Non-SFI mode: Implement nacl_irt_random only for nacl_helper_nonsfi.

src/nonsfi/irt/irt_interfaces.c

Index: src/nonsfi/irt/irt_interfaces.c
diff --git a/src/nonsfi/irt/irt_interfaces.c b/src/nonsfi/irt/irt_interfaces.c
index 562d204b71a58f26605fb3d5cbdf71cf0bf45646..e364d27c9e0b49dd7aab794b15a66b28ecc0d196 100644
--- a/src/nonsfi/irt/irt_interfaces.c
+++ b/src/nonsfi/irt/irt_interfaces.c
@@ -38,6 +38,10 @@
 #include "native_client/src/untrusted/irt/irt_dev.h"
 #include "native_client/src/untrusted/irt/irt_interfaces.h"
 
+#if defined(__native_client__)
+#include "native_client/src/nonsfi/irt/irt_random.h"
+#endif
+
 /*
  * This is an implementation of NaCl's IRT interfaces that runs
  * outside of the NaCl sandbox.
@@ -431,6 +435,22 @@ static int futex_wake(volatile int *addr, int nwake, int *count) {
 }
 #endif
 
+#if defined(__native_client__)
+static int urandom_fd = -1;

[Mark Seaborn, 2014/10/30 18:58:30]

Style nit: Add "g_" prefix to the name

[hidehiko, 2014/10/31 14:03:52]

Done (in irt_random.c).

+
+void nonsfi_set_urandom_fd(int fd) {
+  urandom_fd = fd;
+}
+
+static int irt_get_random_bytes(void *buf, size_t count, size_t *nread) {

[Mark Seaborn, 2014/10/30 18:58:30]

It's rather unfortunate that this isn't tested on the NaCl side.

One of the goals in the newlib switch was to improve testing of IRT interface
implementations, because moving IRT interface implementations to the NaCl side
allows us to run NaCl-side tests against those implementations.

So, could you add a small amount of plumbing so that we can enable
run_random_test_irt to cover this code?  i.e. If urandom_fd == -1, try to open
/dev/urandom.

(An alternative would be to implement irt_random on the Chromium side.  That
would be reasonable, since irt_random is very simple to implement.  However,
implementing irt_random on the NaCl side is more usable since the code can be
reused for the unsandboxed-PNaCl use case.)

[hidehiko, 2014/10/31 14:03:52]

Done.

+  int result = read(urandom_fd, buf, count);
+  if (result < 0)
+    return errno;
+  *nread = result;
+  return 0;
+}
+#endif
+
 #if defined(__linux__) || defined(__native_client__)
 static int irt_clock_getres(nacl_irt_clockid_t clk_id,
                             struct timespec *time_nacl) {
@@ -599,6 +619,12 @@ const struct nacl_irt_futex nacl_irt_futex = {
 };
 #endif
 
+#if defined(__native_client__)
+const struct nacl_irt_random nacl_irt_random = {
+  irt_get_random_bytes,
+};
+#endif
+
 #if defined(__linux__) || defined(__native_client__)
 const struct nacl_irt_clock nacl_irt_clock = {
   irt_clock_getres,
@@ -650,6 +676,9 @@ static const struct nacl_irt_interface irt_interfaces[] = {
   { NACL_IRT_TLS_v0_1, &nacl_irt_tls, sizeof(nacl_irt_tls), NULL },
   { NACL_IRT_THREAD_v0_1, &nacl_irt_thread, sizeof(nacl_irt_thread), NULL },
   { NACL_IRT_FUTEX_v0_1, &nacl_irt_futex, sizeof(nacl_irt_futex), NULL },
+#if defined(__native_client__)
+  { NACL_IRT_RANDOM_v0_1, &nacl_irt_random, sizeof(nacl_irt_random), NULL },
+#endif
 #if defined(__linux__) || defined(__native_client__)
   { NACL_IRT_CLOCK_v0_1, &nacl_irt_clock, sizeof(nacl_irt_clock), NULL },
 #endif