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While working on having PowerTop use libtracevent as a shared object
library, Tzvetomir hit "str_error_r not defined". This was added by commit
c3cec9e68f ("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, and its in the traceevent
library's own tep_strerror() function, we can copy what was done in perf,
and create yet another external file that undefs _GNU_SOURCE to use the more
portable version of the function. We don't need to worry about the errors
that strerror_r() returns. If the buffer isn't big enough, we simply
truncate it.
Reported-by: Tzvetomir Stoyanov <tstoyanov@vmware.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
Cc: linux trace devel <linux-trace-devel@vger.kernel.org>
Link: http://lkml.kernel.org/r/20181005121816.484e654f@gandalf.local.home
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
// SPDX-License-Identifier: LGPL-2.1
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#undef _GNU_SOURCE
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#include <string.h>
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#include <stdio.h>
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#include "event-parse.h"
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#undef _PE
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#define _PE(code, str) str
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static const char * const tep_error_str[] = {
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TEP_ERRORS
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};
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#undef _PE
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/*
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* The tools so far have been using the strerror_r() GNU variant, that returns
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* a string, be it the buffer passed or something else.
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*
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* But that, besides being tricky in cases where we expect that the function
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* using strerror_r() returns the error formatted in a provided buffer (we have
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* to check if it returned something else and copy that instead), breaks the
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* build on systems not using glibc, like Alpine Linux, where musl libc is
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* used.
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*
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* So, introduce yet another wrapper, str_error_r(), that has the GNU
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* interface, but uses the portable XSI variant of strerror_r(), so that users
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* rest asured that the provided buffer is used and it is what is returned.
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*/
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int tep_strerror(struct tep_handle *tep __maybe_unused,
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enum tep_errno errnum, char *buf, size_t buflen)
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{
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const char *msg;
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int idx;
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if (!buflen)
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return 0;
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if (errnum >= 0) {
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int err = strerror_r(errnum, buf, buflen);
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buf[buflen - 1] = 0;
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return err;
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}
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if (errnum <= __TEP_ERRNO__START ||
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errnum >= __TEP_ERRNO__END)
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return -1;
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idx = errnum - __TEP_ERRNO__START - 1;
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msg = tep_error_str[idx];
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snprintf(buf, buflen, "%s", msg);
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return 0;
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}
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