[glibc] linux: fix ntp_gettime abi break (BZ# 30156)

[glibc] linux: fix ntp_gettime abi break (BZ# 30156)

[Adhemerval Zanella]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=e78c4c49831d0ca6253ff5ce5b956cdc4189c8a9

commit e78c4c49831d0ca6253ff5ce5b956cdc4189c8a9
Author: Kacper Piwiński <vfjpl1@gmail.com>
Date:   Thu Mar 9 11:38:59 2023 +0100

    linux: fix ntp_gettime abi break (BZ# 30156)
    
    Between versions v2.11 and v2.12 struct ntptimeval got new fields.
    That wasn't a problem because new function ntp_gettimex was created
    (and made default) to support new struct.  Old ntp_gettime was not
    using new fields so it was safe to call with old struct
    definition.  Then commits 5613afe9e3dff and b6ad64b907a (added for
    64 bit time_t support), ntp_gettime start setting new fields.
    
    Sets fields manually to maintain compatibility with v2.11 struct
    definition.
    
    Resolves #30156
    
    Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

Diff:
---
 sysdeps/unix/sysv/linux/ntp_gettime.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/sysdeps/unix/sysv/linux/ntp_gettime.c b/sysdeps/unix/sysv/linux/ntp_gettime.c
index 4879573530..af1ed920d3 100644
--- a/sysdeps/unix/sysv/linux/ntp_gettime.c
+++ b/sysdeps/unix/sysv/linux/ntp_gettime.c
@@ -26,6 +26,11 @@
 # define modes mode
 #endif
 
+/* glibc 2.12 added the 'tai' field to follow along the kernel, but it did
+   not add a compatibility symbol, instead it added __ntp_gettimex.  However
+   ntptimeval was still used in both cases, so to keep compatibility it
+   can not set all the new field.  */
+
 /* clock_adjtime64 with CLOCK_REALTIME does not trigger EINVAL,
    ENODEV, or EOPNOTSUPP.  It might still trigger EPERM.  */
 
@@ -40,7 +45,7 @@ __ntp_gettime64 (struct __ntptimeval64 *ntv)
   ntv->time = tntx.time;
   ntv->maxerror = tntx.maxerror;
   ntv->esterror = tntx.esterror;
-  ntv->tai = tntx.tai;
+
   return result;
 }
 
@@ -54,7 +59,9 @@ __ntp_gettime (struct ntptimeval *ntv)
   int result;
 
   result = __ntp_gettime64 (&ntv64);
-  *ntv = valid_ntptimeval64_to_ntptimeval (ntv64);
+  ntv->time = valid_timeval64_to_timeval (ntv64.time);
+  ntv->maxerror = ntv64.maxerror;
+  ntv->esterror = ntv64.esterror;
 
   return result;
 }