[Nut-upsuser] upsd crashes with a "broken pipe" error

[Arjen de Korte]

Citeren Zach La Celle <lacelle op roboticresearch.com>:

> You can see where the problem happens in parseconf.c, on line 125  
> with the code:
> /* resize the lists */
> ctx->arglist = realloc(ctx->arglist,
>                                    sizeof(char *) * ctx->numargs);

With the given arguments, this boils down to

     ctx->arglist = realloc(NULL, sizeof(char *));

This is all normal. Upon the first invocation of add_arg_word,  
ctx->arglist will be a NULL pointer (since there is nothing in the  
list yet). This should then allocate a one element array of a pointer  
to char (to store the

"If ptr is a null pointer, realloc() shall be equivalent to malloc()  
for the specified size."

After that, all hell breaks loose, but that's out of our control.

There is a slight problem in lines 131-132

     ctx->argsize = realloc(ctx->argsize, sizeof(int *) * ctx->numargs);

which should really read

     ctx->argsize = realloc(ctx->argsize, sizeof(size_t) * ctx->numargs);

but I doubt that sizeof(size_t) will be smaller that sizeof(int *), so  
this just wastes a few bytes of memory.

> This also might help:
> (gdb) p *ctx
> $4 = {f = 0x0, state = 5, ch = 9, arglist = 0x0, argsize = 0x0,  
> numargs = 1, maxargs = 1, wordbuf = 0x61f2e0 "Z", wordptr = 0x61f2fd  
> "", wordbufsize = 16, linenum = 0, error = 0, errmsg = '\000'  
> <repeats 255 times>, errhandler = 0, magic = 7497264, arg_limit =  
> 32, wordlen_limit = 512}

None of these values is suspect.

> If I go "up" in GDB to the pconf_char function, here is the  
> character which is killing it:
> (gdb) p ch
> $6 = 9 '\t'

This is expected. Any whitespace character ends the collection of  
characters for the current argument and will start a new one. Nothing  
out of the ordinary. If it was, 100% of the NUT installations would  
suffer the same problems as you're seeing 100% of the time they start  
the upsd server. This is not the case and even in your case, the  
problem seems to occur intermittently, which is more an indication  
you're either running out of memory or the system is suffering from  
bad memory. Did you run a memory check lately?

Best regards, Arjen
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