[PATCH v3] linux: fix ntp_gettime abi break

[PATCH v3] linux: fix ntp_gettime abi break

[Kacper Piwiński]

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[-- Attachment #2: v3-0001-linux-fix-ntp_gettime-abi-break.patch --]
[-- Type: text/x-patch, Size: 2008 bytes --]

From c9130bbacfe66c1fe5f1ad7a40293523075b1c91 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kacper=20Piwi=C5=84ski?= <vfjpl1@gmail.com>
Date: Thu, 9 Mar 2023 11:38:59 +0100
Subject: [PATCH v3] linux: fix ntp_gettime abi break

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
---
 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;
 }
-- 
2.34.1

Re: [PATCH v3] linux: fix ntp_gettime abi break

[Adhemerval Zanella Netto]

On 09/03/23 07:45, Kacper Piwiński wrote:
> From c9130bbacfe66c1fe5f1ad7a40293523075b1c91 Mon Sep 17 00:00:00 2001
> From: =?UTF-8?q?Kacper=20Piwi=C5=84ski?= <vfjpl1@gmail.com>
> Date: Thu, 9 Mar 2023 11:38:59 +0100
> Subject: [PATCH v3] linux: fix ntp_gettime abi break
> 
> 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

LGTM, thanks

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

PS: please next time do not send as attachment, but as inline. It is
easy to work with patchwork as inline.


> ---
>  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;
>  }
> -- 
> 2.34.1
>