Improve user service managementHEADmain

- Separate /etc/s6.conf from /etc/s6-user.conf
- Have --system|--user handled at the s6 level, not the s6-frontend level
- Also have --help rewritten at the s6 level because it's cleaner
- On --user, process the config file with sed to import XDG variables
- Do not use s6f_user_get_confdirs() anymore (can remove it if we
decide to stick with this design), --user now only changes the
conf file, and only command-line options such as --scandir can override
what is described in the conf file.
- Document the current behaviour.

12 files changed, 253 insertions, 46 deletions

diff --git a/configure b/configure
index ace7d40..b04abb8 100755
--- a/configure
+++ b/configure
@@ -30,7 +30,9 @@ Fine tuning of the installation directories:
   --repodir=DIR                 default s6-rc repository [s6-rc default: /var/lib/s6-rc/repository]
   --bootdb=LINK                 location of the bootable s6-rc compiled db [s6-rc default: /etc/s6-rc/compiled/current]
   --stmpdir=DIR                 secure location for temporary s6-frontend files [/run/s6-frontend]
-  --conffile=FILE               default configuration file for s6 command [SYSCONFDIR/s6.conf]
+  --conffile=FILE               default system configuration file for the s6 command [SYSCONFDIR/s6.conf]
+  --userconffile=FILE           default user configuration file for the s6 command [SYSCONFDIR/s6-user.conf]
+
  If no --prefix option is given, by default libdir (but not dynlibdir) will be
  /usr/lib, and includedir will be /usr/include.
 
@@ -188,6 +190,7 @@ repodir=
 bootdb=
 stmpdir=/run/s6-frontend
 conffile='$sysconfdir/s6.conf'
+userconffile='$sysconfdir/s6-user.conf'
 storelist='$prefix/share/s6/sources:$sysconfdir/s6/sources'
 defbundle=
 fdhuser=
@@ -240,6 +243,7 @@ for arg ; do
     --bootdb=*) bootdb=${arg#*=} ;;
     --stmpdir=*) stmpdir=${arg#*=} ;;
     --conffile=*) conffile=${arg#*=} ;;
+    --userconffile=*) userconffile=${arg#*=} ;;
     --with-store-list=*) storelist=${arg#*=} ;;
     --with-default-bundle=*) defbundle=${arg#*=} ;;
     --with-fdholder-user=*) fdhuser=${arg#*=} ;;
@@ -277,7 +281,7 @@ fi
 
 # Expand installation directories
 stripdir prefix
-for i in exec_prefix dynlibdir libexecdir bindir libdir includedir sysconfdir pkgconfdir sysdeps sproot stmpdir conffile storelist ; do
+for i in exec_prefix dynlibdir libexecdir bindir libdir includedir sysconfdir pkgconfdir sysdeps sproot stmpdir conffile userconffile storelist ; do
   eval tmp=\${$i}
   eval $i=$tmp
   stripdir $i
@@ -566,6 +570,8 @@ echo "BOOTDB := $bootdb"
 echo "STMPDIR := $stmpdir"
 echo "STORELIST := $storelist"
 echo "FDHUSER := $fdhuser"
+echo "CONFFILE := $conffile"
+echo "USERCONFFILE := $userconffile"
 
 if $usensss ; then
   echo "LIBNSSS := -lnsss"
@@ -677,6 +683,9 @@ echo "#define ${package_macro_name}_STMPDIR \"$stmpdir\""
 echo "#undef ${package_macro_name}_CONF"
 echo "#define ${package_macro_name}_CONF \"$conffile\""
 
+echo "#undef ${package_macro_name}_USER_CONF"
+echo "#define ${package_macro_name}_USER_CONF \"$userconffile\""
+
 echo "#undef ${package_macro_name}_STORELIST"
 echo "#define ${package_macro_name}_STORELIST \"$storelist\""
 
diff --git a/doc/s6-frontend.html b/doc/s6-frontend.html
index 9d563f7..df98186 100644
--- a/doc/s6-frontend.html
+++ b/doc/s6-frontend.html
@@ -38,14 +38,26 @@ users should call <a href="s6.html">s6</a> instead.
 </p>
 
 <ul>
- <li> <a href="s6.html">s6</a> gets the name of its configuration file from the
-<tt>S6_CONF</tt> environment variable, or from the compiled-in default if
-this variable is unset. Normally this default is <tt>/etc/s6.conf</tt>. </li>
+ <li> <a href="s6.html">s6</a> reads its configuration file at
+<tt>/etc/s6.conf</tt> by default, overridable by the admin at build time
+via the <tt>--conffile</tt> configure option, also overridable by the user
+at run time via the <tt>S6_CONF</tt> environment variable.
+  <ul>
+   <li> If <a href="s6.html">s6</a> is run with the <tt>--user</tt> option,
+it looks for <tt>/etc/s6-user.conf</tt> instead, overridable by the admin at
+build time via the <tt>--userconffile</tt> configure option, also overridable
+by the user at run time via the <tt>S6_USER_CONF</tt> environment variable. </li>
+  </ul> </li>
  <li> This configuration file (let's call it <em>conf</em>) contains
 <a href="s6.conf.html">variable definitions</a> that set the default for
 all the parts of the s6 system. </li>
  <li> <a href="s6.html">s6</a> rewrites itself into
-<code>envfile -I <em>conf</em> -- s6-frontend <em>args...</em></code> </li>
+<code>envfile -I <em>conf</em> -- s6-frontend <em>args...</em></code>
+  <ul>
+   <li> If the <tt>--user</tt> flag has been given, some text transformation
+<a href="s6.conf.html#userservices">is first performed on the file</a> to substitute
+the relevant XDG variables. </li>
+  </ul> </li>
  <li> The <a href="//skarnet.org/software/execline/envfile.html">envfile</a> program
 reads and parses <em>conf</em>, and then runs <a href="s6-frontend.html">s6-frontend</a>
 with the additional environment variables defined in <em>conf</em>.
diff --git a/doc/s6.conf.html b/doc/s6.conf.html
index 8120603..9c15615 100644
--- a/doc/s6.conf.html
+++ b/doc/s6.conf.html
@@ -37,6 +37,15 @@ are located).
 what the full path to the <em>foobar</em> service directory is.
 </p>
 
+<h3> Location </h3>
+
+<p>
+The global <tt>/etc/s6.conf</tt> path for the configuration variable can be
+overridden by the admin at build time via the <tt>--conffile</tt> configure
+option, and by the user at <a href="s6.html">s6</a> run time via the
+<tt>S6_CONF</tt> environment variable.
+</p>
+
 <h2 id="description"> Description </h2>
 
 <p>
@@ -107,5 +116,43 @@ The default is <strong>root</strong> and that is fine, but distributions
 may want to set it to an unprivileged user. </dd>
 </dl>
 
+<h2 id="userservices"> User services </h2>
+
+<p>
+  If <a href="s6.html">s6</a> is invoked with the <tt>--user</tt> flag,
+the <tt>/etc/s6-user.conf</tt> file is used instead, with the same
+syntax and the same variables, but additionally, the following
+environment variables, if present, are substituted:
+</p>
+
+<ul>
+ <li> <tt>XDG_RUNTIME_DIR</tt> </li>
+ <li> <tt>XDG_DATA_HOME</tt> </li>
+ <li> <tt>XDG_CONFIG_HOME</tt> </li>
+ <li> <tt>XDG_STATE_HOME</tt> </li>
+ <li> <tt>XDG_CACHE_HOME</tt> </li>
+</ul>
+
+<p>
+ That means that a global <tt>/etc/s6-user.conf</tt> file can for instance declare
+</p>
+
+<pre>
+ scandir=${XDG_RUNTIME_DIR}/service
+</pre>
+
+<p>
+and the correct location for the <tt>scandir</tt> will be obtained, for every user.
+</p>
+
+<h3> Location </h3>
+
+<p>
+The global <tt>/etc/s6-user.conf</tt> path for the configuration variable can be
+overridden by the admin at build time via the <tt>--userconffile</tt> configure
+option, and by the user at <a href="s6.html">s6</a> run time via the
+<tt>S6_USER_CONF</tt> environment variable.
+</p>
+
 </body>
 </html>
diff --git a/doc/s6.html b/doc/s6.html
index 661bc65..9fb6038 100644
--- a/doc/s6.html
+++ b/doc/s6.html
@@ -63,17 +63,6 @@ command, and on the linked documentation page you can find the interpretation
 of its various exit codes.
 </p>
 
-<h2 id="env"> Environment variables </h2>
-
-<ul>
- <li> s6 reads the <code>S6_CONF</code> environment variable
-containing the absolute path to the
-<a href="s6.conf.html">configuration file</a> for the s6 command. </li>
- <li> If this variable is unset, the default is <tt>/etc/s6.conf</tt>,
-possibly overridden by the <tt>--conffile</tt> build-time configure option to
-s6-frontend. </li>
-</ul>
-
 <h2 id="options"> Global options </h2>
 
 <p>
@@ -129,12 +118,18 @@ if <tt>auto</tt>. Not all commands and subcommands will use this
 setting. Also, for pretty-printing of columns, it is recommended to
 have built s6-frontend with util-linux support. </dd>
 
+ <dt> <tt>-S</tt>, <tt>--system</tt> </dt>
+ <dd> Use the <tt>/etc/s6.conf</tt> system <a href="s6.conf.html">configuration file</tt>.
+This is the default.
+The location of the file can be overridden by the admin at install time via the
+<tt>--conffile</tt> configure option, or by the user at run time via the
+<tt>S6_CONF</tt> environment variable. </dd>
+
  <dt> <tt>-u</tt>, <tt>--user</tt> </dt>
- <dd> Override the variables defined in the configuration file with values
-built from XDG environment variables. This option only works if the XDG
-environment variables are present in the environment. This option is
-useful to address user services. You can see what values are used by
-running <tt>s6 -u version export</tt>. </dd>
+ <dd> Use the <tt>/etc/s6-user.conf</tt> system <a href="s6.conf.html">configuration file</tt>.
+The location of the file can be overridden by the admin at install time via the
+<tt>--userconffile</tt> configure option, or by the user at run time via the
+<tt>S6_USER_CONF</tt> environment variable. </dd>
 </dl>
 
 
diff --git a/package/configure-snippets/configure_case_lines b/package/configure-snippets/configure_case_lines
index ed2aaea..d4a1a64 100644
--- a/package/configure-snippets/configure_case_lines
+++ b/package/configure-snippets/configure_case_lines
@@ -4,6 +4,7 @@
     --bootdb=*) bootdb=${arg#*=} ;;
     --stmpdir=*) stmpdir=${arg#*=} ;;
     --conffile=*) conffile=${arg#*=} ;;
+    --userconffile=*) userconffile=${arg#*=} ;;
     --with-store-list=*) storelist=${arg#*=} ;;
     --with-default-bundle=*) defbundle=${arg#*=} ;;
     --with-fdholder-user=*) fdhuser=${arg#*=} ;;
diff --git a/package/configure-snippets/configure_expand_dirs b/package/configure-snippets/configure_expand_dirs
index d4eff64..fed9152 100644
--- a/package/configure-snippets/configure_expand_dirs
+++ b/package/configure-snippets/configure_expand_dirs
@@ -1 +1 @@
-stmpdir conffile storelist
+stmpdir conffile userconffile storelist
diff --git a/package/configure-snippets/configure_generate_configh b/package/configure-snippets/configure_generate_configh
index 3f99a88..171c246 100644
--- a/package/configure-snippets/configure_generate_configh
+++ b/package/configure-snippets/configure_generate_configh
@@ -70,6 +70,9 @@ echo "#define ${package_macro_name}_STMPDIR \"$stmpdir\""
 echo "#undef ${package_macro_name}_CONF"
 echo "#define ${package_macro_name}_CONF \"$conffile\""
 
+echo "#undef ${package_macro_name}_USER_CONF"
+echo "#define ${package_macro_name}_USER_CONF \"$userconffile\""
+
 echo "#undef ${package_macro_name}_STORELIST"
 echo "#define ${package_macro_name}_STORELIST \"$storelist\""
 
diff --git a/package/configure-snippets/configure_generate_make b/package/configure-snippets/configure_generate_make
index d10c04a..765a1d3 100644
--- a/package/configure-snippets/configure_generate_make
+++ b/package/configure-snippets/configure_generate_make
@@ -5,6 +5,8 @@ echo "BOOTDB := $bootdb"
 echo "STMPDIR := $stmpdir"
 echo "STORELIST := $storelist"
 echo "FDHUSER := $fdhuser"
+echo "CONFFILE := $conffile"
+echo "USERCONFFILE := $userconffile"
 
 if $usensss ; then
   echo "LIBNSSS := -lnsss"
diff --git a/package/configure-snippets/configure_help_install b/package/configure-snippets/configure_help_install
index 82ead11..7c4502a 100644
--- a/package/configure-snippets/configure_help_install
+++ b/package/configure-snippets/configure_help_install
@@ -3,4 +3,6 @@
   --repodir=DIR                 default s6-rc repository [s6-rc default: /var/lib/s6-rc/repository]
   --bootdb=LINK                 location of the bootable s6-rc compiled db [s6-rc default: /etc/s6-rc/compiled/current]
   --stmpdir=DIR                 secure location for temporary s6-frontend files [/run/s6-frontend]
-  --conffile=FILE               default configuration file for s6 command [SYSCONFDIR/s6.conf]
+  --conffile=FILE               default system configuration file for the s6 command [SYSCONFDIR/s6.conf]
+  --userconffile=FILE           default user configuration file for the s6 command [SYSCONFDIR/s6-user.conf]
+
diff --git a/package/configure-snippets/configure_init_vars b/package/configure-snippets/configure_init_vars
index a156235..0130a0a 100644
--- a/package/configure-snippets/configure_init_vars
+++ b/package/configure-snippets/configure_init_vars
@@ -4,6 +4,7 @@ repodir=
 bootdb=
 stmpdir=/run/s6-frontend
 conffile='$sysconfdir/s6.conf'
+userconffile='$sysconfdir/s6-user.conf'
 storelist='$prefix/share/s6/sources:$sysconfdir/s6/sources'
 defbundle=
 fdhuser=
diff --git a/src/s6-frontend/s6-frontend.c b/src/s6-frontend/s6-frontend.c
index ff78f8b..c703042 100644
--- a/src/s6-frontend/s6-frontend.c
+++ b/src/s6-frontend/s6-frontend.c
@@ -26,9 +26,7 @@
 
 enum golb_e
 {
-  GOLB_HELP = 0x01,
-  GOLB_VERSION = 0x02,
-  GOLB_USER = 0x04,
+  GOLB_USER = 0x01,
 } ;
 
 enum gola_e
@@ -103,8 +101,8 @@ int main (int argc, char const *const *argv)
 {
   static gol_bool const rgolb[] =
   {
-    { .so = 'h', .lo = "help", .clear = 0, .set = GOLB_HELP },
-    { .so = 'u', .lo = "user", .clear = 0, .set = GOLB_USER },
+    { .so = 0, .lo = "system", .clear = GOLB_USER, .set = 0 },
+    { .so = 0, .lo = "user", .clear = 0, .set = GOLB_USER },
   } ;
   static gol_arg const rgola[] =
   {
@@ -142,7 +140,6 @@ int main (int argc, char const *const *argv)
 
   struct global_s globals_in_the_stack = GLOBAL_ZERO ;
   uint64_t wgolb = 0 ;
-  unsigned int golc ;
   struct command_s *cmd ;
   char const *wgola[GOLA_N] =
   {
@@ -159,16 +156,16 @@ int main (int argc, char const *const *argv)
   PROG = "s6-frontend" ;
   g = &globals_in_the_stack ;
 
-  golc = GOL_main(argc, argv, rgolb, rgola, &wgolb, wgola) ;
-  argc -= golc ; argv += golc ;
+  {
+    unsigned int golc = GOL_main(argc, argv, rgolb, rgola, &wgolb, wgola) ;
+    argc -= golc ; argv += golc ;
+  }
 
   if (wgola[GOLA_VERBOSITY] && !uint0_scan(wgola[GOLA_VERBOSITY], &g->verbosity))
     strerr_dief1x(100, "verbosity must be an unsigned integer") ;
 
-  if (wgolb & GOLB_HELP)  { main_help(argv) ; _exit(0) ; }
-
   g->isuser = !!(wgolb & GOLB_USER) ;
-  if (g->isuser) s6f_user_get_confdirs(&g->dirs, &g->userstorage) ;
+//  if (g->isuser) s6f_user_get_confdirs(&g->dirs, &g->userstorage) ;
 
   if (wgola[GOLA_SCANDIR]) g->dirs.scan = wgola[GOLA_SCANDIR] ;
   if (wgola[GOLA_LIVEDIR]) g->dirs.live = wgola[GOLA_LIVEDIR] ;
diff --git a/src/s6-frontend/s6.c b/src/s6-frontend/s6.c
index 0e49885..96de61c 100644
--- a/src/s6-frontend/s6.c
+++ b/src/s6-frontend/s6.c
@@ -3,27 +3,165 @@
 #include <stdlib.h>
 
 #include <skalibs/envexec.h>
+#include <skalibs/stralloc.h>
+#include <skalibs/djbunix.h>
 
 #include <execline/config.h>
 
 #include <s6-frontend/config.h>
 
+enum golb_e
+{
+  GOLB_HELP = 0x01,
+  GOLB_VERSION = 0x02,
+  GOLB_USER = 0x04,
+} ;
+
+enum gola_e
+{
+  GOLA_SCANDIR,
+  GOLA_LIVEDIR,
+  GOLA_REPODIR,
+  GOLA_BOOTDB,
+  GOLA_STMPDIR,
+  GOLA_STORELIST,
+  GOLA_VERBOSITY,
+  GOLA_FDHUSER,
+  GOLA_COLOR,
+  GOLA_N
+} ;
+
+#define dienomem() strerr_diefusys(111, "build command line")
+
+static inline enum gola_e gola_pos (gol_arg const *tab, size_t n, enum gola_e i)
+{
+  for (enum gola_e j = 0 ; j < n ; j++) if (tab[j].i == i) return j ;
+  strerr_dief(101, "can't happen: rgola does not cover all gola_e values") ;
+}
+
 int main (int argc, char const *const *argv)
 {
-  char const *conffile = getenv("S6_CONF") ;
-  PROG = "s6" ;
-  if (!conffile) conffile = S6_FRONTEND_CONF ;
-  if (!argc--) strerr_dief1x(103, "invalid argc/argv") ;
-  argv++ ;
+  static gol_bool const rgolb[] =
+  {
+    { .so = 'h', .lo = "help", .clear = 0, .set = GOLB_HELP },
+    { .so = 'u', .lo = "user", .clear = 0, .set = GOLB_USER },
+    { .so = 'S', .lo = "system", .clear = GOLB_USER, .set = 0 },
+  } ;
+  static gol_arg const rgola[] =
+  {
+    { .so = 's', .lo = "scandir", .i = GOLA_SCANDIR },
+    { .so = 'l', .lo = "livedir", .i = GOLA_LIVEDIR },
+    { .so = 'r', .lo = "repodir", .i = GOLA_REPODIR },
+    { .so = 'c', .lo = "bootdb", .i = GOLA_BOOTDB },
+    { .so = 0,   .lo = "stmpdir", .i = GOLA_STMPDIR },
+    { .so = 0,   .lo = "storelist", .i = GOLA_STORELIST },
+    { .so = 'v', .lo = "verbosity", .i = GOLA_VERBOSITY },
+    { .so = 0,   .lo = "fdholder-user", .i = GOLA_FDHUSER },
+    { .so = 0,   .lo = "color", .i = GOLA_COLOR },
+  } ;
 
+  stralloc sa = STRALLOC_ZERO ;
+  uint64_t wgolb = 0 ;
+  char const *wgola[GOLA_N] = { 0 } ;
+  size_t optpos[GOLA_N] = { 0 } ;
+  unsigned int conf_overrides = 0 ;
   unsigned int m = 0 ;
-  char const *newargv[6 + argc] ;
-  newargv[m++] = EXECLINE_EXTBINPREFIX "envfile" ;
-  newargv[m++] = "-I" ;
-  newargv[m++] = "--" ;
-  newargv[m++] = conffile ;
+  PROG = "s6" ;
+
+  {
+    unsigned int golc = GOL_main(argc, argv, rgolb, rgola, &wgolb, wgola) ;
+    argc -= golc ; argv += golc ;
+  }
+
+  for (enum gola_e i = 0 ; i < GOLA_N ; i++) if (wgola[i])
+  {
+    enum gola_e j = gola_pos(rgola, sizeof(rgola)/sizeof(gol_arg const), i) ;
+    optpos[i] = sa.len ;
+    if (!stralloc_catb(&sa, "--", 2)
+     || !stralloc_cats(&sa, rgola[j].lo)
+     || !stralloc_catb(&sa, "=", 1)
+     || !stralloc_cats(&sa, wgola[i])
+     || !stralloc_0(&sa))
+      dienomem() ;
+    conf_overrides++ ;
+  }
+
+  char const *newargv[(wgolb & GOLB_USER ? 17 : 4) + 1 + conf_overrides + 1 + (wgolb & GOLB_HELP ? 1 : argc) + 1] ;
+
+  if (wgolb & GOLB_USER)
+  {
+    static char const *const xdgvar[5] =
+    {
+      "XDG_RUNTIME_DIR",
+      "XDG_DATA_HOME",
+      "XDG_CONFIG_HOME",
+      "XDG_STATE_HOME",
+      "XDG_CACHE_HOME",
+    } ;
+    ssize_t xdgpos[5] = { -1, -1, -1, -1, -1 } ;
+    int dosubst = 0 ;
+    int fd ;
+    for (unsigned int i = 0 ; i < 5 ; i++)
+    {
+      char const *x = getenv(xdgvar[i]) ;
+      if (x)
+      {
+        dosubst = 1 ;
+        xdgpos[i] = sa.len ;
+        if (!stralloc_cats(&sa, " s|\\$")
+         || !stralloc_cats(&sa, xdgvar[i])
+         || !stralloc_cats(&sa, "|")
+         || !stralloc_cats(&sa, x)
+         || !stralloc_cats(&sa, "|g;s|\\${")
+         || !stralloc_cats(&sa, xdgvar[i])
+         || !stralloc_cats(&sa, "}|")
+         || !stralloc_cats(&sa, x)
+         || !stralloc_cats(&sa, "|g")
+         || !stralloc_0(&sa))
+          dienomem() ;
+      }
+    }
+    {
+      char const *x = getenv("S6_USER_CONF") ;
+      if (!x) x = S6_FRONTEND_USER_CONF ;
+      fd = open_readb(x) ;
+      if (fd == -1) strerr_diefusys(111, "open ", x, " for reading") ;
+      if (fd_move(0, fd) == -1) strerr_diefusys(111, "fd_move") ;
+    }
+
+    if (dosubst)
+    {
+      newargv[m++] = EXECLINE_BINPREFIX "pipeline" ;
+      newargv[m++] = " sed" ;
+      for (unsigned int i = 0 ; i < 5 ; i++) if (xdgpos[i] >= 0)
+      {
+        newargv[m++] = " -e" ;
+        newargv[m++] = sa.s + xdgpos[i] ;
+      }
+    }
+    newargv[m++] = "" ;
+    newargv[m++] = EXECLINE_EXTBINPREFIX "envfile" ;
+    newargv[m++] = "-I" ;
+    newargv[m++] = "--" ;
+    newargv[m++] = "-" ;
+  }
+  else
+  {
+    char const *conffile = getenv("S6_CONF") ;
+    if (!conffile) conffile = S6_FRONTEND_CONF ;
+    newargv[m++] = EXECLINE_EXTBINPREFIX "envfile" ;
+    newargv[m++] = "-I" ;
+    newargv[m++] = "--" ;
+    newargv[m++] = conffile ;
+  }
+
   newargv[m++] = S6_FRONTEND_LIBEXECPREFIX "s6-frontend" ;
-  while (argc--) newargv[m++] = *argv++ ;
+  for (enum gola_e i = 0 ; i < GOLA_N ; i++)
+    if (wgola[i]) newargv[m++] = sa.s + optpos[i] ;
+  newargv[m++] = "--" ;
+  if (wgolb & GOLB_HELP) newargv[m++] = "help" ;
+  else while (argc--) newargv[m++] = *argv++ ;
+
   newargv[m++] = 0 ;
   xexec(newargv) ;
 }