随着android版本升级，升级包越来越大，当升级包无法存储在cache分区的时候，会把升级包下载到data分区，然后从data分区升级，最近从data分区加载升级包升级的时候，遇到了如下错误：
[ 1.945982] Supported API: 3 [ 1.957270] charge_status 1, charged 1, status -2, capacity -9223372036854775808 [ 1.973917] E:Failed to find CPU thermal info in /sys/class/thermal/ [ 1.990514] I:current maximum temperature: -1 [ 2.007184] Finding update package... [ 2.057199] I:Update location: @/cache/recovery/block.map [ 2.057251] Opening update package... [ 2.092148] E:Failed to read /cache/recovery/block.map: No such file or directory [ 2.107257] E:Map of '@/cache/recovery/block.map' failed [ 2.140532] E:failed to map file [ 2.158867] I:current maximum temperature: -1 [ 2.159049] I:@/cache/recovery/block.map [ 2.159060] I:0 [ 2.159072] I:time_total: 0 [ 2.159079] I:retry: 0 [ 2.159085] I:uncrypt_time: 0 [ 2.159092] I:uncrypt_error: 1 [ 2.159099] I: [ 2.159108] Installation aborted. [ 2.223841] I:Saving locale "en-US"最直接的错误信息就是： E:Failed to read /cache/recovery/block.map: No such file or directory
我们根据提示信息，去查询下cache分区，这个block.map文件是否存在。
busybox mount -t ext4 /dev/block/cache /cache （如果无法挂载，设置selinux权限为 permissive）
# busybox ls -l /cache/recovery/ total 104 __bionic_open_tzdata: couldn't find any tzdata when looking for localtime! __bionic_open_tzdata: couldn't find any tzdata when looking for GMT! __bionic_open_tzdata: couldn't find any tzdata when looking for posixrules! -rw-r--r-- 1 root root 85 Jan 1 00:01 last_install -rw------- 1 system system 61634 Jan 1 00:01 last_kmsg -rw------- 1 root root 5 Jan 1 00:00 last_locale -rw-r----- 1 root root 12160 Jan 1 00:01 last_log -rw------- 1 system system 12160 Jan 1 00:01 log -rw------- 1 system system 24 Jan 1 1970 uncrypt_file -rw------- 1 root root 33 Jan 1 1970 uncrypt_status我们发现，我们需要的 /cache/recovery/block.map文件竟然没有，那么肯定是生成block.map的时候出了问题，我们追寻重启进入recovery之前的log信息：
[ 1212.869820@3] type=1400 audit(1209.144:3355): avc: denied { setattr } for pid=4433 comm="Thread-3" name="uncrypt_file" dev="mmcblk0p3" ino=13 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_recovery_file:s0 tclass=file permissive=0
[ 1212.885402@3] type=1400 audit(1212.820:3356): avc: denied { getattr } for pid=4501 comm="uncrypt" path="/data/cache" dev="mmcblk0p17" ino=19 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=dir permissive=0
[ 1212.906032@2] watchdogd: watchdogd started (interval 10, margin 20)!
[ 1212.906143@2] watchdogd: Failed to open /dev/watchdog: No such file or directory好像是处理/data与/cache分区时候遇到了selinux权限问题。（mmcblk0p3
mmcblk0p17对应的分别是cache与data分区）
我们可能需要为升级的应用赋予相应的selinux权限，但是上面遇到selinux权限就没有继续了，我们需要知道所有需要的selinux权限，那么我们把selinux设置为 permissive 状态，然后再升级一次，我们观察log状态：
[ 98.295965@1] type=1400 audit(84.812:43): avc: denied { open } for pid=2890 comm="HwBinder:2890_1" path="/sys/module/tvin_hdmirx/parameters/en_4k_2_2k" dev="sysfs" ino=6874 scontext=u:r:system_control:s0 tcontext=u:object_r:sysfs_cec:s0 tclass=file permissive=1
[ 98.313718@1] type=1400 audit(98.244:44): avc: denied { remove_name } for pid=4076 comm="Thread-4" name="update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_file:s0 tclass=dir permissive=1
[ 98.333696@1] type=1400 audit(98.244:44): avc: denied { remove_name } for pid=4076 comm="Thread-4" name="update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_file:s0 tclass=dir permissive=1
[ 98.353378@1] type=1400 audit(98.244:45): avc: denied { unlink } for pid=4076 comm="Thread-4" name="update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 98.373096@1] type=1400 audit(98.244:45): avc: denied { unlink } for pid=4076 comm="Thread-4" name="update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 98.392458@1] type=1400 audit(98.304:46): avc: denied { read } for pid=4076 comm="Thread-4" path="/data/cache/update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 98.618368@2] success set parent gpu_p1_composite rate to 500000000
[ 99.302385@1] success set parent gpu_p0_composite rate to 400000000
[ 100.074360@1] success set parent gpu_p1_composite rate to 285714285
[ 101.234329@3] success set parent gpu_p0_composite rate to 125000000
[ 101.344037@0] aml_snd_card_tv aml_snd_tv: I2S playback disable
[ 101.344244@0] aml_snd_card_tv aml_snd_tv: IEC958 playback disable
[ 120.075238@1] type=1400 audit(98.304:46): avc: denied { read } for pid=4076 comm="Thread-4" path="/data/cache/update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 120.090346@1] type=1400 audit(120.024:47): avc: denied { setattr } for pid=4076 comm="Thread-4" name="uncrypt_file" dev="mmcblk0p3" ino=13 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_recovery_file:s0 tclass=file permissive=1
[ 121.326417@0] success set parent gpu_p1_composite rate to 666666666
[ 121.734307@0] success set parent gpu_p0_composite rate to 500000000
[ 121.897440@1] BT_RADIO going: off
[ 121.897470@1] BCM_BT: going OFF
[ 122.342361@2] success set parent gpu_p1_composite rate to 400000000
[ 123.438484@0] success set parent gpu_p0_composite rate to 285714285
[ 123.556904@1] type=1400 audit(120.024:47): avc: denied { setattr } for pid=4076 comm="Thread-4" name="uncrypt_file" dev="mmcblk0p3" ino=13 scontext=u:r:system_app:s0 tcontext=u:object_r:cache_recovery_file:s0 tclass=file permissive=1
[ 123.572107@1] type=1400 audit(123.508:48): avc: denied { getattr } for pid=4211 comm="uncrypt" path="/data/cache" dev="mmcblk0p17" ino=19 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=dir permissive=1
[ 123.591568@1] type=1400 audit(123.508:48): avc: denied { getattr } for pid=4211 comm="uncrypt" path="/data/cache" dev="mmcblk0p17" ino=19 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=dir permissive=1
[ 123.610598@1] type=1400 audit(123.508:49): avc: denied { getattr } for pid=4211 comm="uncrypt" path="/data/cache/update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 123.631453@1] type=1400 audit(123.508:49): avc: denied { getattr } for pid=4211 comm="uncrypt" path="/data/cache/update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 123.652217@1] type=1400 audit(123.512:50): avc: denied { read } for pid=4211 comm="uncrypt" name="update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 123.672583@1] type=1400 audit(123.512:50): avc: denied { read } for pid=4211 comm="uncrypt" name="update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 123.689809@1] type=1400 audit(123.512:51): avc: denied { open } for pid=4211 comm="uncrypt" path="/data/cache/update.zip" dev="mmcblk0p17" ino=316 scontext=u:r:uncrypt:s0 tcontext=u:object_r:cache_file:s0 tclass=file permissive=1
[ 124.950389@3] success set parent gpu_p1_composite rate to 125000000我们根据提示信息，增加相应的selinux权限：
diff --git a/common/sepolicy/system_app.te b/common/sepolicy/system_app.te
index 17e7f4e..3c77d47 100644
--- a/common/sepolicy/system_app.te
+++ b/common/sepolicy/system_app.te
@@ -23,8 +23,8 @@
#allow system_app unlabeled:file { lock open read write getattr };
#
## /cache_file for dvb app creat update.zip file at /cache dir
-allow system_app cache_file:dir { search add_name write };
-allow system_app cache_file:file { create getattr open write };
+allow system_app cache_file:dir { search add_name remove_name write };
+allow system_app cache_file:file { create getattr open write unlink read };
#
#allow system_app log_file:dir { search read open getattr };
#allow system_app log_file:file { read open getattr };
diff --git a/common/sepolicy/uncrypt.te b/common/sepolicy/uncrypt.te
new file mode 100644
index 0000000..578a6d7
--- /dev/null
+++ b/common/sepolicy/uncrypt.te
@@ -0,0 +1,2 @@
+allow uncrypt cache_file:dir getattr;
+allow uncrypt cache_file:file { open read getattr };然后就可以正常升级了。至于如何通过提示的avc: denied信息增加selinux权限，可以自行学习。