Messages in this thread Patch in this message | | | From | Wang Nan <> | Subject | [PATCH v2] perf ctf: Convert invalid chars in a string before set value | Date | Fri, 27 May 2016 11:35:51 +0000 |
| |
We observed some crazy apps on Android set their comm to unprintable string. For example:
# cat /proc/10607/task/*/comm tencent.qqmusic ... Binder_2 日志输出线 <-- Chinese word 'log output thread' WifiManager ...
'perf data convert' fails to convert perf.data with such string to CTF format.
For example: # cat << EOF > ./badguy.c #include <sys/prctl.h> int main(int argc, char *argv[]) { prctl(PR_SET_NAME, "\xe6\x97\xa5\xe5\xbf\x97\xe8\xbe\x93\xe5\x87\xba\xe7\xba\xbf"); while(1) sleep(1); return 0; } EOF # gcc ./badguy.c # perf record -e sched:* ./a.out # perf data convert --to-ctf ./bad.ctf CTF stream 4 flush failed [ perf data convert: Converted 'perf.data' into CTF data './bad.ctf' ] [ perf data convert: Converted and wrote 0.008 MB (78 samples) ] # babeltrace ./bad.ctf/ [error] Packet size (18446744073709551615 bits) is larger than remaining file size (262144 bits). [error] Stream index creation error. [error] Open file stream error. [warning] [Context] Cannot open_trace of format ctf at path ./bad.ctf. [warning] [Context] cannot open trace "./bad.ctf" from ./bad.ctf/ for reading. [error] Cannot open any trace for reading.
[error] opening trace "./bad.ctf/" for reading.
[error] none of the specified trace paths could be opened.
This patch converts unprintable characters to hexadecimal word.
After applying this patch the above test works correctly:
# ~/perf data convert --to-ctf ./good.ctf [ perf data convert: Converted 'perf.data' into CTF data './good.ctf' ] [ perf data convert: Converted and wrote 0.008 MB (78 samples) ] # babeltrace ./good.ctf .. [23:14:35.491665268] (+0.000001100) sched:sched_wakeup: { cpu_id = 4 }, { perf_ip = 0xFFFFFFFF810AEF33, perf_tid = 0, perf_pid = 0, perf_id = 5123, perf_period = 1, common_type = 270, common_flags = 45, common_preempt_count = 4, common_pid = 0, comm = "\xe6\x97\xa5\xe5\xbf\x97\xe8\xbe\x93\xe5\x87\xba\xe7\xba\xbf", pid = 1057, prio = 120, success = 1, target_cpu = 4 } [23:14:35.491666230] (+0.000000962) sched:sched_wakeup: { cpu_id = 4 }, { perf_ip = 0xFFFFFFFF810AEF33, perf_tid = 0, perf_pid = 0, perf_id = 5122, perf_period = 1, common_type = 270, common_flags = 45, common_preempt_count = 4, common_pid = 0, comm = "\xe6\x97\xa5\xe5\xbf\x97\xe8\xbe\x93\xe5\x87\xba\xe7\xba\xbf", pid = 1057, prio = 120, success = 1, target_cpu = 4 } ..
Signed-off-by: Wang Nan <wangnan0@huawei.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Jiri Olsa <jolsa@kernel.org> ---
v1 -> v2: Alloc buffer only when a unprintable char is observed: most of the time string is printable.
Jiri, can I have your Acked-by again?
--- tools/perf/util/data-convert-bt.c | 41 +++++++++++++++++++++++++++++++++++++-- 1 file changed, 39 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c index bbf69d2..9f53020 100644 --- a/tools/perf/util/data-convert-bt.c +++ b/tools/perf/util/data-convert-bt.c @@ -204,6 +204,44 @@ static unsigned long long adjust_signedness(unsigned long long value_int, int si return (value_int & value_mask) | ~value_mask; } +static int string_set_value(struct bt_ctf_field *field, const char *string) +{ + char *buffer = NULL; + size_t len = strlen(string), i, p; + int err; + + for (i = p = 0; i < len; i++, p++) { + if (isprint(string[i])) { + if (!buffer) + continue; + buffer[p] = string[i]; + } else { + char numstr[5]; + + snprintf(numstr, sizeof(numstr), "\\x%02x", + (unsigned int)(string[i]) & 0xff); + + if (!buffer) { + buffer = zalloc(i + (len - i) * 4 + 2); + if (!buffer) { + pr_err("failed to set unprintable string '%s'\n", string); + return bt_ctf_field_string_set_value(field, "UNPRINTABLE-STRING"); + } + if (i > 0) + strncpy(buffer, string, i); + } + strncat(buffer + p, numstr, 4); + p += 3; + } + } + + if (!buffer) + return bt_ctf_field_string_set_value(field, string); + err = bt_ctf_field_string_set_value(field, buffer); + free(buffer); + return err; +} + static int add_tracepoint_field_value(struct ctf_writer *cw, struct bt_ctf_event_class *event_class, struct bt_ctf_event *event, @@ -270,8 +308,7 @@ static int add_tracepoint_field_value(struct ctf_writer *cw, } if (flags & FIELD_IS_STRING) - ret = bt_ctf_field_string_set_value(field, - data + offset + i * len); + ret = string_set_value(field, data + offset + i * len); else { unsigned long long value_int; -- 1.8.3.4
| |