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

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".

diff --git a/libstdc++-v3/include/bits/chrono_io.h b/libstdc++-v3/include/bits/chrono_io.h
index f359571b4dba7a08f584136499f4e951f42543bf..7352df095ff40f78c20ec632cd961eb332cfbcd1 100644 (file)
--- a/libstdc++-v3/include/bits/chrono_io.h
+++ b/libstdc++-v3/include/bits/chrono_io.h
@@ -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)
-                       {
-                         __h = __bad_h;
-                         __min = __bad_min;
-                         __s = __bad_sec;
-                         break;
-                       }
-                     if (!__read_chr(':'))
+                     if (__val == -1 || __val > 23) [[unlikely]]
                        {
-                         __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;
                        }
                    }

diff --git a/libstdc++-v3/testsuite/std/time/parse.cc b/libstdc++-v3/testsuite/std/time/parse.cc
index 46eb7f28c85e79b55ff44a1a88c1721aa626c824..86222d595967a62916542b5c7e1d33b4afe9c872 100644 (file)
--- a/libstdc++-v3/testsuite/std/time/parse.cc
+++ b/libstdc++-v3/testsuite/std/time/parse.cc
@@ -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)