feat: add time syscall & command in shell

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")) {