Reformat calculation of padding size in stack set-up to increase clarity

src/userprog/process.c

@@ -2,6 +2,7 @@
 #include <debug.h>
 #include <inttypes.h>
 #include <round.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -116,7 +117,7 @@ start_process (void *file_name_)
 
   /* Calculate the remaining number of bytes that need to be written
      to the user process stack in order to check for possible overflow. */
-  size_t align_size = (unsigned int) if_.esp % 4;
+  size_t align_size = ((unsigned int) if_.esp % 4) * sizeof (uint8_t);
   size_t argv_data_size = (arg_count + 1) * sizeof (char *);
   size_t argv_size = sizeof (char **);
   size_t argc_size = sizeof (int);
@@ -133,7 +134,7 @@ start_process (void *file_name_)
 
   /* Align stack pointer to word size before pushing argv elements for
      performance. */
-  if_.esp -= align_size * sizeof (uint8_t);
+  if_.esp -= align_size;
   
   /* Push a null pointer sentinel inside argv. */
   if_.esp -= sizeof (char *);