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libstdc++: Fix how chrono::parse handles errors for time-of-day values

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We fail to diagnose an error and extract an incorrect time for cases
like "25:59" >> parse("%H:%M", mins). The bad "25" hour value gets
ignored (on the basis that we might not care about it if trying to
extract something like a weekday or a month name), but then when we get
to the end of the function we think we have a valid time from "59" and
so the result is 00:59.

The problem is that the '__bad_h' value is used for "no hour value read
yet" as well as "bad hour value read". If we just set __h = __bad_h and
continue, we can't tell later that we read an invalid hour.

The fix is to set failbit early when we're trying to extract a
time-of-day (e.g. duration or time_point) and we encounter an invalid
hour, minute, or second value. We can still delay other error checking
to the end.

libstdc++-v3/ChangeLog:

	* include/bits/chrono_io.h (_Parser::operator()): Set failbit
	early if invalid values are read when _M_need & _TimeOfDay is
	non-zero.
	* testsuite/std/time/parse.cc: Check that "25:59" cannot be
	parsed for "%H:%M".
This commit is contained in:
Jonathan Wakely
2023-08-31 15:48:15 +01:00
parent 207c507499
commit e5af77adef
2 changed files with 36 additions and 24 deletions
Download Patch File Download Diff File Expand all files Collapse all files

53
libstdc++-v3/include/bits/chrono_io.h
View File

@@ -3327,7 +3327,16 @@ namespace __detail
__h = __bad_h;
}
else if (__c == 'H' && __val >= 0 && __val <= 23)
__h = hours(__val);
{
__h = hours(__val);
__h12 = __bad_h;
}
else
{
if (_M_need & _ChronoParts::_TimeOfDay)
__err |= ios_base::failbit;
break;
}
}
__parts |= _ChronoParts::_TimeOfDay;
break;
@@ -3392,9 +3401,8 @@ namespace __detail
__min = minutes(__val);
else
{
__h = __bad_h;
__min = __bad_min;
__s = __bad_sec;
if (_M_need & _ChronoParts::_TimeOfDay)
__err |= ios_base::failbit;
break;
}
}
@@ -3481,33 +3489,31 @@ namespace __detail
else
{
auto __val = __read_unsigned(2);
if (__val == -1 || __val > 23)
if (__val == -1 || __val > 23) [[unlikely]]
{
__h = __bad_h;
__min = __bad_min;
__s = __bad_sec;
break;
}
if (!__read_chr(':'))
{
__err |= ios_base::failbit;
if (_M_need & _ChronoParts::_TimeOfDay)
__err |= ios_base::failbit;
break;
}
if (!__read_chr(':')) [[unlikely]]
break;
__h = hours(__val);
__val = __read_unsigned(2);
if (__val == -1 || __val > 60)
if (__val == -1 || __val > 60) [[unlikely]]
{
__h = __bad_h;
__min = __bad_min;
__s = __bad_sec;
if (_M_need & _ChronoParts::_TimeOfDay)
__err |= ios_base::failbit;
break;
}
__min = minutes(__val);
__parts |= _ChronoParts::_TimeOfDay;
if (__c != 'T' || !__read_chr(':'))
if (__c == 'R')
{
__parts |= _ChronoParts::_TimeOfDay;
break;
}
else if (!__read_chr(':')) [[unlikely]]
break;
}
[[fallthrough]];
@@ -3527,13 +3533,12 @@ namespace __detail
ratio<1>>)
{
auto __val = __read_unsigned(__num ? __num : 2);
if (0 <= __val && __val <= 59)
if (0 <= __val && __val <= 59) [[likely]]
__s = seconds(__val);
else
{
__h = __bad_h;
__min = __bad_min;
__s = __bad_sec;
if (_M_need & _ChronoParts::_TimeOfDay)
__err |= ios_base::failbit;
break;
}
}

7
libstdc++-v3/testsuite/std/time/parse.cc
View File

@@ -252,6 +252,13 @@ test_errors()
VERIFY( is.eof() && ! is.fail() );
VERIFY( y == 2010y );
min = -1min;
is.clear();
is.str("25:59");
is >> parse("%H:%M", min); // 25h is out of range and needed
VERIFY( is.fail() );
VERIFY( min == -1min );
is.clear();
is.str("328 00");
is >> parse("%3C %y", y); // 328 is out of range for %C (PR libstdc++/111162)