4 ms·

You shouldn't be writing C if you're not a careful coder.

by chjj 4y ago

samatman 4y ago
And if you're a careful coder writing C, you should give the VLA the stink eye unless it's proving its worth.
pjmlp 4y ago
Yeah, right. https://msrc-blog.microsoft.com/2019/07/16/a-proactive-approach-to-more-secure-code/ https://msrc-blog.microsoft.com/2019/07/16/a-proactive-appro... https://research.google/pubs/pub46800/ https://research.google/pubs/pub46800/ https://support.apple.com/guide/security/memory-safe-iboot-implementation-sec30d8d9ec1/web https://support.apple.com/guide/security/memory-safe-iboot-i... Maybe you could give an helping hand to Microsoft, Apple and Google, they are in need of carefull C coders.
- chjj 4y ago
  I'm not sure if you intentionally missed my point. Everything in C requires careful usage. VLAs aren't special: they're just yet another feature which must be used carefully, if used at all. Personally, I don't use them, but I don't find "they're unsafe" to be a convincing reason for why they shouldn't be included in the already-unsafe language. Saying they're unnecessary might be a better reason.
  - pjmlp 4y ago
    The goal should be to reduce the amount of sharp edges, not increase them even further.
  - _0w8t 4y ago
    VLAs are unsafe in the worst kind of way as it is not possible to query when it is safe to use them. alloca() at least in theory can return null stack overflow, but there is no such provision with VLA.
    - astrange 4y ago
      They're not unsafe (in the memory sense) as long as they check for overflow and reliably crash if there is one.
      - naasking 4y ago
        If a lot of platforms don't implement this check reliably, then it's unsafe in practice at this time, even if not in theory.
        astrange 4y ago
        Who out there has a version of stack checking that doesn't actually check the stack…? If it doesn't check by default, as C doesn't, then it's not "as long as".
kllrnohj 4y ago
Hint, that means nobody should be writing C.
- krallja 4y ago
  Where is the lie?
marcosdumay 4y ago
Too bad we have all that legacy C code that won't just reappear by itself on a safer language. That means there are a lot of not careful enough developers (AKA, human ones) that will write a lot of C just because they need some change here or there.

You shouldn't be writing C if you're not a careful coder.

by chjj 4y ago

You shouldn't be writing C if you're not a careful coder.

samatman 4y ago

And if you're a careful coder writing C, you should give the VLA the stink eye unless it's proving its worth.

pjmlp 4y ago

Yeah, right. https://msrc-blog.microsoft.com/2019/07/16/a-proactive-approach-to-more-secure-code/ https://msrc-blog.microsoft.com/2019/07/16/a-proactive-appro... https://research.google/pubs/pub46800/ https://research.google/pubs/pub46800/ https://support.apple.com/guide/security/memory-safe-iboot-implementation-sec30d8d9ec1/web https://support.apple.com/guide/security/memory-safe-iboot-i... Maybe you could give an helping hand to Microsoft, Apple and Google, they are in need of carefull C coders.

chjj 4y ago
I'm not sure if you intentionally missed my point. Everything in C requires careful usage. VLAs aren't special: they're just yet another feature which must be used carefully, if used at all. Personally, I don't use them, but I don't find "they're unsafe" to be a convincing reason for why they shouldn't be included in the already-unsafe language. Saying they're unnecessary might be a better reason.
- pjmlp 4y ago
  The goal should be to reduce the amount of sharp edges, not increase them even further.
- _0w8t 4y ago
  VLAs are unsafe in the worst kind of way as it is not possible to query when it is safe to use them. alloca() at least in theory can return null stack overflow, but there is no such provision with VLA.
  - astrange 4y ago
    They're not unsafe (in the memory sense) as long as they check for overflow and reliably crash if there is one.
    - naasking 4y ago
      If a lot of platforms don't implement this check reliably, then it's unsafe in practice at this time, even if not in theory.
      - astrange 4y ago
        Who out there has a version of stack checking that doesn't actually check the stack…? If it doesn't check by default, as C doesn't, then it's not "as long as".

kllrnohj 4y ago

Hint, that means nobody should be writing C.

krallja 4y ago
Where is the lie?

marcosdumay 4y ago

Too bad we have all that legacy C code that won't just reappear by itself on a safer language. That means there are a lot of not careful enough developers (AKA, human ones) that will write a lot of C just because they need some change here or there.