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Fix build warnings in resolv/res_send.c

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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.

ChangeLog:

	* resolv/res_send.c (__res_context_send): Disable maybe-uninitialized
	warning.
This commit is contained in:
Stefan Liebler 2019-07-02 14:07:44 +02:00
parent 72edea80c1
commit d1bc2cbbed
2 changed files with 21 additions and 1 deletions
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5
ChangeLog
View File

@ -1,3 +1,8 @@
2019-07-02 Stefan Liebler <stli@linux.ibm.com>
* resolv/res_send.c (__res_context_send): Disable maybe-uninitialized
warning.
2019-07-01 Florian Weimer <fweimer@redhat.com>
* scripts/build-many-glibcs.py (Context.add_all_configs): Add v4t

17
resolv/res_send.c
View File

@ -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,