Test getentropy

We want to ensure that tools that call getentropy() are also
controlled appropriately.

.gitignore

@@ -7,6 +7,7 @@ test/lib*.so
 test/use_lib_random
 test/use_lib_getpid
 test/repeat_random
+test/getentropy_test
 
 src/libfaketime.dylib.1
 src/libfaketime.1.dylib

test/Makefile

@@ -25,7 +25,7 @@ functest:
 %_test: %_test.c
 	${CC} -o $@ ${CFLAGS} $<
 
-randomtest: getrandom_test use_lib_random librandom.so repeat_random
+randomtest: getrandom_test use_lib_random librandom.so repeat_random getentropy_test
 	./randomtest.sh
 
 getpidtest: use_lib_getpid libgetpid.so

test/getentropy_test.c

@@ -0,0 +1,14 @@
+#include <unistd.h>
+#include <stdio.h>
+
+int main() {
+  unsigned char buf[16];
+  if (getentropy(buf, sizeof(buf))) {
+    perror("failed to getentropy()");
+    return 1;
+  }
+  for (size_t i = 0; i < sizeof(buf); i++)
+    printf("%02x", buf[i]);
+  printf("\n");
+  return 0;
+}

test/randomtest.sh

@@ -6,7 +6,7 @@ set -e
 
 error=0
 
-for iface in getrandom; do
+for iface in getrandom getentropy; do
     printf "Testing %s() interception...\n" "$iface"
 
     "./${iface}_test" > "${iface}.alone"