Multi-user external storage support.

Emulated external storage always has multi-user support using paths
like "/data/media/<user_id>".  Creates and destroys these paths along
with user data.  Uses new ensure_dir() to create directories while
always ensuring permissions.

Add external storage mount mode to zygote, supporting both single-
and multi-user devices.  For example, devices with physical SD cards
are treated as single-user.  Begin migrating to mount mode instead
of relying on sdcard_r GID to enforce READ_EXTERNAL_STORAGE.

Bug: 6925012
Change-Id: I9b872ded992cd078e2c013567d59f9f0032ec02b

1 files changed, 23 insertions, 3 deletions

diff --git a/cmds/installd/commands.c b/cmds/installd/commands.c
index d94daf70ea3b..0a7cb2d82fbf 100644
--- a/cmds/installd/commands.c
+++ b/cmds/installd/commands.c
@@ -213,18 +213,30 @@ int make_user_data(const char *pkgname, uid_t uid, uid_t persona)
 
 int delete_persona(uid_t persona)
 {
-    char pkgdir[PKG_PATH_MAX];
+    char data_path[PKG_PATH_MAX];
+    if (create_persona_path(data_path, persona)) {
+        return -1;
+    }
+    if (delete_dir_contents(data_path, 1, NULL)) {
+        return -1;
+    }
 
-    if (create_persona_path(pkgdir, persona))
+    char media_path[PATH_MAX];
+    if (create_persona_media_path(media_path, (userid_t) persona) == -1) {
+        return -1;
+    }
+    if (delete_dir_contents(media_path, 1, NULL) == -1) {
         return -1;
+    }
 
-    return delete_dir_contents(pkgdir, 1, NULL);
+    return 0;
 }
 
 int clone_persona_data(uid_t src_persona, uid_t target_persona, int copy)
 {
     char src_data_dir[PKG_PATH_MAX];
     char pkg_path[PKG_PATH_MAX];
+    char media_path[PATH_MAX];
     DIR *d;
     struct dirent *de;
     struct stat s;
@@ -233,6 +245,9 @@ int clone_persona_data(uid_t src_persona, uid_t target_persona, int copy)
     if (create_persona_path(src_data_dir, src_persona)) {
         return -1;
     }
+    if (create_persona_media_path(media_path, (userid_t) target_persona) == -1) {
+        return -1;
+    }
 
     d = opendir(src_data_dir);
     if (d != NULL) {
@@ -260,6 +275,11 @@ int clone_persona_data(uid_t src_persona, uid_t target_persona, int copy)
         }
         closedir(d);
     }
+
+    // ensure /data/media/<user_id> exists
+    if (ensure_dir(media_path, 0770, AID_MEDIA_RW, AID_MEDIA_RW) == -1) {
+        return -1;
+    }
     return 0;
 }