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https://github.com/RGBCube/serenity
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AK: Fix some overflows/underflows that weren't properly handled
Based on #5699. Closes #5699.
This commit is contained in:
Ben Wiederhake
Andreas Kling
parent
8a8bdb2cd7
commit
81079ae616
3 changed files with 127 additions and 94 deletions
131
AK/Time.cpp
131
AK/Time.cpp
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@ -24,7 +24,6 @@
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <AK/Assertions.h>
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#include <AK/Checked.h>
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#include <AK/Time.h>
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@ -71,22 +70,6 @@ unsigned day_of_week(int year, unsigned month, int day)
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return (year + year / 4 - year / 100 + year / 400 + seek_table[month - 1] + day) % 7;
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}
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ALWAYS_INLINE static i32 sane_mod(i32& numerator, i32 denominator)
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{
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VERIFY(2 <= denominator && denominator <= 1'000'000'000);
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// '%' in C/C++ does not work in the obvious way:
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// For example, -9 % 7 is -2, not +5.
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// However, we want a representation like "(-2)*7 + (+5)".
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i32 dividend = numerator / denominator;
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numerator %= denominator;
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if (numerator < 0) {
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// Does not overflow: different signs.
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numerator += denominator;
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// Does not underflow: denominator >= 2.
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dividend -= 1;
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}
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return dividend;
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}
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Time Time::from_timespec(const struct timespec& ts)
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{
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i32 nsecs = ts.tv_nsec;
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@ -105,48 +88,45 @@ i64 Time::to_truncated_seconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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if (m_seconds < 0 && m_nanoseconds) {
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Checked<i64> seconds(m_seconds);
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seconds++;
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return seconds.has_overflow() ? 0x7fff'ffff'ffff'ffffLL : seconds.value();
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// Since m_seconds is negative, adding 1 can't possibly overflow
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return m_seconds + 1;
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}
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return m_seconds;
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}
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i64 Time::to_truncated_milliseconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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Checked<i64> milliseconds(m_seconds);
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Checked<i64> milliseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
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milliseconds *= 1'000;
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if (!milliseconds.has_overflow()) {
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u32 add_ms = (u32)(m_nanoseconds / 1'000'000);
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if (add_ms) {
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milliseconds += add_ms;
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if (m_seconds < 0 && m_nanoseconds % 1'000'000 != 0)
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milliseconds++;
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if (!milliseconds.has_overflow())
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return milliseconds.value();
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} else {
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return milliseconds.value();
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milliseconds += m_nanoseconds / 1'000'000;
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if (m_seconds < 0) {
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if (m_nanoseconds % 1'000'000 != 0) {
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// Does not overflow: milliseconds <= 1'999.
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milliseconds++;
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}
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// We dropped one second previously, put it back in now that we have handled the rounding.
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milliseconds -= 1'000;
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}
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if (!milliseconds.has_overflow())
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return milliseconds.value();
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return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
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}
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i64 Time::to_truncated_microseconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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Checked<i64> microseconds(m_seconds);
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Checked<i64> microseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
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microseconds *= 1'000'000;
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if (!microseconds.has_overflow()) {
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u32 add_us = (u32)(m_nanoseconds / 1'000);
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if (add_us) {
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microseconds += add_us;
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if (m_seconds < 0 && m_nanoseconds % 1'000 != 0)
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microseconds++;
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if (!microseconds.has_overflow())
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return microseconds.value();
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} else {
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return microseconds.value();
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microseconds += m_nanoseconds / 1'000;
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if (m_seconds < 0) {
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if (m_nanoseconds % 1'000 != 0) {
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// Does not overflow: microseconds <= 1'999'999.
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microseconds++;
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}
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// We dropped one second previously, put it back in now that we have handled the rounding.
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microseconds -= 1'000'000;
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}
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if (!microseconds.has_overflow())
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return microseconds.value();
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return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
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}
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i64 Time::to_seconds() const
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@ -162,64 +142,47 @@ i64 Time::to_seconds() const
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i64 Time::to_milliseconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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Checked<i64> milliseconds(m_seconds);
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Checked<i64> milliseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
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milliseconds *= 1'000;
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if (!milliseconds.has_overflow()) {
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u32 add_ms = (u32)(m_nanoseconds / 1'000'000);
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if (add_ms) {
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milliseconds += add_ms;
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if (!milliseconds.has_overflow()) {
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if (m_seconds >= 0 && m_nanoseconds % 1'000'000 != 0) {
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milliseconds++;
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if (!milliseconds.has_overflow())
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return milliseconds.value();
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} else {
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return milliseconds.value();
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}
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}
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} else {
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return milliseconds.value();
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}
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milliseconds += m_nanoseconds / 1'000'000;
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if (m_seconds >= 0 && m_nanoseconds % 1'000'000 != 0)
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milliseconds++;
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if (m_seconds < 0) {
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// We dropped one second previously, put it back in now that we have handled the rounding.
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milliseconds -= 1'000;
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}
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if (!milliseconds.has_overflow())
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return milliseconds.value();
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return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
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}
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i64 Time::to_microseconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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Checked<i64> microseconds(m_seconds);
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Checked<i64> microseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
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microseconds *= 1'000'000;
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if (!microseconds.has_overflow()) {
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u32 add_us = (u32)(m_nanoseconds / 1'000);
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if (add_us) {
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microseconds += add_us;
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if (!microseconds.has_overflow()) {
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if (m_seconds >= 0 && m_nanoseconds % 1'000 != 0) {
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microseconds++;
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if (!microseconds.has_overflow())
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return microseconds.value();
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} else {
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return microseconds.value();
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}
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}
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} else {
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return microseconds.value();
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}
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microseconds += m_nanoseconds / 1'000;
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if (m_seconds >= 0 && m_nanoseconds % 1'000 != 0)
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microseconds++;
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if (m_seconds < 0) {
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// We dropped one second previously, put it back in now that we have handled the rounding.
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microseconds -= 1'000'000;
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}
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if (!microseconds.has_overflow())
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return microseconds.value();
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return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
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}
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i64 Time::to_nanoseconds() const
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{
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VERIFY(m_nanoseconds < 1'000'000'000);
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Checked<i64> nanoseconds(m_seconds);
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Checked<i64> nanoseconds((m_seconds < 0) ? m_seconds + 1 : m_seconds);
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nanoseconds *= 1'000'000'000;
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if (!nanoseconds.has_overflow()) {
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if (m_nanoseconds) {
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nanoseconds += m_nanoseconds;
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if (!nanoseconds.has_overflow())
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return nanoseconds.value();
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}
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return nanoseconds.value();
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nanoseconds += m_nanoseconds;
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if (m_seconds < 0) {
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// We dropped one second previously, put it back in now that we have handled the rounding.
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nanoseconds -= 1'000'000'000;
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}
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if (!nanoseconds.has_overflow())
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return nanoseconds.value();
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return m_seconds < 0 ? -0x8000'0000'0000'0000LL : 0x7fff'ffff'ffff'ffffLL;
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}
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timespec Time::to_timespec() const
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