Re: [gpsd-dev] C Client API Issues

[Robert Norris]

> From: Hal Murray <address@hidden>
  
>address@hidden said:
> >gpsd needs a flag so close is a noop if it isn't open.
>> Wouldn't such a flag would need to go into the gps_data_t structure? 

>I was being sloppy when I said "flag".  I don't care how it's implemented as 
>long as duplicate calls to close don't cause any problems.

Even though I was on about initialization, currently calling gps_close() twice 
will crash the client with a double free.

privdata should be explicitly set to NULL after the free in gps_socket_close().

There also looks to be issues with gps_shm_* functions too, such as:

gps_shm_open() doesn't set gpsdata->privdata to NULL when attaching to shared 
memory fails.

Thus if you tried to then use gps_shm_read() [which you shouldn't do anyway] it 
would probably crash.

gps_shm_close() never checks if gpsdata->privdata is NULL, so again it would 
crash the client if used after an unsuccessful open.

It should be easy to make these more robust against API incorrect use.