feat: add time syscall & command in shell

kernel/src/Api/Syscall.cpp

@@ -5,6 +5,7 @@
 */
 
 #include "Syscall.hpp"
+#include <Timekeeping/Time.hpp>
 #include <Terminal/Terminal.hpp>
 #include <Fs/Vfs.hpp>
 #include <Memory/Heap.hpp>
@@ -256,6 +257,17 @@ namespace Zenith {
         return (rows << 32) | (cols & 0xFFFFFFFF);
     }
 
+    static void Sys_GetTime(DateTime* out) {
+        if (out == nullptr) return;
+        Timekeeping::DateTime dt = Timekeeping::GetDateTime();
+        out->Year   = dt.Year;
+        out->Month  = dt.Month;
+        out->Day    = dt.Day;
+        out->Hour   = dt.Hour;
+        out->Minute = dt.Minute;
+        out->Second = dt.Second;
+    }
+
     static void Sys_Reset() {
         /*
             Triple fault for now; TODO: implement UEFI runtime function for clean reboot.
@@ -349,6 +361,9 @@ namespace Zenith {
             case SYS_SHUTDOWN:
                 /* Unimplemented */
                 return -1;
+            case SYS_GETTIME:
+                Sys_GetTime((DateTime*)frame->arg1);
+                return 0;
             default:
                 return -1;
         }
@@ -375,7 +390,7 @@ namespace Zenith {
         Hal::WriteMSR(Hal::IA32_FMASK, 0x200);
 
         Kt::KernelLogStream(Kt::OK, "Syscall") << "SYSCALL/SYSRET initialized (LSTAR="
-            << kcp::hex << (uint64_t)SyscallEntry << kcp::dec << ", 26 syscalls)";
+            << kcp::hex << (uint64_t)SyscallEntry << kcp::dec << ", 29 syscalls)";
     }
 
 }

kernel/src/Api/Syscall.hpp

@@ -39,6 +39,16 @@ namespace Zenith {
     static constexpr uint64_t SYS_GETARGS         = 25;
     static constexpr uint64_t SYS_RESET           = 26;
     static constexpr uint64_t SYS_SHUTDOWN        = 27;
+    static constexpr uint64_t SYS_GETTIME         = 28;
+
+    struct DateTime {
+        uint16_t Year;
+        uint8_t Month;
+        uint8_t Day;
+        uint8_t Hour;
+        uint8_t Minute;
+        uint8_t Second;
+    };
 
     struct FbInfo {
         uint64_t width;

kernel/src/Timekeeping/Time.cpp

@@ -4,12 +4,70 @@
 */
 
 #include "Time.hpp"
+#include "ApicTimer.hpp"
 #include <Terminal/Terminal.hpp>
 #include <CppLib/Stream.hpp>
 
 using namespace Kt;
 
+static int64_t g_bootEpoch = 0;
+
+static bool IsLeapYear(int year) {
+    return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
+}
+
+static int DaysInMonth(int month, int year) {
+    static const int days[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
+    if (month == 2 && IsLeapYear(year)) return 29;
+    return days[month];
+}
+
+static int64_t DateToEpoch(int year, int month, int day, int hour, int minute, int second) {
+    int64_t days = 0;
+    for (int y = 1970; y < year; y++) {
+        days += IsLeapYear(y) ? 366 : 365;
+    }
+    for (int m = 1; m < month; m++) {
+        days += DaysInMonth(m, year);
+    }
+    days += day - 1;
+    return days * 86400 + hour * 3600 + minute * 60 + second;
+}
+
+static Timekeeping::DateTime EpochToDate(int64_t epoch) {
+    Timekeeping::DateTime dt = {};
+    int64_t rem = epoch;
+    int year = 1970;
+    while (true) {
+        int64_t daysInYear = IsLeapYear(year) ? 366 : 365;
+        if (rem < daysInYear * 86400) break;
+        rem -= daysInYear * 86400;
+        year++;
+    }
+    dt.Year = (uint16_t)year;
+
+    int dayOfYear = (int)(rem / 86400);
+    rem -= (int64_t)dayOfYear * 86400;
+
+    int month = 1;
+    while (month <= 12) {
+        int dim = DaysInMonth(month, year);
+        if (dayOfYear < dim) break;
+        dayOfYear -= dim;
+        month++;
+    }
+    dt.Month = (uint8_t)month;
+    dt.Day = (uint8_t)(dayOfYear + 1);
+
+    dt.Hour = (uint8_t)(rem / 3600);
+    rem %= 3600;
+    dt.Minute = (uint8_t)(rem / 60);
+    dt.Second = (uint8_t)(rem % 60);
+    return dt;
+}
+
 void Timekeeping::Init(uint16_t Year, uint8_t Month, uint8_t Day, uint8_t Hour, uint8_t Minute, uint8_t Second) {
+    g_bootEpoch = DateToEpoch(Year, Month, Day, Hour, Minute, Second);
     /* Hardcode CET for now */
     TimeZone CET = {
         "Central European Time",
@@ -64,3 +122,11 @@ void Timekeeping::Init(uint16_t Year, uint8_t Month, uint8_t Day, uint8_t Hour,
 
     UpdatePanelBar(dateString);
 }
+
+int64_t Timekeeping::GetUnixTimestamp() {
+    return g_bootEpoch + (int64_t)(Timekeeping::GetMilliseconds() / 1000);
+}
+
+Timekeeping::DateTime Timekeeping::GetDateTime() {
+    return EpochToDate(GetUnixTimestamp());
+}

kernel/src/Timekeeping/Time.hpp

@@ -41,5 +41,16 @@ namespace Timekeeping {
         "December"
     };
 
+    struct DateTime {
+        uint16_t Year;
+        uint8_t Month;
+        uint8_t Day;
+        uint8_t Hour;
+        uint8_t Minute;
+        uint8_t Second;
+    };
+
     void Init(uint16_t Year, uint8_t Month, uint8_t Day, uint8_t Hour, uint8_t Minute, uint8_t Second);
+    int64_t GetUnixTimestamp();
+    DateTime GetDateTime();
 };

programs/include/Api/Syscall.hpp

@@ -39,6 +39,16 @@ namespace Zenith {
     static constexpr uint64_t SYS_GETARGS         = 25;
     static constexpr uint64_t SYS_RESET           = 26;
     static constexpr uint64_t SYS_SHUTDOWN        = 27;
+    static constexpr uint64_t SYS_GETTIME         = 28;
+
+    struct DateTime {
+        uint16_t Year;
+        uint8_t Month;
+        uint8_t Day;
+        uint8_t Hour;
+        uint8_t Minute;
+        uint8_t Second;
+    };
 
     struct FbInfo {
         uint64_t width;

programs/include/zenith/syscall.h

@@ -176,6 +176,9 @@ namespace zenith {
         if (rows) *rows = (int)(r >> 32);
     }
 
+    // Timekeeping (wall-clock)
+    inline void gettime(Zenith::DateTime* out) { syscall1(Zenith::SYS_GETTIME, (uint64_t)out); }
+
     // Power management
     [[noreturn]] inline void reset() {
         syscall0(Zenith::SYS_RESET);

programs/man/shell.1

@@ -47,6 +47,9 @@
     round-trip times. Timeout is 3 seconds per request.
     Example: ping 10.0.2.2
 
+.SS date
+    Display the current date and time in UTC.
+
 .SS uptime
     Display the system uptime in minutes, seconds, and milliseconds.
 

programs/man/syscalls.2

@@ -3,7 +3,7 @@
     syscalls - overview of ZenithOS system calls
 
 .SH DESCRIPTION
-    ZenithOS provides 26 system calls (numbers 0-25) for userspace
+    ZenithOS provides 29 system calls (numbers 0-28) for userspace
     programs. Syscalls use the x86-64 SYSCALL instruction with the
     following register convention:
 
@@ -91,6 +91,12 @@
     Get milliseconds elapsed since boot.
         uint64_t zenith::get_milliseconds();
 
+.B SYS_GETTIME (28)
+    Get the current wall-clock date and time (UTC).
+    Fills a Zenith::DateTime struct with Year, Month, Day,
+    Hour, Minute, and Second fields.
+        void zenith::gettime(Zenith::DateTime* out);
+
 .SH SYSTEM
 .B SYS_GETINFO (15)
     Get OS name, version, and configuration.
@@ -133,5 +139,14 @@
     Get the argument string passed to this process at spawn time.
         int zenith::getargs(char* buf, uint64_t maxLen);
 
+.SH POWER MANAGEMENT
+.B SYS_RESET (26)
+    Reboot the system.
+        [[noreturn]] void zenith::reset();
+
+.B SYS_SHUTDOWN (27)
+    Shut down the system (currently unimplemented).
+        [[noreturn]] void zenith::shutdown();
+
 .SH SEE ALSO
     spawn(2), file(2), framebuffer(2), malloc(3)

programs/src/shell/main.cpp

@@ -94,6 +94,7 @@ static void cmd_help() {
     zenith::print("  cat <file>    Display file contents\n");
     zenith::print("  run <file>    Spawn a new process from an ELF file\n");
     zenith::print("  ping <ip>     Send ICMP echo requests\n");
+    zenith::print("  date          Show current date and time\n");
     zenith::print("  uptime        Show uptime in milliseconds\n");
     zenith::print("  clear         Clear the screen\n");
     zenith::print("  reset         Reboot the system\n");
@@ -390,6 +391,38 @@ static void cmd_man(const char* arg) {
     }
 }
 
+static void print_int_padded(uint64_t n) {
+    if (n < 10) zenith::putchar('0');
+    print_int(n);
+}
+
+static const char* month_name(int m) {
+    static const char* months[] = {
+        "", "January", "February", "March", "April", "May", "June",
+        "July", "August", "September", "October", "November", "December"
+    };
+    if (m >= 1 && m <= 12) return months[m];
+    return "?";
+}
+
+static void cmd_date() {
+    Zenith::DateTime dt;
+    zenith::gettime(&dt);
+
+    print_int(dt.Day);
+    zenith::putchar(' ');
+    zenith::print(month_name(dt.Month));
+    zenith::putchar(' ');
+    print_int(dt.Year);
+    zenith::print(", ");
+    print_int(dt.Hour);
+    zenith::putchar(':');
+    print_int_padded(dt.Minute);
+    zenith::putchar(':');
+    print_int_padded(dt.Second);
+    zenith::print(" UTC\n");
+}
+
 static void cmd_clear() {
     zenith::print("\033[2J");   // Clear entire screen
     zenith::print("\033[H");    // Move cursor to top-left
@@ -428,6 +461,8 @@ static void process_command(const char* line) {
         cmd_ping(line + 5);
     } else if (streq(line, "ping")) {
         cmd_ping("");
+    } else if (streq(line, "date")) {
+        cmd_date();
     } else if (streq(line, "uptime")) {
         cmd_uptime();
     } else if (streq(line, "clear")) {