bounds.mkd

Bounds Checking

C has a bounded pointer type: A variably-modified type, i.e. a type to a VLA.

int N = 10;
char (*p)[N] = malloc(sizeof *p);
if (!p)
 abort();
 
(*p)[N] = 1; // run-time bounds check possible

f(int n, char buf[static n]);
f(N, *p); // bounds checking possible

• Example (bounds checking): https://godbolt.org/z/q9qsax7qY

• Example (static checking): https://godbolt.org/z/xe8oaGad6

• n1990 n2660 n2778 n2779 n2780 n2905 n2906 n2907 n2992 n3121

• https://gcc.gnu.org/legacy-ml/gcc-patches/2015-02/msg01565.html

• https://gcc.gnu.org/legacy-ml/gcc-patches/2015-02/msg01720.html

• https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65280

• https://gcc.gnu.org/git/?p=gcc.git&a=commit;h=de1b5c17fd1418f01f0a57d03023c21d888dc97c

• https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98608

• https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98623