We have now proven that exec() does fail and return to userspace when a file is not a valid executable.
We can now go back to executing a normal program.
That will probably happen a lot. We want userspace to tell us IF THE ERROR IS RELEVANT.
So, these unnecessary warnings are just noise.
Userspace may also use these functions to check for file descriptors.
For example, libc does this at program initialization, it checks whether fd 0 and 1 exist (by calling lseek() and seeing if it fails with errno=EBADF).
exit() now calls registered handlers before calling _exit().
And initialize_libc() can now register a handler to close stdout and stderr on program termination!! :)
Very bare-bones for now. Doesn't support arguments or environment (we don't have that stuff right now), and the executable is not a valid ELF, it terminates the task.
But it's a start!
We were previously looking at its segment registers to see if they were user-like, but this method is bad.
What is the task was executing a system call?
So now, we store that value at creation time.
We lose a LITTLE bit of security, while allowing the compiler to optimize MUCH more.
Very simple functions, like most functions in misc/utils.cpp, were being made very big when some of them can just be "jmp thingy" or "and rax, something" and waste much less space.
This change makes more sense, I think.
If a section needs to be mapped at 0x50f50 and its size is 0x200, then that address space exceeds one page.
But since 0x200 is less than one page, we only map one page.
If we count the offset, 0xf50 + 0x200 need two pages. So we can map the right amount of memory.
getPhysical() now stops at a larger page, unmap() can unmap a larger page, but map() just transforms it into a normal page.
getFlags() larger pages support is still pending.
At least now we don't page fault because we're trying to free a larger page.
