/* Call a script with a par file and env vars */
void FAST_FUNC udhcp_run_script(struct dhcp_packet *packet, const char *name)
{
char **envp, **curr;
char *argv[3];
if (client_config.script == NULL)
return;
envp = fill_envp(packet);
/* call script */
log1("Executing %s", client_config.script);
argv[0] = (char*) client_config.script;
argv[1] = (char*) name;
argv[2] = NULL;
wait4pid(spawn(argv));
for (curr = envp; *curr; curr++) {
log2(" %s", *curr);
bb_unsetenv(*curr);
free(*curr);
}
free(envp);
}
int uevent_main(int argc UNUSED_PARAM, char **argv)
{
struct sockaddr_nl sa;
int fd;
argv++;
// Subscribe for UEVENT kernel messages
sa.nl_family = AF_NETLINK;
sa.nl_pad = 0;
sa.nl_pid = getpid();
sa.nl_groups = 1 << 0;
fd = xsocket(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
xbind(fd, (struct sockaddr *) &sa, sizeof(sa));
close_on_exec_on(fd);
// Without a sufficiently big RCVBUF, a ton of simultaneous events
// can trigger ENOBUFS on read, which is unrecoverable.
// Reproducer:
// uevent mdev &
// find /sys -name uevent -exec sh -c 'echo add >"{}"' ';'
//
// SO_RCVBUFFORCE (root only) can go above net.core.rmem_max sysctl
setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &RCVBUF, sizeof(RCVBUF));
setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &RCVBUF, sizeof(RCVBUF));
if (0) {
int z;
socklen_t zl = sizeof(z);
getsockopt(fd, SOL_SOCKET, SO_RCVBUF, &z, &zl);
bb_error_msg("SO_RCVBUF:%d", z);
}
for (;;) {
char *netbuf;
char *s, *end;
ssize_t len;
int idx;
// In many cases, a system sits for *days* waiting
// for a new uevent notification to come in.
// We use a fresh mmap so that buffer is not allocated
// until kernel actually starts filling it.
netbuf = mmap(NULL, BUFFER_SIZE,
PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANON,
/* ignored: */ -1, 0);
if (netbuf == MAP_FAILED)
bb_perror_msg_and_die("mmap");
// Here we block, possibly for a very long time
len = safe_read(fd, netbuf, BUFFER_SIZE - 1);
if (len < 0)
bb_perror_msg_and_die("read");
end = netbuf + len;
*end = '\0';
// Each netlink message starts with "ACTION@/path"
// (which we currently ignore),
// followed by environment variables.
if (!argv[0])
putchar('\n');
idx = 0;
s = netbuf;
while (s < end) {
if (!argv[0])
puts(s);
if (strchr(s, '=') && idx < MAX_ENV)
env[idx++] = s;
s += strlen(s) + 1;
}
env[idx] = NULL;
idx = 0;
while (env[idx])
putenv(env[idx++]);
if (argv[0])
spawn_and_wait(argv);
idx = 0;
while (env[idx])
bb_unsetenv(env[idx++]);
munmap(netbuf, BUFFER_SIZE);
}
return 0; // not reached
}
void FAST_FUNC bb_unsetenv_and_free(char *var)
{
bb_unsetenv(var);
free(var);
}
