From f3280455ea7fd3730ebe448fb0c9aea56b45093e Mon Sep 17 00:00:00 2001
From: Will Dormann <wd@cert.org>
Date: Tue, 2 Feb 2016 13:55:48 -0500
Subject: [PATCH] Add new "null" opmode which doesn't mutate the file.

---
 src/opts.h | 1 +
 src/zzuf.c | 4 +++-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/opts.h b/src/opts.h
index 619e1ed..28b4ddd 100644
--- a/src/opts.h
+++ b/src/opts.h
@@ -59,6 +59,7 @@ struct zzuf_opts
     {
         OPMODE_PRELOAD,
         OPMODE_COPY,
+        OPMODE_NULL,
     } opmode;
     char **oldargv;
     int oldargc;
diff --git a/src/zzuf.c b/src/zzuf.c
index c46b84b..f132889 100644
--- a/src/zzuf.c
+++ b/src/zzuf.c
@@ -307,6 +307,8 @@ int main(int argc, char *argv[])
                 opts->opmode = OPMODE_PRELOAD;
             else if (!strcmp(zz_optarg, "copy"))
                 opts->opmode = OPMODE_COPY;
+            else if (!strcmp(zz_optarg, "null"))
+                opts->opmode = OPMODE_NULL;
             else
             {
                 fprintf(stderr, "%s: invalid operating mode -- `%s'\n",
@@ -1278,7 +1280,7 @@ static void usage(void)
     printf("  -M, --max-memory <n>      maximum child virtual memory in MiB (default %u)\n", DEFAULT_MEM);
 #endif
     printf("  -n, --network             fuzz network input\n");
-    printf("  -O, --opmode <mode>       use operating mode <mode> ([preload] copy)\n");
+    printf("  -O, --opmode <mode>       use operating mode <mode> ([preload] copy null)\n");
     printf("  -p, --ports <list>        only fuzz network destination ports in <list>\n");
     printf("  -P, --protect <list>      protect bytes and characters in <list>\n");
     printf("  -q, --quiet               do not print children's messages\n");