Peter Miller <pmil...@opensource.org.au> writes:
> Here is a fun puzzle to kick off the new year...
[...]
> Is there a simple way (preferably a single system call) to discover if
> a user space memory range (rather than a C string) is all valid?
I believe you already know, or could cache, the system page size.
On that basis, mincore should be sufficient: round the pointer to the
start of the next page down, pass an appropriate length, and consider
ENOMEM to reflect invalid memory.
> E.g. write(fildes, data, data_size) trying to discover whether or not
> (data,data_size) describes a piece of user memory none of which will
> segfault when accessed?
>
> Portable posix tests are better than linux-specific tests.
mincore isn't posix, but should be portable enough for most uses.
Regards,
Daniel
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