OMS: extract verifyIdmap from createIdmap

For clarity, split IIdmap2::createIdmap into two separate functions:

  - IIdmap2::verifyIdmap [check if an existing idmap file is OK to use]
  - IIdmap2::createIdmap [unconditionally (re)create an idmap file]

Teach the IdmapManager to call verifyIdmap and to proceed with
createIdmap only if actually needed.

Test: atest OverlayDeviceTests OverlayHostTests
Change-Id: I9f6f1192011fcb094adffeca1eb3f709520bbd24

1 files changed, 13 insertions, 11 deletions

diff --git a/cmds/idmap2/idmap2d/Idmap2Service.cpp b/cmds/idmap2/idmap2d/Idmap2Service.cpp
index cf72cb94da2c..86b00f1d6e95 100644
--- a/cmds/idmap2/idmap2d/Idmap2Service.cpp
+++ b/cmds/idmap2/idmap2d/Idmap2Service.cpp
@@ -78,6 +78,18 @@ Status Idmap2Service::removeIdmap(const std::string& overlay_apk_path,
   }
 }
 
+Status Idmap2Service::verifyIdmap(const std::string& overlay_apk_path,
+                                  int32_t user_id ATTRIBUTE_UNUSED, bool* _aidl_return) {
+  assert(_aidl_return);
+  const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_apk_path);
+  std::ifstream fin(idmap_path);
+  const std::unique_ptr<const IdmapHeader> header = IdmapHeader::FromBinaryStream(fin);
+  fin.close();
+  std::stringstream dev_null;
+  *_aidl_return = header && header->IsUpToDate(dev_null);
+  return ok();
+}
+
 Status Idmap2Service::createIdmap(const std::string& target_apk_path,
                                   const std::string& overlay_apk_path, int32_t user_id,
                                   std::unique_ptr<std::string>* _aidl_return) {
@@ -90,17 +102,6 @@ Status Idmap2Service::createIdmap(const std::string& target_apk_path,
 
   _aidl_return->reset(nullptr);
 
-  const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_apk_path);
-  std::ifstream fin(idmap_path);
-  const std::unique_ptr<const IdmapHeader> header = IdmapHeader::FromBinaryStream(fin);
-  fin.close();
-  // do not reuse error stream from IsUpToDate below, or error messages will be
-  // polluted with irrelevant data
-  std::stringstream dev_null;
-  if (header && header->IsUpToDate(dev_null)) {
-    return ok();
-  }
-
   const std::unique_ptr<const ApkAssets> target_apk = ApkAssets::Load(target_apk_path);
   if (!target_apk) {
     return error("failed to load apk " + target_apk_path);
@@ -119,6 +120,7 @@ Status Idmap2Service::createIdmap(const std::string& target_apk_path,
   }
 
   umask(0133);  // u=rw,g=r,o=r
+  const std::string idmap_path = Idmap::CanonicalIdmapPathFor(kIdmapCacheDir, overlay_apk_path);
   std::ofstream fout(idmap_path);
   if (fout.fail()) {
     return error("failed to open idmap path " + idmap_path);