[Devel] Re: [PATCH 1/2] signal checkpoint: define /proc/pid/sig/

[Cedric Le Goater]

[ ... ]

>>> +static int print_sigpending_alloc(char **bufp, struct sigpending *pending)
>>> +{
>>> +	int alloced=0;
>>> +	char *buf, *p;
>>> +	struct sigqueue *q;
>>> +	struct siginfo *info;
>>> +
>>> +	alloced = PAGE_SIZE;
>>> +	p = buf = kmalloc(alloced, GFP_KERNEL);
>>> +	if (!buf)
>>> +		return -ENOMEM;
>>> +	
>>> +	p += print_sigset(buf, &pending->signal);
>>> +	p += sprintf(p, "\n");
>>> +
>>> +	list_for_each_entry(q, &pending->list, list) {
>>> +		info = &q->info;
>>> +		if (p-buf+215 > alloced) {
>>> +			int len=p-buf;
>>> +			char *buf2;
>>> +			alloced += PAGE_SIZE;
>>> +			buf2 = kmalloc(alloced, GFP_KERNEL);
>>> +			if (!buf2) {
>>> +				kfree(buf);
>>> +				return -ENOMEM;
>>> +			}
>>> +			memcpy(buf2, buf, alloced - PAGE_SIZE);
>>> +			kfree(buf);
>>> +			buf = buf2;
>>> +			p = buf+len;
>>> +		}
>>> +
>>> +		p += sprintf(p, "sig %d: user %d flags %d",
>>> +			info->si_signo, (int)q->user->uid, q->flags);
>>> +		p += sprintf(p, " errno %d code %d\n",
>>> +			info->si_errno, info->si_code);
>>> +
>>> +		switch(info->si_signo) {
>>> +		case SIGKILL:
>>> +			p += sprintf(p, "  spid %d suid %d\n",
>>> +				info->_sifields._kill._pid,
>>> +				info->_sifields._kill._uid);
>>> +			break;
>>> +		/* XXX skipping posix1b timers and signals for now */
>>> +		case SIGCHLD:
>>> +			p += sprintf(p, "  pid %d uid %d status %d utime %lu stime %lu\n",
>>> +				info->_sifields._sigchld._pid,
>>> +				info->_sifields._sigchld._uid,
>>> +				info->_sifields._sigchld._status,
>>> +				info->_sifields._sigchld._utime,
>>> +				info->_sifields._sigchld._stime);
>>> +			break;
>>> +		case SIGILL:
>>> +		case SIGFPE:
>>> +		case SIGSEGV:
>>> +		case SIGBUS:
>>> +#ifdef __ARCH_SI_TRAPNO
>>> +			p += sprintf(p, "  addr %lu trapno %d\n",
>>> +				(unsigned long)info->_sifields._sigfault._addr,
>>> +				info->_sifields._sigfault._trapno);
>>> +#else
>>> +			p += sprintf(p, "  addr %lu\n",
>>> +				(unsigned long)info->_sifields._sigfault._addr);
>>> +#endif
>>> +			break;
>>> +		case SIGPOLL:
>>> +			p += sprintf(p, "  band %ld fd %d\n",
>>> +				(long)info->_sifields._sigpoll._band,
>>> +				info->_sifields._sigpoll._fd);
>>> +			break;
>>> +		default:
>>> +			p += sprintf(p, "  Unsupported siginfo for signal %d\n",
>>> +				info->si_signo);
>>> +			break;
>>> +		}
>>> +	}
>>> +	*bufp = buf;
>>> +	return p-buf;
>>> +}
>> I think we are reaching the limit of /proc when we expose the pending siginfos.
> 
> Why?

well, we are really exposing the internals of signal delivery, which are
not that useful for /proc. IMO, it would be better to use an "opaque" to 
get/set the data we need.

C.


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