init.rc: logd: Add logpersistd (nee logcatd)

(cherry pick from commit 100658c303)

- logpersistd is defined as a thread or process in the context of the
  logd domain. Here we define logpersistd as logcat -f in logd domain
  and call it logcatd to represent its service mechanics.
- Use logcatd to manage content in /data/misc/logd/ directory.
- Only turn on for persist.logd.logpersistd = logcatd.
- Add logpersist.start, logpersist.stop and logpersist.cat debug
  class executables, thus only in the eng and userdebug builds.

ToDo: Wish to add Developer Options menu to turn this feature on or
off, complicated by the fact that user builds have no tools with
access rights to /data/misc/logd.

Bug: 19608716
Change-Id: I57ad757f121c473d04f9fabe9d4820a0eca06f31

logd/Android.mk

@@ -41,4 +41,15 @@ LOCAL_CFLAGS := -Werror $(event_flag)
 
 include $(BUILD_EXECUTABLE)
 
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := logpersist.start
+LOCAL_MODULE_TAGS := debug
+LOCAL_MODULE_CLASS := EXECUTABLES
+LOCAL_MODULE_PATH := $(bin_dir)
+LOCAL_SRC_FILES := logpersist
+ALL_TOOLS := logpersist.start logpersist.stop logpersist.cat
+LOCAL_POST_INSTALL_CMD := $(hide) $(foreach t,$(filter-out $(LOCAL_MODULE),$(ALL_TOOLS)),ln -sf $(LOCAL_MODULE) $(TARGET_OUT)/bin/$(t);)
+include $(BUILD_PREBUILT)
+
 include $(call first-makefiles-under,$(LOCAL_PATH))

logd/README.property

@@ -10,6 +10,8 @@ ro.config.low_ram           bool  false  if true, logd.statistics & logd.klogd
                                          default false
 ro.build.type               string       if user, logd.statistics & logd.klogd
                                          default false
+persist.logd.logpersistd    string       Enable logpersist daemon, "logcatd"
+                                         turns on logcat -f in logd context
 persist.logd.size          number 256K   default size of the buffer for all
                                          log ids at initial startup, at runtime
                                          use: logcat -b all -G <value>

logd/logpersist

@@ -0,0 +1,36 @@
+#! /system/bin/sh
+# logpersist cat start and stop handlers
+data=/data/misc/logd
+property=persist.logd.logpersistd
+service=logcatd
+progname="${0##*/}"
+if [ X"${1}" = "-h" -o X"${1}" = X"--help" ]; then
+  echo "${progname%.*}.cat            - dump current ${service%d} logs"
+  echo "${progname%.*}.start          - start ${service} service"
+  echo "${progname%.*}.stop [--clear] - stop ${service} service"
+  exit 0
+fi
+case ${progname} in
+*.cat)
+  su 1036 ls "${data}" |
+  tr -d '\r' |
+  sort -ru |
+  sed "s#^#${data}/#" |
+  su 1036 xargs cat
+  ;;
+*.start)
+  su 0 setprop ${property} ${service}
+  getprop ${property}
+  sleep 1
+  ps -t | grep "${data##*/}.*${service%d}"
+  ;;
+*.stop)
+  su 0 stop ${service}
+  su 0 setprop ${property} ""
+  [ X"${1}" != X"-c" -a X"${1}" != X"--clear" ] ||
+  ( sleep 1 ; su 1036,9998 rm -rf "${data}" )
+  ;;
+*)
+  echo "Unexpected command ${0##*/} ${@}" >&2
+  exit 1
+esac

rootdir/init.rc

@@ -668,3 +668,17 @@ service perfprofd /system/xbin/perfprofd
     class late_start
     user root
     oneshot
+
+on property:persist.logd.logpersistd=logcatd
+    # all exec/services are called with umask(077), so no gain beyond 0700
+    mkdir /data/misc/logd 0700 logd log
+    # logd for write to /data/misc/logd, log group for read from pstore (-L)
+    exec - logd log -- /system/bin/logcat -L -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 64 -n 256
+    start logcatd
+
+service logcatd /system/bin/logcat -b all -v threadtime -v usec -v printable -D -f /data/misc/logd/logcat -r 64 -n 256
+    class late_start
+    disabled
+    # logd for write to /data/misc/logd, log group for read from log daemon
+    user logd
+    group log