[PATCH] fix 19432 - iconv rejects redundant escape sequences in IBM90{0,3,5,7,9}

[Martin Sebor]

Ping: I'm still looking for a review/feedback on the following
patch:

   https://sourceware.org/ml/libc-alpha/2016-01/msg00074.html

Thanks
Martin

On 01/05/2016 09:07 PM, Martin Sebor wrote:
> Quoting the bug Description:
>
>    In the problem report corresponding to bug 17197 submitted
>    against the RHEL GLIBC, even though the focus of the customer's
>    complaint is on GLIBC emitting redundant shift sequences,
>    the provided test case implies the customer is actually having
>    a problem interpreting already encoded data (i.e., with iconv()
>    treating the duplicate/redundant escape sequences as errors).
>    If iconv() accepted the duplicate sequences the customer wouldn't
>    be affected.
>
>    The solution implemented in response to bug 17197, changing
>    the converter to avoid emitting the redundant escape sequences,
>    while a worthwhile improvement, is not sufficient to resolve
>    the complaint because there may already be IBM930-encoded data
>    containing redundant shift sequences that need to be converted.
>    The current fix will not help users avoid the errors when
>    converting such data.
>
>    Looking for guidance, I checked POSIX to see if it provides
>    support for the current behavior (rejecting redundant escape
>    sequences) in POSIX.  I don't see anything in POSIX to sanction
>    rejecting such input.  Even if POSIX did allow for such behavior,
>    since other GLIBC converters accept redundant escape sequences,
>    it seems that the IBM930 converter should accept them as well
>    for consistency.  Doing otherwise makes the iconv interfaces
>    needlessly error-prone to use.
>
> The attached patch removes the checking for redundant escape
> sequences from the converters for the five encoders to allow
> them to successfully convert data containing such sequences.
>
> Tested on powerpc64le-redhat-linux-gnu.
>
> Martin