Typesafety versus Worse is Better - was Re: Fwd: is there any word processing software for the pdp11?

Toby Thain toby at telegraphics.com.au
Wed Dec 3 21:25:03 CST 2014

On 03/12/14 6:47 PM, Eric Smith wrote:
> On Wed, Dec 3, 2014 at 4:09 PM, Sean Caron <scaron at umich.edu> wrote:
>> Clearly you're on a religious crusade here.. I just don't buy the line that
>> were it not for everyone using this pesky C language, we could live in this
>> mythical world where exploits don't exist...
> If you use a language in which buffer overruns can't occur, and will
> either trigger exception handling or abort the program, then almost
> all circumstances that are privilege escalation or information
> disclosure due to buffer overruns in C or C++ program become at worst
> denial of service. I'm not arguing that we don't need to be concerned
> with DoS vulnerabilities, but that they are far less severe.
> So if simply by programming in a different language you can
> substantially reduce the severity of an entire class of bugs, why
> wouldn't you do it?

+1000. That's it, in a nutshell.

> I haven't tried to count them, but it seems like a very large number
> of tracked vulnerabilities are due to buffer overruns and related
> problems that fall into this category.
>> You must be a professional programmer?
> Yes.


>> Certainly you have strong ideas of what's right and what's wrong in programming practice...
> Yes.
>> but I feel like you are faulting the
>> language here while giving what are essentially (sorry, strong language)
>> hack programmers a pass...
> That's the argument that only if programmers were smarter or more
> disciplined, these problems wouldn't occur. That's a nice hypothesis,
> but I don't buy it, because software written by some of the world's
> smartest and most disciplined C and C++ programmers still routinely
> exhibit these problems.

Yes. There is NO "sufficiently smart programmer". But let's assume that 
one exists. Imagine what they could do with better tools (let alone the 
rest of us)! Sometimes it's just not about the user, it's about the tool.

Maybe we should be having this debate with the hypothetical programmer 
who doesn't make type bugs, memory safety bugs, or concurrency bugs. 
Perhaps they can tell us what we're all doing wrong?

Anyone with enough experience will straight out admit that they can't 
for example manage mutable state with sufficient reliability, let alone 
mutable state with concurrency. You'll meet many seasoned programmers 
who have figured that out. We even have many good strategies for 
eliminating many classes of bugs (which aren't "just use C better, 
idiot"). It's professionally inept to ignore them.

> Programming is *hard*, and debugging is even *harder*. If you can use
> a tool that doesn't help much, or a different tool that helps more,
> why would you want to stick with the less helpful tool?

But here we are. Having to defend the idea that "simple mechanical 
checks of program properties"* are a bad idea (machines happen to be 
much better, not to mention millions of times faster, than humans at 
this; which is why I waste hours on silly JavaScript or PHP or Blub bugs 
that a compiler can check in microseconds). That is an expensive waste 
of programmer time. (Also see Gershom Bazerman's quote linked below.)

>> Why should it be the responsibility of the language to save programmers from themselves?

Because that is _precisely_ what languages and abstractions exist to do.

> Why should a table saw have a finger guard?

Any sufficiently smart carpenter will never injure themselves in a career!

> In the case of the table saw, having a safety feature is even less
> important than in a programming language. With an unsafe table saw,
> I'm likely to only cause harm to myself. With an unsafe programming
> language, a programmer can cause problems for literally billions of
> people (e.g., exploits of bugs in Windows, MacOS, Linux).

I like writing assembler from time to time. But I don't try to write 
business services in it; I'd be fired, and rightly so. Tools at the 
wrong level of abstraction are only shades of the same error.


* - Benjamin Pierce's words. For more expert opinions:

> I'm not arguing that the language should totally disallow doing
> anything it thinks is questionable.  I'm arguing that it should by
> *default* disable doing such things, and require the programmer to
> take explicit action to circumvent the normal checking when there's a
> good reason to do so.  (On the other hand, I think most programmers
> are too willing to jump to the conclusion that such is necessary,
> without spending enough time analyzing the real problem.)

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