[nft PATCH] libnftables: Fix exit_cookie()

[Phil Sutter]

The output and error buffer feature depends on cookie->orig_fp to
indicate the current status of buffering: If it is set, a prior call to
init_cookie() is assumed. Though exit_cookie() missed to reset that
pointer to NULL. causing weird behaviour in applications if they do:

| nft = nft_ctx_new(0);
| nft_ctx_buffer_output(nft);
| nft_ctx_unbuffer_output(nft);
| nft_ctx_buffer_output(nft);

While being at it, apply the same fix to error path in init_cookie() as
well.

Signed-off-by: Phil Sutter <p...@nwl.cc>
---
 src/libnftables.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/libnftables.c b/src/libnftables.c
index 5ee4b8965fc81..760deecf2b899 100644
--- a/src/libnftables.c
+++ b/src/libnftables.c
@@ -198,6 +198,7 @@ static int init_cookie(struct cookie *cookie)
        cookie->fp = fopencookie(cookie, "w", cookie_fops);
        if (!cookie->fp) {
                cookie->fp = cookie->orig_fp;
+               cookie->orig_fp = NULL;
                return 1;
        }
 
@@ -211,6 +212,7 @@ static int exit_cookie(struct cookie *cookie)
 
        fclose(cookie->fp);
        cookie->fp = cookie->orig_fp;
+       cookie->orig_fp = NULL;
        free(cookie->buf);
        cookie->buf = NULL;
        cookie->buflen = 0;
-- 
2.17.0

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