lib/41085: sigaction returns EINVAL instead of -1

[matteo%beccati.com@localhost]

>Number:         41085
>Category:       lib
>Synopsis:       sigaction returns EINVAL instead of -1
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    lib-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Mar 27 13:15:00 +0000 2009
>Originator:     Matteo Beccati
>Release:        4.0 (XEN DOM0)
>Organization:
>Environment:
NetBSD epia.hq.beccati.com 4.0_STABLE NetBSD 4.0_STABLE (EPIA) #4: Thu Mar 26 
18:25:20 CET 2009  
toor%epia.hq.beccati.com@localhost:/mnt/usb/src/sys/arch/i386/compile/obj/EPIA 
i386

>Description:
Under some circumstances sigaction returns the errno instead of returning -1 
and setting the errno variable. Unfortunately I wasn't able to write a self 
contained test case. The bug is triggered when running a unit test for the php 
pcntl extension (CVS HEAD).

Here's what I found out when running gdb:

Breakpoint 1, php_signal (signo=-1, func=0x82d00f3 <pcntl_signal_handler>,
    restart=1) at /root/compile/php-HEAD/ext/pcntl/php_signal.c:28

called php_signal with a valid func pointer and invalid signo.

28              act.sa_handler = func;
(gdb) next
29              sigemptyset(&act.sa_mask);
(gdb) next
30              act.sa_flags = 0;
(gdb) next

sigaction act was set

33              if (signo == SIGALRM || (! restart)) {
(gdb) next
39                      act.sa_flags |= SA_RESTART; /* SVR4, 4.3+BSD */
(gdb) next

restart flag also set.

43              retval = sigaction(signo, &act, &oact);
(gdb) step
45              if (retval < 0)
(gdb) print retval
$1 = 22

retval == EINVAL

(gdb) print act
$2 = {_sa_u = {_sa_handler = 0x82d00f3 <pcntl_signal_handler>,
    _sa_sigaction = 0x82d00f3 <pcntl_signal_handler>}, sa_mask = {__bits = {0,
      0, 0, 0}}, sa_flags = 2}

act looks fine to me

(gdb) print errno
$3 = 0

errno == 0

(gdb) print oact
$4 = {_sa_u = {_sa_handler = 0x8537160, _sa_sigaction = 0x8537160}, sa_mask = {
    __bits = {138096588, 136402289, 138096544, 6}}, sa_flags = 15}


oact looks a bit weird.

>How-To-Repeat:

>Fix: