perf ctf: Convert invalid chars in a string before set value

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 }
  ..

Committer note:

To build perf with libabeltrace, use:

  $ mkdir -p /tmp/build/perf
  $ make LIBBABELTRACE=1 LIBBABELTRACE_DIR=/usr/local O=/tmp/build/perf -C tools/perf install-bin

Or equivalent (no O=, fixup LIBBABELTRACE_DIR, etc).

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1464348951-179595-1-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/data-convert-bt.c b/tools/perf/util/data-convert-bt.c
index bbf69d248ec56ad187f68969367b15c282fbb7fe..9f53020c32697e0aeb52de6ab8fa8d24a0ac24fa 100644 (file)
--- 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;