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Update process_init_stack to return success, refactoring error handling to occur inside start_process

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This commit is contained in:
Themis Demetriades
2024-11-10 11:13:11 +00:00
parent 5ed999bc9c
commit b37f205334
1 changed files with 18 additions and 12 deletions
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30
src/userprog/process.c
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@@ -60,8 +60,7 @@ process_execute (const char *file_name)
return tid; return tid;
} }
static void process_init_stack (void *file_name_, char *saveptr, void **esp, static bool process_init_stack (char *saveptr, void **esp, char *file_name);
char *file_name);
static void *push_to_stack (void **esp, void *data, size_t data_size); static void *push_to_stack (void **esp, void *data, size_t data_size);
/* A thread function that loads a user process and starts it /* A thread function that loads a user process and starts it
@@ -97,8 +96,17 @@ start_process (void *file_name_)
thread_exit (); thread_exit ();
} }
process_init_stack (file_name_, saveptr, &if_.esp, file_name); /* Initialize user process stack and free page used to store the
command that executed the process. */
success = process_init_stack (saveptr, &if_.esp, file_name);
palloc_free_page (file_name_); palloc_free_page (file_name_);
/* If stack initialization failed, free resources and quit. */
if (!success)
{
process_exit ();
thread_exit ();
}
/* Start the user process by simulating a return from an /* Start the user process by simulating a return from an
interrupt, implemented by intr_exit (in interrupt, implemented by intr_exit (in
@@ -111,10 +119,9 @@ start_process (void *file_name_)
} }
/* Helper function that initializes the stack of a newly created /* Helper function that initializes the stack of a newly created
user process. */ user process. Returns true if successful, false otherwise. */
static void static bool
process_init_stack (void *file_name_, char *saveptr, void **esp, process_init_stack (char *saveptr, void **esp, char *file_name)
char *file_name)
{ {
/* Load command line argument *data* to user process stack. /* Load command line argument *data* to user process stack.
This can't cause overflow due to enforcing that the size of This can't cause overflow due to enforcing that the size of
@@ -134,9 +141,7 @@ process_init_stack (void *file_name_, char *saveptr, void **esp,
{ {
printf("ERROR: Couldn't allocate argument pointer memory for %s!\n", printf("ERROR: Couldn't allocate argument pointer memory for %s!\n",
thread_current ()->name); thread_current ()->name);
palloc_free_page (file_name_); return false;
process_exit ();
thread_exit ();
} }
arg_elem->arg = *esp; arg_elem->arg = *esp;
@@ -196,11 +201,12 @@ process_init_stack (void *file_name_, char *saveptr, void **esp,
/* Push fake return address (null pointer). */ /* Push fake return address (null pointer). */
*esp -= sizeof (char *); *esp -= sizeof (char *);
*(char *) *esp = 0; *(char *) *esp = 0;
return true;
} }
/* Helper function that pushes the first 'data_size' bytes stored in the /* Helper function that pushes the first 'data_size' bytes stored in the
address '*data' into the stack given a pointer to the stack pointer address '*data' into the stack given a pointer to the stack pointer '**esp'. */
'**esp'. */
static void * static void *
push_to_stack (void **esp, void *data, size_t data_size) push_to_stack (void **esp, void *data, size_t data_size)
{ {