hi all,
this code is from namei.c -> do_getname which is called from getname()
--> which is from sys_open()..
static inline int do_getname(const char *filename, char *page)
{
int retval;
unsigned long len = PATH_MAX;
if ((unsigned long) filename >= TASK_SIZE) {
if (!segment_eq(get_fs(), KERNEL_DS))
return -EFAULT;
Here , TASK_SIZE has been #defined as :
#define TASK_SIZE (PAGE_OFFSET)
and PAGE_OFFSET as :
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
/*
* A __PAGE_OFFSET of 0xC0000000 means that the kernel has
* a virtual address space of one gigabyte, which limits the
* amount of physical memory you can use to about 950MB.
*
*/
#define __PAGE_OFFSET (0xC0000000)
Now, refering to the code above :
if ((unsigned long) filename >= TASK_SIZE)
why is this if() for ?
and why is it checking filename >= TASK_SIZE ?
i beleive filename is still in userspace right ? is it checking for the
same ?
and also please explain what this TASK_SIZE stands for - i'am confused.
cheers,
Amith
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