Test whether /dev/zero works before attemping to us it

1 files changed, 28 insertions, 0 deletions

diff --git a/sim/ppc/configure.in b/sim/ppc/configure.in
index 1314a93..4924f78 100644
--- a/sim/ppc/configure.in
+++ b/sim/ppc/configure.in
@@ -593,6 +593,33 @@ else
   ac_cv_termio_cline=no
 fi
 
+dnl Figure out if /dev/zero exists or not
+sim_devzero=""
+AC_MSG_CHECKING(for /dev/zero)
+AC_CACHE_VAL(ac_cv_devzero,
+[AC_TRY_RUN([#include <fcntl.h>
+main () {
+  char buf[2048];
+  int i;
+  int fd = open ("/dev/zero", O_RDONLY);
+  if (fd < 0)
+    return 1;
+  for (i = 0; i < sizeof (buf); i++)
+    buf[i] = 1;
+  if (read (fd, buf, sizeof (buf)) != sizeof (buf))
+    return 1;
+  for (i = 0; i < sizeof (buf); i++)
+    if (buf[i])
+      return 1;
+  return 0;
+}],[ac_cv_devzero=yes],[ac_cv_devzero=no],[ac_cv_devzero=no])])
+AC_MSG_RESULT($ac_cv_devzero)
+if test $ac_cv_devzero = yes; then
+  sim_devzero="-DHAVE_DEVZERO"
+else
+  sim_devzero=""
+fi
+
 AC_SUBST(CC_FOR_BUILD)
 AC_SUBST(CFLAGS)
 AC_SUBST(HDEFINES)
@@ -637,6 +664,7 @@ AC_SUBST(sim_default_model)
 AC_SUBST(sim_model_issue)
 AC_SUBST(sim_stdio)
 AC_SUBST(sim_termio)
+AC_SUBST(sim_devzero)
 
 AC_OUTPUT(Makefile,
 [case x$CONFIG_HEADERS in xconfig.h:config.in) echo > stamp-h ;; esac])