SOAAP can now find leaks of sandbox-private data via global variables.
Sample error message:

*** Sandboxed method dostuff executing in sandboxes: [network] may leak private data through global variable x
+++ Line 20 of file test-sandboxprivate-leakviaglobal.c

  4 int x;
  5
  6 void dostuff();
  7
  8 int main() {
  9   dostuff();
 10   printf("value of secret sandbox-private local variable: %d\n", x);
 11   return 0;
 12 }
 13
 14 __soaap_sandbox_persistent_named("network")
 15 void dostuff() {
 16   int y __soaap_sandbox_private("network");
 17   y = 25;
 18   int z = y;
 19   printf("leaking sandbox-private y to global x\n");
 20   x = z;
 21 }