From patchwork Tue Oct 2 21:55:39 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 10759463 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:56806 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725767AbeJCElJ (ORCPT ); Wed, 3 Oct 2018 00:41:09 -0400 Date: Tue, 2 Oct 2018 17:55:39 -0400 From: Steven Rostedt To: Arnaldo Carvalho de Melo Cc: LKML , Jiri Olsa , Ingo Molnar , Namhyung Kim , Tzvetomir Stoyanov , Linux Trace Devel , Colin Patrick McCabe Subject: [PATCH v3] tools/lib/traceevent: Replace str_error_r() with an open coded implementation Message-ID: <20181002175539.2ac894c7@gandalf.local.home> MIME-Version: 1.0 Sender: linux-trace-devel-owner@vger.kernel.org List-ID: Content-Length: 2278 From: "Steven Rostedt (VMware)" While working on having PowerTop use libtracevent as a shared object library, Tzvetomir hit "str_error_r not defined". This was added by commit c3cec9e68f12d ("tools lib traceevent: Use str_error_r()") because strerror_r() has two definitions, where one is GNU specific, and the other is XSI complient. The strerror_r() is in a wrapper str_error_r() to keep the code from having to worry about which compiler is being used. The problem is that str_error_r() is external to libtraceevent, and not part of the library. If it is used as a shared object then the tools using it will need to define that function. I do not want that function defined in libtraceevent itself, as it is out of scope for that library. As there's only a single instance of this call, I replaced it with an open coded algorithm that uses sys_nerr and sys_errlist error array with strncpy() to place the error message in the given buffer. We don't need to worry about the errors that strerror_r() returns. If the buffer isn't big enough, we simply truncate it. The sys_nerr and sys_errlist idea was found here: http://www.club.cc.cmu.edu/~cmccabe/blog_strerror.html Cc: Colin Patrick McCabe Reported-by: Tzvetomir Stoyanov Signed-off-by: Steven Rostedt (VMware) --- Changes since v2: Use sys_nerr and sys_errlist idea. tools/lib/traceevent/event-parse.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c index 7980fc6c3bac..d23d10bc5314 100644 --- a/tools/lib/traceevent/event-parse.c +++ b/tools/lib/traceevent/event-parse.c @@ -18,7 +18,6 @@ #include #include #include -#include #include #include @@ -6215,7 +6214,13 @@ int tep_strerror(struct tep_handle *pevent __maybe_unused, const char *msg; if (errnum >= 0) { - str_error_r(errnum, buf, buflen); + if (buflen > 0) { + if (errnum < sys_nerr) + strncpy(buf, sys_errlist[errnum], buflen); + else + snprintf(buf, buflen, "Unknown error %d", errnum); + buf[buflen - 1] = 0; + } return 0; }