Rudimentary implementation of the .it request (input line trap).

As with any low-level roff request involving subtle interactions
with macro internals, this implementation is not exact, but it
does handle the simplest cases.

This request occurs in man(7) code generated from DocBook,
for example mysql(1) and yasm_arch(7).
Thanks to brad@ for reporting the issue back in January 2011.

4 files changed, 60 insertions, 15 deletions

diff --git a/TODO b/TODO
index 59a03e6d..54f7f5ab 100644
--- a/TODO
+++ b/TODO
@@ -37,10 +37,6 @@ None known right now.
 - .fc (field control)
   found by naddy@ in xloadimage(1)
   
-- .it (line traps) occur in mysql(1), yasm_arch(7)
-  generated by DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
-  reported by brad@  Sat, 15 Jan 2011 15:48:18 -0500
-
 - .ns (no-space mode) occurs in xine-config(1)
   reported by brad@  Sat, 15 Jan 2011 15:45:23 -0500
 
diff --git a/mandoc.h b/mandoc.h
index 28319f2f..09dd6567 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -1,7 +1,7 @@
 /*	$Id$ */
 /*
  * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2012 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2012, 2013 Ingo Schwarze <schwarze@openbsd.org>
  *
  * Permission to use, copy, modify, and distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
@@ -145,6 +145,7 @@ enum	mandocerr {
 	MANDOCERR_NOARGS, /* macro requires line argument(s) */
 	MANDOCERR_NOBODY, /* macro requires body argument(s) */
 	MANDOCERR_NOARGV, /* macro requires argument(s) */
+	MANDOCERR_NUMERIC, /* request requires a numeric argument */
 	MANDOCERR_LISTTYPE, /* missing list type */
 	MANDOCERR_ARGSLOST, /* line argument(s) will be lost */
 	MANDOCERR_BODYLOST, /* body argument(s) will be lost */
diff --git a/read.c b/read.c
index 54d26eb6..52daedc4 100644
--- a/read.c
+++ b/read.c
@@ -185,6 +185,7 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 	"macro requires line argument(s)",
 	"macro requires body argument(s)",
 	"macro requires argument(s)",
+	"request requires a numeric argument",
 	"missing list type",
 	"line argument(s) will be lost",
 	"body argument(s) will be lost",
diff --git a/roff.c b/roff.c
index d48668ab..8a37326d 100644
--- a/roff.c
+++ b/roff.c
@@ -21,6 +21,7 @@
 
 #include <assert.h>
 #include <ctype.h>
+#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
@@ -186,12 +187,13 @@ static	void		 roff_freestr(struct roffkv *);
 static	char		*roff_getname(struct roff *, char **, int, int);
 static	const char	*roff_getstrn(const struct roff *, 
 				const char *, size_t);
+static	enum rofferr	 roff_it(ROFF_ARGS);
 static	enum rofferr	 roff_line_ignore(ROFF_ARGS);
 static	enum rofferr	 roff_nr(ROFF_ARGS);
 static	void		 roff_openeqn(struct roff *, const char *,
 				int, int, const char *);
 static	enum rofft	 roff_parse(struct roff *, const char *, int *);
-static	enum rofferr	 roff_parsetext(char *);
+static	enum rofferr	 roff_parsetext(char **, size_t *, int, int *);
 static	enum rofferr	 roff_res(struct roff *, 
 				char **, size_t *, int, int);
 static	enum rofferr	 roff_rm(ROFF_ARGS);
@@ -233,7 +235,7 @@ static	struct roffmac	 roffs[ROFF_MAX] = {
 	{ "ie", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
 	{ "if", roff_cond, roff_cond_text, roff_cond_sub, ROFFMAC_STRUCT, NULL },
 	{ "ig", roff_block, roff_block_text, roff_block_sub, 0, NULL },
-	{ "it", roff_line_ignore, NULL, NULL, 0, NULL },
+	{ "it", roff_it, NULL, NULL, 0, NULL },
 	{ "ne", roff_line_ignore, NULL, NULL, 0, NULL },
 	{ "nh", roff_line_ignore, NULL, NULL, 0, NULL },
 	{ "nr", roff_nr, NULL, NULL, 0, NULL },
@@ -295,6 +297,9 @@ static	const struct predef predefs[PREDEFS_MAX] = {
 /* See roffhash_find() */
 #define	ROFF_HASH(p)	(p[0] - ASCII_LO)
 
+static	int	 roffit_lines;  /* number of lines to delay */
+static	char	*roffit_macro;  /* nil-terminated macro line */
+
 static void
 roffhash_init(void)
 {
@@ -596,16 +601,20 @@ again:
 }
 
 /*
- * Process text streams: convert all breakable hyphens into ASCII_HYPH.
+ * Process text streams:
+ * Convert all breakable hyphens into ASCII_HYPH.
+ * Decrement and spring input line trap.
  */
 static enum rofferr
-roff_parsetext(char *p)
+roff_parsetext(char **bufp, size_t *szp, int pos, int *offs)
 {
 	size_t		 sz;
 	const char	*start;
+	char		*p;
+	int		 isz;
 	enum mandoc_esc	 esc;
 
-	start = p;
+	start = p = *bufp + pos;
 
 	while ('\0' != *p) {
 		sz = strcspn(p, "-\\");
@@ -633,6 +642,22 @@ roff_parsetext(char *p)
 		p++;
 	}
 
+	/* Spring the input line trap. */
+	if (1 == roffit_lines) {
+		isz = asprintf(&p, "%s\n.%s", *bufp, roffit_macro);
+		if (-1 == isz) {
+			perror(NULL);
+			exit((int)MANDOCLEVEL_SYSERR);
+		}
+		free(*bufp);
+		*bufp = p;
+		*szp = isz + 1;
+		*offs = 0;
+		free(roffit_macro);
+		roffit_lines = 0;
+		return(ROFF_REPARSE);
+	} else if (1 < roffit_lines)
+		--roffit_lines;
 	return(ROFF_CONT);
 }
 
@@ -677,13 +702,13 @@ roff_parseln(struct roff *r, int ln, char **bufp,
 			return(eqn_read(&r->eqn, ln, *bufp, pos, offs));
 		if (r->tbl)
 			return(tbl_read(r->tbl, ln, *bufp, pos));
-		return(roff_parsetext(*bufp + pos));
+		return(roff_parsetext(bufp, szp, pos, offs));
 	} else if ( ! ctl) {
 		if (r->eqn)
 			return(eqn_read(&r->eqn, ln, *bufp, pos, offs));
 		if (r->tbl)
 			return(tbl_read(r->tbl, ln, *bufp, pos));
-		return(roff_parsetext(*bufp + pos));
+		return(roff_parsetext(bufp, szp, pos, offs));
 	} else if (r->eqn)
 		return(eqn_read(&r->eqn, ln, *bufp, ppos, offs));
 
@@ -1120,9 +1145,6 @@ static enum rofferr
 roff_line_ignore(ROFF_ARGS)
 {
 
-	if (ROFF_it == tok)
-		mandoc_msg(MANDOCERR_REQUEST, r->parse, ln, ppos, "it");
-
 	return(ROFF_IGN);
 }
 
@@ -1297,6 +1319,31 @@ roff_rm(ROFF_ARGS)
 
 /* ARGSUSED */
 static enum rofferr
+roff_it(ROFF_ARGS)
+{
+	char		*cp;
+	size_t		 len;
+	int		 iv;
+
+	/* Parse the number of lines. */
+	cp = *bufp + pos;
+	len = strcspn(cp, " \t");
+	cp[len] = '\0';
+	if ((iv = mandoc_strntoi(cp, len, 10)) <= 0) {
+		mandoc_msg(MANDOCERR_NUMERIC, r->parse,
+				ln, ppos, *bufp + 1);
+		return(ROFF_IGN);
+	}
+	cp += len + 1;
+
+	/* Arm the input line trap. */
+	roffit_lines = iv;
+	roffit_macro = mandoc_strdup(cp);
+	return(ROFF_IGN);
+}
+
+/* ARGSUSED */
+static enum rofferr
 roff_Dd(ROFF_ARGS)
 {
 	const char *const	*cp;