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### 563. stringbuf seeking from end

Section: 29.8.2.5 [stringbuf.virtuals] Status: CD1 Submitter: Martin Sebor Opened: 2006-02-23 Last modified: 2016-01-28

Priority: Not Prioritized

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Discussion:

According to Table 92 (unchanged by issue 432), when `(way == end)` the `newoff` value in out mode is computed as the difference between `epptr()` and `pbase()`.

This value isn't meaningful unless the value of `epptr()` can be precisely controlled by a program. That used to be possible until we accepted the resolution of issue 432, but since then the requirements on `overflow()` have been relaxed to allow it to make more than 1 write position available (i.e., by setting `epptr()` to some unspecified value past `pptr()`). So after the first call to `overflow()` positioning the output sequence relative to end will have unspecified results.

In addition, in `in|out` mode, since `(egptr() == epptr())` need not hold, there are two different possible values for `newoff`: `epptr() - pbase()` and `egptr() - eback()`.

Proposed resolution:

Change the `newoff` column in the last row of Table 94 to read:

> the end high mark pointer minus the beginning pointer (`xend high_mark - xbeg`).

[ Kona (2007) Moved to Ready. ]