37 lines
1.6 KiB
Diff
37 lines
1.6 KiB
Diff
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commit c8126360dfa98024cc40bce915e126309993cdf9
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Author: Joseph Myers <joseph@codesourcery.com>
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Date: Mon Aug 23 16:18:42 2021 +0000
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Fix iconv build with GCC mainline
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Current GCC mainline produces -Wstringop-overflow errors building some
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iconv converters, as discussed at
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<https://gcc.gnu.org/pipermail/gcc/2021-July/236943.html>. Add an
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__builtin_unreachable call as suggested so that GCC can see the case
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that would involve a buffer overflow is unreachable; because the
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unreachability depends on valid conversion state being passed into the
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function from previous conversion steps, it's not something the
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compiler can reasonably deduce on its own.
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Tested with build-many-glibcs.py that, together with
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<https://sourceware.org/pipermail/libc-alpha/2021-August/130244.html>,
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it restores the glibc build for powerpc-linux-gnu.
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diff --git a/iconv/loop.c b/iconv/loop.c
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index 062cc1b868c1efa5..560a5f6394e8faf6 100644
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--- a/iconv/loop.c
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+++ b/iconv/loop.c
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@@ -436,6 +436,12 @@ SINGLE(LOOPFCT) (struct __gconv_step *step,
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return __GCONV_FULL_OUTPUT;
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/* Now add characters from the normal input buffer. */
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+ if (inlen >= MAX_NEEDED_INPUT)
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+ /* Avoid a -Wstringop-overflow= warning when this loop is
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+ unrolled. The compiler cannot otherwise see that this is
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+ unreachable because it depends on (state->__count & 7) not
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+ being too large after a previous conversion step. */
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+ __builtin_unreachable ();
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do
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bytebuf[inlen++] = *inptr++;
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while (inlen < MAX_NEEDED_INPUT && inptr < inend);
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