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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
Notes:
sideshowbarker
2024-07-18 21:25:22 +09:00
Author: https://github.com/BenWiederhake Commit: https://github.com/SerenityOS/serenity/commit/81079ae6163 Pull-request: https://github.com/SerenityOS/serenity/pull/5740
3 changed files with 127 additions and 94 deletions
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@ -227,10 +227,29 @@ TEST_CASE(rounding)
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EXPECT_EQ(TIME(0, 0).to_milliseconds(), 0);
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EXPECT_EQ(TIME(0, 0).to_microseconds(), 0);
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EXPECT_EQ(TIME(0, 0).to_nanoseconds(), 0);
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EXPECT_EQ(TIME(0, 1).to_seconds(), 1);
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EXPECT_EQ(TIME(0, 1).to_milliseconds(), 1);
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EXPECT_EQ(TIME(0, 1).to_microseconds(), 1);
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EXPECT_EQ(TIME(0, 1).to_nanoseconds(), 1);
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EXPECT_EQ(TIME(0, -1).to_seconds(), -1);
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EXPECT_EQ(TIME(0, -1).to_milliseconds(), -1);
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EXPECT_EQ(TIME(0, -1).to_microseconds(), -1);
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EXPECT_EQ(TIME(0, -1).to_nanoseconds(), -1);
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EXPECT_EQ(TIME(-9223372037, 145'224'191).to_nanoseconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(TIME(-9223372037, 145'224'192).to_nanoseconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(TIME(-9223372037, 145'224'193).to_nanoseconds(), -0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(9223372036, 854'775'806).to_nanoseconds(), 0x7fff'ffff'ffff'fffe);
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EXPECT_EQ(TIME(9223372036, 854'775'807).to_nanoseconds(), 0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(9223372036, 854'775'808).to_nanoseconds(), 0x7fff'ffff'ffff'ffff);
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}
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TEST_CASE(truncation)
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{
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// Sanity
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EXPECT_EQ(TIME(2, 0).to_truncated_seconds(), 2);
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EXPECT_EQ(TIME(-2, 0).to_truncated_seconds(), -2);
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EXPECT_EQ(TIME(2, 800'800'800).to_truncated_seconds(), 2);
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EXPECT_EQ(TIME(2, 800'800'800).to_truncated_milliseconds(), 2'800);
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EXPECT_EQ(TIME(2, 800'800'800).to_truncated_microseconds(), 2'800'800);
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@ -238,13 +257,29 @@ TEST_CASE(truncation)
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EXPECT_EQ(TIME(-2, -800'800'800).to_truncated_milliseconds(), -2'800);
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EXPECT_EQ(TIME(-2, -800'800'800).to_truncated_microseconds(), -2'800'800);
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EXPECT_EQ(TIME(0, 0).to_truncated_seconds(), 0);
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EXPECT_EQ(TIME(1, 999'999'999).to_truncated_seconds(), 1);
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EXPECT_EQ(TIME(1, 1'000'000'000).to_truncated_seconds(), 2);
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EXPECT_EQ(TIME(-2, 0).to_truncated_seconds(), -2);
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// Overflow, seconds
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EXPECT_EQ(Time::min().to_truncated_seconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(Time::max().to_truncated_seconds(), 0x7fff'ffff'ffff'ffff);
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// Overflow, milliseconds
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EXPECT_EQ(TIME(-9223372036854776, 191'000'000).to_truncated_milliseconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(TIME(-9223372036854776, 192'000'000).to_truncated_milliseconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(TIME(-9223372036854776, 192'000'001).to_truncated_milliseconds(), -0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(-9223372036854776, 193'000'000).to_truncated_milliseconds(), -0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(9223372036854775, 806'000'000).to_truncated_milliseconds(), 0x7fff'ffff'ffff'fffe);
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EXPECT_EQ(TIME(9223372036854775, 806'999'999).to_truncated_milliseconds(), 0x7fff'ffff'ffff'fffe);
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EXPECT_EQ(TIME(9223372036854775, 807'000'000).to_truncated_milliseconds(), 0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(9223372036854775, 808'000'000).to_truncated_milliseconds(), 0x7fff'ffff'ffff'ffff);
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// Overflow, microseconds
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EXPECT_EQ(TIME(-9223372036855, 224'191'000).to_truncated_microseconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(TIME(-9223372036855, 224'192'000).to_truncated_microseconds(), (i64)-0x8000'0000'0000'0000);
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EXPECT_EQ(TIME(-9223372036855, 224'192'001).to_truncated_microseconds(), (i64)-0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(-9223372036855, 224'193'000).to_truncated_microseconds(), (i64)-0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(9223372036854, 775'806'000).to_truncated_microseconds(), 0x7fff'ffff'ffff'fffe);
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EXPECT_EQ(TIME(9223372036854, 775'806'999).to_truncated_microseconds(), 0x7fff'ffff'ffff'fffe);
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EXPECT_EQ(TIME(9223372036854, 775'807'000).to_truncated_microseconds(), 0x7fff'ffff'ffff'ffff);
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EXPECT_EQ(TIME(9223372036854, 775'808'000).to_truncated_microseconds(), 0x7fff'ffff'ffff'ffff);
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}
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TEST_MAIN(Time)
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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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45
AK/Time.h
45
AK/Time.h
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@ -26,6 +26,7 @@
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#pragma once
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#include <AK/Assertions.h>
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#include <AK/Platform.h>
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#include <AK/Types.h>
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@ -100,18 +101,51 @@ public:
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return *this;
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}
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private:
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// This must be part of the header in order to make the various 'from_*' functions constexpr.
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// However, sane_mod can only deal with a limited range of values for 'denominator', so this can't be made public.
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ALWAYS_INLINE static constexpr i64 sane_mod(i64& numerator, i64 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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i64 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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ALWAYS_INLINE static constexpr i32 sane_mod(i32& numerator, i32 denominator)
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{
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i64 numerator_64 = numerator;
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i64 dividend = sane_mod(numerator_64, denominator);
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// Does not underflow: numerator can only become smaller.
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numerator = numerator_64;
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// Does not overflow: Will be smaller than original value of 'numerator'.
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return dividend;
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}
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public:
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constexpr static Time from_seconds(i64 seconds) { return Time(seconds, 0); }
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constexpr static Time from_nanoseconds(i64 nanoseconds)
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{
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return Time(nanoseconds / 1'000'000'000, nanoseconds % 1'000'000'000);
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i64 seconds = sane_mod(nanoseconds, 1'000'000'000);
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return Time(seconds, nanoseconds);
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}
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constexpr static Time from_microseconds(i64 microseconds)
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{
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return Time(microseconds / 1'000'000, (microseconds % 1'000'000) * 1'000);
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i64 seconds = sane_mod(microseconds, 1'000'000);
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return Time(seconds, microseconds * 1'000);
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}
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constexpr static Time from_milliseconds(i64 milliseconds)
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{
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return Time(milliseconds / 1'000, (milliseconds % 1'000) * 1'000'000);
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i64 seconds = sane_mod(milliseconds, 1'000);
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return Time(seconds, milliseconds * 1'000'000);
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}
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static Time from_timespec(const struct timespec&);
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static Time from_timeval(const struct timeval&);
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@ -119,16 +153,17 @@ public:
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static Time zero() { return Time(0, 0); };
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static Time max() { return Time(0x7fff'ffff'ffff'ffffLL, 999'999'999); };
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// Truncates "2.8 seconds" to 2 seconds.
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// Truncates "-2.8 seconds" to -2 seconds.
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// Truncates towards zero (2.8s to 2s, -2.8s to -2s).
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i64 to_truncated_seconds() const;
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i64 to_truncated_milliseconds() const;
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i64 to_truncated_microseconds() const;
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// Rounds away from zero (2.3s to 3s, -2.3s to -3s).
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i64 to_seconds() const;
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i64 to_milliseconds() const;
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i64 to_microseconds() const;
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i64 to_nanoseconds() const;
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timespec to_timespec() const;
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// Rounds towards -inf (it was the easiest to implement).
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timeval to_timeval() const;
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bool is_zero() const { return !m_seconds && !m_nanoseconds; }
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