[iproute PATCH v2] ipaddress: Fix segfault in 'addr showdump'

[Phil Sutter]

Obviously, 'addr showdump' feature wasn't adjusted to json output
support. As a consequence, calls to print_string() in print_addrinfo()
tried to dereference a NULL FILE pointer.

Cc: Julien Fortin <jul...@cumulusnetworks.com>
Fixes: d0e720111aad2 ("ip: ipaddress.c: add support for json output")
Signed-off-by: Phil Sutter <p...@nwl.cc>
--
Changes since v1:
Align json output with that of 'ip -j addr show':
- Interface index label is 'ifindex', not 'index' and it doesn't belong
  to 'addr_info' array.
- Create one 'addr_info' array per dumped address, not one for all.
---
 ip/ipaddress.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

diff --git a/ip/ipaddress.c b/ip/ipaddress.c
index 9797145023966..4c47809570410 100644
--- a/ip/ipaddress.c
+++ b/ip/ipaddress.c
@@ -1801,17 +1801,33 @@ static int show_handler(const struct sockaddr_nl *nl,
 {
        struct ifaddrmsg *ifa = NLMSG_DATA(n);
 
-       printf("if%d:\n", ifa->ifa_index);
+       open_json_object(NULL);
+       print_int(PRINT_ANY, "ifindex", "if%d:\n", ifa->ifa_index);
+
+       open_json_array(PRINT_JSON, "addr_info");
+       open_json_object(NULL);
+
        print_addrinfo(NULL, n, stdout);
+
+       close_json_object();
+       close_json_array(PRINT_JSON, NULL);
+
+       close_json_object();
        return 0;
 }
 
 static int ipaddr_showdump(void)
 {
+       int err;
+
        if (ipadd_dump_check_magic())
                exit(-1);
 
-       exit(rtnl_from_file(stdin, &show_handler, NULL));
+       new_json_obj(json, stdout);
+       err = rtnl_from_file(stdin, &show_handler, NULL);
+       delete_json_obj();
+
+       exit(err);
 }
 
 static int restore_handler(const struct sockaddr_nl *nl,
-- 
2.13.1