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/* ISC license. */
#ifndef _GNU_SOURCE
#define _GNU_SOURCE
#endif
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <asm/types.h>
#include <linux/netlink.h>
#include <skalibs/allreadwrite.h>
#include <skalibs/bytestr.h>
#include <skalibs/uint.h>
#include <skalibs/sgetopt.h>
#include <skalibs/strerr2.h>
#include <skalibs/iopause.h>
#include <skalibs/bufalloc.h>
#include <skalibs/djbunix.h>
#include <skalibs/sig.h>
#include <skalibs/selfpipe.h>
#define USAGE "s6-uevent-listener [ -v verbosity ] [ -b kbufsz ] helperprogram..."
#define dieusage() strerr_dieusage(100, USAGE)
#define dienomem() strerr_diefu1sys(111, "build string") ;
static unsigned int cont = 1, verbosity = 1 ;
static pid_t pid ;
static inline int fd_recvmsg (int fd, struct msghdr *hdr)
{
int r ;
do r = recvmsg(fd, hdr, MSG_DONTWAIT) ;
while ((r == -1) && (errno == EINTR)) ;
return r ;
}
static inline int netlink_init_stdin (unsigned int kbufsz)
{
struct sockaddr_nl nl = { .nl_family = AF_NETLINK, .nl_pad = 0, .nl_groups = 0, .nl_pid = 0 } ;
close(0) ;
return socket_internal(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT, DJBUNIX_FLAG_NB|DJBUNIX_FLAG_COE) == 0
&& bind(0, (struct sockaddr *)&nl, sizeof(struct sockaddr_nl)) == 0
&& setsockopt(0, SOL_SOCKET, SO_RCVBUFFORCE, &kbufsz, sizeof(unsigned int)) == 0 ;
}
static inline void handle_signals (void)
{
for (;;)
{
char c = selfpipe_read() ;
switch (c)
{
case -1 : strerr_diefu1sys(111, "selfpipe_read") ;
case 0 : return ;
case SIGTERM :
cont = 0 ;
fd_close(0) ;
break ;
case SIGCHLD :
{
char fmt[UINT_FMT] ;
int wstat ;
int r = wait_pid_nohang(pid, &wstat) ;
if (r < 0)
if (errno != ECHILD) strerr_diefu1sys(111, "wait_pid_nohang") ;
else break ;
else if (!r) break ;
if (WIFSIGNALED(wstat))
{
fmt[uint_fmt(fmt, WTERMSIG(wstat))] = 0 ;
strerr_dief2x(1, "child crashed with signal ", fmt) ;
}
else
{
fmt[uint_fmt(fmt, WEXITSTATUS(wstat))] = 0 ;
strerr_dief2x(1, "child exited ", fmt) ;
}
}
default :
strerr_dief1x(101, "internal error: inconsistent signal state. Please submit a bug-report.") ;
}
}
}
static void doit (char const *s, unsigned int len)
{
if (!bufalloc_put(bufalloc_1, s, len)) dienomem() ;
}
static void terminate (void)
{
if (!bufalloc_put(bufalloc_1, "", 1)) dienomem() ;
}
static inline void handle_netlink (void)
{
char buf[8192] ;
static int inmulti = 0 ;
struct sockaddr_nl nl;
struct iovec iov = { .iov_base = &buf, .iov_len = sizeof(buf) } ;
struct msghdr msg =
{
.msg_name = &nl,
.msg_namelen = sizeof(struct sockaddr_nl),
.msg_iov = &iov,
.msg_iovlen = 1,
.msg_control = 0,
.msg_controllen = 0,
.msg_flags = 0
} ;
struct nlmsghdr *nlh = (struct nlmsghdr *)buf ;
int r = sanitize_read(fd_recvmsg(0, &msg)) ;
if (r < 0)
{
if (errno == EPIPE)
{
if (verbosity >= 2) strerr_warnw1x("received EOF on netlink") ;
cont = 0 ;
fd_close(0) ;
return ;
}
else strerr_diefu1sys(111, "receive netlink message") ;
}
if (!r) return ;
if (msg.msg_flags & MSG_TRUNC)
strerr_diefu2x(111, "buffer too small for ", "netlink message") ;
if (nl.nl_pid)
{
if (verbosity >= 3)
{
char fmt[UINT_FMT] ;
fmt[uint_fmt(fmt, nl.nl_pid)] = 0 ;
strerr_warnw3x("netlink message", " from userspace process ", fmt) ;
}
return ;
}
for (; NLMSG_OK(nlh, r) ; nlh = NLMSG_NEXT(nlh, r))
switch (nlh->nlmsg_type)
{
case NLMSG_NOOP : break ;
case NLMSG_ERROR :
if (verbosity >= 3)
strerr_warnw2x("spurious NLMSG_ERROR ", "netlink message") ;
break ;
case NLMSG_DONE :
if (inmulti)
{
inmulti = 0 ;
terminate() ;
}
else if (verbosity >= 3)
strerr_warnw2x("spurious NLMSG_DONE ", "netlink message") ;
break ;
default :
if (nlh->nlmsg_flags & NLM_F_MULTI) inmulti = 1 ;
else if (inmulti)
{
inmulti = 0 ;
terminate() ;
if (verbosity >= 3)
strerr_warnw2x("unterminated multipart ", "netlink message") ;
}
doit(NLMSG_DATA(nlh), (unsigned int)NLMSG_PAYLOAD(nlh, r)) ;
if (!inmulti) terminate() ;
break ;
}
}
int main (int argc, char const *const *argv, char const *const *envp)
{
iopause_fd x[3] = { { .events = IOPAUSE_READ }, { .fd = 1 }, { .fd = 0, .events = IOPAUSE_READ } } ;
PROG = "s6-uevent-listener" ;
{
unsigned int kbufsz = 65536 ;
subgetopt_t l = SUBGETOPT_ZERO ;
for (;;)
{
register int opt = subgetopt_r(argc, argv, "v:b:", &l) ;
if (opt == -1) break ;
switch (opt)
{
case 'v' : if (!uint0_scan(l.arg, &verbosity)) dieusage() ; break ;
case 'b' : if (!uint0_scan(l.arg, &kbufsz)) dieusage() ; break ;
default : dieusage() ;
}
}
argc -= l.ind ; argv += l.ind ;
if (!argc) strerr_dieusage(100, USAGE) ;
if (!netlink_init_stdin(kbufsz)) strerr_diefu1sys(111, "init netlink") ;
}
x[0].fd = selfpipe_init() ;
if (x[0].fd < 0) strerr_diefu1sys(111, "init selfpipe") ;
if (sig_ignore(SIGPIPE) < 0) strerr_diefu1sys(111, "ignore SIGPIPE") ;
{
sigset_t set ;
sigemptyset(&set) ;
sigaddset(&set, SIGTERM) ;
sigaddset(&set, SIGCHLD) ;
if (selfpipe_trapset(&set) < 0) strerr_diefu1sys(111, "trap signals") ;
}
{
int fd ;
pid = child_spawn1_pipe(argv[0], argv, envp, &fd, 0) ;
if (!pid) strerr_diefu2sys(111, "spawn ", argv[0]) ;
if (fd_move(1, fd) < 0) strerr_diefu1sys(111, "move pipe to stdout") ;
}
if (verbosity >= 2) strerr_warni1x("starting") ;
while (cont || bufalloc_len(bufalloc_1))
{
register int r ;
x[1].events = bufalloc_len(bufalloc_1) ? IOPAUSE_WRITE : 0 ;
r = iopause(x, 2 + cont, 0, 0) ;
if (r < 0) strerr_diefu1sys(111, "iopause") ;
if (!r) continue ;
if (x[0].revents & IOPAUSE_EXCEPT)
strerr_diefu1x(111, "iopause: trouble with selfpipe") ;
if (x[0].revents & IOPAUSE_READ) handle_signals() ;
if (x[1].revents & IOPAUSE_WRITE)
if (!bufalloc_flush(bufalloc_1)) strerr_diefu1sys(111, "flush stdout") ;
if (cont && x[2].revents & IOPAUSE_READ) handle_netlink() ;
}
if (verbosity >= 2) strerr_warni1x("exiting") ;
return 0 ;
}
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