From 5cace94ee99bbfa107a01558871762b64b7af0da Mon Sep 17 00:00:00 2001
From: s2-fidan <Sude2.Fidan@live.uwe.ac.uk>
Date: Thu, 1 Dec 2022 00:55:09 +0000
Subject: [PATCH] ERROR CORRECTION
---
src/threads/thread.h | 3 +
src/userprog/process.c | 2 +-
src/userprog/syscall.c | 126 ++++++++++++++++++++++++++++++++++++++++-
src/userprog/syscall.h | 11 ++++
4 files changed, 138 insertions(+), 4 deletions(-)
diff --git a/src/threads/thread.h b/src/threads/thread.h
index c1e7aab..f5988da 100644
--- a/src/threads/thread.h
+++ b/src/threads/thread.h
@@ -96,6 +96,9 @@ struct thread
#ifdef USERPROG
/* Owned by userprog/process.c. */
uint32_t *pagedir; /* Page directory. */
+ uint8_t *current_esp; /* The current value of the user program’s stack pointer.
+ A page fault might occur in the kernel, so we might
+ need to store esp on transition to kernel mode*/
#endif
/* Owned by thread.c. */
diff --git a/src/userprog/process.c b/src/userprog/process.c
index 8593431..e0f4408 100644
--- a/src/userprog/process.c
+++ b/src/userprog/process.c
@@ -45,7 +45,7 @@ process_execute(const char *file_name)
/* Parse first argument as program name */
strlcpy(program, file_name, file_name_length);
strtok_r(program, " ", &ptr);
- printf("\nProgram name: %s\n", program) ;
+ printf("\nProgram name: %s\n\n", program) ;
/* Create a new thread to execute FILE_NAME. */
tid = thread_create(file_name, PRI_DEFAULT, start_process, file_copy);
diff --git a/src/userprog/syscall.c b/src/userprog/syscall.c
index 0463515..e32359c 100644
--- a/src/userprog/syscall.c
+++ b/src/userprog/syscall.c
@@ -1,4 +1,5 @@
#include "userprog/syscall.h"
+#include <stdbool.h>
#include <stdio.h>
#include <syscall-nr.h>
#include "threads/interrupt.h"
@@ -6,16 +7,135 @@
static void syscall_handler (struct intr_frame *);
+/*System call initializer*/
void
syscall_init (void)
{
intr_register_int (0x30, 3, INTR_ON, syscall_handler, "syscall");
}
-
+/*Handler for system commands.*/
static void
syscall_handler (struct intr_frame *f UNUSED)
{
- printf ("system call!\n");
- thread_exit ();
+ /* References: J,Choi(2014), pintos. Available from: https://github.com/wookayin/pintos [accessed on 27/11/22]*/
+ int syscall_number;
+ ASSERT( sizeof(syscall_number) == 4 ); /*assuming x86*/
+
+ /*The system call number is in the 32-bit word at the caller's stack pointer.*/
+ read(f->esp, &syscall_number, sizeof(syscall_number));
+
+ /*Store the esp, which is needed in the page fault handler.*/
+ thread_current()->current_esp = f->esp;
+
+ switch (syscall_number) {
+ case SYS_HALT: // 0
+ {
+ /*Terminate PintOS*/
+ syscall_halt();
+ break;
+ }
+ case SYS_WAIT: // 2
+ {
+ tid_t tid;
+ /*Get argument*/
+ read(f->esp + 4, &tid, sizeof(tid_t));
+ /*Wait for child process*/
+ f->eax = syscall_wait(tid);
+ break;
+ }
+
+ case SYS_CREATE: // 3
+ {
+ const char* file_name;
+ unsigned initial_size;
+
+ /*Get file name and size*/
+ read(f->esp + 4, &file_name, sizeof(file_name));
+ read(f->esp + 8, &initial_size, sizeof(initial_size));
+
+ /*Create file*/
+ f->eax = syscall_create(file_name, initial_size);
+ break;
+ }
+
+ case SYS_REMOVE: // 4
+ {
+ const char* file_name;
+ bool return_code;
+
+ /*Get file name*/
+ read(f->esp + 4, &file_name, sizeof(file_name));
+
+ /*Remove file*/
+ f->eax = syscall_remove(file_name);
+ break;
+ }
+ /* Unimplemented system calls */
+ default:
+ printf("ERROR: system call ( %d ) has not implemented!\n", syscall_number);
+
+ /* Terminate. */
+ syscall_exit(-1);
+ break;
+ }
+}
+
+
+/********SYSTEMCALLS********/
+
+/* Halt */
+void syscall_halt(void) {
+ shutdown_power_off(); /* From shutdown.h */
+}
+
+/* Exit */
+void syscall_exit(int status) {
+ struct thread *current_process=thread_current();
+ current_process->process_exit_status = status;
+
+ printf("%s: exit(%d)\n",current_process->name,status);
+
+ thread_exit();
+}
+
+/* Wait */
+int syscall_wait(tid_t tid)
+{
+ return process_wait(tid);
+}
+
+/* Create File */
+bool syscall_create(const char* file_name, unsigned initial_size) {
+ bool if_created = false;
+ if( filesys_create(file_name, initial_size)==true){
+ if_created = true;
+ }
+ return if_created;
+}
+
+/* Remove File */
+bool syscall_remove(const char* file_name) {
+ bool if_removed = false;
+ if( filesys_remove(file_name)==true){
+ if_removed = true;
+ }
+ return if_removed;
+}
+
+
+/****OTHER FUNCTIONS****/
+static int read(void *src, void *dst, size_t bytes)
+{
+ int32_t value;
+ size_t i;
+ for (i = 0; i < bytes; i++)
+ {
+ value = get_user(src + i);
+ if (value == -1) // segfault or invalid memory access
+ fail_invalid_access();
+
+ *(char *)(dst + i) = value & 0xff;
+ }
+ return (int)bytes;
}
diff --git a/src/userprog/syscall.h b/src/userprog/syscall.h
index 9059096..7289c24 100644
--- a/src/userprog/syscall.h
+++ b/src/userprog/syscall.h
@@ -1,6 +1,17 @@
#ifndef USERPROG_SYSCALL_H
#define USERPROG_SYSCALL_H
+#include "threads/thread.h"
+#include <stdbool.h>
+#include <stddef.h>
void syscall_init (void);
+void syscall_halt(void);
+void syscall_exit(int status);
+int syscall_wait(tid_t tid);
+bool syscall_create(const char* file_name, unsigned initial_size);
+bool syscall_remove(const char* file_name);
+
+static int read(void *src, void *dst, size_t bytes);
+
#endif /* userprog/syscall.h */
--
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