Add more comments for resolv apex.

Describe the link of resolv apex detailedly.

Bug: 119527674
Test: make; flash; lsof -p $(pidof netd)
Change-Id: I0f6038eb9950c6b862a257d0a6f35f19cb83a328

3 files changed, 27 insertions, 0 deletions

diff --git a/rootdir/etc/ld.config.legacy.txt b/rootdir/etc/ld.config.legacy.txt
index 1321c241f..f998ae218 100644
--- a/rootdir/etc/ld.config.legacy.txt
+++ b/rootdir/etc/ld.config.legacy.txt
@@ -38,6 +38,12 @@ namespace.default.asan.search.paths +=           /odm/${LIB}
 additional.namespaces = runtime,conscrypt,media,resolv
 
 # Keep in sync with ld.config.txt in the com.android.runtime APEX.
+# If a shared library or an executable requests a shared library that
+# cannot be loaded into the default namespace, the dynamic linker tries
+# to load the shared library from the runtime namespace.And then, if the
+# shared library cannot be loaded from the runtime namespace either, the
+# dynamic linker tries to load the shared library from the resolv namespace.
+# Finally, if all attempts fail, the dynamic linker returns an error.
 namespace.default.links = runtime,resolv
 namespace.default.asan.links = runtime,resolv
 # Visible because some libraries are dlopen'ed, e.g. libopenjdk is dlopen'ed by
@@ -49,6 +55,9 @@ namespace.default.link.runtime.shared_libs += libnativebridge.so
 namespace.default.link.runtime.shared_libs += libnativehelper.so
 namespace.default.link.runtime.shared_libs += libnativeloader.so
 
+# When libnetd_resolv.so can't be found in the default namespace, search for it
+# in the resolv namespace. Don't allow any other libraries from the resolv namespace
+# to be loaded in the default namespace.
 namespace.default.link.resolv.shared_libs = libnetd_resolv.so
 
 ###############################################################################
diff --git a/rootdir/etc/ld.config.txt b/rootdir/etc/ld.config.txt
index f37f92266..269928661 100644
--- a/rootdir/etc/ld.config.txt
+++ b/rootdir/etc/ld.config.txt
@@ -106,6 +106,12 @@ namespace.default.asan.permitted.paths += /%PRODUCT_SERVICES%/priv-app
 namespace.default.asan.permitted.paths += /mnt/expand
 
 # Keep in sync with ld.config.txt in the com.android.runtime APEX.
+# If a shared library or an executable requests a shared library that
+# cannot be loaded into the default namespace, the dynamic linker tries
+# to load the shared library from the runtime namespace.And then, if the
+# shared library cannot be loaded from the runtime namespace either, the
+# dynamic linker tries to load the shared library from the resolv namespace.
+# Finally, if all attempts fail, the dynamic linker returns an error.
 namespace.default.links = runtime,resolv
 # Visible because some libraries are dlopen'ed, e.g. libopenjdk is dlopen'ed by
 # libart.
@@ -116,6 +122,9 @@ namespace.default.link.runtime.shared_libs += libnativebridge.so
 namespace.default.link.runtime.shared_libs += libnativehelper.so
 namespace.default.link.runtime.shared_libs += libnativeloader.so
 
+# When libnetd_resolv.so can't be found in the default namespace, search for it
+# in the resolv namespace. Don't allow any other libraries from the resolv namespace
+# to be loaded in the default namespace.
 namespace.default.link.resolv.shared_libs = libnetd_resolv.so
 
 ###############################################################################
diff --git a/rootdir/etc/ld.config.vndk_lite.txt b/rootdir/etc/ld.config.vndk_lite.txt
index a8ed04f24..bd889d1c8 100644
--- a/rootdir/etc/ld.config.vndk_lite.txt
+++ b/rootdir/etc/ld.config.vndk_lite.txt
@@ -57,6 +57,12 @@ namespace.default.asan.search.paths +=           /%PRODUCT_SERVICES%/${LIB}
 
 # Keep in sync with the platform namespace in the com.android.runtime APEX
 # ld.config.txt.
+# If a shared library or an executable requests a shared library that
+# cannot be loaded into the default namespace, the dynamic linker tries
+# to load the shared library from the runtime namespace.And then, if the
+# shared library cannot be loaded from the runtime namespace either, the
+# dynamic linker tries to load the shared library from the resolv namespace.
+# Finally, if all attempts fail, the dynamic linker returns an error.
 namespace.default.links = runtime,resolv
 # Visible because some libraries are dlopen'ed, e.g. libopenjdk is dlopen'ed by
 # libart.
@@ -66,6 +72,9 @@ namespace.default.link.runtime.shared_libs += libdexfile_external.so
 namespace.default.link.runtime.shared_libs += libnativehelper.so
 namespace.default.link.runtime.shared_libs += libnativeloader.so
 
+# When libnetd_resolv.so can't be found in the default namespace, search for it
+# in the resolv namespace. Don't allow any other libraries from the resolv namespace
+# to be loaded in the default namespace.
 namespace.default.link.resolv.shared_libs = libnetd_resolv.so
 
 ###############################################################################