        string line;
-       string_view key = "DEFAULT_TIMEZONE=";
+       // Old versions of Suse use TIMEZONE. Old versions of RHEL use ZONE.
+       const string_view keys[] = { "TIMEZONE=" , "ZONE=" };
        while (std::getline(tzf, line))
-         if (line.starts_with(key))
-           {
-             string_view name = line;
-             name.remove_prefix(key.size());
-             if (name.size() != 0 && name.front() == '"')
-               {
-                 name.remove_prefix(1);
-                 if (auto pos = name.find('"'); pos != name.npos)
-                   name = name.substr(0, pos);
-               }
-             if (auto tz = do_locate_zone(this->zones, this->links, name))
-               return tz;
-           }
+         for (string_view key : keys)
+           if (line.starts_with(key))
+             {
+               string_view name = line;
+               name.remove_prefix(key.size());
+               if (name.size() != 0 && name.front() == '"')
+                 {
+                   name.remove_prefix(1);
+                   if (auto pos = name.find('"'); pos != name.npos)
+                     name = name.substr(0, pos);
+                 }
+               if (auto tz = do_locate_zone(this->zones, this->links, name))
+                 return tz;
+             }
       }
 #else
     // AIX stores current zone in $TZ in /etc/environment but the value