From 618d0dec5037df0fad1ce5cc90da2b7fc2c88b0c Mon Sep 17 00:00:00 2001
From: Mark Salyzyn <salyzyn@google.com>
Date: Mon, 13 Jul 2015 10:19:34 -0700
Subject: [PATCH] logd: refine is_prio

- Heuristics associated with translation of kernel messages to
  Android user space logs.
- Limit is_prio to 4 characters, we got false positives on hex
  values like <register contents> with no alpha chars.
- x11 and other register definitions are not valid tags, en0 is
- fix some Android coding standard issues

Change-Id: Idc3dcc53a2cb75ac38628c8ef7a5d5b53f12587a
---
 logd/LogKlog.cpp | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/logd/LogKlog.cpp b/logd/LogKlog.cpp
index d578c04db..d3a73a189 100644
--- a/logd/LogKlog.cpp
+++ b/logd/LogKlog.cpp
@@ -43,8 +43,10 @@ static char *is_prio(char *s) {
     if (!isdigit(*s++)) {
         return NULL;
     }
+    static const size_t max_prio_len = 4;
+    size_t len = 0;
     char c;
-    while ((c = *s++)) {
+    while (((c = *s++)) && (++len <= max_prio_len)) {
         if (!isdigit(c)) {
             return (c == '>') ? s : NULL;
         }
@@ -73,7 +75,7 @@ static char *is_timestamp(char *s) {
 }
 
 // Like strtok_r with "\r\n" except that we look for log signatures (regex)
-// \(\(<[0-9]+>\)\([[] *[0-9]+[.][0-9]+[]] \)\{0,1\}\|[[] *[0-9]+[.][0-9]+[]] \)
+//  \(\(<[0-9]\{1,4\}>\)\([[] *[0-9]+[.][0-9]+[]] \)\{0,1\}\|[[] *[0-9]+[.][0-9]+[]] \)
 // and split if we see a second one without a newline.
 
 #define SIGNATURE_MASK     0xF0
@@ -165,7 +167,7 @@ char *log_strtok_r(char *s, char **last) {
             break;
         }
     }
-    /* NOTREACHED */
+    // NOTREACHED
 }
 
 log_time LogKlog::correction = log_time(CLOCK_REALTIME) - log_time(CLOCK_MONOTONIC);
@@ -465,7 +467,7 @@ int LogKlog::log(const char *buf) {
             if (strncmp(bt, cp, size)) {
                 // <PRI>[<TIME>] <tag>_host '<tag>.<num>' : message
                 if (!strncmp(bt + size - 5, "_host", 5)
-                 && !strncmp(bt, cp, size - 5)) {
+                        && !strncmp(bt, cp, size - 5)) {
                     const char *b = cp;
                     cp += size - 5;
                     if (*cp == '.') {
@@ -535,11 +537,15 @@ int LogKlog::log(const char *buf) {
         }
         size = etag - tag;
         if ((size <= 1)
-         || ((size == 2) && (isdigit(tag[0]) || isdigit(tag[1])))
-         || ((size == 3) && !strncmp(tag, "CPU", 3))
-         || ((size == 7) && !strncmp(tag, "WARNING", 7))
-         || ((size == 5) && !strncmp(tag, "ERROR", 5))
-         || ((size == 4) && !strncmp(tag, "INFO", 4))) {
+            // register names like x9
+                || ((size == 2) && (isdigit(tag[0]) || isdigit(tag[1])))
+            // register names like x18 but not driver names like en0
+                || ((size == 3) && (isdigit(tag[1]) && isdigit(tag[2])))
+            // blacklist
+                || ((size == 3) && !strncmp(tag, "CPU", 3))
+                || ((size == 7) && !strncmp(tag, "WARNING", 7))
+                || ((size == 5) && !strncmp(tag, "ERROR", 5))
+                || ((size == 4) && !strncmp(tag, "INFO", 4))) {
             buf = start;
             etag = tag = "";
         }