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authorStefan Liebler <stli@linux.ibm.com>2022-06-03 14:52:51 +0200
committerStefan Liebler <stli@linux.ibm.com>2022-06-14 11:03:06 +0200
commit876cdf517d1c464ce3d8f7eaf4199565e5592f16 (patch)
treed5906a4a65ad2800c5164253819233d97db7446f /iconv
parentfdaf78656fb6cc7caeb7b4e37068e8a8bf4dc639 (diff)
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Avoid -Wstringop-overflow= warning in iconv module.
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>
Diffstat (limited to 'iconv')
-rw-r--r--iconv/loop.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/iconv/loop.c b/iconv/loop.c
index f8727a637a..09ade3b765 100644
--- a/iconv/loop.c
+++ b/iconv/loop.c
@@ -435,11 +435,17 @@ SINGLE(LOOPFCT) (struct __gconv_step *step,
return __GCONV_FULL_OUTPUT;
/* Now add characters from the normal input buffer. */
- if (inlen >= MAX_NEEDED_INPUT)
+ if (inlen >= MAX_NEEDED_INPUT || inptr >= inend)
/* Avoid a -Wstringop-overflow= warning when this loop is
unrolled. The compiler cannot otherwise see that this is
unreachable because it depends on (state->__count & 7) not
- being too large after a previous conversion step. */
+ being too large after a previous conversion step.
+ Starting with GCC 12, we also have mark the inptr >= inend
+ case as unreachable to omit the warning. Note that this 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. */
__builtin_unreachable ();
do
bytebuf[inlen++] = *inptr++;