nshlib: fix ls_handler style compliance and add host sync

a) Added time module only incase of simulation.
b) Used linux/cpu based functions for getting time only then.
c) Checked if the device is timekeeping before ls-l for accuracy.
d) if hostfs present syncing new file time to /data.
e) Manual epoch-time calculation to fit it in microcontrollers.

Signed-off-by: Biancaa Ramesh <biancaa2210329@ssn.edu.in>

Author: Biancaa Ramesh

nshlib/nsh_fscmds.c

@@ -44,12 +44,11 @@
 #include <libgen.h>
 #include <errno.h>
 #include <debug.h>
-#include <time.h>
 #include "nsh.h"
 
-#define CONFIG_LIBC_LOCALTIME 1
-#define CONFIG_CLOCK_TIMEKEEPING 1
-
+#ifdef CONFIG_ARCH_SIM
+#  include <time.h>
+#endif
 
 #if !defined(CONFIG_DISABLE_MOUNTPOINT)
 #  include <sys/mount.h>
@@ -364,52 +363,132 @@ static int ls_handler(FAR struct nsh_vtbl_s *vtbl, FAR const char *dirpath,
 
   if ((lsflags & (LSFLAGS_SIZE | LSFLAGS_LONG | LSFLAGS_UID_GID)) != 0)
     {
-      struct stat buf; 
+      struct stat buf;
 
-    memset(&buf, 0, sizeof(buf));
+      memset(&buf, 0, sizeof(struct stat));
 
-    /* stat the file */
-    if (entryp != NULL)
-    {
-      FAR char *fullpath = nsh_getdirpath(vtbl, dirpath, entryp->d_name);
-      ret = stat(fullpath, &buf);
-      free(fullpath);
-    }
-    else
-    {
-    ret = stat(dirpath, &buf);
-    }
+      /* If entryp is provided, listing a directory and need to
+       * construct the full path to stat the file. Otherwise, dirpath
+       * is the target itself. (no separate file name as entryp)
+       */
 
-    #ifdef CONFIG_CLOCK_TIMEKEEPING
-    if (ret == 0 && buf.st_mtime > 0 && buf.st_mtime < 0x7FFFFFFF)
-    {
-      struct tm tm;
-      time_t t = buf.st_mtime;
+      if (entryp != NULL)
+        {
+          FAR char *fullpath = nsh_getdirpath(vtbl, dirpath, entryp->d_name);
+          ret = stat(fullpath, &buf);
+          free(fullpath);
+        }
+      else
+        {
+          ret = stat(dirpath, &buf);
+        }
 
-      #ifdef CONFIG_LIBC_LOCALTIME
-      localtime_r(&t, &tm);
-      nsh_output(vtbl, " %04d-%02d-%02d %02d:%02d",
-               tm.tm_year + 1900,
-               tm.tm_mon + 1,
-               tm.tm_mday,
-               tm.tm_hour,
-               tm.tm_min);
-      #else
-        nsh_output(vtbl, " %ld", (long)t);
-      #endif
-    }
-    else
-    {
-      nsh_output(vtbl, " ----/--/-- --:--");
-    }
-    #endif
+#ifdef CONFIG_CLOCK_TIMEKEEPING
+      /* manual epoch time to date calculation to reduce extra memory
+       * by using includes For boards with minimal flash.
+       */
+
+#  ifdef CONFIG_ARCH_SIM
+      struct timespec ts;
+
+      /* This pulls the ACTUAL current time from your Linux Host */
+
+      /* Sometime defaults to 2008 */
+
+      if (clock_gettime(CLOCK_REALTIME, &ts) == 0)
+        {
+          clock_settime(CLOCK_REALTIME, &ts);
+        }
+#  endif
+
+      /* for referencing /data : if not mounted the reference will fail. */
+
+#  if defined(CONFIG_ARCH_SIM) && defined(CONFIG_FS_HOSTFS)
+      static bool g_time_synced = false;
+
+      if (!g_time_synced)
+        {
+          struct stat hstat;
+
+          /* Data section always maintains the current time value. */
+
+          if (stat("/data", &hstat) == 0)
+            {
+              struct timespec ts_sync;
+
+              ts_sync.tv_sec  = hstat.st_mtime;
+              ts_sync.tv_nsec = 0;
 
+              /* This is the magic line that sets the system clock */
 
-    memset(&buf, 0, sizeof(struct stat));
+              if (clock_settime(CLOCK_REALTIME, &ts_sync) == 0)
+                {
+                  g_time_synced = true;
+                }
+            }
+        }
+#  endif
+
+      if (ret == 0 && buf.st_mtime > 0 && buf.st_mtime < 0x7fffffff)
+        {
+          uint32_t seconds = (uint32_t)buf.st_mtime;
+          uint32_t minutes = seconds / 60;
+          uint32_t hours   = minutes / 60;
+          uint32_t days    = hours / 24;
+          uint32_t y       = 1970;
+          uint32_t m       = 0;
+
+          while (1)
+            {
+              uint32_t diy = (y % 4 == 0 && (y % 100 != 0 ||
+                              y % 400 == 0)) ? 366 : 365;
+
+              if (days < diy)
+                {
+                  break;
+                }
+
+              days -= diy;
+              y++;
+            }
+
+          static const uint8_t dim[] =
+          {
+            31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+          };
+
+          for (m = 0; m < 12; m++)
+            {
+              uint32_t d_m = dim[m];
+
+              if (m == 1 && (y % 4 == 0 && (y % 100 != 0 || y % 400 == 0)))
+                {
+                  d_m = 29;
+                }
+
+              if (days < d_m)
+                {
+                  break;
+                }
+
+              days -= d_m;
+            }
+
+          nsh_output(vtbl, " %04u-%02u-%02u %02u:%02u:%02u",
+                     (unsigned int)y, (unsigned int)m + 1,
+                     (unsigned int)days + 1, (unsigned int)(hours % 24),
+                     (unsigned int)(minutes % 60),
+                     (unsigned int)(seconds % 60));
+        }
+      else
+        {
+          /* Incase valid time entry was not maintained in the stat struct. */
 
-    /* stat the file */
+          nsh_output(vtbl, " ----/--/-- --:--");
+        }
+#endif
 
-    if (entryp != NULL)
+      if (entryp != NULL)
         {
           FAR char *fullpath = nsh_getdirpath(vtbl, dirpath, entryp->d_name);
           ret = stat(fullpath, &buf);
@@ -561,39 +640,24 @@ static int ls_handler(FAR struct nsh_vtbl_s *vtbl, FAR const char *dirpath,
 
       if ((lsflags & LSFLAGS_SIZE) != 0)
         {
+#ifdef CONFIG_HAVE_FLOAT
           if (lsflags & LSFLAGS_HUMANREADBLE && buf.st_size >= KB)
             {
-              uint32_t integer_part;
-              uint32_t decimal_part;
-              uint32_t unit;
-              char suffix;
-
-              /* Determine the appropriate unit and suffix */
-
               if (buf.st_size >= GB)
                 {
-                  unit = GB;
-                  suffix = 'G';
+                  nsh_output(vtbl, "%11.1fG", (float)buf.st_size / GB);
                 }
               else if (buf.st_size >= MB)
                 {
-                  unit = MB;
-                  suffix = 'M';
+                  nsh_output(vtbl, "%11.1fM", (float)buf.st_size / MB);
                 }
               else
                 {
-                  unit = KB;
-                  suffix = 'K';
+                  nsh_output(vtbl, "%11.1fK", (float)buf.st_size / KB);
                 }
-
-              /* Use integer arithmetic to avoid floating point */
-
-              integer_part = buf.st_size / unit;
-              decimal_part = ((buf.st_size % unit) * 10) / unit;
-              nsh_output(vtbl, "%10" PRIu32 ".%" PRIu32 "%c",
-                         integer_part, decimal_part, suffix);
             }
           else
+#endif
             {
               nsh_output(vtbl, "%12" PRIdOFF, buf.st_size);
             }