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[PATCH] Fix build warnings in resolv/res_send.c
- From: Stefan Liebler <stli at linux dot ibm dot com>
- To: GNU C Library <libc-alpha at sourceware dot org>
- Date: Tue, 25 Jun 2019 15:18:25 +0200
- Subject: [PATCH] Fix build warnings in resolv/res_send.c
Hi,
this patch fixes the gcc warnings seen with gcc 9 -march>=z13 on s390x:
res_send.c: In function ‘__res_context_send’:
res_send.c:498:7: error: ‘resplen’ may be used uninitialized in this
function [-Werror=maybe-uninitialized]
498 | if (n == 0 && (buf2 == NULL || *resplen2 == 0))
| ^
In this case send_vc is inlined into __res_context_send
and the maybe uninitialized resplen belongs to the one in send_vc.
In send_vc there is already a DIAG_IGNORE_NEEDS_COMMENT (5,
"-Wmaybe-uninitialized")
and a comment which explains that this is a false-positive.
Note that resplen is used as return value.
This patch adds a further DIAG_IGNORE_NEEDS_COMMENT around the
declaration of n
in __res_context_send and the comparison after n was set to the return
value of send_vc.
Bye
Stefan
ChangeLog:
* resolv/res_send.c (__res_context_send):
Disable maybe-uninitialized warning.
commit 6c3b01619ec2260a95bb7651e9c3a7aa3619745b
Author: Stefan Liebler <stli@linux.ibm.com>
Date: Tue Jun 25 13:59:28 2019 +0200
Fix build warnings in resolv/res_send.c
This patch fixes the gcc warnings seen with gcc 9 -march>=z13 on s390x:
res_send.c: In function â??__res_context_sendâ??:
res_send.c:498:7: error: â??resplenâ?? may be used uninitialized in this function [-Werror=maybe-uninitialized]
498 | if (n == 0 && (buf2 == NULL || *resplen2 == 0))
| ^
In this case send_vc is inlined into __res_context_send
and the maybe uninitialized resplen belongs to the one in send_vc.
In send_vc there is already a DIAG_IGNORE_NEEDS_COMMENT (5, "-Wmaybe-uninitialized")
and a comment which explains that this is a false-positive.
Note that resplen is used as return value.
This patch adds a further DIAG_IGNORE_NEEDS_COMMENT around the declaration of n
in __res_context_send and the comparison after n was set to the return value of send_vc.
ChangeLog:
* resolv/res_send.c (__res_context_send): Disable maybe-uninitialized warning.
diff --git a/resolv/res_send.c b/resolv/res_send.c
index eeeb8acf27..ed27f3abf8 100644
--- a/resolv/res_send.c
+++ b/resolv/res_send.c
@@ -401,7 +401,18 @@ __res_context_send (struct resolv_context *ctx,
int *nansp2, int *resplen2, int *ansp2_malloced)
{
struct __res_state *statp = ctx->resp;
- int gotsomewhere, terrno, try, v_circuit, resplen, n;
+ int gotsomewhere, terrno, try, v_circuit, resplen;
+ /* On some architectures send_vc is inlined and the compiler might emit
+ a warning indicating 'resplen' may be used uninitialized. Note that
+ the warning belongs to resplen in send_vc which is used as return
+ value! There the maybe-uninitialized warning is already ignored as
+ it is a false-positive - see comment in send_vc.
+ Here the variable n is set to the return value of send_vc.
+ See below. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_NEEDS_COMMENT (9, "-Wmaybe-uninitialized");
+ int n;
+ DIAG_POP_NEEDS_COMMENT;
if (statp->nscount == 0) {
__set_errno (ESRCH);
@@ -495,8 +506,12 @@ __res_context_send (struct resolv_context *ctx,
ansp2_malloced);
if (n < 0)
return (-1);
+ /* See comment at the declaration of n. */
+ DIAG_PUSH_NEEDS_COMMENT;
+ DIAG_IGNORE_NEEDS_COMMENT (9, "-Wmaybe-uninitialized");
if (n == 0 && (buf2 == NULL || *resplen2 == 0))
goto next_ns;
+ DIAG_POP_NEEDS_COMMENT;
} else {
/* Use datagrams. */
n = send_dg(statp, buf, buflen, buf2, buflen2,