Deduplicates NaClSysSysconf implementation

src/trusted/service_runtime/nacl_syscall_common.c

Index: src/trusted/service_runtime/nacl_syscall_common.c
diff --git a/src/trusted/service_runtime/nacl_syscall_common.c b/src/trusted/service_runtime/nacl_syscall_common.c
index ec0998041640179738151bd15c12dde85dc6a7bd..2e1acf6f84e435421378b9fd4089f034406be041 100644
--- a/src/trusted/service_runtime/nacl_syscall_common.c
+++ b/src/trusted/service_runtime/nacl_syscall_common.c
@@ -11,6 +11,9 @@
 #include <sys/stat.h>
 
 #include <stdio.h>
+#if NACL_WINDOWS
+#include <windows.h>
+#endif
 
 #include "native_client/src/trusted/service_runtime/nacl_syscall_common.h"
 
@@ -47,6 +50,7 @@
 #include "native_client/src/trusted/service_runtime/include/sys/errno.h"
 #include "native_client/src/trusted/service_runtime/include/sys/fcntl.h"
 #include "native_client/src/trusted/service_runtime/include/sys/stat.h"
+#include "native_client/src/trusted/service_runtime/include/sys/unistd.h"
 
 #include "native_client/src/trusted/service_runtime/include/sys/nacl_test_crash.h"
 #include "native_client/src/trusted/service_runtime/internal_errno.h"
@@ -3419,6 +3423,66 @@ int32_t NaClSysSchedYield(struct NaClAppThread *natp) {
   return 0;
 }
 
+int32_t NaClSysSysconf(struct NaClAppThread *natp,
+                       int32_t              name,
+                       int32_t              *result) {
+  struct NaClApp  *nap = natp->nap;
+  int32_t         retval = -NACL_ABI_EINVAL;
+  int32_t         result_value;
+
+  NaClLog(3,
+          ("Entered NaClSysSysconf(%08"NACL_PRIxPTR
+           "x, %d, 0x%08"NACL_PRIxPTR")\n"),
+          (uintptr_t) natp, name, (uintptr_t) result);
+
+  switch (name) {
+    case NACL_ABI__SC_NPROCESSORS_ONLN: {
+#if NACL_WINDOWS
+      if (0 == nap->sc_nprocessors_onln) {

[Mark Seaborn, 2013/09/09 21:39:38]

Double-checking a field like this will still be reported as a data race by
race-checking tools.

Why do you want to cache the result of GetSystemInfo()?  Do you believe it is
slow?

You're still doing >1 thing in one change.  I'd prefer if you left out this
caching change.

[Petr Hosek, 2013/09/09 21:46:54]

Because the original implementation does the some, just uses an extra static
variable instead of the existing field; I have reverted this change if you
prefer the original way.

+        NaClXMutexLock(&nap->mu);
+        if (0 == nap->sc_nprocessors_onln) {
+          SYSTEM_INFO si;
+          GetSystemInfo(&si);
+          nap->sc_nprocessors_onln = (int32_t) si.dwNumberOfProcessors;
+        }
+        NaClXMutexUnlock(&nap->mu);
+      }
+#elif NACL_LINUX || NACL_OSX
+      if (-1 == nap->sc_nprocessors_onln) {
+        /* Unable to get the number of processors at startup. */
+        goto cleanup;
+      }
+#else
+#error Unsupported platform
+#endif
+      result_value = nap->sc_nprocessors_onln;
+      break;
+    }
+    case NACL_ABI__SC_SENDMSG_MAX_SIZE: {
+      /* TODO(sehr,bsy): this value needs to be determined at run time. */
+      const int32_t kImcSendMsgMaxSize = 1 << 16;
+      result_value = kImcSendMsgMaxSize;
+      break;
+    }
+    case NACL_ABI__SC_PAGESIZE: {
+      result_value = 1 << 16;  /* always 64k pages */
+      break;
+    }
+    default: {
+      retval = -NACL_ABI_EINVAL;
+      goto cleanup;
+    }
+  }
+  if (!NaClCopyOutToUser(nap, (uintptr_t) result, &result_value,
+                         sizeof result_value)) {
+    retval = -NACL_ABI_EFAULT;
+    goto cleanup;
+  }
+  retval = 0;
+cleanup:
+  return retval;
+}
+
 int32_t NaClSysExceptionHandler(struct NaClAppThread *natp,
                                 uint32_t             handler_addr,
                                 uint32_t             old_handler) {