Date functions (get current time)

src/boot/boot.c

@@ -35,6 +35,12 @@ volatile struct limine_kernel_address_request kerneladdr_request = {
 	.revision = 0
 };
 
+__attribute__((used, section(".limine_requests")))
+volatile struct limine_boot_time_request date_request = {
+	.id = LIMINE_BOOT_TIME_REQUEST,
+	.revision = 0
+};
+
 __attribute__((used, section(".limine_requests_start")))
 volatile LIMINE_REQUESTS_START_MARKER;
 

src/kapps/kshell.c

@@ -10,6 +10,7 @@
 #include <string/string.h>
 #include <stdint.h>
 #include <kernel.h>
+#include <time/date.h>
 
 /*
  * pedicel_main - Kernel shell main function
@@ -31,9 +32,13 @@ void pedicel_main(void* arg)
         keyboard_getline(input_buf, PEDICEL_INPUT_SIZE);
         
         if (strncmp(input_buf, "help", 4) == 0) {
-            printf("\r\npanic   - trigger a test panic\r\n"
+            printf("\r\nYou are currently running the test kernel shell. This is not\r\n"
+                        "a fully-fledged shell like you'd find in a complete operating system,\r\n"
+                        "but rather a toy to play around in the meantime.\r\n\r\n"
+                            "panic   - trigger a test panic\r\n"
                             "syscall - trigger int 0x80\r\n"
-                            "pf      - trigger a page fault\r\n");
+                            "pf      - trigger a page fault\r\n"
+                            "now     - get current date\r\n");
             continue;
         }
 
@@ -52,6 +57,13 @@ void pedicel_main(void* arg)
             fault[0] = 1;
         }
 
+        if (strncmp(input_buf, "now", 3) == 0) {
+            struct date now = date_now();
+            printf("Now is %02u:%02u:%02u on %u/%u/%u\r\n", now.hour, now.minute,
+                now.second, now.day, now.month, now.year);
+            continue;
+        }
+
         printf("%s: command not found\r\n", input_buf);
     }
 }

src/kmain.c

@@ -5,6 +5,7 @@
  */
 
 #include "arch/x86.h"
+#include "time/date.h"
 #include <stdbool.h>	
 #include <stddef.h>
 #include <limine.h>
@@ -61,6 +62,7 @@ extern volatile struct limine_framebuffer_request framebuffer_request;
 extern volatile struct limine_memmap_request memmap_request;
 extern volatile struct limine_hhdm_request hhdm_request;
 extern volatile struct limine_kernel_address_request kerneladdr_request;
+extern volatile struct limine_boot_time_request date_request;
 
 extern struct process_t* processes_list;
 extern struct process_t* current_process;
@@ -97,10 +99,12 @@ void kmain()
 	if (!LIMINE_BASE_REVISION_SUPPORTED) hcf();
 
 	// Populate boot context
+	// This stays valid only if the BOOTLOADER_RECLAIMABLE regions are preserved
  	boot_ctx.fb = framebuffer_request.response ? framebuffer_request.response->framebuffers[0] : NULL;
 	boot_ctx.mmap = memmap_request.response ? memmap_request.response : NULL;
 	boot_ctx.hhdm = hhdm_request.response ? hhdm_request.response : NULL;
 	boot_ctx.kaddr = kerneladdr_request.response ? kerneladdr_request.response : NULL;
+	boot_ctx.bootdate = date_request.response ? date_request.response : NULL;
 
 	term_init();
 	serial_init();

src/time/date.c

@@ -0,0 +1,89 @@
+/*
+ * @author  xamidev <xamidev@riseup.net>
+ * @brief   Date helper functions
+ * @license GPL-3.0-only
+ */
+
+#include <stdint.h>
+#include <time/date.h>
+#include <mem/utils.h>
+#include <kernel.h>
+
+extern struct boot_context boot_ctx;
+
+// Unix epoch used as reference: Jan 1st 1970, 00:00:00 UTC
+struct date epoch = {
+    .year = 1970,
+    .month = 1,
+    .day = 1,
+    .hour = 0,
+    .minute = 0,
+    .second = 0
+};
+
+/*
+ * date_timestamp_to_date - Convert UNIX timestamp to a date structure
+ * @timestamp: UNIX timestamp
+ * 
+ * Return:
+ * <date> - date structure
+ */
+struct date date_timestamp_to_date(uint64_t timestamp)
+{
+    struct date result;
+    memcpy(&result, &epoch, sizeof(struct date));
+    uint64_t nr_days = timestamp / 86400;
+
+    while (nr_days > 0) {
+        unsigned int nr_month = 0;
+        int leap_year = 0;
+
+        if (result.year % 4 == 0 && (result.year % 100 != 0 || result.year % 400 == 0)) {
+            leap_year = 1;
+        } else {
+            leap_year = 0;
+        }
+
+        if (result.month == 2) {
+            if (leap_year != 0) {
+                nr_month = 29;
+            } else {
+                nr_month = 28;
+            }
+        } else {
+            nr_month = 31 - ((result.month -1) % 7 % 2);
+        }
+        
+        if (nr_days >= nr_month) {
+            nr_days -= nr_month;
+            result.month++;
+            if (result.month > 12) {
+                result.month = 1;
+                result.year++;
+            }
+        } else {
+            result.day += nr_days;
+            nr_days = 0;
+        }
+    }
+
+    result.second = timestamp % 60;
+    timestamp /= 60;
+    result.minute = timestamp % 60;
+    timestamp /= 60;
+    result.hour = timestamp % 24;
+
+    return result;
+}
+
+/*
+ * date_now - Get the current date (time at boot + timer ticks)
+ *
+ * Return:
+ * <date> - date structure
+ */
+struct date date_now()
+{
+    uint64_t timestamp_now = boot_ctx.bootdate->boot_time + (ticks/1000);
+    return date_timestamp_to_date(timestamp_now);
+}