[committed] libstdc++: Add workaround for old tzdata.zi files
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Commit Message
Tested x86_64-linux (Fedora 36 and RHEL 6.10). Pushed to trunk.
-- >8 --
The tzdata.zi file in the RHEL 6 tzdata-2018e-3.el6 package (with
version "unknown") does not conform to the current rules described in
the zic(8) man page. Specifically, a Rule name must not start with the
character '+' in the current rules, but the older tzdata.zi file
used "+" as the name of rules for the "Europe/Sofia" zone.
Add a special case to the logic that detects whether a RULES field
refers to a named rule or is an offset from standard time. For a string
matching exactly "+" treat it as a named Rule, but for any other string
starting with '+' treat it as an offset.
libstdc++-v3/ChangeLog:
* src/c++20/tzdb.cc (operator>>(istream&, ZoneInfo&)): Allow
rules named "+" for compatibility with older tzdata.zi files.
---
libstdc++-v3/src/c++20/tzdb.cc | 49 +++++++++++++++++++++++-----------
1 file changed, 34 insertions(+), 15 deletions(-)
@@ -1967,6 +1967,22 @@ namespace std::chrono
return in;
}
+ // Test whether the RULES field of a Zone line is a valid Rule name.
+ inline bool
+ is_rule_name(string_view rules) noexcept
+ {
+ // The NAME field of a Rule line must start with a character that is
+ // neither an ASCII digit nor '-' nor '+'.
+ if (('0' <= rules[0] && rules[0] <= '9') || rules[0] == '-')
+ return false;
+ // However, some older tzdata.zi files (e.g. in tzdata-2018e-3.el6 RPM)
+ // used "+" as a Rule name, so we need to handle that special case.
+ if (rules[0] == '+')
+ return rules.size() == 1; // "+" is a rule name, "+1" is not.
+ // Everything else is the name of a Rule.
+ return true;
+ }
+
istream& operator>>(istream& in, ZoneInfo& inf)
{
// STDOFF RULES FORMAT [UNTIL]
@@ -1976,25 +1992,28 @@ namespace std::chrono
in >> off >> quoted{rules} >> fmt;
inf.m_offset = off.time;
- if (rules == "-")
+ if (is_rule_name(rules))
{
- // Standard time always applies, no DST.
- inf.set_abbrev(fmt);
- }
- else if (string_view("0123456789-+").find(rules[0]) != string_view::npos)
- {
- // rules specifies the difference from standard time.
- at_time rules_time;
- istringstream in2(std::move(rules));
- in2 >> rules_time;
- inf.m_save = duration_cast<minutes>(rules_time.time);
- select_std_or_dst_abbrev(fmt, inf.m_save);
- inf.set_abbrev(fmt);
+ // `rules` refers to a named Rule which describes transitions.
+ inf.set_rules_and_format(rules, fmt);
}
else
{
- // rules refers to a named Rule which describes transitions.
- inf.set_rules_and_format(rules, fmt);
+ if (rules == "-")
+ {
+ // Standard time always applies, no DST.
+ }
+ else
+ {
+ // `rules` specifies the difference from standard time,
+ // e.g., "-2:30"
+ at_time rules_time;
+ istringstream in2(std::move(rules));
+ in2 >> rules_time;
+ inf.m_save = duration_cast<minutes>(rules_time.time);
+ select_std_or_dst_abbrev(fmt, inf.m_save);
+ }
+ inf.set_abbrev(fmt);
}
// YEAR [MONTH [DAY [TIME]]]