[libc++] random_device fails if open returns zero

random_device::random_device(const string&) wrongly assumes that open
can only validly return a file descriptor greater than zero.

This results in random_device believing that it didn't successfully open
the device causing it to throw in it's constructor, this ends up leaking
a file descriptor.

The fix is simple, don't error on file descriptors which are zero.


git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@210060 91177308-0d34-0410-b5e6-96231b3b80d8

src/random.cpp

diff --git a/src/random.cpp b/src/random.cpp
index bd24f2e..21e2168 100644
--- a/src/random.cpp
+++ b/src/random.cpp
@@ -49,7 +49,7 @@
 random_device::random_device(const string& __token)
     : __f_(open(__token.c_str(), O_RDONLY))
 {
-    if (__f_ <= 0)
+    if (__f_ < 0)
         __throw_system_error(errno, ("random_device failed to open " + __token).c_str());
 }
 

test/numerics/rand/rand.device/ctor.pass.cpp

diff --git a/test/numerics/rand/rand.device/ctor.pass.cpp b/test/numerics/rand/rand.device/ctor.pass.cpp
index a7c38d4..dfa546b 100644
--- a/test/numerics/rand/rand.device/ctor.pass.cpp
+++ b/test/numerics/rand/rand.device/ctor.pass.cpp
@@ -15,6 +15,7 @@
 
 #include <random>
 #include <cassert>
+#include <unistd.h>
 
 int main()
 {
@@ -30,6 +31,16 @@
         std::random_device r;
     }
     {
+        int ec;
+        ec = close(STDIN_FILENO);
+        assert(!ec);
+        ec = close(STDOUT_FILENO);
+        assert(!ec);
+        ec = close(STDERR_FILENO);
+        assert(!ec);
+        std::random_device r;
+    }
+    {
         std::random_device r("/dev/urandom");;
     }
     {