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Add constant MAX_SYSCALL_ARGS to avoid magic numbers [Gleb]

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This commit is contained in:
sBubshait
2024-11-13 17:15:56 +00:00
parent eb4f23c290
commit d890c2353e
1 changed files with 7 additions and 5 deletions
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12
src/userprog/syscall.c
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@@ -13,6 +13,8 @@
#include <stdio.h> #include <stdio.h>
#include <syscall-nr.h> #include <syscall-nr.h>
#define MAX_SYSCALL_ARGS 3
static unsigned fd_counter = MIN_USER_FD; static unsigned fd_counter = MIN_USER_FD;
struct open_file struct open_file
@@ -96,8 +98,8 @@ static void
syscall_handler (struct intr_frame *f) syscall_handler (struct intr_frame *f)
{ {
/* First, read the system call number from the stack. */ /* First, read the system call number from the stack. */
validate_user_pointer (f->esp, 1); validate_user_pointer (f->esp, sizeof (uintptr_t));
unsigned syscall_number = *(int *) f->esp; uintptr_t syscall_number = *(int *) f->esp;
/* Ensures the number corresponds to a system call that can be handled. */ /* Ensures the number corresponds to a system call that can be handled. */
if (syscall_number >= LOOKUP_SIZE) if (syscall_number >= LOOKUP_SIZE)
@@ -108,9 +110,9 @@ syscall_handler (struct intr_frame *f)
/* Next, read and copy the arguments from the stack pointer. */ /* Next, read and copy the arguments from the stack pointer. */
validate_user_pointer (f->esp + sizeof (uintptr_t), validate_user_pointer (f->esp + sizeof (uintptr_t),
syscall.arity * sizeof (uintptr_t)); syscall.arity * sizeof (uintptr_t));
uintptr_t args[3] = {0}; uintptr_t args[MAX_SYSCALL_ARGS] = {0};
for (int i=0; i < syscall.arity; i++) for (int i = 0; i < syscall.arity && i < MAX_SYSCALL_ARGS; i++)
args[i] = *(uintptr_t *) (f->esp + sizeof (uintptr_t) * (i + 1)); args[i] = *(uintptr_t *) (f->esp + sizeof (uintptr_t) * (i + 1));
/* Call the function that handles this system call with the arguments. When /* Call the function that handles this system call with the arguments. When
there is a return value it is stored in f->eax. */ there is a return value it is stored in f->eax. */