Initial commit.

6 files changed, 964 insertions, 0 deletions

diff --git a/src/alias/deps-exe/s6-frontend-alias b/src/alias/deps-exe/s6-frontend-alias
new file mode 100644
index 0000000..e7187fe
--- /dev/null
+++ b/src/alias/deps-exe/s6-frontend-alias
@@ -0,0 +1 @@
+-lskarnet
diff --git a/src/alias/deps-exe/s6-frontend-alias-chpst b/src/alias/deps-exe/s6-frontend-alias-chpst
new file mode 100644
index 0000000..e7187fe
--- /dev/null
+++ b/src/alias/deps-exe/s6-frontend-alias-chpst
@@ -0,0 +1 @@
+-lskarnet
diff --git a/src/alias/deps-exe/s6-frontend-alias-sv b/src/alias/deps-exe/s6-frontend-alias-sv
new file mode 100644
index 0000000..b3e8440
--- /dev/null
+++ b/src/alias/deps-exe/s6-frontend-alias-sv
@@ -0,0 +1,3 @@
+-ls6
+-lskarnet
+${SPAWN_LIB}
diff --git a/src/alias/s6-frontend-alias-chpst.c b/src/alias/s6-frontend-alias-chpst.c
new file mode 100644
index 0000000..860654e
--- /dev/null
+++ b/src/alias/s6-frontend-alias-chpst.c
@@ -0,0 +1,347 @@
+ /* ISC license. */
+
+#include <string.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <limits.h>
+#include <errno.h>
+#include <pwd.h>
+#include <grp.h>
+
+#include <skalibs/uint64.h>
+#include <skalibs/types.h>
+#include <skalibs/bytestr.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/buffer.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/genalloc.h>
+#include <skalibs/env.h>
+#include <skalibs/djbunix.h>
+
+#include <execline/config.h>
+
+#include <s6/config.h>
+
+#define USAGE "s6-frontend-alias-chpst [ -v ] [ -P ] [ -0 ] [ -1 ] [ -2 ] [ -u user ] [ -U user ] [ -b argv0 ] [ -e dir ] [ -n niceness ] [ -l lock | -L lock ] [ -m bytes ] [ -d bytes ] [ -o n ] [ -p n ] [ -f bytes ] [ -c bytes ] prog..."
+
+#define dienomem() strerr_diefu1sys(111, "stralloc_catb")
+#define dieusage() strerr_dieusage(100, USAGE)
+
+static unsigned int verbosity = 0 ;
+
+static void printit (char const *const *argv)
+{
+  buffer_puts(buffer_2, PROG) ;
+  buffer_puts(buffer_2, ": info: executing the following command line:") ;
+  for (; *argv ; argv++)
+  {
+    buffer_puts(buffer_2, " ") ;
+    buffer_puts(buffer_2, *argv) ;
+  }
+  buffer_putsflush(buffer_2, "\n") ;
+}
+
+static inline size_t parseuggnum (char const *s, uint32_t *flags, uid_t *uid, gid_t *gid, gid_t *tab)
+{
+  size_t n = 0 ;
+  size_t pos = uid_scan(s, uid) ;
+  if (!pos) dieusage() ;
+  if (!s[pos]) return 0 ;
+  if (s[pos] != ':') dieusage() ;
+  s += pos+1 ;
+  pos = gid_scan(s, gid) ;
+  if (!pos) dieusage() ;
+  *flags |= 32768 ;
+  if (!s[pos]) return 0 ;
+  if (s[pos] != ':') dieusage() ;
+  s += pos+1 ;
+  if (!gid_scanlist(tab, NGROUPS_MAX, s, &n)) dieusage() ;
+  return n ;
+}
+
+static struct passwd *do_getpwnam (char const *s)
+{
+  struct passwd *pw = getpwnam(s) ;
+  if (!pw)
+  {
+    if (errno) strerr_diefu1sys(111, "read user database") ;
+    else strerr_dief2x(100, "user not found in user database: ", s) ;
+  }
+  return pw ;
+}
+
+static struct group *do_getgrnam (char const *s)
+{
+  struct group *gr = getgrnam(s) ;
+  if (!gr)
+  {
+    if (errno) strerr_diefu1sys(111, "read group database") ;
+    else strerr_dief2x(100, "group not found in group database: ", s) ;
+  }
+  return gr ;
+}
+
+static inline size_t parseuggsym (char const *s, uint32_t *flags, uid_t *uid, gid_t *gid, gid_t *tab)
+{
+  size_t n = 0 ;
+  struct passwd *pw ;
+  struct group *gr ;
+  size_t pos = str_chr(s, ':') ;
+  *flags |= 32768 ;
+  errno = 0 ;
+  if (!s[pos]) pw = do_getpwnam(s) ;
+  else
+  {
+    char tmp[pos+1] ;
+    memcpy(tmp, s, pos) ;
+    tmp[pos] = 0 ;
+    pw = do_getpwnam(tmp) ;
+  }
+  *uid = pw->pw_uid ;
+  if (!s[pos])
+  {
+    *gid = pw->pw_gid ;
+    return 0 ;
+  }
+  s += pos+1 ;
+  pos = str_chr(s, ':') ;
+  errno = 0 ;
+  if (!s[pos]) gr = do_getgrnam(s) ;
+  else
+  {
+    char tmp[pos+1] ;
+    memcpy(tmp, s, pos) ;
+    tmp[pos] = 0 ;
+    gr = do_getgrnam(tmp) ;
+  }
+  *gid = gr->gr_gid ;
+  if (!s[pos]) return 0 ;
+  s += pos+1 ;
+  while (*s)
+  {
+    if (n >= NGROUPS_MAX)
+      strerr_dief1x(100, "too many supplementary groups listed for the -u option") ;
+    pos = str_chr(s, ':') ;
+    errno = 0 ;
+    if (!s[pos]) gr = do_getgrnam(s) ;
+    else
+    {
+      char tmp[pos+1] ;
+      memcpy(tmp, s, pos) ;
+      tmp[pos] = 0 ;
+      gr = do_getgrnam(tmp) ;
+    }
+    tab[n++] = gr->gr_gid ;
+    s += s[pos] ? pos+1 : pos ;
+  }
+  return n ;
+}
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  static char const *valopt[6] = { "-m", "-d", "-o", "-p", "-f", "-c" } ;
+  genalloc envdirs = GENALLOC_ZERO ; /* char const * */
+  stralloc newroot = STRALLOC_ZERO ;
+  unsigned int newargc = 0 ;
+  char const *argv0 = 0 ;
+  char const *lockfile = 0 ;
+  char const *envug = 0 ;
+  uint32_t flags = 0 ;
+  int niceval = 0 ;
+  char valfmt[6][UINT64_FMT] ;
+  char nicefmt[INT_FMT] ;
+  char uidfmt[UID_FMT] ;
+  char gidfmt[GID_FMT] ;
+  char gidlistfmt[GID_FMT * NGROUPS_MAX] ;
+  PROG = "s6-frontend-alias-chpst" ;
+
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      int opt = subgetopt_r(argc, argv, "vP012u:U:b:e:/:n:l:L:m:d:o:p:f:c:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'v' : verbosity++ ; break ;
+        case '0' : flags |= 1 ; newargc += 2 ; break ;
+        case '1' : flags |= 2 ; newargc += 2 ; break ;
+        case '2' : flags |= 4 ; newargc += 2 ; break ;
+        case 'P' : flags |= 8 ; newargc += 2 ; break ;
+        case 'b' : argv0 = l.arg ; newargc += 4 ; break ;
+        case 'u' :
+        {
+          size_t n ;
+          uid_t uid ;
+          gid_t gid ;
+          gid_t tab[NGROUPS_MAX] ;
+          newargc += 6 ;
+          flags |= 16384 ; flags &= ~32768 ;
+          n = l.arg[0] == ':' ?
+            parseuggnum(l.arg + 1, &flags, &uid, &gid, tab) :
+            parseuggsym(l.arg, &flags, &uid, &gid, tab) ;
+          uidfmt[uid_fmt(uidfmt, uid)] = 0 ;
+          if (flags & 32768)
+          {
+            newargc += 2 ;
+            gidfmt[gid_fmt(gidfmt, gid)] = 0 ;
+          }
+          gidlistfmt[gid_fmtlist(gidlistfmt, tab, n)] = 0 ;
+          break ;
+        }
+        case 'U' :
+          envug = l.arg ;
+          newargc += 3 ;
+          if (envug[0] == ':') { flags |= 4096 ; envug++ ; newargc++ ; } else flags &= ~4096 ;
+          if (strchr(envug, ':')) { flags |= 8192 ; newargc++ ; } else flags &= ~8192 ;
+          break ;
+        case 'e' :
+          if (!genalloc_append(char const *, &envdirs, &l.arg)) dienomem() ;
+          newargc += 3 ;
+          break ;
+        case '/' :
+          newroot.len = 0 ;
+          if (sarealpath(&newroot, l.arg) < 0 || !stralloc_0(&newroot)) dienomem() ;
+          newargc += 2 ;
+          break ;
+        case 'n' :
+          if (!int0_scan(l.arg, &niceval)) dieusage() ;
+          newargc += 3 ;
+          break ;
+        case 'l' : lockfile = l.arg ; flags &= ~16 ; newargc += 4 ; break ;
+        case 'L' : lockfile = l.arg ; flags |= 16 ; newargc += 4 ; break ;
+        case 'm' :
+        case 'd' :
+        case 'o' :
+        case 'p' :
+        case 'f' :
+        case 'c' :
+        {
+          uint64_t val ;
+          size_t pos = byte_chr("mdopfc", 6, opt) ;
+          if (!uint640_scan(l.arg, &val)) dieusage() ;
+          valfmt[pos][uint64_fmt(valfmt[pos], val)] = 0 ;
+          flags |= 32 | (1 << (6 + pos)) ;
+          newargc += 2 ;
+          break ;
+        }
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+  }
+
+  if (flags & 32) newargc += 2 ;
+  newargc += argc ;
+
+  {
+    unsigned int m = 0 ;
+    char const *newargv[newargc + 1] ;
+
+    if (niceval)
+    {
+      nicefmt[int_fmt(nicefmt, niceval)] = 0 ;
+      newargv[m++] = "nice" ;
+      newargv[m++] = "-n" ;
+      newargv[m++] = nicefmt ;
+      newargv[m++] = "--" ;
+    }
+
+    if (flags & 8)
+    {
+      newargv[m++] = S6_EXTBINPREFIX "s6-setsid" ;
+      newargv[m++] = "--" ;
+    }
+
+    if (genalloc_len(char const *, &envdirs))
+    {
+      for (size_t i = 0 ; i < genalloc_len(char const *, &envdirs) ; i++)
+      {
+        newargv[m++] = S6_EXTBINPREFIX "s6-envdir" ;
+        newargv[m++] = "--" ;
+        newargv[m++] = genalloc_s(char const *, &envdirs)[i] ;
+      }
+    }
+
+    if (lockfile)
+    {
+      newargv[m++] = S6_EXTBINPREFIX "s6-setlock" ;
+      newargv[m++] = flags & 16 ? "-n" : "-N" ;
+      newargv[m++] = "--" ;
+      newargv[m++] = lockfile ;
+    }
+
+    if (flags & 16384)
+    {
+      newargv[m++] = S6_EXTBINPREFIX "s6-applyuidgid" ;
+      newargv[m++] = "-u" ;
+      newargv[m++] = uidfmt ;
+      if (flags & 32768)
+      {
+        newargv[m++] = "-g" ;
+        newargv[m++] = gidfmt ;
+      }
+      newargv[m++] = "-G" ;
+      newargv[m++] = gidlistfmt ;
+      newargv[m++] = "--" ;
+    }
+
+    if (envug)
+    {
+      newargv[m++] = S6_EXTBINPREFIX "s6-envuidgid" ;
+      if (flags & 4096) newargv[m++] = "-n" ;
+      if (flags & 8192) newargv[m++] = "-B" ;
+      newargv[m++] = "--" ;
+      newargv[m++] = envug ;
+    }
+
+    if (flags & 32)
+    {
+      newargv[m++] = S6_EXTBINPREFIX "s6-softlimit" ;
+      for (unsigned int i = 0 ; i < 6 ; i++) if (flags & (1 << (i + 6)))
+      {
+        newargv[m++] = valopt[i] ;
+        newargv[m++] = valfmt[i] ;
+      }
+      newargv[m++] = "--" ;
+    }
+
+    if (flags & 1)
+    {
+      newargv[m++] = EXECLINE_EXTBINPREFIX "fdclose" ;
+      newargv[m++] = "0" ;
+    }
+
+    if (flags & 2)
+    {
+      newargv[m++] = EXECLINE_EXTBINPREFIX "fdclose" ;
+      newargv[m++] = "1" ;
+    }
+
+    if (flags & 4)
+    {
+      newargv[m++] = EXECLINE_EXTBINPREFIX "fdclose" ;
+      newargv[m++] = "2" ;
+    }
+
+    if (argv0)
+    {
+      newargv[m++] = EXECLINE_BINPREFIX "exec" ;
+      newargv[m++] = "-a" ;
+      newargv[m++] = argv0 ;
+      newargv[m++] = "--" ;
+    }
+
+    if (newroot.s)
+    {
+      newargv[m++] = "chroot" ;
+      newargv[m++] = newroot.s ;
+      if (argv0) strerr_warnw1x("the -b option is ineffective when the -/ option is also given") ;
+    }
+
+    for (int i = 0 ; i < argc+1 ; i++) newargv[m++] = argv[i] ;
+    if (verbosity) printit(newargv) ;
+    xpathexec0_run(newargv, envp) ;
+  }
+}
diff --git a/src/alias/s6-frontend-alias-sv.c b/src/alias/s6-frontend-alias-sv.c
new file mode 100644
index 0000000..e6e0ec8
--- /dev/null
+++ b/src/alias/s6-frontend-alias-sv.c
@@ -0,0 +1,377 @@
+ /* ISC license. */
+
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/wait.h>
+
+#include <skalibs/uint32.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/djbunix.h>
+
+#include <s6/config.h>
+#include <s6/s6-supervise.h>
+
+#define USAGE "s6-frontend-alias-sv [ -v ] [ -w sec ] command services..."
+#define dieusage() strerr_dieusage(100, USAGE)
+#define dienomem() strerr_diefu1sys(111, "stralloc_catb")
+
+typedef int execfunc_t (char const *, char const *const *) ;
+typedef execfunc_t *execfunc_t_ref ;
+
+typedef struct info_s info_t, *info_t_ref ;
+struct info_s
+{
+  char const *name ;
+  execfunc_t_ref f ;
+} ;
+
+static int dowait = 0 ;
+static uint32_t secs = 7 ;
+
+static void warnnolog (void)
+{
+  strerr_warnw1x("s6-svc only sends commands to a single service, even if it has a dedicated logger") ;
+}
+
+static void warnnokill (void)
+{
+  strerr_warnw1x("s6-supervise pilots a kill signal via the timeout-kill file in the service directory") ;
+}
+
+static int info_cmp (void const *a, void const *b)
+{
+  char const *name = a ;
+  info_t const *info = b ;
+  return strcmp(name, info->name) ;
+}
+
+static int spawnit (char const *const *argv, char const *const *envp)
+{
+  int wstat ;
+  pid_t r ;
+  pid_t pid = child_spawn0(argv[0], argv, envp) ;
+  if (!pid)
+  {
+    strerr_warnwu2sys("spawn ", argv[0]) ;
+    return 1 ;
+  }
+  r = wait_pid(pid, &wstat) ;
+  if (r != pid)
+  {
+    strerr_warnwu2sys("wait for ", argv[0]) ;
+    return 1 ;
+  }
+  return !!WIFSIGNALED(wstat) || !!WEXITSTATUS(wstat) ;
+}
+
+static int simple_svc (char const *dir, char const *options, char const *const *envp)
+{
+  char const *argv[5] = { S6_EXTBINPREFIX "s6-svc", options, "--", dir, 0 } ;
+  return spawnit(argv, envp) ;
+}
+
+static int complex_svc (char const *dir, char const *order, char waitfor, char const *const *envp)
+{
+  char warg[4] = "-w?" ;
+  char fmt[2 + UINT32_FMT] = "-T" ;
+  char const *argv[7] = { S6_EXTBINPREFIX "s6-svc", warg, fmt, order, "--", dir, 0 } ;
+  fmt[2 + uint32_fmt(fmt + 2, 1000 * secs)] = 0 ;
+  warg[2] = waitfor ;
+  return spawnit(argv, envp) ;
+}
+
+static int status (char const *dir, char const *const *envp)
+{
+  char const *argv[4] = { S6_EXTBINPREFIX "s6-svstat", "--", dir, 0 } ;
+  return spawnit(argv, envp) ;
+}
+
+static int usr1_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-1", envp) ;
+}
+
+static int usr2_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-2", envp) ;
+}
+
+static int alarm_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-a", envp) ;
+}
+
+static int cont_h (char const *dir, char const *const *envp)
+{
+  if (dowait)
+  {
+    complex_svc(dir, "-o", 'U', envp) ;
+    return status(dir, envp) ;
+  }
+  else return simple_svc(dir, "-c", envp) ;
+}
+
+static int down (char const *dir, char const *const *envp)
+{
+  if (dowait)
+  {
+    complex_svc(dir, "-d", 'D', envp) ;
+    return status(dir, envp) ;
+  }
+  else return simple_svc(dir, "-d", envp) ;
+}
+
+static int bail (char const *dir, char const *const *envp)
+{
+  warnnolog() ;
+  if (dowait)
+  {
+    complex_svc(dir, "-d", 'D', envp) ;
+    status(dir, envp) ;
+  }
+  return simple_svc(dir, "-xd", envp) ;
+}
+
+static int hup_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-h", envp) ;
+}
+
+static int int_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-i", envp) ;
+}
+
+static int kill_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-k", envp) ;
+}
+
+static int once (char const *dir, char const *const *envp)
+{
+  if (dowait)
+  {
+    complex_svc(dir, "-o", 'U', envp) ;
+    return status(dir, envp) ;
+  }
+  else return simple_svc(dir, "-o", envp) ;
+}
+
+static int pause_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-p", envp) ;
+}
+
+static int quit_h (char const *dir, char const *const *envp)
+{
+  return simple_svc(dir, "-q", envp) ;
+}
+
+static int term_h (char const *dir, char const *const *envp)
+{
+  if (dowait)
+  {
+    complex_svc(dir, "-r", 'R', envp) ;
+    return status(dir, envp) ;
+  }
+  else return simple_svc(dir, "-t", envp) ;
+}
+
+static int up (char const *dir, char const *const *envp)
+{
+  if (dowait)
+  {
+    complex_svc(dir, "-u", 'U', envp) ;
+    return status(dir, envp) ;
+  }
+  else return simple_svc(dir, "-u", envp) ;
+}
+
+static int check (char const *dir, char const *const *envp)
+{
+  s6_svstatus_t svst ;
+  char warg[3] = "-?" ;
+  char fmt[2 + UINT32_FMT] = "-t" ;
+  char const *argv[6] = { S6_EXTBINPREFIX "s6-svwait", warg, fmt, "--", dir, 0 } ;
+  fmt[2 + uint32_fmt(fmt + 2, 1000 * secs)] = 0 ;
+  if (!s6_svstatus_read(dir, &svst)) return 1 ;
+  warg[1] = svst.flagwantup ? 'U' : 'D' ;
+  spawnit(argv, envp) ;
+  return status(dir, envp) ;
+}
+
+static int lsb_reload (char const *dir, char const *const *envp)
+{
+  hup_h(dir, envp) ;
+  return status(dir, envp) ;
+}
+
+static int lsb_restart (char const *dir, char const *const *envp)
+{
+  complex_svc(dir, "-ru", 'U', envp) ;
+  return status(dir, envp) ;
+}
+
+static int lsb_start (char const *dir, char const *const *envp)
+{
+  complex_svc(dir, "-u", 'U', envp) ;
+  return status(dir, envp) ;
+}
+
+static int lsb_stop (char const *dir, char const *const *envp)
+{
+  complex_svc(dir, "-d", 'D', envp) ;
+  return status(dir, envp) ;
+}
+
+static int lsb_shutdown (char const *dir, char const *const *envp)
+{
+  warnnolog() ;
+  complex_svc(dir, "-d", 'D', envp) ;
+  status(dir, envp) ;
+  return simple_svc(dir, "-x", envp) ;
+}
+
+static int lsb_forcereload (char const *dir, char const *const *envp)
+{
+  warnnokill() ;
+  return lsb_reload(dir, envp) ;
+}
+
+static int lsb_forcerestart (char const *dir, char const *const *envp)
+{
+  warnnokill() ;
+  return lsb_restart(dir, envp) ;
+}
+
+static int lsb_forcestop (char const *dir, char const *const *envp)
+{
+  warnnokill() ;
+  return lsb_stop(dir, envp) ;
+}
+
+static int lsb_forceshutdown (char const *dir, char const *const *envp)
+{
+  warnnokill() ;
+  return lsb_shutdown(dir, envp) ;
+}
+
+static int lsb_tryrestart (char const *dir, char const *const *envp)
+{
+  s6_svstatus_t svst ;
+  if (s6_svstatus_read(dir, &svst) && svst.flagwantup && svst.pid && !svst.flagfinishing)
+    complex_svc(dir, "-r", 'U', envp) ;    
+  return status(dir, envp) ;
+}
+
+static info_t const commands[] =
+{
+  { .name = "1", .f = &usr1_h },
+  { .name = "2", .f = &usr2_h },
+  { .name = "a", .f = &alarm_h },
+  { .name = "alarm", .f = &alarm_h },
+  { .name = "c", .f = &cont_h },
+  { .name = "check", .f = &check },
+  { .name = "cont", .f = &cont_h },
+  { .name = "d", .f = &down },
+  { .name = "down", .f = &down },
+  { .name = "e", .f = &bail },
+  { .name = "exit", .f = &bail },
+  { .name = "force-reload", .f = &lsb_forcereload },
+  { .name = "force-restart", .f = &lsb_forcerestart },
+  { .name = "force-shutdown", .f = &lsb_forceshutdown },
+  { .name = "force-stop", .f = &lsb_forcestop },
+  { .name = "h", .f = &hup_h },
+  { .name = "hup", .f = &hup_h },
+  { .name = "i", .f = &int_h },
+  { .name = "interrupt", .f = &int_h },
+  { .name = "k", .f = &kill_h },
+  { .name = "kill", .f = &kill_h },
+  { .name = "o", .f = &once },
+  { .name = "once", .f = &once },
+  { .name = "p", .f = &pause_h },
+  { .name = "pause", .f = &pause_h },
+  { .name = "q", .f = &quit_h },
+  { .name = "quit", .f = &quit_h },
+  { .name = "reload", .f = &lsb_reload },
+  { .name = "restart", .f = &lsb_restart },
+  { .name = "s", .f = &status },
+  { .name = "shutdown", .f = &lsb_shutdown },
+  { .name = "start", .f = &lsb_start },
+  { .name = "status", .f = &status },
+  { .name = "stop", .f = &lsb_stop },
+  { .name = "t", .f = &term_h },
+  { .name = "term", .f = &term_h },
+  { .name = "try-restart", .f = &lsb_tryrestart },
+  { .name = "u", .f = &up },
+  { .name = "up", .f = &up }
+} ;
+
+int main (int argc, char const *const *argv, char const *const *envp)
+{
+  int e = 0 ;
+  info_t *p ;
+  char const *x = getenv("SVWAIT") ;
+  char const *scandir = getenv("SVDIR") ;
+  size_t scandirlen ;
+  PROG = "s6-frontend-alias-sv" ;
+  if (!scandir) scandir = "/run/service" ; /* TODO: infer from s6li config */
+  scandirlen = strlen(scandir) ;
+  if (x)
+  {
+    if (!uint320_scan(x, &secs))
+      strerr_warnw1x("invalid SVWAIT value") ;
+  }
+
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      int opt = subgetopt_r(argc, argv, "vw:", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'v' : dowait = 1 ; break ;
+        case 'w' : if (!uint320_scan(l.arg, &secs)) dieusage() ; break ;
+        default : dieusage() ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+  }
+
+  if (argc < 2) dieusage() ;
+  p = bsearch(argv[0], commands, sizeof(commands) / sizeof(info_t), sizeof(info_t), &info_cmp) ;
+  if (!p) strerr_dief2x(100, "unknown command: ", argv[0]) ;
+
+  for (argv++ ; *argv ; argv++)
+  {
+    if ((argv[0][0] == '.' && (argv[0][1] == '/' || (argv[0][1] == '.' && argv[0][2] == '/'))) || argv[0][0] == '/')
+      e += (*p->f)(*argv, envp) ;
+    else
+    {
+      int what = 1 ;
+      struct stat st ;
+      size_t len = strlen(*argv) ;
+      char fn[scandirlen + len + 2] ;
+      memcpy(fn, scandir, scandirlen) ;
+      fn[scandirlen] = '/' ;
+      memcpy(fn + scandirlen + 1, *argv, len + 1) ;
+      if (stat(fn, &st) < 0)  /* XXX: TOCTOU but we don't care */
+      {
+        if (errno != ENOENT)
+        {
+          e++ ;
+          what = 0 ;
+          strerr_warnwu2sys("stat ", fn) ;
+        }
+      }
+      else if (S_ISDIR(st.st_mode)) what = 2 ;
+      if (what) e += (*p->f)(what > 1 ? fn : *argv, envp) ;
+    }
+  }
+  return e ;
+}
diff --git a/src/alias/s6-frontend-alias.c b/src/alias/s6-frontend-alias.c
new file mode 100644
index 0000000..7467632
--- /dev/null
+++ b/src/alias/s6-frontend-alias.c
@@ -0,0 +1,235 @@
+ /* ISC license. */
+
+#include <string.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include <skalibs/buffer.h>
+#include <skalibs/sgetopt.h>
+#include <skalibs/strerr2.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/djbunix.h>
+#include <skalibs/skamisc.h>
+
+#include <s6/config.h>
+
+#include <s6-frontend/config.h>
+
+#define USAGE "s6-frontend-alias [ -v ] cmdname options..."
+#define dienomem() strerr_diefu1sys(111, "stralloc_catb")
+#define dieusage() strerr_dieusage(100, USAGE)
+
+static unsigned int verbosity = 0 ;
+
+typedef void execfunc_t (int, char const *const *, char const *const *) ;
+typedef execfunc_t *execfunc_t_ref ;
+
+typedef struct info_s info_t, *info_t_ref ;
+struct info_s
+{
+  char const *name ;
+  char const *cmd ;
+  execfunc_t_ref f ;
+} ;
+
+static int info_cmp (void const *a, void const *b)
+{
+  char const *name = a ;
+  info_t const *info = b ;
+  return strcmp(name, info->name) ;
+}
+
+#if defined(S6_FRONTEND_WRAP_DAEMONTOOLS) || defined (S6_FRONTEND_WRAP_RUNIT)
+static void noboot (char const *name)
+{
+  strerr_dief3x(100, "s6 does not provide a ", name, " emulation. To boot on a s6 supervision tree, please consider the s6-linux-init package.") ;
+}
+#endif
+
+#ifdef S6_FRONTEND_WRAP_DAEMONTOOLS
+
+static void readproctitle (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  noboot("readproctitle") ;
+}
+
+static void svscanboot (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  noboot("svscanboot") ;
+}
+
+#endif
+
+#ifdef S6_FRONTEND_WRAP_RUNIT
+
+static void runit (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  noboot("runit") ;
+}
+
+static void runit_init (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  noboot("runit-init") ;
+}
+
+static void runsvchdir (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  strerr_dief1x(100, "s6 does not provide a runsvchdir emulation. To handle several different sets of services, please consider the s6-rc package.") ;
+}
+
+static void runsvdir (int argc, char const *const *argv, char const *const *envp)
+{
+  char const *newargv[4] = { S6_EXTBINPREFIX "s6-svscan", "-St14000", 0, 0 } ;
+  int dosetsid = 0 ;
+  subgetopt_t l = SUBGETOPT_ZERO ;
+  for (;;)
+  {
+    int opt = subgetopt_r(argc, argv, "P", &l) ;
+    if (opt == -1) break ;
+    switch (opt)
+    {
+      case 'P' : dosetsid = 1 ; break ;
+      default : dieusage() ;
+    }
+  }
+  argc -= l.ind ; argv += l.ind ;
+  if (dosetsid)
+    strerr_warnw1x("-P option ignored: s6-svscan does not run its supervisor processes (s6-supervise) in a new session. However, by default, it runs every service in a new session.") ;
+  if (argc >= 2)
+    strerr_warnw1x("s6-svscan does not support logging to a readproctitle process. To log the output of your supervision tree, please consider using the s6-linux-init package.") ;
+  newargv[2] = argv[0] ;
+  if (verbosity)
+  {
+    buffer_puts(buffer_2, PROG) ;
+    buffer_puts(buffer_2, ": info: executing command line:") ;
+    for (char const *const *p = argv ; *p ; p++)
+    {
+      buffer_puts(buffer_2, " ") ;
+      buffer_puts(buffer_2, *p) ;
+    }
+    buffer_putsflush(buffer_2, "\n") ;
+  }
+  xpathexec_run(newargv[0], newargv, envp) ;
+}
+
+static void svlogd (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  strerr_dief1x(100, "the s6-log program is similar to svlogd, but uses a different filtering syntax and does not use a config file in the logdir. Please see https://skarnet.org/software/s6/s6-log.html") ;
+}
+
+static void utmpset (int argc, char const *const *argv, char const *const *envp)
+{
+  (void)argc ;
+  (void)argv ;
+  (void)envp ;
+  strerr_dief1x(100, "s6 does not provide a utmpset emulation. To handle utmp records, please consider the s6-linux-init package, along with the utmps package if necessary.") ;
+}
+
+#endif
+
+static info_t const aliases[] =
+{
+#ifdef S6_FRONTEND_WRAP_RUNIT
+  { .name = "chpst", .cmd = S6_FRONTEND_BINPREFIX "s6-frontend-alias-chpst", .f = 0 },
+#endif
+#ifdef S6_FRONTEND_WRAP_DAEMONTOOLS
+  { .name = "envdir", .cmd = S6_EXTBINPREFIX "s6-envdir", .f = 0 },
+  { .name = "envuidgid", .cmd = S6_EXTBINPREFIX "s6-envuidgid", .f = 0 },
+  { .name = "fghack", .cmd = S6_EXTBINPREFIX "s6-fghack", .f = 0 },
+  { .name = "multilog", .cmd = S6_EXTBINPREFIX "s6-log", .f = 0 },
+  { .name = "pgrphack", .cmd = S6_EXTBINPREFIX "s6-setsid", .f = 0 },
+  { .name = "readproctitle", .cmd = 0, .f = &readproctitle },
+#endif
+#ifdef S6_FRONTEND_WRAP_RUNIT
+  { .name = "runit", .cmd = 0, .f = &runit },
+  { .name = "runit-init", .cmd = 0, .f = &runit_init },
+  { .name = "runsv", .cmd = S6_EXTBINPREFIX "s6-supervise", .f = 0 },
+  { .name = "runsvchdir", .cmd = 0, .f = &runsvchdir },
+  { .name = "runsvdir", .cmd = 0, .f = &runsvdir },
+#endif
+#ifdef S6_FRONTEND_WRAP_DAEMONTOOLS
+  { .name = "setlock", .cmd = S6_EXTBINPREFIX "s6-setlock", .f = 0 },
+  { .name = "setuidgid", .cmd = S6_EXTBINPREFIX "s6-setuidgid", .f = 0 },
+  { .name = "softlimit", .cmd = S6_EXTBINPREFIX "s6-softlimit", .f = 0 },
+  { .name = "supervise", .cmd = S6_EXTBINPREFIX "s6-supervise", .f = 0 },
+#endif
+#ifdef S6_FRONTEND_WRAP_RUNIT
+  { .name = "sv", .cmd = S6_FRONTEND_BINPREFIX "s6-frontend-alias-sv", .f = 0 },
+#endif
+#ifdef S6_FRONTEND_WRAP_DAEMONTOOLS
+  { .name = "svc", .cmd = S6_EXTBINPREFIX "s6-svc", .f = 0 },
+#endif
+#ifdef S6_FRONTEND_WRAP_RUNIT
+  { .name = "svlogd", .cmd = 0, .f = &svlogd },
+#endif
+#ifdef S6_FRONTEND_WRAP_DAEMONTOOLS
+  { .name = "svok", .cmd = S6_EXTBINPREFIX "s6-svok", .f = 0 },
+  { .name = "svscan", .cmd = S6_EXTBINPREFIX "s6-svscan", .f = 0 },
+  { .name = "svscanboot", .cmd = 0, .f = &svscanboot },
+  { .name = "svstat", .cmd = S6_EXTBINPREFIX "s6-svstat", .f = 0 },
+  { .name = "tai64n", .cmd = S6_EXTBINPREFIX "s6-tai64n", .f = 0 },
+  { .name = "tai64nlocal", .cmd = S6_EXTBINPREFIX "s6-tai64nlocal", .f = 0 },
+#endif
+#ifdef S6_FRONTEND_WRAP_RUNIT
+  { .name = "utmpset", .cmd = 0, .f = &utmpset },
+#endif
+} ;
+
+int main (int argc, char const **argv, char const *const *envp)
+{
+  char const *name = argv[0] ;
+  stralloc sa = STRALLOC_ZERO ;
+  info_t *p ;
+  PROG = "s6-frontend-alias" ;
+
+  if (!sabasename(&sa, name, strlen(name)) || !stralloc_0(&sa)) dienomem() ;
+  if (!strcmp(sa.s, PROG))
+  {
+    subgetopt_t l = SUBGETOPT_ZERO ;
+    for (;;)
+    {
+      int opt = subgetopt_r(argc, argv, "v", &l) ;
+      if (opt == -1) break ;
+      switch (opt)
+      {
+        case 'v' : verbosity++ ; break ;
+        default : strerr_dieusage(100, USAGE) ;
+      }
+    }
+    argc -= l.ind ; argv += l.ind ;
+    if (!argc) dieusage() ;
+    name = *argv ;
+    stralloc_free(&sa) ;
+  }
+  else name = sa.s ;
+
+  p = bsearch(name, aliases, sizeof(aliases) / sizeof(info_t), sizeof(info_t), &info_cmp) ;
+  if (!p) strerr_dief2x(100, "unknown alias: ", name) ;
+  if (p->cmd)
+  {
+    argv[0] = p->cmd ;
+    if (verbosity)
+      strerr_warni4x("the s6 version of ", name, " is ", p->cmd) ;
+    xpathexec_run(argv[0], argv, envp) ;
+  }
+  else (*p->f)(argc, argv, envp) ;
+  strerr_dief1x(101, "can't happen: incorrect alias handler. Please submit a bug-report.") ;
+}