procyberian/gcc
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

libstdc++: Add workaround for old tzdata.zi files

Browse source 
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.
This commit is contained in:
Jonathan Wakely 2023-01-26 11:35:00 +00:00
parent 3376467ce0
commit 2e445d9e99
1 changed files with 34 additions and 15 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

49
libstdc++-v3/src/c++20/tzdb.cc
View file

@ -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]]]