Reverted previous input filter changes.

Added noop macro to scanner output.
Modified scan.l to escape m4 quotes found in user code.

1 files changed, 20 insertions, 63 deletions

diff --git a/filter.c b/filter.c
index 409f044..e60e083 100644
--- a/filter.c
+++ b/filter.c
@@ -126,7 +126,7 @@ struct filter *filter_create_int (struct filter *chain,
  *  @param chain The head of the chain.
  *  @return true on success.
  */
-bool filter_apply_chain (struct filter * chain, const bool parent_to_child)
+bool filter_apply_chain (struct filter * chain)
 {
 	int     pid, pipes[2];
 
@@ -135,7 +135,7 @@ bool filter_apply_chain (struct filter * chain, const bool parent_to_child)
 	 * to be children of the main flex process.
 	 */
 	if (chain)
-		filter_apply_chain (chain->next, parent_to_child);
+		filter_apply_chain (chain->next);
 	else
 		return true;
 
@@ -154,29 +154,17 @@ bool filter_apply_chain (struct filter * chain, const bool parent_to_child)
 	if (pid == 0) {
 		/* child */
 
-        /* For the parent_to_child direction, we need stdin (the FILE* stdin)
-         * to connect to this new pipe.  There is no portable way to set stdin
-         * to a new file descriptor, as stdin is not an lvalue on some systems
-         * (BSD).  So we dup the new pipe onto the stdin descriptor and use a
-         * no-op fseek to sync the stream.  This is a Hail Mary situation. It
-         * seems to work.  Note that the same concept applies, but opposite,
-         * for child_to_parent filters.
+        /* We need stdin (the FILE* stdin) to connect to this new pipe.
+         * There is no portable way to set stdin to a new file descriptor,
+         * as stdin is not an lvalue on some systems (BSD).
+         * So we dup the new pipe onto the stdin descriptor and use a no-op fseek
+         * to sync the stream. This is a Hail Mary situation. It seems to work.
          */
-
-        if (parent_to_child){
-            close (pipes[1]);
-            if (dup2 (pipes[0], fileno (stdin)) == -1)
-                flexfatal (_("dup2(pipes[0],0)"));
-            close (pipes[0]);
-            fseek (stdin, 0, SEEK_CUR);
-        }
-        else{
-            close (pipes[0]);
-            if (dup2 (pipes[1], fileno (stdout)) == -1)
-                flexfatal (_("dup2(pipes[1],1)"));
-            close (pipes[1]);
-            fseek (stdout, 0, SEEK_CUR);
-        }
+		close (pipes[1]);
+		if (dup2 (pipes[0], fileno (stdin)) == -1)
+			flexfatal (_("dup2(pipes[0],0)"));
+		close (pipes[0]);
+        fseek (stdin, 0, SEEK_CUR);
 
 		/* run as a filter, either internally or by exec */
 		if (chain->filter_func) {
@@ -196,20 +184,11 @@ bool filter_apply_chain (struct filter * chain, const bool parent_to_child)
 	}
 
 	/* Parent */
-    if (parent_to_child){
-        close (pipes[0]);
-        if (dup2 (pipes[1], fileno (stdout)) == -1)
-            flexfatal (_("dup2(pipes[1],1)"));
-        close (pipes[1]);
-        fseek (stdout, 0, SEEK_CUR);
-    }
-    else{
-        close (pipes[1]);
-        if (dup2 (pipes[0], fileno (stdin)) == -1)
-            flexfatal (_("dup2(pipes[0],0)"));
-        close (pipes[0]);
-        fseek (stdin, 0, SEEK_CUR);
-    }
+	close (pipes[0]);
+	if (dup2 (pipes[1], fileno (stdout)) == -1)
+		flexfatal (_("dup2(pipes[1],1)"));
+	close (pipes[1]);
+    fseek (stdout, 0, SEEK_CUR);
 
 	return true;
 }
@@ -267,7 +246,7 @@ int filter_tee_header (struct filter *chain)
 		if (freopen ((char *) chain->extra, "w", stdout) == NULL)
 			flexfatal (_("freopen(headerfilename) failed"));
 
-		filter_apply_chain (chain->next, true);
+		filter_apply_chain (chain->next);
 		to_h = stdout;
 	}
 
@@ -279,6 +258,7 @@ int filter_tee_header (struct filter *chain)
 		fputs ("m4_changecom`'m4_dnl\n", to_h);
 		fputs ("m4_changequote`'m4_dnl\n", to_h);
 		fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_h);
+	    fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_h);
 		fputs ("m4_define( [[M4_YY_IN_HEADER]],[[]])m4_dnl\n",
 		       to_h);
 		fprintf (to_h, "#ifndef %sHEADER_H\n", prefix);
@@ -294,6 +274,7 @@ int filter_tee_header (struct filter *chain)
 	fputs ("m4_changecom`'m4_dnl\n", to_c);
 	fputs ("m4_changequote`'m4_dnl\n", to_c);
 	fputs ("m4_changequote([[,]])[[]]m4_dnl\n", to_c);
+	fputs ("m4_define([[M4_YY_NOOP]])[[]]m4_dnl\n", to_c);
 	fprintf (to_c, "m4_define( [[M4_YY_OUTFILE_NAME]],[[%s]])m4_dnl\n",
 		 outfilename ? outfilename : "<stdout>");
 
@@ -424,28 +405,4 @@ int filter_fix_linedirs (struct filter *chain)
 	return 0;
 }
 
-/* set_input_file - open the given file (if NULL, stdin) for scanning */
-
-void set_input_file( file )
-char *file;
-{
-    /* Preprocess the input to quote m4 escapes.*/
-	if ( file && strcmp( file, "-" ) )
-		{
-		infilename = copy_string( file );
-		yyin = fopen( infilename, "r" );
-
-		if ( yyin == NULL )
-			lerrsf( _( "can't open %s" ), file );
-		}
-
-	else
-		{
-		yyin = stdin;
-		infilename = copy_string( "<stdin>" );
-		}
-
-	linenum = 1;
-}
-
 /* vim:set expandtab cindent tabstop=4 softtabstop=4 shiftwidth=4 textwidth=0: */