Automatically probe for sys/poll.h

Include example of nasty program where strace (by design) gives
incorrect output.

2 files changed, 31 insertions, 1 deletions

diff --git a/test/Makefile b/test/Makefile
index 36670cb..ddaa404 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -2,7 +2,7 @@
 # $Id$
 #
 
-all: fork sig
+all: fork sig skodic
 
 clean distclean:
 	rm -f fork sig *.o core
diff --git a/test/skodic.c b/test/skodic.c
new file mode 100644
index 0000000..4e65d5d
--- /dev/null
+++ b/test/skodic.c
@@ -0,0 +1,30 @@
+/* This demonstrates races: kernel may actually open other file then
+ * you read at strace output. Create /tmp/delme with 10K of zeros and
+ * 666 mode, then run this under strace. If you see open successfull
+ * open of /etc/shadow, you know you've seen a race.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/mman.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+void
+main(void)
+{
+  char *c = 0x94000000;
+  open( "/tmp/delme", O_RDWR );
+  mmap( c, 4096, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_SHARED, 3, 0 );
+  *c = 0;
+  if (fork()) {
+    while(1) {
+      strcpy( c, "/etc/passwd" );    
+      strcpy( c, "/etc/shadow" );
+    }
+  } else
+    while (1)
+      open( c, 0 );
+}