vim-patch:8.1.1313: warnings for using localtime() and ctime()

Problem:    Warnings for using localtime() and ctime().
Solution:   Use localtime_r() if available.  Avoid using ctime().
63d2555c9c

src/nvim/hardcopy.c

@@ -2416,9 +2416,7 @@ static int prt_add_resource(struct prt_ps_resource_S *resource)
 
 int mch_print_begin(prt_settings_T *psettings)
 {
-  time_t now;
   int bbox[4];
-  char        *p_time;
   double left;
   double right;
   double top;
@@ -2442,10 +2440,10 @@ int mch_print_begin(prt_settings_T *psettings)
   }
   prt_dsc_textline("For", buffer);
   prt_dsc_textline("Creator", longVersion);
-  /* Note: to ensure Clean8bit I don't think we can use LC_TIME */
-  now = time(NULL);
-  p_time = ctime(&now);
-  /* Note: ctime() adds a \n so we have to remove it :-( */
+  // Note: to ensure Clean8bit I don't think we can use LC_TIME
+  char ctime_buf[50];
+  char *p_time = os_ctime(ctime_buf, sizeof(ctime_buf));
+  // Note: os_ctime() adds a \n so we have to remove it :-(
   p = vim_strchr((char_u *)p_time, '\n');
   if (p != NULL)
     *p = NUL;

src/nvim/memline.c

@@ -1504,16 +1504,15 @@ static time_t swapfile_info(char_u *fname)
   int fd;
   struct block0 b0;
   time_t x = (time_t)0;
-  char            *p;
 #ifdef UNIX
   char uname[B0_UNAME_SIZE];
 #endif
 
-  /* print the swap file date */
+  // print the swap file date
   FileInfo file_info;
   if (os_fileinfo((char *)fname, &file_info)) {
 #ifdef UNIX
-    /* print name of owner of the file */
+    // print name of owner of the file
     if (os_get_uname(file_info.stat.st_uid, uname, B0_UNAME_SIZE) == OK) {
       MSG_PUTS(_("          owned by: "));
       msg_outtrans((char_u *)uname);
@@ -1522,11 +1521,8 @@ static time_t swapfile_info(char_u *fname)
 #endif
     MSG_PUTS(_("             dated: "));
     x = file_info.stat.st_mtim.tv_sec;
-    p = ctime(&x);  // includes '\n'
-    if (p == NULL)
-      MSG_PUTS("(invalid)\n");
-    else
-      MSG_PUTS(p);
+    char ctime_buf[50];
+    MSG_PUTS(os_ctime_r(&x, ctime_buf, sizeof(ctime_buf)));
   }
 
   /*
@@ -3267,15 +3263,13 @@ attention_message (
 )
 {
   assert(buf->b_fname != NULL);
-  time_t x, sx;
-  char        *p;
 
   ++no_wait_return;
   (void)EMSG(_("E325: ATTENTION"));
   MSG_PUTS(_("\nFound a swap file by the name \""));
   msg_home_replace(fname);
   MSG_PUTS("\"\n");
-  sx = swapfile_info(fname);
+  const time_t swap_mtime = swapfile_info(fname);
   MSG_PUTS(_("While opening file \""));
   msg_outtrans(buf->b_fname);
   MSG_PUTS("\"\n");
@@ -3284,14 +3278,12 @@ attention_message (
     MSG_PUTS(_("      CANNOT BE FOUND"));
   } else {
     MSG_PUTS(_("             dated: "));
-    x = file_info.stat.st_mtim.tv_sec;
-    p = ctime(&x);  // includes '\n'
-    if (p == NULL)
-      MSG_PUTS("(invalid)\n");
-    else
-      MSG_PUTS(p);
-    if (sx != 0 && x > sx)
+    time_t x = file_info.stat.st_mtim.tv_sec;
+    char ctime_buf[50];
+    MSG_PUTS(os_ctime_r(&x, ctime_buf, sizeof(ctime_buf)));
+    if (swap_mtime != 0 && x > swap_mtime) {
       MSG_PUTS(_("      NEWER than swap file!\n"));
+    }
   }
   /* Some of these messages are long to allow translation to
    * other languages. */

src/nvim/os/time.c

@@ -144,6 +144,39 @@ struct tm *os_localtime(struct tm *result) FUNC_ATTR_NONNULL_ALL
   return os_localtime_r(&rawtime, result);
 }
 
+/// Portable version of POSIX ctime_r()
+///
+/// @param clock[in]
+/// @param result[out] Pointer to a 'char' where the result should be placed
+/// @param result_len length of result buffer
+/// @return human-readable string of current local time
+char *os_ctime_r(const time_t *restrict clock, char *restrict result,
+                 size_t result_len)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
+{
+  struct tm clock_local;
+  struct tm *clock_local_ptr = os_localtime_r(clock, &clock_local);
+  // MSVC returns NULL for an invalid value of seconds.
+  if (clock_local_ptr == NULL) {
+    snprintf(result, result_len, "%s\n", _("(Invalid)"));
+  } else {
+    strftime(result, result_len, "%a %b %d %H:%M:%S %Y\n", clock_local_ptr);
+  }
+  return result;
+}
+
+/// Gets the current Unix timestamp and adjusts it to local time.
+///
+/// @param result[out] Pointer to a 'char' where the result should be placed
+/// @param result_len length of result buffer
+/// @return human-readable string of current local time
+char *os_ctime(char *result, size_t result_len)
+  FUNC_ATTR_NONNULL_ALL FUNC_ATTR_NONNULL_RET
+{
+  time_t rawtime = time(NULL);
+  return os_ctime_r(&rawtime, result, result_len);
+}
+
 /// Obtains the current Unix timestamp.
 ///
 /// @return Seconds since epoch.