command_seqno should wrap

[armersong]

I did a long loop test with rust binding. There is a "*** buffer overflow detected ***" error and the issue can be duplicated. It seems the buffer is small. Please check

version:
paho.mqtt.c-1.3.0

debug info:
#11 MQTTAsync_persistCommand (qcmd=0x7ffff646c584) at src/MQTTAsync.c:695
695 sprintf(key, "%s%d", PERSISTENCE_COMMAND_KEY, ++aclient->command_seqno);
(gdb) p aclient->command_seqno
$6 = 1000000
(gdb) p key
$7 = "c-100000"
(gdb) p *aclient
$5 = {serverURI = 0x7ffff64222d4 "bluesilva.net:1883", ssl = 0, c = 0x7ffff64a4004, cl = 0x55555557c0a0 <paho_mqtt::async_client::AsyncClient::on_connection_lost::h98ec138cadd93f1d>,
ma = 0x55555557c770 <paho_mqtt::async_client::AsyncClient::on_message_arrived::hb901e6c91ebb32e6>, dc = 0x0, context = 0x7fffffffc5d0, connected = 0x0, connected_context = 0x0, connect = {
type = 1, onSuccess = 0x0, onFailure = 0x55555557ad30 <paho_mqtt::async_client::Token::on_failure::h734c691fd930d752>, token = 0, context = 0x7ffff64a40f0, start_time = timeval = {
tv_sec = 1540552642, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
tv_usec = 875619}, details = {sub = {count = 0, topics = 0x0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
qoss = 0x0}, unsub = {count = 0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
topics = 0x0}, pub = {
destinationName = 0x400000000 <error: Cannot access memory at address 0x400000000>, payloadlen = 0, payload = 0x0, qos = 0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
retained = 0}, dis = {internal = 0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
timeout = 4}, conn = {
currentURI = 0, MQTTVersion = 4}}}, disconnect = {type = 0, onSuccess = 0x0, onFailure = 0x0, token = 0, context = 0x0, start_time = timeval = {tv_sec = 0, tv_usec = 0}, details = {
Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
sub = {count = 0, topics = 0x0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
qoss = 0x0}, unsub = {count = 0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
topics = 0x0}, pub = {destinationName = 0x0, payloadlen = 0, payload = 0x0, qos = 0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
retained = 0}, dis = {
internal = 0, Python Exception <class 'AttributeError'> 'NoneType' object has no attribute 'startswith':
timeout = 0}, conn = {currentURI = 0, MQTTVersion = 0}}}, pending_write = 0x0, responses = 0x7ffff6453204, command_seqno = 1000000, pack = 0x0,
createOptions = 0x7ffff6499524, shouldBeConnected = 1, automaticReconnect = 0, minRetryInterval = 1, maxRetryInterval = 60, serverURIcount = 0, serverURIs = 0x0, connectTimeout = 30,
currentInterval = 0, lastConnectionFailedTime = timeval = {tv_sec = 0, tv_usec = 0}, retrying = 0, reconnectNow = 0}

backtrace:
Thread 1 "async_subscribe" received signal SIGABRT, Aborted.
0x00007ffff6f4d428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
54 ../sysdeps/unix/sysv/linux/raise.c:
(gdb) bt
#0 0x00007ffff6f4d428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
#1 0x00007ffff6f4f02a in __GI_abort () at abort.c:89
#2 0x00007ffff6f8f7ea in __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7ffff70a749f "*** %s ***: %s terminated\n") at ../sysdeps/posix/libc_fatal.c:175
#3 0x00007ffff703115c in __GI___fortify_fail (msg=, msg@entry=0x7ffff70a7430 "buffer overflow detected") at fortify_fail.c:37
#4 0x00007ffff702f160 in __GI___chk_fail () at chk_fail.c:28
#5 0x00007ffff702e6c9 in _IO_str_chk_overflow (fp=, c=) at vsprintf_chk.c:31
#6 0x00007ffff6f936b0 in __GI__IO_default_xsputn (f=0x7fffffffbe50, data=, n=7) at genops.c:455
#7 0x00007ffff6f65e00 in _IO_vfprintf_internal (s=s@entry=0x7fffffffbe50, format=, format@entry=0x7ffff7b3812d "%s%d", ap=ap@entry=0x7fffffffbf88) at vfprintf.c:1631
#8 0x00007ffff702e754 in ___vsprintf_chk (s=0x7fffffffc06f "c-100000", flags=1, slen=9, format=0x7ffff7b3812d "%s%d", args=args@entry=0x7fffffffbf88) at vsprintf_chk.c:82
#9 0x00007ffff702e6ad in _sprintf_chk (s=s@entry=0x7fffffffc06f "c-100000", flags=flags@entry=1, slen=slen@entry=9, format=format@entry=0x7ffff7b3812d "%s%d") at sprintf_chk.c:31
#10 0x00007ffff7b2b5d1 in sprintf (__fmt=0x7ffff7b3812d "%s%d", __s=0x7fffffffc06f "c-100000") at /usr/include/x86_64-linux-gnu/bits/stdio2.h:33
#11 MQTTAsync_persistCommand (qcmd=0x7ffff646c584) at src/MQTTAsync.c:695
#12 MQTTAsync_addCommand (command=command@entry=0x7ffff646c584, command_size=command_size@entry=8) at src/MQTTAsync.c:901
#13 0x00007ffff7b2ee1f in MQTTAsync_send (handle=handle@entry=0x7ffff64a1004, destinationName=destinationName@entry=0x7ffff646b270 "t/375136", payloadlen=31, payload=0x7ffff6458480, qos=1,
retained=0, response=0x7fffffffc3d8) at src/MQTTAsync.c:2852
#14 0x00007ffff7b2eefe in MQTTAsync_sendMessage (handle=0x7ffff64a1004, destinationName=0x7ffff646b270 "t/375136", message=0x7ffff6471858, response=0x7fffffffc3d8) at src/MQTTAsync.c:2878
#15 0x000055555557d642 in paho_mqtt::async_client::AsyncClient::publish::he876860930413357 (self=0x7fffffffc5d0, msg=Message = {...}) at src/async_client.rs:748
#16 0x000055555556bf40 in async_subscribe::main::h1b3319aa5505cfea () at examples/async_subscribe.rs:125
#17 0x000055555556c9b0 in std::rt::lang_start::$u7b$$u7b$closure$u7d$$u7d$::h0e475f0414f4d345 () at /checkout/src/libstd/rt.rs:74
#18 0x00005555556b0293 in std::rt::lang_start_internal::$u7b$$u7b$closure$u7d$$u7d$::h2d27f966df62f613 () at libstd/rt.rs:59
#19 std::panicking::try::do_call::h0208f3354fcc3e87 () at libstd/panicking.rs:310
#20 0x00005555556cb45a in __rust_maybe_catch_panic () at libpanic_unwind/lib.rs:105
#21 0x00005555556b1456 in std::panicking::try::h8cfae114cfc320aa () at libstd/panicking.rs:289
#22 std::panic::catch_unwind::h9e48b3e6dc9f9394 () at libstd/panic.rs:392
#23 std::rt::lang_start_internal::h56481fc9d09c36f4 () at libstd/rt.rs:58
#24 0x000055555556c988 in std::rt::lang_start::h0620b1b50fc85b20 (main=0x55555556b970 <async_subscribe::main::h1b3319aa5505cfea>, argc=1, argv=0x7fffffffd2f8)
at /checkout/src/libstd/rt.rs:74
#25 0x000055555556c2ea in main ()

[icraggs]

So it seems like you've hit the million messages. We can increase the PERSISTENCE_MAX_KEY_LENGTH from 8 to 10 for instance, which will give a maximum of 100 million.

Or we can make the command sequence number wrap at a million. Storing one million commands in persistence simultaneously of this library would not be a good approach anyway.

[armersong]

ok