The warning is not supported by clang.

Reviewed-by: Sam James <sam@gentoo.org>

Commit 6cbf845fcdc7 ("iconv: Preserve iconv -c error exit on invalid
inputs (bug 32046)") changed the error exit code to report an error when
an input character has been transliterated. This looks like a bug as the
moto in the iconv program is to report an error code in the same
condition as the iconv() function.

This happens because the STANDARD_TO_LOOP_ERR_HANDLER macro sets a
default value for result and later updates it if the transliteration
succeed. With the changes, setting the default value also marks the
input as illegal.

Fix that by setting up the default value of result only when the
transliteration is not used. This works because __gconv_transliterate()
calls __gconv_mark_illegal_input() to return an error. At the same time
also fix the typo outself -> ourselves.

Fixes: 6cbf845fcdc7
Resolves: BZ #32448
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

In several converters, a __GCONV_ILLEGAL_INPUT result gets overwritten
with __GCONV_FULL_OUTPUT.  As a result, iconv (the function) returns
E2BIG instead of EILSEQ.  The iconv program does not see the original
EILSEQ failure, does not recognize the invalid input, and may
incorrectly exit successfully.

To address this, a new __flags bit is used to indicate a sticky input
error state.  All __GCONV_ILLEGAL_INPUT results are replaced with a
function call that sets this new __GCONV_ENCOUNTERED_ILLEGAL_INPUT and
returns __GCONV_ILLEGAL_INPUT.  The iconv program checks for
__GCONV_ENCOUNTERED_ILLEGAL_INPUT and overrides the exit status.

The converter changes introducing __gconv_mark_illegal_input are
mostly mechanical, except for the res variable initialization in
iconvdata/iso-2022-jp.c: this error gets overwritten with __GCONV_OK
and other results in the following code.  If res ==
__GCONV_ILLEGAL_INPUT afterwards, STANDARD_TO_LOOP_ERR_HANDLER below
will handle it.

The __gconv_mark_illegal_input changes do not alter the errno value
set by the iconv function.  This is simpler to implement than
reviewing each __GCONV_FULL_OUTPUT result and adjust it not to
override a previous __GCONV_ILLEGAL_INPUT result.  Doing it that way
would also change some E2BIG errors in to EILSEQ errors, so it had to
be done conditionally (under a flag set by the iconv program only), to
avoid confusing buffer management in other applications.

Reviewed-by: DJ Delorie <dj@redhat.com>

Use put/get macros __builtin_bswap32 instead.  It allows to remove
the unaligned routines, the compiler will generate unaligned access
if the ABI allows it.

Checked on x86_64-linux-gnu and i686-linux-gnu.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

And use a packed structure instead.  The compiler generates optimized
unaligned code if the architecture supports it.

Checked on x86_64-linux-gnu and i686-linux-gnu.

Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>

On s390x when compiling with GCC 12, I get this warning:
utf8-utf16-z9.c:
../iconv/loop.c: In function ‘__from_utf8_loop_etf3eh_single’:
../iconv/loop.c:445:22: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
  445 |     bytebuf[inlen++] = *inptr++;
      |     ~~~~~~~~~~~~~~~~~^~~~~~~~~~
../iconv/loop.c:381:17: note: at offset 4 into destination object ‘bytebuf’ of size 4
  381 |   unsigned char bytebuf[MAX_NEEDED_INPUT];
      |                 ^~~~~~~
../iconv/loop.c:445:22: error: writing 1 byte into a region of size 0 [-Werror=stringop-overflow=]
  445 |     bytebuf[inlen++] = *inptr++;
      |     ~~~~~~~~~~~~~~~~~^~~~~~~~~~
../iconv/loop.c:381:17: note: at offset 5 into destination object ‘bytebuf’ of size 4
  381 |   unsigned char bytebuf[MAX_NEEDED_INPUT];
      |                 ^~~~~~~

This patch tells the compiler that inend is always behind inptr which
avoids the warning.  Note that the SINGLE function is only used to
implement the mb*towc*() or wc*tomb*() functions.  Those functions use
inptr and inend pointing to a variable on stack, compute the inend pointer
or explicitly check the arguments which always leads to inptr < inend.

Special notes for backporters (according to Siddhesh Poyarekar):
If someone wants to backport this patch to release branches, they should
also backport the following wcrtomb change. Otherwise the assumptions
assumed by this patch are not true.

commit 9bcd12d223a8990254b65e2dada54faa5d2742f3
Author: Siddhesh Poyarekar <siddhesh@sourceware.org>
Date:   Fri May 13 19:10:15 2022 +0530

    wcrtomb: Make behavior POSIX compliant

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

I used these shell commands:

../glibc/scripts/update-copyrights $PWD/../gnulib/build-aux/update-copyright
(cd ../glibc && git commit -am"[this commit message]")

and then ignored the output, which consisted lines saying "FOO: warning:
copyright statement not found" for each of 7061 files FOO.

I then removed trailing white space from math/tgmath.h,
support/tst-support-open-dev-null-range.c, and
sysdeps/x86_64/multiarch/strlen-vec.S, to work around the following
obscure pre-commit check failure diagnostics from Savannah.  I don't
know why I run into these diagnostics whereas others evidently do not.

remote: *** 912-#endif
remote: *** 913:
remote: *** 914-
remote: *** error: lines with trailing whitespace found
...
remote: *** error: sysdeps/unix/sysv/linux/statx_cp.c: trailing lines