Clean up: Pass File* to DexFileLoader instead of fd.

The DexFileLoader used to always close the fd, which led to
need to duplicate the fds using DupCloexec, or it was easy
to accidentally close the fd while it was still needed.

Make the DexFileLoader take File pointer, which moves the
lifetime management responsibilities to the caller.
The DexFileLoader never closes a file that it didn't open.

Test: ./art/test.py -b --host --64 --optimizing
Change-Id: Ie428edcae6c9062845c57c53528baee249046d70

1 files changed, 10 insertions, 7 deletions

diff --git a/runtime/class_loader_context.cc b/runtime/class_loader_context.cc
index 73546ed0a9..6dc94fbd25 100644
--- a/runtime/class_loader_context.cc
+++ b/runtime/class_loader_context.cc
@@ -462,7 +462,7 @@ bool ClassLoaderContext::OpenDexFiles(const std::string& classpath_dir,
       // If file descriptors were provided for the class loader context dex paths,
       // get the descriptor which corresponds to this dex path. We assume the `fds`
       // vector follows the same order as a flattened class loader context.
-      int fd = -1;
+      File file;
       if (!fds.empty()) {
         if (dex_file_index >= fds.size()) {
           LOG(WARNING) << "Number of FDs is smaller than number of dex files in the context";
@@ -470,32 +470,35 @@ bool ClassLoaderContext::OpenDexFiles(const std::string& classpath_dir,
           return false;
         }
 
-        fd = fds[dex_file_index++];
-        DCHECK_GE(fd, 0);
+        file = File(fds[dex_file_index++], /*check_usage=*/false);
+        DCHECK(file.IsValid());
       }
 
       std::string error_msg;
       std::optional<uint32_t> dex_checksum;
       if (only_read_checksums) {
         bool zip_file_only_contains_uncompress_dex;
-        ArtDexFileLoader dex_file_loader(DupCloexec(fd), location);
+        ArtDexFileLoader dex_file_loader(&file, location);
         if (!dex_file_loader.GetMultiDexChecksum(
                 &dex_checksum, &error_msg, &zip_file_only_contains_uncompress_dex)) {
-          LOG(WARNING) << "Could not get dex checksums for location " << location << ", fd=" << fd;
+          LOG(WARNING) << "Could not get dex checksums for location " << location
+                       << ", fd=" << file.Fd();
           dex_files_state_ = kDexFilesOpenFailed;
         }
+        file.Release();  // Don't close the file yet (we have only read the checksum).
       } else {
         // When opening the dex files from the context we expect their checksum to match their
         // contents. So pass true to verify_checksum.
         // We don't need to do structural dex file verification, we only need to
         // check the checksum, so pass false to verify.
         size_t i = info->opened_dex_files.size();
-        ArtDexFileLoader dex_file_loader(fd, location);
+        ArtDexFileLoader dex_file_loader(&file, location);
         if (!dex_file_loader.Open(/*verify=*/false,
                                   /*verify_checksum=*/true,
                                   &error_msg,
                                   &info->opened_dex_files)) {
-          LOG(WARNING) << "Could not open dex files for location " << location << ", fd=" << fd;
+          LOG(WARNING) << "Could not open dex files for location " << location
+                       << ", fd=" << file.Fd();
           dex_files_state_ = kDexFilesOpenFailed;
         } else {
           dex_checksum = DexFileLoader::GetMultiDexChecksum(info->opened_dex_files, &i);