init: clean up file / socket descriptor creation

clang-tidy hinted that some of this code wasn't right.  Looking
deeper, there is really not much related to file and socket
descriptors, except that they're published in similar ways to the
environment.  All of the abstraction into a 'Descriptor' class takes
us further away from specifying what we really mean.

This removes that abstraction, adds stricter checks and better errors
for parsing init scripts, reports sockets and files that are unable to
be acquired before exec, and updates the README.md for the passcred
option.

Test: build, logd (uses files and sockets) works
Change-Id: I59e611e95c85bdbefa779ef69b32b9dd4ee203e2

1 files changed, 19 insertions, 0 deletions

diff --git a/init/service_utils.h b/init/service_utils.h
index 365cb298b..befce253a 100644
--- a/init/service_utils.h
+++ b/init/service_utils.h
@@ -29,6 +29,25 @@
 namespace android {
 namespace init {
 
+struct SocketDescriptor {
+    std::string name;
+    int type = 0;
+    uid_t uid = 0;
+    gid_t gid = 0;
+    int perm = 0;
+    std::string context;
+    bool passcred = false;
+
+    Result<void> CreateAndPublish(const std::string& global_context) const;
+};
+
+struct FileDescriptor {
+    std::string name;
+    std::string type;
+
+    Result<void> CreateAndPublish() const;
+};
+
 struct NamespaceInfo {
     int flags;
     // Pair of namespace type, path to name.