liblog: logcat: Add printable format modifier

(cherry pick from commit b932b2f8bac124b088edc93966281cca4567dc54)

- added printable format modifier:
  logcat -v printable
- opencoded borrowed individual utf8 validity checking algorithm
  from utf8_length() in libutils/Unicode.cpp
- if considered basic one-character ASCII, use popular \x escape
  sequences for non-printable
- logprint convert to C comments to drop mixed-mode

Bug: 19000361
Change-Id: I122a5b8fb41216fc0bc816178c0b768f3df56586

1 files changed, 2 insertions, 1 deletions

diff --git a/include/log/logprint.h b/include/log/logprint.h
index 96249e9..4b812cc 100644
--- a/include/log/logprint.h
+++ b/include/log/logprint.h
@@ -36,9 +36,10 @@ typedef enum {
     FORMAT_TIME,
     FORMAT_THREADTIME,
     FORMAT_LONG,
-    /* The following two are modifiers to above formats */
+    /* The following three are modifiers to above formats */
     FORMAT_MODIFIER_COLOR,     /* converts priority to color */
     FORMAT_MODIFIER_TIME_USEC, /* switches from msec to usec time precision */
+    FORMAT_MODIFIER_PRINTABLE, /* converts non-printable to printable escapes */
 } AndroidLogPrintFormat;
 
 typedef struct AndroidLogFormat_t AndroidLogFormat;