Make execline dependency optional

 This includes:
 - adding a configure option to disable execline support
 - duplicating el_semicolon() and el_getstrict() into the s6 library
when execline is disabled at build time, making a compat shim and
using it where needed (s6-svlisten, s6-ftrig-listen)
 - Creating alternatives for execlineb script spawning:
   * s6-log: '?' directive (done in the previous commit)
   * s6-notifyoncheck: require hardcoding the check in ./data/check
   * s6-ipcserver-access: no support for exec files, add a warning
 - Updating the relevant parts of the doc

 --enable-execline will remain the default, and whiners can choke
on their tears.

1 files changed, 14 insertions, 0 deletions

diff --git a/configure b/configure
index 3fc733a..7838b5b 100755
--- a/configure
+++ b/configure
@@ -46,6 +46,7 @@ Optional features:
   --enable-absolute-paths       do not rely on PATH to access this package's binaries,
                                   hardcode absolute BINDIR/foobar paths instead [disabled]
   --enable-nsss                 use the nsss library for user information [disabled]
+  --disable-execline            don't use the execline library [enabled]
 
 EOF
 exit 0
@@ -149,6 +150,7 @@ allpic=true
 slashpackage=false
 abspath=false
 usensss=false
+useexecline=true
 sproot=
 home=
 exthome=
@@ -192,6 +194,8 @@ for arg ; do
     --disable-absolute-paths|--enable-absolute-paths=no) abspath=false ;;
     --enable-nsss|--enable-nsss=yes) usensss=true ;;
     --disable-nsss|--enable-nsss=no) usensss=false ;;
+    --enable-execline|--enable-execline=yes) useexecline=true ;;
+    --disable-execline|--enable-execline=no) useexecline=false ;;
     --enable-*|--disable-*|--with-*|--without-*|--*dir=*) ;;
     --host=*|--target=*) target=${arg#*=} ;;
     --build=*) build=${arg#*=} ;;
@@ -448,6 +452,11 @@ else
   echo "LIBNSSS :="
   echo "MAYBEPTHREAD_LIB :="
 fi
+if $useexecline ; then
+  echo "LIBEXECLINE := -lexecline"
+else
+  echo "LIBEXECLINE :="
+fi
 
 exec 1>&3 3>&-
 echo "  ... done."
@@ -477,6 +486,11 @@ else
 fi
 echo "#define ${package_macro_name}_LIBEXECPREFIX \"$libexecdir/\""
 echo
+echo "#undef ${package_macro_name}_USE_EXECLINE"
+if $useexecline ; then
+  echo "#define ${package_macro_name}_USE_EXECLINE"
+fi
+echo
 echo "#endif"
 exec 1>&3 3>&-
 echo "  ... done."