Fix tail -F semantics when want_record=F and add tests for the new features

While writing a test for the new "tail -F semantics" I found that
the $want_record=F case was broken (errno 25). So instead of opening
/dev/null when the input file is missing change READER_RAW to avoid
I/O until it can be opened.

Add two tests, one for when the event handler is called with a
record and one for when it's called with a string.

src/input/readers/raw/Raw.cc

@@ -281,14 +281,12 @@ bool Raw::OpenInput()
 	else
 		{
 		file = std::unique_ptr<FILE, int (*)(FILE*)>(fopen(fname.c_str(), "r"), fclose);
-		if ( ! file && Info().mode == MODE_STREAM )
-			{
-			// Watch /dev/null until the file appears
-			file = std::unique_ptr<FILE, int (*)(FILE*)>(fopen("/dev/null", "r"), fclose);
-			}
-
 		if ( ! file )
 			{
+			if ( Info().mode == MODE_STREAM )
+				// Wait for file to appear
+				return true;
+
 			Error(Fmt("Init: cannot open %s", fname.c_str()));
 			return false;
 			}
@@ -624,7 +622,7 @@ bool Raw::DoUpdate()
 					break;
 
 				// Is it the same file?
-				if ( sb.st_ino == ino && sb.st_dev == dev )
+				if ( file && sb.st_ino == ino && sb.st_dev == dev )
 					break;
 
 				// File was replaced
@@ -638,10 +636,10 @@ bool Raw::DoUpdate()
 					{
 					// This is unlikely to fail
 					Error(Fmt("Could not fstat %s", fname.c_str()));
-					fclose(tfile);
 					return false;
 					}
-				file.reset(nullptr);
+				if ( file )
+					file.reset(nullptr);
 				file = std::unique_ptr<FILE, int (*)(FILE*)>(tfile, fclose);
 				ino = sb.st_ino;
 				dev = sb.st_dev;
@@ -661,6 +659,10 @@ bool Raw::DoUpdate()
 		if ( stdin_towrite > 0 )
 			WriteToStdin();
 
+		if ( ! file && Info().mode == MODE_STREAM )
+			// Wait for file to appear
+			break;
+
 		int64_t length = GetLine(file.get());
 		// printf("Read %lld bytes\n", length);
 

testing/btest/Baseline/scripts.base.frameworks.input.raw.streamtail/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.
+../input.log, Input::READER_RAW, Input::STREAM, input
+Input::EVENT_NEW
+sdfkh:KH;fdkncv;ISEUp34:Fkdj;YVpIODhfDF
+../input.log, Input::READER_RAW, Input::STREAM, input
+Input::EVENT_NEW
+DSF"DFKJ"SDFKLh304yrsdkfj@#(*U$34jfDJup3UF
+../input.log, Input::READER_RAW, Input::STREAM, input
+Input::EVENT_NEW
+3rw43wRRERLlL#RWERERERE.

testing/btest/Baseline/scripts.base.frameworks.input.raw.streamtail2/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.
+../input.log, Input::READER_RAW, Input::STREAM, input
+Input::EVENT_NEW
+sdfkh:KH;fdkncv;ISEUp34:Fkdj;YVpIODhfDF
+../input.log, Input::READER_RAW, Input::STREAM, input
+Input::EVENT_NEW
+DSF"DFKJ"SDFKLh304yrsdkfj@#(*U$34jfDJup3UF
+../input.log, Input::READER_RAW, Input::STREAM, input
+Input::EVENT_NEW
+3rw43wRRERLlL#RWERERERE.

testing/btest/scripts/base/frameworks/input/raw/streamtail.zeek

@@ -0,0 +1,74 @@
+# Test "tail -F" functionality (record version)
+
+# Start without the file
+# @TEST-EXEC: rm -f input.log
+# @TEST-EXEC: btest-bg-run zeek zeek -b %INPUT
+# @TEST-EXEC: sleep 1
+
+# Create the file
+# @TEST-EXEC: cp input1.log input.log
+# @TEST-EXEC: $SCRIPTS/wait-for-file zeek/got1 5 || (btest-bg-wait -k 1 && false)
+
+# Append to the file
+# @TEST-EXEC: cat input2.log >> input.log
+# @TEST-EXEC: $SCRIPTS/wait-for-file zeek/got2 5 || (btest-bg-wait -k 1 && false)
+
+# Move onto the file
+# @TEST-EXEC: cp input3.log _input.log
+# @TEST-EXEC: mv _input.log input.log
+
+# Done!
+# @TEST-EXEC: btest-bg-wait 60
+# @TEST-EXEC: btest-diff out
+
+redef exit_only_after_terminate = T;
+
+@TEST-START-FILE input1.log
+sdfkh:KH;fdkncv;ISEUp34:Fkdj;YVpIODhfDF
+@TEST-END-FILE
+
+@TEST-START-FILE input2.log
+DSF"DFKJ"SDFKLh304yrsdkfj@#(*U$34jfDJup3UF
+@TEST-END-FILE
+
+@TEST-START-FILE input3.log
+3rw43wRRERLlL#RWERERERE.
+@TEST-END-FILE
+
+module A;
+
+type lineVal: record {
+	s: string;
+};
+
+global try: count;
+global outfile: file;
+
+event line(description: Input::EventDescription, tpe: Input::Event, s: lineVal)
+	{
+	print outfile, description$source, description$reader, description$mode, description$name;
+	print outfile, tpe;
+	print outfile, s$s;
+
+	try = try + 1;
+
+	if ( try == 1 )
+		system("touch got1");
+	else if ( try == 2 )
+		system("touch got2");
+	else if ( try == 3 )
+		{
+		close(outfile);
+		Input::remove("input");
+		terminate();
+		}
+	}
+
+event zeek_init()
+	{
+	outfile = open("../out");
+	try = 0;
+	Input::add_event([$source="../input.log",
+	    $reader=Input::READER_RAW, $mode=Input::STREAM, $name="input",
+	    $fields=lineVal, $ev=line]);
+	}

testing/btest/scripts/base/frameworks/input/raw/streamtail2.zeek

@@ -0,0 +1,74 @@
+# Test "tail -F" functionality (string version)
+
+# Start without the file
+# @TEST-EXEC: rm -f input.log
+# @TEST-EXEC: btest-bg-run zeek zeek -b %INPUT
+# @TEST-EXEC: sleep 1
+
+# Create the file
+# @TEST-EXEC: cp input1.log input.log
+# @TEST-EXEC: $SCRIPTS/wait-for-file zeek/got1 5 || (btest-bg-wait -k 1 && false)
+
+# Append to the file
+# @TEST-EXEC: cat input2.log >> input.log
+# @TEST-EXEC: $SCRIPTS/wait-for-file zeek/got2 5 || (btest-bg-wait -k 1 && false)
+
+# Move onto the file
+# @TEST-EXEC: cp input3.log _input.log
+# @TEST-EXEC: mv _input.log input.log
+
+# Done!
+# @TEST-EXEC: btest-bg-wait 60
+# @TEST-EXEC: btest-diff out
+
+redef exit_only_after_terminate = T;
+
+@TEST-START-FILE input1.log
+sdfkh:KH;fdkncv;ISEUp34:Fkdj;YVpIODhfDF
+@TEST-END-FILE
+
+@TEST-START-FILE input2.log
+DSF"DFKJ"SDFKLh304yrsdkfj@#(*U$34jfDJup3UF
+@TEST-END-FILE
+
+@TEST-START-FILE input3.log
+3rw43wRRERLlL#RWERERERE.
+@TEST-END-FILE
+
+module A;
+
+type lineVal: record {
+	s: string;
+};
+
+global try: count;
+global outfile: file;
+
+event line(description: Input::EventDescription, tpe: Input::Event, s: string)
+	{
+	print outfile, description$source, description$reader, description$mode, description$name;
+	print outfile, tpe;
+	print outfile, s;
+
+	try = try + 1;
+
+	if ( try == 1 )
+		system("touch got1");
+	else if ( try == 2 )
+		system("touch got2");
+	else if ( try == 3 )
+		{
+		close(outfile);
+		Input::remove("input");
+		terminate();
+		}
+	}
+
+event zeek_init()
+	{
+	outfile = open("../out");
+	try = 0;
+	Input::add_event([$source="../input.log",
+	    $reader=Input::READER_RAW, $mode=Input::STREAM, $name="input",
+	    $fields=lineVal, $want_record=F, $ev=line]);
+	}