Enforce correct JSON config format

[igaw]

While working on the a related topic, I run into several crashes due to wrong formatted JSON.

The crashes happened inside the json-c library:

(gdb) bt
#0  __pthread_kill_implementation (threadid=<optimized out>, signo=signo@entry=6, no_tid=no_tid@entry=0) at pthread_kill.c:44
#1  0x00007ffff7dbe893 in __pthread_kill_internal (signo=6, threadid=<optimized out>) at pthread_kill.c:78
#2  0x00007ffff7d6b846 in __GI_raise (sig=sig@entry=6) at ../sysdeps/posix/raise.c:26
#3  0x00007ffff7d5481c in __GI_abort () at abort.c:79
#4  0x00007ffff7d5472b in __assert_fail_base (fmt=0x7ffff7edaa80 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x7ffff7f721f0 "json_object_get_type(jso) == json_type_array", 
    file=0x7ffff7f72048 "/home/abuild/rpmbuild/BUILD/json-c-json-c-0.16-20220414/json_object.c", line=1473, function=<optimized out>) at assert.c:92
#5  0x00007ffff7d63c46 in __GI___assert_fail (assertion=0x7ffff7f721f0 "json_object_get_type(jso) == json_type_array", 
    file=0x7ffff7f72048 "/home/abuild/rpmbuild/BUILD/json-c-json-c-0.16-20220414/json_object.c", line=1473, function=0x7ffff7f72510 <__PRETTY_FUNCTION__.7> "json_object_array_length") at assert.c:101
#6  0x00007ffff7f68b7a in json_object_array_length () from /lib64/libjson-c.so.5
#7  0x00007ffff7fafb2f in json_read_config (r=0x4f9c50, config_file=0x4a58f5 "/etc/nvme/config.json") at ../subprojects/libnvme/src/nvme/json.c:180
#8  0x00007ffff7fa8da4 in nvme_read_config (r=0x4f9c50, config_file=0x4a58f5 "/etc/nvme/config.json") at ../subprojects/libnvme/src/nvme/tree.c:162
#9  0x000000000040a06c in nvmf_discover (desc=0x4b0210 "Discover NVMeoF subsystems and connect to them", argc=1, argv=0x7fffffffe120, connect=true) at ../fabrics.c:738
#10 0x0000000000426da4 in connect_all_cmd (argc=1, argv=0x7fffffffe120, command=0x4f23c0 <connect_all_cmd_cmd>, plugin=0x4f2900 <builtin>) at ../nvme.c:8266
#11 0x000000000044b0df in handle_plugin (argc=1, argv=0x7fffffffe120, plugin=0x4f2900 <builtin>) at ../plugin.c:164
#12 0x0000000000426f6f in main (argc=2, argv=0x7fffffffe118) at ../nvme.c:8318

This is due the fact we sometimes blindly operate on the json object tree.

[igaw]

We might want to add some more type checks ontop of this.

[igaw]

Ideally we would validate against the schema.

[igaw]

Ideally we would validate against the schema.

After some discussion during ALPSS we should aim to move all the config reading parts to the fronted. There are all the data structs available to config data to the library.