- Added s6-uevent-listener and s6-uevent-spawner

 - s6-devd is now a wrapper around the former two
 - version: bump to 2.0.2.0, still missing s6-devd doc

1 files changed, 233 insertions, 0 deletions

diff --git a/src/minutils/s6-uevent-listener.c b/src/minutils/s6-uevent-listener.c
new file mode 100644
index 0000000..b2cf455
--- /dev/null
+++ b/src/minutils/s6-uevent-listener.c
@@ -0,0 +1,233 @@
+/* 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 ;
+}