Merge remote-tracking branch 'origin/topic/awelzel/find-in-zeekpath'

* origin/topic/awelzel/find-in-zeekpath:
  NEWS: Mention can_load() and find_in_zeekpath()
  utils: Introduce packages.zeek with can_load() helper
  zeek.bif: Add find_in_zeekpath() helper

NEWS

@@ -18,6 +18,15 @@ New Functionality
 	delete v;
 	assert |v| == 0;
 
+- A new helper function ``can_load()`` backed by a new bif ``find_in_zeekpath()``
+  was added to determine if a non-relative ``@load`` directive might work. This
+  can be used to guard ``@load`` directives when script packages may or may not
+  be installed.
+
+	@if ( can_load("my-package") )
+	@load my-package
+	@endif
+
 Changed Functionality
 ---------------------
 

scripts/base/init-default.zeek

@@ -17,6 +17,7 @@
 @load base/utils/geoip-distance
 @load base/utils/hash_hrw
 @load base/utils/numbers
+@load base/utils/packages
 @load base/utils/paths
 @load base/utils/patterns
 @load base/utils/queue

scripts/base/utils/packages.zeek

@@ -0,0 +1,16 @@
+##! Rudimentary functions for helping with Zeek packages.
+
+## Checks whether @load of a given package name could
+## be successful.
+##
+## This tests for the existence of corresponding script files
+## in ZEEKPATH. It does not attempt to parse and validate
+## any actual Zeek script code.
+##
+## path: The filename, package or path to test.
+##
+## Returns: T if the given filename, package or path may load.
+function can_load(p: string): bool
+	{
+	return find_in_zeekpath(p) != "";
+	}

src/zeek.bif

@@ -5328,3 +5328,35 @@ function table_pattern_matcher_stats%(tbl: any%) : MatcherStats
 
 	return std::move(result);
 	%}
+
+## Determine the path used by a non-relative @load directive.
+##
+## This function is package aware: Passing *package* will yield the
+## path to *package.zeek*, *package/__load__.zeek* or an empty string
+## if neither can be found. Note that passing a relative path or absolute
+## path is an error.
+##
+## path: The filename, package or path to search for in ZEEKPATH.
+##
+## Returns: Path of script file that would be loaded by an @load directive.
+function find_in_zeekpath%(p: string%): string
+	%{
+	auto path = p->ToStdString();
+	if ( ! path.empty() && (path[0] == '.' || path[0] == '/') )
+		{
+		zeek::reporter->Error("find_in_zeek_path: path must be relative or absolute");
+		return zeek::val_mgr->EmptyString();
+		}
+
+	auto resolved = zeek::util::find_script_file(path, zeek::util::zeek_path());
+	if ( ! resolved.empty() && zeek::util::is_dir(resolved.c_str()) )
+		{
+		// If it's a directory, try opening the package using
+		// the absolute path. This is zeek::util::open_package()
+		// without the noisy error log.
+		resolved.append("/__load__.zeek");
+		resolved = zeek::util::find_file(resolved, "");
+		}
+
+	return zeek::make_intrusive<zeek::StringVal>(resolved.c_str());
+	%}

testing/btest/Baseline/bifs.find_in_zeekpath/.stderr

@@ -0,0 +1 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.

testing/btest/Baseline/bifs.find_in_zeekpath/errors.stderr

@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+error: find_in_zeek_path: path must be relative or absolute
+error: find_in_zeek_path: path must be relative or absolute

testing/btest/Baseline/bifs.find_in_zeekpath/errors.stdout

@@ -0,0 +1,3 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+relative, 
+absolute, 

testing/btest/Baseline/bifs.find_in_zeekpath/out

@@ -0,0 +1,10 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+find_in_zeekpath base/protocols/conn, base/protocols/conn/__load__.zeek
+find_in_zeekpath protocols/conn (empty expected, no __load__.zeek), 
+find_in_zeekpath protocols/conn/vlan-logging, policy/protocols/conn/vlan-logging.zeek
+find_in_zeekpath pkg1, ./pkg1.zeek
+find_in_zeekpath pkg1.zeek, ./pkg1.zeek
+find_in_zeekpath pkg2, ./pkg2/__load__.zeek
+find_in_zeekpath pkg3, 
+pkg1!
+pkg2!

testing/btest/Baseline/coverage.default-load-baseline/canonified_loaded_scripts.log

@@ -290,6 +290,7 @@ scripts/base/init-default.zeek
   scripts/base/utils/files.zeek
   scripts/base/utils/geoip-distance.zeek
   scripts/base/utils/numbers.zeek
+  scripts/base/utils/packages.zeek
   scripts/base/utils/queue.zeek
   scripts/base/utils/strings.zeek
   scripts/base/utils/thresholds.zeek

testing/btest/Baseline/scripts.base.utils.packages/output

@@ -0,0 +1,4 @@
+### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
+no pkg3
+pkg1!
+pkg2!

testing/btest/bifs/find_in_zeekpath.zeek

@@ -0,0 +1,59 @@
+# @TEST-DOC: Test find_in_zeekpath() and demo conditional @load'ing.
+#
+# @TEST-EXEC: zeek -b %INPUT >out
+# @TEST-EXEC: btest-diff out
+# @TEST-EXEC: btest-diff .stderr
+#
+# @TEST-EXEC: zeek -b errors.zeek >errors.stdout 2>errors.stderr
+# @TEST-EXEC: btest-diff errors.stdout
+# @TEST-EXEC: btest-diff errors.stderr
+
+
+@if ( find_in_zeekpath("pkg1") != "" )
+@load pkg1
+@endif
+
+@if ( find_in_zeekpath("pkg2") != "" )
+@load pkg2
+@endif
+
+@if ( find_in_zeekpath("pkg3") != "" )
+@load pkg3
+@endif
+
+function path_tail(r: string): string
+	{
+	if ( |r| == 0 )
+		return r;
+	local parts = split_string(r, /\//);
+	return join_string_vec(parts[-4:], "/");
+	}
+
+print "find_in_zeekpath base/protocols/conn", path_tail(find_in_zeekpath("base/protocols/conn"));
+print "find_in_zeekpath protocols/conn (empty expected, no __load__.zeek)", find_in_zeekpath("protocols/conn");
+print "find_in_zeekpath protocols/conn/vlan-logging", path_tail(find_in_zeekpath("protocols/conn/vlan-logging"));
+
+print "find_in_zeekpath pkg1", find_in_zeekpath("pkg1");
+print "find_in_zeekpath pkg1.zeek", find_in_zeekpath("pkg1.zeek");
+print "find_in_zeekpath pkg2", find_in_zeekpath("pkg2");
+print "find_in_zeekpath pkg3", find_in_zeekpath("pkg3");
+
+@TEST-START-FILE pkg1.zeek
+event zeek_init()
+	{
+	print "pkg1!";
+	}
+@TEST-END-FILE
+
+@TEST-START-FILE pkg2/__load__.zeek
+event zeek_init()
+	{
+	print "pkg2!";
+	}
+@TEST-END-FILE
+
+@TEST-START-FILE errors.zeek
+# Using relative and absolute paths is an error (empty string)
+print "relative", find_in_zeekpath("./pkg1.zeek");
+print "absolute", find_in_zeekpath("/pkg1");
+@TEST-END-FILE

testing/btest/scripts/base/utils/packages.zeek

@@ -0,0 +1,32 @@
+# @TEST-EXEC: zeek -b %INPUT >output
+# @TEST-EXEC: btest-diff output
+
+@load base/utils/packages
+
+@if ( can_load("pkg1") )
+@load pkg1
+@endif
+
+@if ( can_load("pkg2") )
+@load pkg2
+@endif
+
+@if ( can_load("pkg3") )
+@load pkg3
+@else
+print "no pkg3";
+@endif
+
+@TEST-START-FILE pkg1.zeek
+event zeek_init()
+	{
+	print "pkg1!";
+	}
+@TEST-END-FILE
+
+@TEST-START-FILE pkg2/__load__.zeek
+event zeek_init()
+	{
+	print "pkg2!";
+	}
+@TEST-END-FILE