On Mon, 16 Mar 2015 11:18:16 -0700, Charles Hixson via Digitalmars-d-learn wrote:
> My current best answer is to turn the "unused" into a vector of bytes, > and then pass that to the using routines as a ref. This still is wide > open to errors at the calling end, but the BlockHead end can ensure that > the length of the vector remains constant whenever it accesses it (well, > whenever the head is being written to disk. The byte vector would be a > static array at the BlockHead end. This would seem to allow the using > end to cast the byte vector into an appropriate struct for its own use, > and that writes to it would be seen by BlockHead as writes to the > header...but only to restricted parts of the header. The problem here > is that the ref array might allow itself to be resized at the user end. > That's not a problem as long as the resizing is to something smaller, > but I'm not sure what happens if it gets resized to something larger. It > looks like allowing a buffer overflow. if you passing the array, not a slice, it can't be resized. i.e.: void foo (ref ubyte[8] a) { a[2] = 42; //a.length = 6; // this will not compile: constant a.length is not an lvalue } void main () { ubyte[8] aa; assert(aa[2] == 0); foo(aa); assert(aa[2] == 42); }
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