[glibc] nss: Group merge does not react to ERANGE during merge (bug 33361)

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=0fceed254559836b57ee05188deac649bc505d05

commit 0fceed254559836b57ee05188deac649bc505d05
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Sep 12 21:33:34 2025 +0200

    nss: Group merge does not react to ERANGE during merge (bug 33361)
    
    The break statement in CHECK_MERGE is expected to exit the surrounding
    while loop, not the do-while loop with in the macro.  Remove the
    do-while loop from the macro.  It is not needed to turn the macro
    expansion into a single statement due to the way CHECK_MERGE is used
    (and the statement expression would cover this anyway).
    
    Reviewed-by: Collin Funk <collin.funk1@gmail.com>

Diff:
---
 nss/getXXbyYY_r.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/nss/getXXbyYY_r.c b/nss/getXXbyYY_r.c
index eae6c3480e..2b0735fb6a 100644
--- a/nss/getXXbyYY_r.c
+++ b/nss/getXXbyYY_r.c
@@ -157,19 +157,15 @@ __merge_einval (LOOKUP_TYPE *a,
 
 #define CHECK_MERGE(err, status)		\
   ({						\
-    do						\
+    if (err)					\
       {						\
-	if (err)				\
-	  {					\
-	    __set_errno (err);			\
-	    if (err == ERANGE)			\
-	      status = NSS_STATUS_TRYAGAIN;	\
-	    else				\
-	      status = NSS_STATUS_UNAVAIL;	\
-	    break;				\
-	  }					\
+	__set_errno (err);			\
+	if (err == ERANGE)			\
+	  status = NSS_STATUS_TRYAGAIN;		\
+	else					\
+	  status = NSS_STATUS_UNAVAIL;		\
+	break;					\
       }						\
-    while (0);					\
   })
 
 /* Type of the lookup function we need here.  */