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author | Steven Rostedt (VMware) <rostedt@goodmis.org> | 2018-10-05 19:18:16 +0300 |
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committer | Arnaldo Carvalho de Melo <acme@redhat.com> | 2018-10-08 20:30:45 +0300 |
commit | bbbab191c2c474d183e93799d008b412e97f5936 (patch) | |
tree | 85a14941644c3a9c7f616b29eb52ab9e3eb8d6e6 /tools/lib/traceevent | |
parent | 8b2f245faa6238e28a1d801e8633515251d1acfc (diff) | |
download | linux-bbbab191c2c474d183e93799d008b412e97f5936.tar.xz |
tools lib traceevent: Separate out tep_strerror() for strerror_r() issues
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, 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>
Diffstat (limited to 'tools/lib/traceevent')
-rw-r--r-- | tools/lib/traceevent/Build | 1 | ||||
-rw-r--r-- | tools/lib/traceevent/event-parse.c | 30 | ||||
-rw-r--r-- | tools/lib/traceevent/tep_strerror.c | 53 |
3 files changed, 54 insertions, 30 deletions
diff --git a/tools/lib/traceevent/Build b/tools/lib/traceevent/Build index c681d0575d16..0050c145d806 100644 --- a/tools/lib/traceevent/Build +++ b/tools/lib/traceevent/Build @@ -4,6 +4,7 @@ libtraceevent-y += trace-seq.o libtraceevent-y += parse-filter.o libtraceevent-y += parse-utils.o libtraceevent-y += kbuffer-parse.o +libtraceevent-y += tep_strerror.o plugin_jbd2-y += plugin_jbd2.o plugin_hrtimer-y += plugin_hrtimer.o diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c index 7980fc6c3bac..233179a712d6 100644 --- a/tools/lib/traceevent/event-parse.c +++ b/tools/lib/traceevent/event-parse.c @@ -18,7 +18,6 @@ #include <errno.h> #include <stdint.h> #include <limits.h> -#include <linux/string.h> #include <linux/time64.h> #include <netinet/in.h> @@ -6201,35 +6200,6 @@ enum tep_errno tep_parse_event(struct tep_handle *pevent, const char *buf, return __parse_event(pevent, &event, buf, size, sys); } -#undef _PE -#define _PE(code, str) str -static const char * const tep_error_str[] = { - TEP_ERRORS -}; -#undef _PE - -int tep_strerror(struct tep_handle *pevent __maybe_unused, - enum tep_errno errnum, char *buf, size_t buflen) -{ - int idx; - const char *msg; - - if (errnum >= 0) { - str_error_r(errnum, buf, buflen); - return 0; - } - - if (errnum <= __TEP_ERRNO__START || - errnum >= __TEP_ERRNO__END) - return -1; - - idx = errnum - __TEP_ERRNO__START - 1; - msg = tep_error_str[idx]; - snprintf(buf, buflen, "%s", msg); - - return 0; -} - int get_field_val(struct trace_seq *s, struct tep_format_field *field, const char *name, struct tep_record *record, unsigned long long *val, int err) diff --git a/tools/lib/traceevent/tep_strerror.c b/tools/lib/traceevent/tep_strerror.c new file mode 100644 index 000000000000..4ac26445b2f6 --- /dev/null +++ b/tools/lib/traceevent/tep_strerror.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: LGPL-2.1 +#undef _GNU_SOURCE +#include <string.h> +#include <stdio.h> + +#include "event-parse.h" + +#undef _PE +#define _PE(code, str) str +static const char * const tep_error_str[] = { + TEP_ERRORS +}; +#undef _PE + +/* + * The tools so far have been using the strerror_r() GNU variant, that returns + * a string, be it the buffer passed or something else. + * + * But that, besides being tricky in cases where we expect that the function + * using strerror_r() returns the error formatted in a provided buffer (we have + * to check if it returned something else and copy that instead), breaks the + * build on systems not using glibc, like Alpine Linux, where musl libc is + * used. + * + * So, introduce yet another wrapper, str_error_r(), that has the GNU + * interface, but uses the portable XSI variant of strerror_r(), so that users + * rest asured that the provided buffer is used and it is what is returned. + */ +int tep_strerror(struct tep_handle *tep __maybe_unused, + enum tep_errno errnum, char *buf, size_t buflen) +{ + const char *msg; + int idx; + + if (!buflen) + return 0; + + if (errnum >= 0) { + int err = strerror_r(errnum, buf, buflen); + buf[buflen - 1] = 0; + return err; + } + + if (errnum <= __TEP_ERRNO__START || + errnum >= __TEP_ERRNO__END) + return -1; + + idx = errnum - __TEP_ERRNO__START - 1; + msg = tep_error_str[idx]; + snprintf(buf, buflen, "%s", msg); + + return 0; +} |