commit e2cac6148b9e1357596e545900b40acd9509749c
author Jae Hoon Kim <kimjae@chromium.org> Mon Nov 02 18:30:29 2020 -0800
committer Commit Bot <commit-bot@chromium.org> Tue Nov 10 00:17:27 2020 +0000
tree d55f650c01477bae990e21fdf50f15a905b19389
parent 5611cd3e418bc1e7451d4247daef836077efa9a0

update_engine: Support DLC Cohorts

UE at the moment doesn't send the correct cohorts to Omaha for DLCs. In
fact, the platform cohorts that are persisted are used for all DLCs.
This is incorrect and this CL fixes it.

```
Example DLC Response:
... cohort="1:7:" cohortname="eve_dlc_pita_canary"...

localhost ~ # ls /var/lib/update_engine/prefs/dlc/pita/omaha-cohort*
/var/lib/update_engine/prefs/dlc/pita/omaha-cohort
/var/lib/update_engine/prefs/dlc/pita/omaha-cohort-name
localhost ~ # cat /var/lib/update_engine/prefs/dlc/pita/omaha-cohort
1:7:
localhost ~ # cat
/var/lib/update_engine/prefs/dlc/pita/omaha-cohort-name
eve_dlc_pita_canary
```

BUG=b:162463872
TEST=FEATURES=test emerge-$B update_engine
TEST=# cros deploy + comment above

Change-Id: Ie503f0a63d3b19a51abb88379cb2e8f85919858b
Reviewed-on: https://chromium-review.googlesource.com/c/aosp/platform/system/update_engine/+/2515072
Tested-by: Jae Hoon Kim <kimjae@chromium.org>
Reviewed-by: Amin Hassani <ahassani@chromium.org>
Commit-Queue: Jae Hoon Kim <kimjae@chromium.org>

cros/omaha_request_builder_xml.cc

diff --git a/cros/omaha_request_builder_xml.cc b/cros/omaha_request_builder_xml.cc
index 43ee548..739abbf 100644
--- a/cros/omaha_request_builder_xml.cc
+++ b/cros/omaha_request_builder_xml.cc
@@ -215,9 +215,10 @@
   return app_body;
 }
 
-string OmahaRequestBuilderXml::GetCohortArg(const string arg_name,
-                                            const string prefs_key,
-                                            const string override_value) const {
+string OmahaRequestBuilderXml::GetCohortArg(
+    const string& arg_name,
+    const string& prefs_key,
+    const string& override_value) const {
   string cohort_value;
   if (!override_value.empty()) {
     // |override_value| take precedence over pref value.
@@ -296,14 +297,30 @@
   }
 
   string app_cohort_args;
-  app_cohort_args += GetCohortArg("cohort", kPrefsOmahaCohort);
-  app_cohort_args += GetCohortArg("cohortname", kPrefsOmahaCohortName);
+  string cohort_key = kPrefsOmahaCohort;
+  string cohortname_key = kPrefsOmahaCohortName;
+  string cohorthint_key = kPrefsOmahaCohortHint;
 
+  // Override the cohort keys for DLC App IDs.
+  const auto& dlc_apps_params = params_->dlc_apps_params();
+  auto itr = dlc_apps_params.find(app_data.id);
+  if (itr != dlc_apps_params.end()) {
+    auto dlc_id = itr->second.name;
+    cohort_key =
+        prefs_->CreateSubKey({kDlcPrefsSubDir, dlc_id, kPrefsOmahaCohort});
+    cohortname_key =
+        prefs_->CreateSubKey({kDlcPrefsSubDir, dlc_id, kPrefsOmahaCohortName});
+    cohorthint_key =
+        prefs_->CreateSubKey({kDlcPrefsSubDir, dlc_id, kPrefsOmahaCohortHint});
+  }
+
+  app_cohort_args += GetCohortArg("cohort", cohort_key);
+  app_cohort_args += GetCohortArg("cohortname", cohortname_key);
   // Policy provided value overrides pref.
-  string autoupdate_token = params_->autoupdate_token();
-  app_cohort_args += GetCohortArg("cohorthint",
-                                  kPrefsOmahaCohortHint,
-                                  autoupdate_token /* override_value */);
+  app_cohort_args +=
+      GetCohortArg("cohorthint",
+                   cohorthint_key,
+                   params_->autoupdate_token() /* override_value */);
 
   string fingerprint_arg;
   if (!params_->os_build_fingerprint().empty()) {