Re: [9fans] lpdaemon

[Don Bailey <don.bailey@gmail.com>]

Not exactly. But, functionally close enough. 

I skipped commenting on strncpy to ignore the plethora of issues with lpd and focus on the question at hand.

D

On Jun 5, 2013, at 7:20 AM, erik quanstrom <quanstro@quanstro.net> wrote:

> On Wed Jun  5 09:15:11 EDT 2013, don.bailey@gmail.com wrote:
>> The first opportunity to write a nil byte should always be taken.
>> Using sizeof only means that in corner cases memory disclosure may
>> occur between where the nil should be and the end of the array.  While
>> this isn't a security critical app, it is still good coding practice.
>> 
>> x = strlen(info.host) < sizeof info.host ? strlen() : sizeof ;
>> info.host[x] = 0;
> 
> let's start at the beginning.  strncpy is not good coding practice.
> and lpdaemon is not well written by today's standards.  ☺
> 
> however, unless i'm missing something, the code has exactly that.
> 
> /sys/src/cmd/lp/lpdaemon.c:297,310
>        case 'H':
>            if (ap[1] == '\0')
>                strncpy(info.host, "unknown", NAMELEN);
>            else
>                strncpy(info.host, (const char *)&ap[1], NAMELEN);
>            info.host[NAMELEN] = '\0';
>            break;
>        case 'P':
>            if (ap[1] == '\0')
>                strncpy(info.user, "unknown", NAMELEN);
>            else
>                strncpy(info.user, (const char *)&ap[1], NAMELEN);
>            info.user[NAMELEN] = '\0';
>            break;
> 
> - erik
>