fix possible buffer overrun and memory leak

Use snprintf instead of sprintf and fclose() before return.

Change-Id: I3ed193464cc0dc90e9935ae19162667ad367628b

core/jni/android_util_Binder.cpp

@@ -951,13 +951,20 @@ static jboolean android_os_BinderProxy_isBinderAlive(JNIEnv* env, jobject obj)
 }
 
 static int getprocname(pid_t pid, char *buf, size_t len) {
-    char filename[20];
+    char filename[32];
     FILE *f;
 
-    sprintf(filename, "/proc/%d/cmdline", pid);
+    snprintf(filename, sizeof(filename), "/proc/%d/cmdline", pid);
     f = fopen(filename, "r");
-    if (!f) { *buf = '\0'; return 1; }
-    if (!fgets(buf, len, f)) { *buf = '\0'; return 2; }
+    if (!f) {
+        *buf = '\0';
+        return 1;
+    }
+    if (!fgets(buf, len, f)) {
+        *buf = '\0';
+        fclose(f);
+        return 2;
+    }
     fclose(f);
     return 0;
 }