1 files changed, 117 insertions, 33 deletions

diff --git a/src/init/s6-linux-init.c b/src/init/s6-linux-init.c
index 78cf3d0..530093e 100644
--- a/src/init/s6-linux-init.c
+++ b/src/init/s6-linux-init.c
@@ -23,20 +23,53 @@
 #include "defaults.h"
 #include "initctl.h"
 
-#define USAGE "s6-linux-init [ -c basedir ] [ -p initpath ] [ -s envdumpdir ] [ -m umask ] [ -d devtmpfs ] [ -D initdefault ] [ -n | -N ]"
+#define USAGE "s6-linux-init [ -c basedir ] [ -p initpath ] [ -s envdumpdir ] [ -m umask ] [ -d devtmpfs ] [ -D initdefault ] [ -n | -N ] [ -C ] [ -B ]"
 #define dieusage() strerr_dieusage(100, USAGE)
 
 #define BANNER "\n  s6-linux-init version " S6_LINUX_INIT_VERSION "\n\n"
 
+static int inns = 0 ;
+static int nologger = 0 ;
+static int notifpipe[2] ;
+
 static inline char const *scan_cmdline (char const *initdefault, char const *const *argv, unsigned int argc)
 {
-  static char const *valid[] = { "default", "2", "3", "4", "5", 0 } ;
-  for (unsigned int i = 0 ; i < argc ; i++)
-    for (char const *const *p = valid ; *p ; p++)
-      if (!strcmp(argv[i], *p)) return argv[i] ;
+  if (!inns)
+  {
+    static char const *valid[] = { "default", "2", "3", "4", "5", 0 } ;
+    for (unsigned int i = 0 ; i < argc ; i++)
+      for (char const *const *p = valid ; *p ; p++)
+        if (!strcmp(argv[i], *p)) return argv[i] ;
+  }
   return initdefault ;
 }
 
+static inline void wait_for_notif (int fd)
+{
+  char buf[16] ;
+  for (;;)
+  {
+    ssize_t r = read(fd, buf, 16) ;
+    if (r < 0) strerr_diefu1sys(111, "read from notification pipe") ;
+    if (!r)
+    {
+      strerr_warnw1x("s6-svscan failed to send a notification byte!") ;
+      break ;
+    }
+    if (memchr(buf, '\n', r)) break ;
+  }
+  close(fd) ;
+}
+
+static void disablecad (void)
+{
+  if (!inns)
+  {
+    if (reboot(RB_DISABLE_CAD) == -1)
+      strerr_warnwu1sys("trap ctrl-alt-del") ;
+  }
+}
+
 static inline void run_stage2 (char const *basedir, char const **argv, unsigned int argc, char const *const *envp, size_t envlen, char const *modifs, size_t modiflen, char const *initdefault)
 {
   size_t dirlen = strlen(basedir) ;
@@ -51,11 +84,20 @@ static inline void run_stage2 (char const *basedir, char const **argv, unsigned
     childargv[i+2] = argv[i] ;
   childargv[argc + 2] = 0 ;
   setsid() ;
-  fd_close(1) ;
-  if (open(LOGFIFO, O_WRONLY) != 1)  /* blocks until catch-all logger is up */
-    strerr_diefu1sys(111, "open " LOGFIFO " for writing") ;
-  if (fd_copy(2, 1) == -1)
-    strerr_diefu1sys(111, "fd_copy stdout to stderr") ;
+  if (nologger)
+  {
+    close(notifpipe[1]) ;
+    wait_for_notif(notifpipe[0]) ;
+  }
+  else
+  {
+   /* block on opening the log fifo until the catch-all logger is up */
+    close(1) ;
+    if (open(LOGFIFO, O_WRONLY) != 1)
+      strerr_diefu1sys(111, "open " LOGFIFO " for writing") ;
+    if (fd_copy(2, 1) == -1)
+      strerr_diefu1sys(111, "fd_copy stdout to stderr") ;
+  }
   xpathexec_r(childargv, envp, envlen, modifs, modiflen) ;
 }
 
@@ -74,15 +116,14 @@ int main (int argc, char const **argv, char const *const *envp)
   if (getpid() != 1)
   {
     argv[0] = S6_LINUX_INIT_BINPREFIX "s6-linux-init-telinit" ;
-    pathexec_run(argv[0], argv, envp) ;
-    strerr_dieexec(111, argv[0]) ;
+    xpathexec_run(argv[0], argv, envp) ;
   }
 
   {
     subgetopt_t l = SUBGETOPT_ZERO ;
     for (;;)
     {
-      int opt = subgetopt_r(argc, argv, "c:p:s:m:d:D:nN", &l) ;
+      int opt = subgetopt_r(argc, argv, "c:p:s:m:d:D:nNCB", &l) ;
       if (opt == -1) break ;
       switch (opt)
       {
@@ -94,35 +135,60 @@ int main (int argc, char const **argv, char const *const *envp)
         case 'D' : initdefault = l.arg ; break ;
         case 'n' : mounttype = 2 ; break ;
         case 'N' : mounttype = 0 ; break ;
+        case 'C' : inns = 1 ; break ;
+        case 'B' : nologger = 1 ; break ;
         default : dieusage() ;
       }
     }
     argc -= l.ind ; argv += l.ind ;
   }
 
-  allwrite(1, BANNER, sizeof(BANNER) - 1) ;
+  if (inns)
+  { /* If there's a Docker synchronization pipe, wait on it */
+    char c ;
+    ssize_t r = read(3, &c, 1) ;
+    if (r < 0)
+    {
+      if (errno != EBADF) strerr_diefu1sys(111, "read from fd 3") ;
+    }
+    else
+    {
+      if (r) strerr_warnw1x("parent wrote to fd 3!") ;
+      close(3) ;
+    }
+  }
+  else allwrite(1, BANNER, sizeof(BANNER) - 1) ;
   if (chdir("/") == -1) strerr_diefu1sys(111, "chdir to /") ;
   umask(mask) ;
   setpgid(0, 0) ;
-  fd_close(0) ;
+  close(0) ;
+
   if (slashdev)
   {
-    fd_close(1) ;
-    fd_close(2) ;
-    if (mount("dev", slashdev, "devtmpfs", MS_NOSUID | MS_NOEXEC, "") == -1)
+    int nope, e ;
+    close(1) ;
+    close(2) ;
+   /* at this point we're totally in the dark, hoping /dev/console will work */
+    nope = mount("dev", slashdev, "devtmpfs", MS_NOSUID | MS_NOEXEC, "") < 0 ;
+    e = errno ;
+    if (open("/dev/console", O_WRONLY)
+     || fd_move(2, 0) < 0
+     || fd_copy(1, 2) < 0) return 111 ;
+    if (nope)
     {
-      int e = errno ;
-      open("/dev/null", O_RDONLY) ;
-      open("/dev/console", O_WRONLY) ;
-      fd_copy(2, 1) ;
       errno = e ;
-      strerr_diefu2sys(111, "mount ", slashdev) ;
+      strerr_diefu1sys(111, "mount a devtmpfs on /dev") ;
     }
-    if (open("/dev/console", O_WRONLY)
-     || fd_copy(1, 0) == -1
-     || fd_move(2, 0) == -1) return 111 ;
   }
-  if (open("/dev/null", O_RDONLY)) strerr_diefu1sys(111, "open /dev/null") ;
+
+  if (open("/dev/null", O_RDONLY))
+  {  /* ghetto /dev/null to the rescue */
+    int p[2] ;
+    strerr_warnwu1sys("open /dev/null") ;
+    if (pipe(p) < 0) strerr_diefu1sys(111, "pipe") ;
+    close(p[1]) ;
+    if (fd_move(0, p[0]) < 0) strerr_diefu1sys(111, "fd_move to stdin") ;
+  }
 
   if (mounttype)
   {
@@ -157,6 +223,8 @@ int main (int argc, char const **argv, char const *const *envp)
   }
   if (envdumpdir && !env_dump(envdumpdir, 0700, envp))
     strerr_warnwu2sys("dump kernel environment to ", envdumpdir) ;
+
+  if (!nologger)
   {
     int fdr = open_read(LOGFIFO) ;
     if (fdr == -1) strerr_diefu1sys(111, "open " LOGFIFO) ;
@@ -164,11 +232,13 @@ int main (int argc, char const **argv, char const *const *envp)
     if (open(LOGFIFO, O_WRONLY) != 1) strerr_diefu1sys(111, "open " LOGFIFO) ;
     fd_close(fdr) ;
   }
+
   {
-    static char const *const newargv[5] = { S6_EXTBINPREFIX "s6-svscan", "-st0", "--", S6_LINUX_INIT_TMPFS "/" SCANDIR, 0 } ;
     char const *newenvp[2] = { 0, 0 } ;
-    pid_t pid ;
     size_t pathlen = path ? strlen(path) : 0 ;
+    pid_t pid ;
+    char fmtfd[2 + UINT_FMT] = "-" ;
+    char const *newargv[6] = { S6_EXTBINPREFIX "s6-svscan", "-st0", fmtfd, "--", S6_LINUX_INIT_TMPFS "/" SCANDIR, 0 } ;
     char pathvar[6 + pathlen] ;
     if (path)
     {
@@ -178,13 +248,27 @@ int main (int argc, char const **argv, char const *const *envp)
       memcpy(pathvar + 5, path, pathlen + 1) ;
       newenvp[0] = pathvar ;
     }
+    if (nologger && pipe(notifpipe) < 0) strerr_diefu1sys(111, "pipe") ;
     pid = fork() ;
     if (pid == -1) strerr_diefu1sys(111, "fork") ;
     if (!pid) run_stage2(basedir, argv, argc, newenvp, !!path, envmodifs.s, envmodifs.len, initdefault) ;
-    if (reboot(RB_DISABLE_CAD) == -1)
-      strerr_warnwu1sys("trap ctrl-alt-del") ;
-    if (fd_copy(2, 1) == -1)
-      strerr_diefu1sys(111, "redirect output file descriptor") ;
+    if (nologger)
+    {
+      close(notifpipe[0]) ;
+      fmtfd[1] = 'd' ;
+      fmtfd[2 + uint_fmt(fmtfd + 2, notifpipe[1])] = 0 ;
+      disablecad() ;
+    }
+    else
+    {
+      int fd = dup(2) ;
+      if (fd < 0) strerr_diefu1sys(111, "dup stderr") ;
+      fmtfd[1] = 'X' ;
+      fmtfd[2 + uint_fmt(fmtfd + 2, (unsigned int)fd)] = 0 ;
+      disablecad() ;
+      if (fd_copy(2, 1) == -1)
+        strerr_diefu1sys(111, "redirect output file descriptor") ;
+    }
     xpathexec_r(newargv, newenvp, !!path, envmodifs.s, envmodifs.len) ;
   }
 }