Implement search path for #include and #include_once.

* src/Makefile.am (AM_CPPFLAGS): Define INCLUDE_PATH_ARGS
* src/cmdline.opt: New option --include-directory (-I).
(help_hook): Print the actual content of the include search path.
* src/config.c (config_finish): Remove.
(config_init): New function. Set up include search path.
(config_parse): New function.
* src/direvent.c (main): Call config_init and config_parse.
* src/direvent.h (config_finish): Remove.
(config_init,config_parse): New proto.

* grecs: Upgrade.

* NEWS: Document changes.
* README: Document the --with-include-path option.
* configure.ac: New option --with-include-path.
* doc/direvent.8: Document the -I option and include search paths.
* doc/direvent.conf.5: Document include search paths.
* doc/direvent.texi: Document the -I option and include search paths.

12 files changed, 166 insertions, 29 deletions

diff --git a/NEWS b/NEWS
index 7da595f..2077f82 100644
--- a/NEWS
+++ b/NEWS
@@ -1,4 +1,4 @@
-direvent -- history of user-visible changes. 2016-06-18
+direvent -- history of user-visible changes. 2016-06-20
 Copyright (C) 2012-2016 Sergey Poznyakoff
 See the end of file for copying conditions.
 
@@ -21,11 +21,40 @@ The 'shell' option causes watcher command to be executed via
 function).  For example:
 
   watcher {
-     path "/etc/httpd/vhosts"
-     command "/usr/bin/scanhosts && service httpd restart"
+     path "/etc/httpd/vhosts";
+     command "/usr/bin/scanhosts && service httpd restart";
      option (shell);
   }
 
+* Include path
+
+If the argument to the #include (#include_once) statement is not an
+absolute file name or globbing pattern, it is looked up in the include
+search path.  The order of look up is as follows.  First, directories 
+given with '-I' options (see below) are scanned, in the same order as
+given on the command line.  If no matching file is found in any of
+them, directories in the standard include search path are scanned.
+
+By default, the standard include search path contains two directories:
+'$(pkgdatadir)/$(VERSION)' and '$(pkgdatadir)/include', where
+$(pkgdatadir) and $(VERSION) stand for the package data directory, and
+package version, correspondingly.  It can be redefined at compile time using
+the '--with-include-path' to configure, e.g.:
+
+ ./configure --with-include-path='$(sysconfdir)/direvent.d:$(pkgdatadir)/$(VERSION):$(pkgdatadir)/include'
+
+(see the file INSTALL, section "Building and Configuring", for a
+detailed discussion of this option).
+ 
+To inspect the actual path at runtime, run \fBdirevent \-\-help\fR,
+and look for the string 'Include search path:' in its output.
+  
+* New command line option -I (--include)
+
+The '-I DIR' command line option adds DIR to the include search path.
+When looking for include files, directories given with '-I' options
+are scanned first.  If the file is not found, the directories in the
+standard include path are scanned.
 
 
 Version 5.0, 2014-09-06
diff --git a/README b/README
index 80075c8..ea4713f 100644
--- a/README
+++ b/README
@@ -25,6 +25,23 @@ The usual incantation applies:
 See the file INSTALL for the description of ./configure and its
 generic options.
 
+Following are the package-specific options:
+
+ --with-include-path=PATH
+ 
+   Define standard include path.  This is a list of directories where
+   files given in the #include and #include_once configuration
+   statements will be searched.  PATH is a list of directories
+   separated by colons.  Directory names can contain references to
+   Makefile variables, which will be expanded to their actual values
+   at compile time.  The default PATH is
+
+      $(pkgdatadir)/$(VERSION):$(pkgdatadir)/include
+  
+   See the documentation, section 5.1.2 "Pragmatic Comments", for a
+   detailed description of #include and #include_path statements and
+   the meaning of the include search path.
+
 * Usage Instructions
 
 Complete documentation is included with the package, both in man
diff --git a/configure.ac b/configure.ac
index e7285f0..35ccf1a 100644
--- a/configure.ac
+++ b/configure.ac
@@ -73,6 +73,13 @@ AM_ICONV
 AM_GNU_GETTEXT([external], [need-formatstring-macros])
 AM_GNU_GETTEXT_VERSION([0.18])
 
+AC_SUBST(INCLUDE_PATH_ARGS,[$(pkgdatadir)/$(VERSION):$(pkgdatadir)/include])
+AC_ARG_WITH([include-path],
+            [AC_HELP_STRING([--with-include-path=PATH],
+	         [set direvent runtime include path])],
+            [INCLUDE_PATH_ARGS=$withval])
+INCLUDE_PATH_ARGS=$(echo "$INCLUDE_PATH_ARGS" | sed 's/:/\",\"/g;s/^/\"/;s/$/\"/')
+
 # Initialize the test suite.
 AC_CONFIG_TESTDIR(tests)
 AC_CONFIG_FILES([tests/Makefile tests/atlocal po/Makefile.in])
diff --git a/doc/direvent.8 b/doc/direvent.8
index 6e8f63b..b4add02 100644
--- a/doc/direvent.8
+++ b/doc/direvent.8
@@ -13,17 +13,19 @@
 .\"
 .\" You should have received a copy of the GNU General Public License along
 .\" with direvent. If not, see <http://www.gnu.org/licenses/>.
-.TH DIREVENT 8 "September 1, 2014" "DIREVENT" "Direvent User Reference"
+.TH DIREVENT 8 "June 20, 2016" "DIREVENT" "Direvent User Reference"
 .SH NAME
 direvent \- directory event monitor
 .SH SYNOPSIS
 \fBdirevent\fR [\fB\-HVdfh\fR] [\fB\-F\fR \fINAME\fR]\
  [\fB\-P\fR \fIFILE\fR]\
- [\fB-l\fR \fIPRIO\fR]\
- [\fB-T\fR \fICOMMAND\fR]\
+ [\fB\-l\fR \fIPRIO\fR]\
+ [\fB\-I\fR \fIDIR\fR]\
+ [\fB\-T\fR \fICOMMAND\fR]\
  [\fB\-\-debug\fR]\
  [\fB\-\-facility\fR=\fINAME\fR]\
  [\fB\-\-foreground\fB]\
+ [\fB\-\-include=\fIDIR\fR]\
  [\fB\-\-pidfile\fR=\fIFILE\fR]\
  [\fB\-\-self\-test\fR=\fICOMMAND\fR]\
  [\fB\-\-user\fR=\fINAME\fR]\
@@ -122,6 +124,15 @@ The option \fB\-F 0\fR directs logging to the standard error.
 .BR \-f ", " \-\-foreground 
 Run in the foreground.
 .TP
+\fB\-I\fR, \fB\-\-include=\fIDIR\fR
+Add \fIDIR\fR to the include search path.  When looking for a file to
+be included in the \fB#include\fR (\fB#include_once\fR) statement,
+\fBdirevent\fR scans first the directories given with \fB\-I\fR
+options (in the same order as given on the command line), and then the
+directories in the standard include search path.  The latter is
+defined at compile time and can be inspected in the output of the
+\fB\-\-help\fR option.
+.TP
 \fB\-l\fR \fIPRIO\fR
 While connected to a terminal \fBdirevent\fR outputs its diagnostics
 messages to stderr and, if configured, to \fBsyslog\fR.  This option
diff --git a/doc/direvent.conf.5 b/doc/direvent.conf.5
index 4eaf5e6..265a2d2 100644
--- a/doc/direvent.conf.5
+++ b/doc/direvent.conf.5
@@ -13,7 +13,7 @@
 .\"
 .\" You should have received a copy of the GNU General Public License along
 .\" with direvent. If not, see <http://www.gnu.org/licenses/>.
-.TH DIREVENT.CONF 5 "June 18, 2016" "DIREVENT" "Direvent User Reference"
+.TH DIREVENT.CONF 5 "June 20, 2016" "DIREVENT" "Direvent User Reference"
 .SH NAME
 direvent.conf \- configuration file for
 .BR direvent (8).
@@ -68,18 +68,22 @@ absolute file name, the named file is included.  An error message will
 be issued if it does not exist.
 
 If \fIFILE\fR contains wildcard characters (\fB*\fR, \fB[\fR,
-\fB]\fR, or \fB?\fR), it is interpreted as shell globbing pattern and
+\fB]\fR, or \fB?\fR), it is interpreted as a shell globbing pattern and
 all files matching that pattern are included, in lexicographical
 order.  If no matching files are found, the directive is replaced with
 an empty line.
-.\" If it is an
-.\" absolute file name, both forms are equivalent.  Otherwise, the form
-.\" with angle brackets searches for the file in the \fIinclude 
-.\" search path\fR, while the second one looks for it in the current working
-.\" directory first, and, if not found there, in the include search
-.\" path.
-.\" .sp
-.\" The default include search path is:  \fBFIXME\fR.
+
+Otherwise, the form with angle brackets searches for file in the
+include search path, while the second one looks for it in the
+current working directory first, and, if not found there, in the
+include search path.  If the file is not found, an error message will
+be issued.
+
+The order of directories is as follows.  First, \fBdirevent\fR scans
+any directories given with \fB\-I\fR options, in the same order as
+given on the command line, and then the directories in the standard
+include search path.  The latter is defined at compile time and can be
+inspected in the output of the \fB\-\-help\fR option.
 .TP
 .BI "#include_once <" "FILE" >
 .PD 0
diff --git a/doc/direvent.texi b/doc/direvent.texi
index a7ce4a4..47db410 100644
--- a/doc/direvent.texi
+++ b/doc/direvent.texi
@@ -331,6 +331,13 @@ Set syslog facility.
 @item -f
 @itemx --foreground
 Remain in foreground.
+@opindex -I
+@opindex --include
+@anchor{include option}
+@item -I @var{dir}
+@itemx --include=@var{dir}
+Add @var{dir} to the beginning of the include search path
+(@pxref{include search path}).
 @opindex -l
 @item -l @var{prio}
 While connected to a terminal, @command{direvent} outputs its diagnostics
@@ -497,11 +504,44 @@ absolute file name, the named file is included.  An error message will
 be issued if it does not exist.
 
 If @var{file} contains wildcard characters (@samp{*}, @samp{[},
-@samp{]} or @samp{?}), it is interpreted as shell globbing pattern and
+@samp{]} or @samp{?}), it is interpreted as a shell globbing pattern and
 all files matching that pattern are included, in lexicographical
 order.  If no matching files are found, the directive is replaced with
 an empty line.
 
+Otherwise, the form with angle brackets searches for file in the
+@dfn{include search path}, while the second one looks for it in the
+current working directory first, and, if not found there, in the
+include search path.  If the file is not found, an error message will
+be issued.
+
+@cindex include search path, preprocessor
+@cindex include directories, preprocessor
+@cindex preprocessor include search path
+@anchor{include search path}
+@dfn{Include search path} is formed by two directory sets: the
+user-defined search path, as defined by eventual @option{-I}
+(@pxref{include option}) command line options, and the standard include
+search path, defined at compile time.  The latter can be inspected
+using the @option{--help} option.
+
+The order of directories is as follows.  First, @command{direvent} scans
+any directories given with @option{-I} options, in the same order as
+given on the command line.  If @var{file} is not found in any of them,
+the standard include search path is scanned.  It is defined at the
+compile time and by default consists of two directories:
+
+@itemize @bullet
+@item @file{@var{prefix}/share/direvent/@value{VERSION}/include}
+@item @file{@var{prefix}/share/direvent/include}
+@end itemize
+
+@noindent
+where @var{prefix} is the installation prefix.  The default can be
+changed when configuring the package.  To inspect the actual standard
+include search path at the runtime, run @code{direvent --help}, and
+look for the string @samp{Include search path:} in its output.
+
 @kwindex #include_once
 @item #include_once <@var{file}>
 @itemx #include_once @var{file}
diff --git a/grecs b/grecs
-Subproject 59f9073082a0033a9a54ea27b2409bd087d6370
+Subproject 6ab660a7f9a9857a56cff44765144016356bd9f
diff --git a/src/Makefile.am b/src/Makefile.am
index cdb5bef..703edac 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -44,7 +44,8 @@ endif
 LDADD=@GRECS_LDADD@ @LIBINTL@
 AM_CPPFLAGS=\
  -I$(top_srcdir)/grecs/src/\
- -DLOCALEDIR=\"$(localedir)\"
+ -DLOCALEDIR=\"$(localedir)\"\
+ -DINCLUDE_PATH_ARGS='$(INCLUDE_PATH_ARGS)'
 
 BUILT_SOURCES=cmdline.h
 EXTRA_DIST=cmdline.opt
diff --git a/src/cmdline.opt b/src/cmdline.opt
index a200ab8..39f34ec 100644
--- a/src/cmdline.opt
+++ b/src/cmdline.opt
@@ -34,6 +34,12 @@ BEGIN
 	opt_foreground++;
 END
 
+OPTION(include-directory,I,DIR,
+       [<add include directory>])
+BEGIN
+        grecs_preproc_add_include_dir(optarg);
+END
+	 
 OPTION(self-test,T,PROG,
        [<self-test mode>])
 BEGIN
@@ -72,6 +78,14 @@ END
 
 OPTIONS_END
 
+static int
+print_dir(int flag, const char *dir, void *data)
+{
+	FILE *fp = data;
+	fprintf(fp, "%s\n", dir);
+	return 0;
+}
+
 static void
 help_hook(FILE *fp)
 {
@@ -81,6 +95,13 @@ help_hook(FILE *fp)
 	          "to use instead of %s.\n\n"), DEFAULT_CONFFILE); 
 	/* TRANSLATORS: %s is one of: inotify, kqueue */
 	fprintf(fp, _("This direvent uses %s interface.\n\n"), INTERFACE);
+
+	if (grecs_include_path_count(GRECS_STD_INCLUDE)) {
+		fprintf(fp, _("Include search path:\n"));
+		grecs_foreach_include_dir(GRECS_STD_INCLUDE, print_dir, fp);
+	} else
+		fprintf(fp, _("No include search path.\n"));
+	fprintf(fp, "\n");
 }
 
 void
diff --git a/src/config.c b/src/config.c
index 16f5701..6b7563b 100644
--- a/src/config.c
+++ b/src/config.c
@@ -747,8 +747,20 @@ config_help()
 }
 
 void
-config_finish(struct grecs_node *tree)
-{	
+config_init(void)
+{
+	grecs_include_path_setup(INCLUDE_PATH_ARGS, NULL);
+}
+
+void
+config_parse(char const *conffile)
+{
+	struct grecs_node *tree;
+
+	tree = grecs_parse(conffile);
+	if (!tree)
+		exit(1);
 	if (grecs_tree_process(tree, direvent_kw))
 		exit(1);
+	
 }
diff --git a/src/direvent.c b/src/direvent.c
index e24d619..b79df38 100644
--- a/src/direvent.c
+++ b/src/direvent.c
@@ -455,7 +455,6 @@ int
 main(int argc, char **argv)
 {
 	int i;
-	struct grecs_node *tree;
 
 #ifdef ENABLE_NLS
 	setlocale(LC_ALL, "");
@@ -467,7 +466,8 @@ main(int argc, char **argv)
 	tag = estrdup(program_name);
 
 	genev_init();
-
+	config_init();
+	
 	parse_options(argc, argv, &i);
 
 	argc -= i;
@@ -484,11 +484,7 @@ main(int argc, char **argv)
 		break;
 	}
 
-	tree = grecs_parse(conffile);
-	if (!tree)
-		exit(1);
-
-	config_finish(tree);
+	config_parse(conffile);
 	if (lint_only)
 		return 0;
 
diff --git a/src/direvent.h b/src/direvent.h
index 3ce4693..2cd5344 100644
--- a/src/direvent.h
+++ b/src/direvent.h
@@ -201,8 +201,7 @@ struct pathent {
 };
 
 void config_help(void);
-struct grecs_node;
-void config_finish(struct grecs_node *tree);
+void config_init(void);
 void config_parse(const char *file);
 
 int get_facility(const char *arg);