init: Put init in group AID_READPROC
bootcharts currently only show root's processes, which isn't very
useful. To investigate and track boot duration issues, we need a way for
init to see all the pids. Add init to GID 3009 (aka AID_READPROC)
Ensure that init's children don't inherit this GID by always clearing
supplementary group IDs on fork.
Bug: 32506197
Test: Device boots and /proc/1/status says init is in gid 3009
Test: zygote starts and the Group: line in /proc/ZYGOTEPID/status is empty
Change-Id: Iba90717aaa591f1d6030a379a272aee003600c0a
Not-Tested: bootchart actually works. Speculative fix.
diff --git a/init/init.cpp b/init/init.cpp
index 957527b..38cf45c 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -585,6 +585,8 @@
mount("devpts", "/dev/pts", "devpts", 0, NULL);
#define MAKE_STR(x) __STRING(x)
mount("proc", "/proc", "proc", 0, "hidepid=2,gid=" MAKE_STR(AID_READPROC));
+ gid_t groups[] = { AID_READPROC };
+ setgroups(arraysize(groups), groups);
mount("sysfs", "/sys", "sysfs", 0, NULL);
mount("selinuxfs", "/sys/fs/selinux", "selinuxfs", 0, NULL);
mknod("/dev/kmsg", S_IFCHR | 0600, makedev(1, 11));