diff options
Diffstat (limited to 'src/minutils/s6-devd.c')
| -rw-r--r-- | src/minutils/s6-devd.c | 288 |
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 ; +} |