* [PATCH bpf-next] tools/bpf: make libbpf _GNU_SOURCE friendly
@ 2018-11-29 20:38 Yonghong Song
2018-11-29 21:00 ` Jakub Kicinski
0 siblings, 1 reply; 3+ messages in thread
From: Yonghong Song @ 2018-11-29 20:38 UTC (permalink / raw)
To: ast, daniel, netdev; +Cc: kernel-team
During porting libbpf to bcc, I got some warnings like below:
...
[ 2%] Building C object src/cc/CMakeFiles/bpf-shared.dir/libbpf/src/libbpf.c.o
/home/yhs/work/bcc2/src/cc/libbpf/src/libbpf.c:12:0:
warning: "_GNU_SOURCE" redefined [enabled by default]
#define _GNU_SOURCE
...
[ 3%] Building C object src/cc/CMakeFiles/bpf-shared.dir/libbpf/src/libbpf_errno.c.o
/home/yhs/work/bcc2/src/cc/libbpf/src/libbpf_errno.c: In function ‘libbpf_strerror’:
/home/yhs/work/bcc2/src/cc/libbpf/src/libbpf_errno.c:45:7:
warning: assignment makes integer from pointer without a cast [enabled by default]
ret = strerror_r(err, buf, size);
...
bcc is built with _GNU_SOURCE defined and this caused the above warning.
This patch intends to make libpf _GNU_SOURCE friendly by
. define _GNU_SOURCE unless it is not defined
. gnu version strerror_r has different return value than non-gnu version,
so strerror_r return value is handled differently if _GNU_SOURCE is defined.
Signed-off-by: Yonghong Song <yhs@fb.com>
---
tools/lib/bpf/libbpf.c | 2 ++
tools/lib/bpf/libbpf_errno.c | 10 ++++++++++
2 files changed, 12 insertions(+)
diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index ed4212a4c5f9..59b748ebd15f 100644
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -9,7 +9,9 @@
* Copyright (C) 2017 Nicira, Inc.
*/
+#ifndef _GNU_SOURCE
#define _GNU_SOURCE
+#endif
#include <stdlib.h>
#include <stdio.h>
#include <stdarg.h>
diff --git a/tools/lib/bpf/libbpf_errno.c b/tools/lib/bpf/libbpf_errno.c
index d83b17f8435c..286e497c50ec 100644
--- a/tools/lib/bpf/libbpf_errno.c
+++ b/tools/lib/bpf/libbpf_errno.c
@@ -40,9 +40,19 @@ int libbpf_strerror(int err, char *buf, size_t size)
err = err > 0 ? err : -err;
if (err < __LIBBPF_ERRNO__START) {
+#ifdef _GNU_SOURCE
+ const char *ret_buf;
+#endif
int ret;
+#ifdef _GNU_SOURCE
+ ret_buf = strerror_r(err, buf, size);
+ if (ret_buf != buf)
+ snprintf(buf, size, "%s", ret_buf);
+ ret = 0;
+#else
ret = strerror_r(err, buf, size);
+#endif
buf[size - 1] = '\0';
return ret;
}
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] tools/bpf: make libbpf _GNU_SOURCE friendly
2018-11-29 20:38 [PATCH bpf-next] tools/bpf: make libbpf _GNU_SOURCE friendly Yonghong Song
@ 2018-11-29 21:00 ` Jakub Kicinski
2018-11-29 23:26 ` Yonghong Song
0 siblings, 1 reply; 3+ messages in thread
From: Jakub Kicinski @ 2018-11-29 21:00 UTC (permalink / raw)
To: Yonghong Song; +Cc: ast, daniel, netdev, kernel-team
On Thu, 29 Nov 2018 12:38:03 -0800, Yonghong Song wrote:
> diff --git a/tools/lib/bpf/libbpf_errno.c b/tools/lib/bpf/libbpf_errno.c
> index d83b17f8435c..286e497c50ec 100644
> --- a/tools/lib/bpf/libbpf_errno.c
> +++ b/tools/lib/bpf/libbpf_errno.c
> @@ -40,9 +40,19 @@ int libbpf_strerror(int err, char *buf, size_t size)
> err = err > 0 ? err : -err;
>
> if (err < __LIBBPF_ERRNO__START) {
> +#ifdef _GNU_SOURCE
> + const char *ret_buf;
> +#endif
> int ret;
>
> +#ifdef _GNU_SOURCE
> + ret_buf = strerror_r(err, buf, size);
> + if (ret_buf != buf)
> + snprintf(buf, size, "%s", ret_buf);
> + ret = 0;
> +#else
> ret = strerror_r(err, buf, size);
> +#endif
> buf[size - 1] = '\0';
> return ret;
> }
That is kinda strange, the whole point for this file was to have
non-GNU strerror_r, would doing #undef _GNU_SOURCE at the top not work?
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH bpf-next] tools/bpf: make libbpf _GNU_SOURCE friendly
2018-11-29 21:00 ` Jakub Kicinski
@ 2018-11-29 23:26 ` Yonghong Song
0 siblings, 0 replies; 3+ messages in thread
From: Yonghong Song @ 2018-11-29 23:26 UTC (permalink / raw)
To: Jakub Kicinski; +Cc: Alexei Starovoitov, daniel, netdev, Kernel Team
On 11/29/18 1:00 PM, Jakub Kicinski wrote:
> On Thu, 29 Nov 2018 12:38:03 -0800, Yonghong Song wrote:
>> diff --git a/tools/lib/bpf/libbpf_errno.c b/tools/lib/bpf/libbpf_errno.c
>> index d83b17f8435c..286e497c50ec 100644
>> --- a/tools/lib/bpf/libbpf_errno.c
>> +++ b/tools/lib/bpf/libbpf_errno.c
>> @@ -40,9 +40,19 @@ int libbpf_strerror(int err, char *buf, size_t size)
>> err = err > 0 ? err : -err;
>>
>> if (err < __LIBBPF_ERRNO__START) {
>> +#ifdef _GNU_SOURCE
>> + const char *ret_buf;
>> +#endif
>> int ret;
>>
>> +#ifdef _GNU_SOURCE
>> + ret_buf = strerror_r(err, buf, size);
>> + if (ret_buf != buf)
>> + snprintf(buf, size, "%s", ret_buf);
>> + ret = 0;
>> +#else
>> ret = strerror_r(err, buf, size);
>> +#endif
>> buf[size - 1] = '\0';
>> return ret;
>> }
>
> That is kinda strange, the whole point for this file was to have
> non-GNU strerror_r, would doing #undef _GNU_SOURCE at the top not work?
Thanks for suggestion as I did not the history of this file.
Yes, #undef _GNU_SOURCE works. Will send a revision shortly.
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-11-30 10:34 UTC | newest]
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2018-11-29 20:38 [PATCH bpf-next] tools/bpf: make libbpf _GNU_SOURCE friendly Yonghong Song
2018-11-29 21:00 ` Jakub Kicinski
2018-11-29 23:26 ` Yonghong Song
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