void
str_free(string_ty *s)
{
str_hash_ty idx;
string_ty **spp;
assert(str_valid(s));
if (s->str_references > 1)
{
s->str_references--;
return;
}
assert(s->str_references == 1);
/*
* find the hash bucket it was in,
* and remove it
*/
idx = s->str_hash & hash_mask;
assert(idx < hash_modulus);
for (spp = &hash_table[idx]; *spp; spp = &(*spp)->str_next)
{
if (*spp == s)
{
*spp = s->str_next;
free(s);
--hash_load;
return;
}
}
/* should never reach here! */
fatal_raw("attempted to free non-existent string (bug)");
}
static void
syscall_handler (struct intr_frame *f)
{
/* Validate the first addr of the stack frame */
void *esp = utok_addr (f->esp, NULL);
if (esp == NULL) {
syscall_exit (-1);
return;
}
enum SYSCALL_NUMBER call_number = *(enum SYSCALL_NUMBER *) esp;
if (call_number < syscall_first_call || call_number > syscall_last_call) {
syscall_exit (-1);
return;
}
/* Buffer the arguments for validation */
int argc = syscall_argc[call_number];
uint32_t argbuf[3];
int i = 0;
for (; i < argc; i++) {
/* Validate each argument */
void *vaddr = uptr_valid((uint32_t *) f->esp + 1 + i, f->esp);
if (vaddr == NULL) {
syscall_exit (-1);
return;
}
/* Translate the argument to kernel virtual (== physical) memory */
argbuf[i] = *(uint32_t *) vaddr;
}
int retval = 0;
/* Switch based on call_number to delegate to corresponding syscall.
Have not implemented several syscalls as of this project.
Use validation methods to check user-provided arguments.
*/
switch (call_number) {
case SYS_HALT:
syscall_halt ();
break;
case SYS_EXIT:
syscall_exit ((int) argbuf[0]);
break;
case SYS_EXEC:
if (str_valid ((void *) argbuf[0], f->esp) == NULL) {
syscall_exit (-1);
return;
}
retval = syscall_exec ((char *) argbuf[0]);
break;
case SYS_WAIT:
retval = syscall_wait ((int) argbuf[0]);
break;
case SYS_CREATE:
if (str_valid ((char *) argbuf[0], f->esp) == NULL) {
syscall_exit (-1);
return;
}
retval = (int) syscall_create ((char *) argbuf[0],
(unsigned) argbuf[1]);
break;
case SYS_REMOVE:
if (!uptr_valid ((char *) argbuf[0], f->esp)) {
syscall_exit (-1);
return;
}
retval = (int) syscall_remove ((char *) argbuf[0]);
break;
case SYS_OPEN:
if (str_valid ((char *) argbuf[0], f->esp) == NULL) {
syscall_exit (-1);
return;
}
retval = (int) syscall_open ((char *) argbuf[0]);
break;
case SYS_FILESIZE:
retval = syscall_filesize ((int) argbuf[0]);
break;
case SYS_READ:
if (buffer_valid ((void *) argbuf[1], f->esp,
(unsigned) argbuf[2]) == NULL) {
syscall_exit (-1);
return;
}
retval = syscall_read ((int) argbuf[0],
(void *) argbuf[1],
(unsigned) argbuf[2]);
break;
case SYS_WRITE:
if (buffer_valid ((void *) argbuf[1], f->esp,
(unsigned) argbuf[2]) == NULL) {
syscall_exit (-1);
return;
}
retval = syscall_write ((int) argbuf[0],
(void *) argbuf[1],
(unsigned) argbuf[2]);
break;
case SYS_SEEK:
syscall_seek ((int) argbuf[0], (unsigned) argbuf[1]);
break;
case SYS_TELL:
retval = (int) syscall_tell ((int) argbuf[0]);
break;
case SYS_CLOSE:
syscall_close ((int) argbuf[0]);
break;
#ifdef VM
case SYS_MMAP:
// addr will be checked internally inside mmap
retval = (int) syscall_mmap ((int) argbuf[0], (void *) argbuf[1]);
break;
case SYS_MUNMAP:
syscall_munmap ((int) argbuf[0]);
break;
#endif
default:
printf("unhandled system call!\n");
thread_exit();
}
f->eax = retval;
}
