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SubjectRFC: Inconsistent short read behaviour in __do_proc_dointvec vs _proc_do_string
Should repeated short reads in __do_proc_dointvec behave consistently with _proc_do_string ?

Consider:

> char c[1];
> int n;
>
> while (1)
> {
> n = read(0, c, 1);
>
> if (n <= 0) break;
>
> write (1, c, 1);
> }

Running this program on /proc/self/stat emits the expected output.

Running this program on /proc/sys/kernel/random/poolsize does not :-(

The issue is that __do_proc_dointvec does not accommodate non-zero file positions
when reading:

> if (!tbl_data || !table->maxlen || !*lenp || (*ppos && !write)) {
> *lenp = 0;
> return 0;
> }


OTOH _proc_do_string seems quite willing to accommodate it:

> if (write) {
> ...
> } else {
> len = strlen(data);
> if (len > maxlen)
> len = maxlen;
>
> if (*ppos > len) {
> *lenp = 0;
> return 0;
> }


Should __do_proc_intvec behave more like _proc_do_string, or vice-versa ?


Earl




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