1 files changed, 54 insertions, 0 deletions
diff --git a/src/sysdeps/trydevrandom.c b/src/sysdeps/trydevrandom.c
new file mode 100644
index 0000000..395d008
--- /dev/null
+++ b/src/sysdeps/trydevrandom.c
@@ -0,0 +1,54 @@
+/* ISC license. */
+
+#include <unistd.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <errno.h>
+
+static int fd_read (int fd, char *buf, unsigned int len)
+{
+  register int r ;
+  do r = read(fd, buf, len) ;
+  while ((r == -1) && (errno == EINTR)) ;
+  return r ;
+}
+
+static unsigned int allread (int fd, register char *buf, register unsigned int len)
+{
+  register unsigned int written = 0 ;
+  while (len)
+  {
+    register int w = fd_read(fd, buf, len) ;
+    if (!w) errno = EPIPE ;
+    if (w <= 0) break ;
+    written += w ;
+    buf += w ;
+    len -= w ;
+  }
+  return written ;
+}
+
+static int byte_diff (char *s, unsigned int n, char *t)
+{
+  for (;;)
+  {
+    if (!n) return 0 ;
+    if (*s != *t) break ;
+    ++s ; ++t ; --n ;
+  }
+  return ((int)(unsigned int)(unsigned char) *s)
+       - ((int)(unsigned int)(unsigned char) *t);
+}
+
+int main ()
+{
+  char a[64] ;
+  char b[64] ;
+  int fd = open("/dev/random", O_RDONLY) ;
+  if ((fd == -1) || (allread(fd, a, 64) < 64) ) return 111 ;
+  close(fd) ;
+  fd = open("/dev/random", O_RDONLY) ;
+  if ((fd == -1) || (allread(fd, b, 64) < 64) ) return 111 ;
+  close(fd) ;
+  return !byte_diff(a, 64, b) ;
+}