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.

2 files changed, 57 insertions, 2 deletions

diff --git a/src/libs6/deps-lib/s6 b/src/libs6/deps-lib/s6
index 65612cc..ddd86dc 100644
--- a/src/libs6/deps-lib/s6
+++ b/src/libs6/deps-lib/s6
@@ -26,12 +26,13 @@ s6_accessrules_keycheck_uidgid.o
 s6_accessrules_params_free.o
 s6_accessrules_uidgid_cdb.o
 s6_accessrules_uidgid_fs.o
-s6_supervise_lock.o
-s6_supervise_lock_mode.o
+s6_compat_el_semicolon.o
 s6_dtally_pack.o
 s6_dtally_unpack.o
 s6_dtally_read.o
 s6_dtally_write.o
+s6_supervise_lock.o
+s6_supervise_lock_mode.o
 s6_svc_lock_take.o
 s6_svc_lock_release.o
 s6_svc_ok.o
diff --git a/src/libs6/s6_compat_el_semicolon.c b/src/libs6/s6_compat_el_semicolon.c
new file mode 100644
index 0000000..d6fdd06
--- /dev/null
+++ b/src/libs6/s6_compat_el_semicolon.c
@@ -0,0 +1,54 @@
+/* ISC license. */
+
+#include <s6/config.h>
+
+#ifndef S6_USE_EXECLINE
+
+#include <stdlib.h>
+
+#include <skalibs/types.h>
+#include <skalibs/strerr2.h>
+
+static unsigned int el_getstrict (void)
+{
+  static unsigned int strict = 0 ;
+  static int first = 1 ;
+  if (first)
+  {
+    char const *x = getenv("EXECLINE_STRICT") ;
+    first = 0 ;
+    if (x) uint0_scan(x, &strict) ;
+  }
+  return strict ;
+}
+
+int s6_compat_el_semicolon (char const **argv)
+{
+  static unsigned int nblock = 0 ;
+  int argc1 = 0 ;
+  nblock++ ;
+  for (;; argc1++, argv++)
+  {
+    char const *arg = *argv ;
+    if (!arg) return argc1 + 1 ;
+    if (!arg[0]) return argc1 ;
+    else if (arg[0] == ' ') ++*argv ;
+    else
+    {
+      unsigned int strict = el_getstrict() ;
+      if (strict)
+      {
+        char fmt1[UINT_FMT] ;
+        char fmt2[UINT_FMT] ;
+        fmt1[uint_fmt(fmt1, nblock)] = 0 ;
+        fmt2[uint_fmt(fmt2, (unsigned int)argc1)] = 0 ;
+        if (strict >= 2)
+          strerr_dief6x(100, "unquoted argument ", arg, " at block ", fmt1, " position ", fmt2) ;
+        else
+          strerr_warnw6x("unquoted argument ", arg, " at block ", fmt1, " position ", fmt2) ;
+      }
+    }
+  }
+}
+
+#endif