Fix handling of file descriptor zero

If opening /dev/*random resulted in fd 0, we would both not use
that RNG and leak the file descriptor. Found with Coverity.

1 files changed, 11 insertions, 13 deletions

diff --git a/src/lib/entropy/dev_random/dev_random.cpp b/src/lib/entropy/dev_random/dev_random.cpp
index b51f19ecb..f37831d2e 100644
--- a/src/lib/entropy/dev_random/dev_random.cpp
+++ b/src/lib/entropy/dev_random/dev_random.cpp
@@ -38,18 +38,7 @@ Device_EntropySource::Device_EntropySource(const std::vector<std::string>& fsnam
       {
       int fd = ::open(fsname.c_str(), flags);
 
-      if(fd > 0)
-         {
-         if(fd > FD_SETSIZE)
-            {
-            ::close(fd);
-            throw Exception("Open of OS RNG succeeded but fd is too large for fd_set");
-            }
-
-         m_dev_fds.push_back(fd);
-         m_max_fd = std::max(m_max_fd, fd);
-         }
-      else
+      if(fd < 0)
          {
          /*
          ENOENT or EACCES is normal as some of the named devices may not exist
@@ -57,10 +46,19 @@ Device_EntropySource::Device_EntropySource(const std::vector<std::string>& fsnam
          either a bug in the application or file descriptor exhaustion.
          */
          if(errno != ENOENT && errno != EACCES)
-            {
             throw Exception("Opening OS RNG device failed with errno " +
                             std::to_string(errno));
+         }
+      else
+         {
+         if(fd > FD_SETSIZE)
+            {
+            ::close(fd);
+            throw Exception("Open of OS RNG succeeded but fd is too large for fd_set");
             }
+
+         m_dev_fds.push_back(fd);
+         m_max_fd = std::max(m_max_fd, fd);
          }
       }
    }