diff options
Diffstat (limited to 'base')
| -rw-r--r-- | base/time_posix.cc | 43 |
1 files changed, 38 insertions, 5 deletions
diff --git a/base/time_posix.cc b/base/time_posix.cc index 784a9f5..9532620 100644 --- a/base/time_posix.cc +++ b/base/time_posix.cc @@ -10,6 +10,8 @@ #include <sys/time.h> #include <time.h> +#include <limits> + #include "base/basictypes.h" #include "base/logging.h" @@ -21,8 +23,8 @@ namespace base { // Time ----------------------------------------------------------------------- -// The internal representation of Time uses time_t directly, so there is no -// offset. The epoch is 1970-01-01 00:00:00 UTC. +// Some functions in time.cc use time_t directly, so we provide a zero offset +// for them. The epoch is 1970-01-01 00:00:00 UTC. // static const int64 Time::kTimeTToMicrosecondsOffset = GG_INT64_C(0); @@ -58,16 +60,47 @@ Time Time::FromExploded(bool is_local, const Exploded& exploded) { seconds = mktime(×truct); else seconds = timegm(×truct); - DCHECK(seconds >= 0) << "mktime/timegm could not convert from exploded"; - uint64 milliseconds = seconds * kMillisecondsPerSecond + exploded.millisecond; + int64 milliseconds; + // Handle overflow. Clamping the range to what mktime and timegm might + // return is the best that can be done here. It's not ideal, but it's better + // than failing here or ignoring the overflow case and treating each time + // overflow as one second prior to the epoch. + if (seconds == -1 && + (exploded.year < 1969 || exploded.year > 1970)) { + // If exploded.year is 1969 or 1970, take -1 as correct, with the + // time indicating 1 second prior to the epoch. (1970 is allowed to handle + // time zone and DST offsets.) Otherwise, return the most future or past + // time representable. Assumes the time_t epoch is 1970-01-01 00:00:00 UTC. + // + // The minimum and maximum representible times that mktime and timegm could + // return are used here instead of values outside that range to allow for + // proper round-tripping between exploded and counter-type time + // representations in the presence of possible truncation to time_t by + // division and use with other functions that accept time_t. + // + // When representing the most distant time in the future, add in an extra + // 999ms to avoid the time being less than any other possible value that + // this function can return. + if (exploded.year < 1969) { + milliseconds = std::numeric_limits<time_t>::min() * + kMillisecondsPerSecond; + } else { + milliseconds = (std::numeric_limits<time_t>::max() * + kMillisecondsPerSecond) + + kMillisecondsPerSecond - 1; + } + } else { + milliseconds = seconds * kMillisecondsPerSecond + exploded.millisecond; + } + return Time(milliseconds * kMicrosecondsPerMillisecond); } void Time::Explode(bool is_local, Exploded* exploded) const { // Time stores times with microsecond resolution, but Exploded only carries // millisecond resolution, so begin by being lossy. - uint64 milliseconds = us_ / kMicrosecondsPerMillisecond; + int64 milliseconds = us_ / kMicrosecondsPerMillisecond; time_t seconds = milliseconds / kMillisecondsPerSecond; struct tm timestruct; |