--- /dev/null
+/*
+ * gcc link_failure.c -o link_failure.so -shared -ldl
+ * LD_PRELOAD=./link_failure.so FAILURE_PATH=/etc/shadow ./test /etc/shadow
+ */
+
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+
+typedef int (*link_type) (const char *oldpath, const char *newpath);
+static link_type next_link;
+
+static const char *failure_path = NULL;
+
+int link (const char *oldpath, const char *newpath)
+{
+ if (NULL == next_link)
+ {
+ next_link = dlsym (RTLD_NEXT, "link");
+ assert (NULL != next_link);
+ }
+ if (NULL == failure_path) {
+ failure_path = getenv ("FAILURE_PATH");
+ if (NULL == failure_path) {
+ fputs ("No FAILURE_PATH defined\n", stderr);
+ }
+ }
+
+ if ( (NULL != newpath)
+ && (NULL != failure_path)
+ && (strcmp (newpath, failure_path) == 0))
+ {
+ fprintf (stderr, "link FAILURE %s %s\n", oldpath, newpath);
+ errno = EIO;
+ return -1;
+ }
+
+ return next_link (oldpath, newpath);
+}
+
--- /dev/null
+/*
+ * gcc unlinkat_failure.c -o unlinkat_failure.so -shared -ldl
+ * LD_PRELOAD=./unlinkat_failure.so FAILURE_PATH=/etc/shadow ./test /etc/shadow
+ */
+
+#define _GNU_SOURCE
+#include <dlfcn.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <stdarg.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <assert.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+
+typedef int (*unlinkat_type) (int dirfd, const char *pathname, int flags);
+static unlinkat_type next_unlinkat;
+
+static const char *failure_path = NULL;
+static dev_t failure_dev = -1;
+static ino_t failure_ino = -1;
+
+int unlinkat (int dirfd, const char *pathname, int flags)
+{
+ if (NULL == next_unlinkat)
+ {
+ next_unlinkat = dlsym (RTLD_NEXT, "unlinkat");
+ assert (NULL != next_unlinkat);
+ }
+ if (NULL == failure_path) {
+ struct stat sb;
+ failure_path = getenv ("FAILURE_PATH");
+ if (NULL == failure_path) {
+ fputs ("No FAILURE_PATH defined\n", stderr);
+ }
+ if (lstat (failure_path, &sb) != 0) {
+ fputs ("Can't lstat FAILURE_PATH\n", stderr);
+ }
+ failure_dev = sb.st_dev;
+ failure_ino = sb.st_ino;
+ }
+
+ if ( (NULL != pathname)
+ && (NULL != failure_path)) {
+ struct stat sb;
+ if ( (fstatat (dirfd, pathname, &sb, flags) == 0)
+ && (sb.st_dev == failure_dev)
+ && (sb.st_ino == failure_ino)) {
+ fprintf (stderr, "unlinkat FAILURE %s\n", failure_path);
+ errno = EBUSY;
+ return -1;
+ }
+ }
+
+ return next_unlinkat (dirfd, pathname, flags);
+}
+