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authorLaurent Bercot <ska-skaware@skarnet.org>2014-09-19 15:01:58 +0000
committerLaurent Bercot <ska-skaware@skarnet.org>2014-09-19 15:01:58 +0000
commit54b6467013bfbdb3ee606961c02fbff1271ca582 (patch)
treee3969743e61542979f12fca01017e67c4480eca8 /src/minutils/s6-devd.c
downloads6-linux-utils-54b6467013bfbdb3ee606961c02fbff1271ca582.tar.xz
initial commit
Diffstat (limited to 'src/minutils/s6-devd.c')
-rw-r--r--src/minutils/s6-devd.c288
1 files changed, 288 insertions, 0 deletions
diff --git a/src/minutils/s6-devd.c b/src/minutils/s6-devd.c
new file mode 100644
index 0000000..2e5c9ce
--- /dev/null
+++ b/src/minutils/s6-devd.c
@@ -0,0 +1,288 @@
+/* ISC license. */
+
+#ifndef _GNU_SOURCE
+#define _GNU_SOURCE
+#endif
+
+#include <sys/types.h>
+#include <unistd.h>
+#include <spawn.h>
+#include <signal.h>
+#include <sys/socket.h>
+#include <linux/netlink.h>
+#include <errno.h>
+#include <skalibs/allreadwrite.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/uint.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/tai.h>
+#include <skalibs/iopause.h>
+#include <skalibs/env.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/sig.h>
+#include <skalibs/selfpipe.h>
+
+#define USAGE "s6-devd [ -q | -v ] [ -b kbufsz ] [ -t maxlife:maxterm:maxkill ] helperprogram..."
+#define dieusage() strerr_dieusage(100, USAGE)
+
+static unsigned int cont = 1, state = 0, verbosity = 1 ;
+static pid_t pid ;
+static tain_t lifetto = TAIN_INFINITE_RELATIVE,
+ termtto = TAIN_INFINITE_RELATIVE,
+ killtto = TAIN_INFINITE_RELATIVE,
+ deadline ;
+
+static inline int fd_recvmsg (int fd, struct msghdr *hdr)
+{
+ int r ;
+ do r = recvmsg(fd, hdr, 0) ;
+ while ((r == -1) && (errno == EINTR)) ;
+ return r ;
+}
+
+static inline int netlink_init (unsigned int kbufsz)
+{
+ struct sockaddr_nl nl = { .nl_family = AF_NETLINK, .nl_pad = 0, .nl_groups = 1, .nl_pid = 0 } ;
+ int fd = socket_internal(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT, DJBUNIX_FLAG_NB|DJBUNIX_FLAG_COE) ;
+ if (fd < 0) return -1 ;
+ if (bind(fd, (struct sockaddr *)&nl, sizeof(struct sockaddr_nl)) < 0) goto err ;
+ if (setsockopt(fd, SOL_SOCKET, SO_RCVBUFFORCE, &kbufsz, sizeof(unsigned int)) < 0) goto err ;
+ return fd ;
+ err:
+ {
+ register int e = errno ;
+ fd_close(fd) ;
+ errno = e ;
+ }
+ return -1 ;
+}
+
+static inline void on_death (void)
+{
+ pid = 0 ;
+ state = 0 ;
+ tain_add_g(&deadline, &tain_infinite_relative) ;
+ if (cont == 2) cont = 0 ;
+}
+
+static inline void on_event (char const *const *argv, char const *const *envp, char const *s, unsigned int len)
+{
+ unsigned int envlen = env_len(envp) ;
+ unsigned int n = envlen + 1 + byte_count(s, len, '\0') ;
+ int e ;
+ char const *v[n] ;
+ if (!env_merge(v, n, envp, envlen, s, len))
+ strerr_diefu1sys(111, "env_merge") ;
+ e = posix_spawnp(&pid, argv[0], 0, 0, (char *const *)argv, (char * const *)v) ;
+ if (e) { errno = e ; strerr_diefu2sys(111, "spawn ", argv[0]) ; }
+ state = 1 ;
+ tain_add_g(&deadline, &lifetto) ;
+}
+
+static inline void handle_timeout (void)
+{
+ switch (state)
+ {
+ case 0 :
+ tain_add_g(&deadline, &tain_infinite_relative) ;
+ break ;
+ case 1 :
+ kill(pid, SIGTERM) ;
+ tain_add_g(&deadline, &termtto) ;
+ state++ ;
+ break ;
+ case 2 :
+ kill(pid, SIGKILL) ;
+ tain_add_g(&deadline, &killtto) ;
+ state++ ;
+ break ;
+ case 3 :
+ strerr_dief1x(99, "child resisted SIGKILL - check your kernel logs.") ;
+ default :
+ strerr_dief1x(101, "internal error: inconsistent state. Please submit a bug-report.") ;
+ }
+}
+
+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 = pid ? 2 : 0 ;
+ break ;
+ case SIGCHLD :
+ if (!pid) wait_reap() ;
+ else
+ {
+ 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 ;
+ on_death() ;
+ }
+ break ;
+ default :
+ strerr_dief1x(101, "internal error: inconsistent signal state. Please submit a bug-report.") ;
+ }
+ }
+}
+
+static inline void handle_netlink (int fd, char const *const *argv, char const *const *envp)
+{
+ char buf[4096] ;
+ int r ;
+ {
+ struct sockaddr_nl nl;
+ struct iovec iov = { .iov_base = &buf, .iov_len = sizeof(buf) } ;
+ char ctlmsg[CMSG_SPACE(sizeof(struct ucred))] ;
+ struct msghdr msg = {
+ .msg_name = &nl,
+ .msg_namelen = sizeof(struct sockaddr_nl),
+ .msg_iov = &iov,
+ .msg_iovlen = 1,
+ .msg_control = ctlmsg,
+ .msg_controllen = sizeof(ctlmsg),
+ .msg_flags = 0
+ } ;
+ r = sanitize_read(fd_recvmsg(fd, &msg)) ;
+ if (r < 0)
+ {
+ if (errno == EPIPE)
+ {
+ if (verbosity >= 2) strerr_warnw1x("received EOF on netlink") ;
+ cont = 0 ;
+ return ;
+ }
+ else strerr_diefu1sys(111, "receive netlink message") ;
+ }
+ if (!r) return ;
+ if (r < 32 || r > 4096)
+ {
+ if (verbosity >= 2)
+ strerr_warnw2x("received and ignored netlink message ", "with invalid length") ;
+ return ;
+ }
+ if (nl.nl_pid)
+ {
+ if (verbosity >= 3)
+ {
+ char fmt[UINT_FMT] ;
+ fmt[uint_fmt(fmt, nl.nl_pid)] = 0 ;
+ strerr_warnw3x("received and ignored netlink message ", "from userspace process ", fmt) ;
+ }
+ return ;
+ }
+ }
+ {
+ unsigned int start = str_len(buf) + 1 ;
+ if (start < 5 || start > (unsigned int)r)
+ {
+ if (verbosity >= 2)
+ strerr_warnw3x("received and ignored netlink message ", "with invalid header", " length") ;
+ return ;
+ }
+ if (str_strn(buf, start, "@/", 2) >= start)
+ {
+ if (verbosity >= 2)
+ strerr_warnw2x("received and ignored netlink message ", "with invalid header") ;
+ return ;
+ }
+ on_event(argv, envp, buf + start, r - start) ;
+ }
+}
+
+static inline int make_ttos (char const *s)
+{
+ unsigned int tlife = 0, tterm = 0, tkill = 0, pos = 0 ;
+ pos += uint_scan(s + pos, &tlife) ;
+ if (s[pos] && s[pos++] != ':') return 0 ;
+ if (!tlife) return 1 ;
+ tain_from_millisecs(&lifetto, tlife) ;
+ pos += uint_scan(s + pos, &tterm) ;
+ if (s[pos] && s[pos++] != ':') return 0 ;
+ if (!tterm) return 1 ;
+ tain_from_millisecs(&termtto, tterm) ;
+ tain_add(&termtto, &termtto, &lifetto) ;
+ pos += uint_scan(s + pos, &tkill) ;
+ if (s[pos]) return 0 ;
+ if (!tkill) return 1 ;
+ tain_from_millisecs(&killtto, tkill) ;
+ tain_add(&killtto, &killtto, &termtto) ;
+ return 1 ;
+}
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+ iopause_fd x[2] = { { -1, IOPAUSE_READ, 0 }, { -1, IOPAUSE_READ, 0 } } ;
+ PROG = "s6-devd" ;
+ {
+ unsigned int kbufsz = 65536 ;
+ subgetopt_t l = SUBGETOPT_ZERO ;
+ for (;;)
+ {
+ register int opt = subgetopt_r(argc, argv, "qvb:t:", &l) ;
+ if (opt == -1) break ;
+ switch (opt)
+ {
+ case 'q' : if (verbosity) verbosity-- ; break ;
+ case 'v' : verbosity++ ; break ;
+ case 'b' : if (!uint0_scan(l.arg, &kbufsz)) dieusage() ; break ;
+ case 't' : if (!make_ttos(l.arg)) dieusage() ; break ;
+ default : dieusage() ;
+ }
+ }
+ argc -= l.ind ; argv += l.ind ;
+ if (!argc) strerr_dieusage(100, USAGE) ;
+ {
+ int fd = open_readb("/dev/null") ;
+ if (fd < 0) strerr_diefu2sys(111, "open /dev/null for ", "reading") ;
+ if (fd_move(0, fd) < 0) strerr_diefu2sys(111, "redirect std", "in") ;
+ fd = open_write("/dev/null") ;
+ if (fd < 0) strerr_diefu2sys(111, "open /dev/null for ", "writing") ;
+ if (ndelay_off(fd) < 0) strerr_diefu1sys(111, "ndelay_off /dev/null") ;
+ if (fd_move(1, fd) < 0) strerr_diefu2sys(111, "redirect std", "out") ;
+ }
+ x[1].fd = netlink_init(kbufsz) ;
+ if (x[1].fd < 0) strerr_diefu1sys(111, "init netlink") ;
+ }
+
+ x[0].fd = selfpipe_init() ;
+ if (x[0].fd == -1) 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") ;
+ }
+
+ tain_now_g() ;
+ tain_add_g(&deadline, &tain_infinite_relative) ;
+ if (verbosity >= 2) strerr_warni1x("starting") ;
+
+ while (cont)
+ {
+ register int r = iopause_g(x, 1 + !pid, &deadline) ;
+ if (r < 0) strerr_diefu1sys(111, "iopause") ;
+ else if (!r) handle_timeout() ;
+ else
+ {
+ if ((x[0].revents | x[1].revents) & IOPAUSE_EXCEPT)
+ strerr_diefu1x(111, "iopause: trouble with pipes") ;
+ if (x[0].revents & IOPAUSE_READ) handle_signals() ;
+ else if (!pid && (x[1].revents & IOPAUSE_READ))
+ handle_netlink(x[1].fd, argv, envp) ;
+ }
+ }
+ if (verbosity >= 2) strerr_warni1x("exiting") ;
+ return 0 ;
+}