Add a graceful jumping off point with a new .error directive.

PR:		6720
Submitted by:	Niall Smart <njs3@doc.ic.ac.uk>

2 files changed, 60 insertions, 21 deletions

diff --git a/usr.bin/make/make.1 b/usr.bin/make/make.1
index 1b997ab..89a1e3f 100644
--- a/usr.bin/make/make.1
+++ b/usr.bin/make/make.1
@@ -30,7 +30,7 @@
 .\" SUCH DAMAGE.
 .\"
 .\"	from: @(#)make.1	8.4 (Berkeley) 3/19/94
-.\"	$Id: make.1,v 1.10 1997/03/09 15:50:58 wosch Exp $
+.\"	$Id: make.1,v 1.11 1997/07/24 06:58:07 charnier Exp $
 .\"
 .Dd March 19, 1994
 .Dt MAKE 1
@@ -551,35 +551,40 @@ is the substring of
 to be replaced in
 .Ar new_string
 .El
-.Sh INCLUDE STATEMENTS, CONDITIONALS AND FOR LOOPS
-Makefile inclusion, conditional structures and for loops  reminiscent
+.Sh DIRECTIVES, CONDITIONALS AND FOR LOOPS
+Directives, conditionals and for loops reminiscent
 of the C programming language are provided in
 .Nm make .
 All such structures are identified by a line beginning with a single
 dot
 .Pq Ql \&.
-character.
-Files are included with either
-.Ql .include <file>
-or
-.Ql .include \*qfile\*q .
-Variables between the angle brackets or double quotes are expanded
-to form the file name.
-If angle brackets are used, the included makefile is expected to be in
-the system makefile directory.
-If double quotes are used, the including makefile's directory and any
-directories specified using the
+character.  The following directives are supported:
+.Bl -tag -width Ds
+.It Ic \&.include Ar <file>
+.It Ic \&.include Ar \*qfile\*q
+Include the specified makefile.  Variables between the angle brackets
+or double quotes are expanded to form the file name.  If angle brackets
+are used, the included makefile is expected to be in the system
+makefile directory.  If double quotes are used, the including
+makefile's directory and any directories specified using the
 .Fl I
 option are searched before the system
 makefile directory.
-.Pp
-Conditional expressions are also preceded by a single dot as the first
-character of a line.
-The possible conditionals are as follows:
-.Bl -tag -width Ds
-.It Ic .undef Ar variable
+.It Ic \&.undef Ar variable
 Un-define the specified global variable.
 Only global variables may be un-defined.
+.It Ic \&.error Ar message
+Terminate processing of the makefile immediately. The filename of the
+makefile, the line on which the error was encountered and the specified
+message are printed to standard output and
+.Nm make
+terminates with exit code 1.  Variables in the message are expanded.
+.El
+.Pp
+Conditionals are used to determine which parts of the Makefile
+to process.  They are used similarly to the conditionals supported
+by the C pre-processor.  The following conditionals are supported:
+.Bl -tag -width Ds
 .It Xo
 .Ic \&.if
 .Oo \&! Oc Ns Ar expression
diff --git a/usr.bin/make/parse.c b/usr.bin/make/parse.c
index 448aa96..388fa07 100644
--- a/usr.bin/make/parse.c
+++ b/usr.bin/make/parse.c
@@ -41,7 +41,7 @@
 static char sccsid[] = "@(#)parse.c	8.3 (Berkeley) 3/19/94";
 #endif
 static const char rcsid[] =
-	"$Id$";
+	"$Id: parse.c,v 1.18 1997/07/24 06:58:08 charnier Exp $";
 #endif /* not lint */
 
 /*-
@@ -251,6 +251,7 @@ static int ParseReadc __P((void));
 static void ParseUnreadc __P((int));
 static void ParseHasCommands __P((ClientData));
 static void ParseDoInclude __P((char *));
+static void ParseDoError __P((char *));
 #ifdef SYSVINCLUDE
 static void ParseTraditionalInclude __P((char *));
 #endif
@@ -1552,6 +1553,35 @@ Parse_AddIncludeDir (dir)
     Dir_AddDir (parseIncPath, dir);
 }
 
+/*---------------------------------------------------------------------
+ * ParseDoError  --
+ *	Handle error directive
+ *
+ *	The input is the line minus the ".error".  We substitute variables,
+ *	print the message and exit(1) or just print a warning if the ".error"
+ *	directive is malformed.
+ *
+ *---------------------------------------------------------------------
+ */
+static void
+ParseDoError(errmsg)
+    char          *errmsg;	/* error message */
+{
+	if (!isspace(*errmsg)) {
+		Parse_Error(PARSE_WARNING, "invalid syntax: .error%s", errmsg);
+		return;
+	}
+	
+	while (isspace(*errmsg))
+		errmsg++;
+	
+	errmsg = Var_Subst(NULL, errmsg, VAR_GLOBAL, FALSE);
+
+	/* use fprintf/exit instead of Parse_Error to terminate immediately */
+	fprintf(stderr, "\"%s\", line %d: %s\n", fname, lineno, errmsg);
+	exit(1);
+}
+
 /*-
  *---------------------------------------------------------------------
  * ParseDoInclude  --
@@ -1734,6 +1764,7 @@ ParseDoInclude (file)
 }
 
 
+
 /*-
  *---------------------------------------------------------------------
  * Parse_FromString  --
@@ -2385,6 +2416,9 @@ Parse_File(name, stream)
 		if (strncmp (cp, "include", 7) == 0) {
 		    ParseDoInclude (cp + 7);
 		    goto nextLine;
+		} else if (strncmp (cp, "error", 5) == 0) {
+		    ParseDoError(cp + 5);
+	            goto nextLine;	    
 		} else if (strncmp(cp, "undef", 5) == 0) {
 		    char *cp2;
 		    for (cp += 5; isspace((unsigned char) *cp); cp++) {