Added an failure log message when the fwdlock engine fails to open a given file.

Change-Id: I0e7f60b61f03fde046fc1ad668b28cdee635898b

drm/libdrmframework/plugins/forward-lock/internal-format/decoder/FwdLockFile.c

@@ -14,6 +14,7 @@
  * limitations under the License.
  */
 
+#include <utils/Log.h>
 #include <assert.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -107,6 +108,7 @@ static int FwdLockFile_AcquireSession(int fileDesc) {
         }
         pthread_mutex_unlock(&sessionAcquisitionMutex);
         if (i == MAX_NUM_SESSIONS) {
+            ALOGE("Too many sessions opened at the same time");
             errno = ENFILE;
         }
     }
@@ -293,7 +295,12 @@ int FwdLockFile_attach(int fileDesc) {
 
 int FwdLockFile_open(const char *pFilename) {
     int fileDesc = open(pFilename, O_RDONLY);
-    if (fileDesc >= 0 && FwdLockFile_attach(fileDesc) < 0) {
+    if (fileDesc < 0) {
+        ALOGE("failed to open file '%s': %s", pFilename, strerror(errno));
+        return fileDesc;
+    }
+
+    if (FwdLockFile_attach(fileDesc) < 0) {
         (void)close(fileDesc);
         fileDesc = -1;
     }