Unify roff macro argument parsing (in roff.c, roff_userdef()) and man macro

argument parsing (in man_argv.c, man_args()), both having different bugs,
to use one common macro argument parser (in mandoc.c, mandoc_getarg()),
because from the point of view of roff, man macros are just roff macros,
hence their arguments are parsed in exactly the same way.

While doing so, fix these bugs:
 * Escaped blanks (i.e. those preceded by an odd number of backslashes)
   were mishandled as argument separators in unquoted arguments to
   user-defined roff macros.
 * Unescaped blanks preceded by an even number of backslashes were not
   recognized as argument separators in unquoted arguments to man macros.
 * Escaped backslashes (i.e. pairs of backslashes) were not reduced
   to single backslashes both in unquoted and quoted arguments both
   to user-defined roff macros and to man macros.
 * Escaped quotes (i.e. pairs of quotes inside quoted arguments) were
   not reduced to single quotes in man macros.

OK kristaps@

Note that mdoc macro argument parsing is yet another beast for no good
reason and is probably afflicted by similar bugs.  But i don't attempt
to fix that right now because it is intricately entangled with lots of
unrelated high-level mdoc(7) functionality, like delimiter handling and
column list phrase handling.  Disentagling that would waste too much
time now.

4 files changed, 95 insertions, 113 deletions

diff --git a/libmandoc.h b/libmandoc.h
index 5059e600..18415071 100644
--- a/libmandoc.h
+++ b/libmandoc.h
@@ -24,6 +24,7 @@ void		*mandoc_calloc(size_t, size_t);
 char		*mandoc_strdup(const char *);
 void		*mandoc_malloc(size_t);
 void		*mandoc_realloc(void *, size_t);
+char		*mandoc_getarg(char **, mandocmsg, void *, int, int *);
 time_t		 mandoc_a2time(int, const char *);
 #define		 MTIME_CANONICAL	(1 << 0)
 #define		 MTIME_REDUCED		(1 << 1)
diff --git a/man_argv.c b/man_argv.c
index 998c7a68..f091d0f2 100644
--- a/man_argv.c
+++ b/man_argv.c
@@ -1,6 +1,6 @@
 /*	$Id$ */
 /*
- * Copyright (c) 2008, 2009 Kristaps Dzonsons <kristaps@bsd.lv>
+ * Copyright (c) 2011 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
@@ -21,84 +21,24 @@
 #include <sys/types.h>
 
 #include <assert.h>
-#include <stdlib.h>
-#include <string.h>
 
 #include "mandoc.h"
 #include "libman.h"
+#include "libmandoc.h"
 
 
 int
 man_args(struct man *m, int line, int *pos, char *buf, char **v)
 {
+	char	 *start;
 
 	assert(*pos);
-	assert(' ' != buf[*pos]);
+	*v = start = buf + *pos;
+	assert(' ' != *start);
 
-	if (0 == buf[*pos])
+	if ('\0' == *start)
 		return(ARGS_EOLN);
 
-	*v = &buf[*pos];
-
-	/* 
-	 * Process a quoted literal.  A quote begins with a double-quote
-	 * and ends with a double-quote NOT preceded by a double-quote.
-	 * Whitespace is NOT involved in literal termination.
-	 */
-
-	if ('\"' == buf[*pos]) {
-		*v = &buf[++(*pos)];
-
-		for ( ; buf[*pos]; (*pos)++) {
-			if ('\"' != buf[*pos])
-				continue;
-			if ('\"' != buf[*pos + 1])
-				break;
-			(*pos)++;
-		}
-
-		if (0 == buf[*pos]) {
-			if ( ! man_pmsg(m, line, *pos, MANDOCERR_BADQUOTE))
-				return(ARGS_ERROR);
-			return(ARGS_QWORD);
-		}
-
-		buf[(*pos)++] = 0;
-
-		if (0 == buf[*pos])
-			return(ARGS_QWORD);
-
-		while (' ' == buf[*pos])
-			(*pos)++;
-
-		if (0 == buf[*pos])
-			if ( ! man_pmsg(m, line, *pos, MANDOCERR_EOLNSPACE))
-				return(ARGS_ERROR);
-
-		return(ARGS_QWORD);
-	}
-
-	/* 
-	 * A non-quoted term progresses until either the end of line or
-	 * a non-escaped whitespace.
-	 */
-
-	for ( ; buf[*pos]; (*pos)++)
-		if (' ' == buf[*pos] && '\\' != buf[*pos - 1])
-			break;
-
-	if (0 == buf[*pos])
-		return(ARGS_WORD);
-
-	buf[(*pos)++] = 0;
-
-	while (' ' == buf[*pos])
-		(*pos)++;
-
-	if (0 == buf[*pos])
-		if ( ! man_pmsg(m, line, *pos, MANDOCERR_EOLNSPACE))
-			return(ARGS_ERROR);
-
-	return(ARGS_WORD);
+	*v = mandoc_getarg(v, m->msg, m->data, line, pos);
+	return('"' == *start ? ARGS_QWORD : ARGS_WORD);
 }
-
diff --git a/mandoc.c b/mandoc.c
index f0697831..24a3a24f 100644
--- a/mandoc.c
+++ b/mandoc.c
@@ -1,14 +1,15 @@
 /*	$Id$ */
 /*
  * Copyright (c) 2008, 2009, 2010 Kristaps Dzonsons <kristaps@bsd.lv>
+ * Copyright (c) 2011 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
  * copyright notice and this permission notice appear in all copies.
  *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHORS DISCLAIM ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR
  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
@@ -283,6 +284,83 @@ mandoc_strdup(const char *ptr)
 	return(p);
 }
 
+/*
+ * Parse a quoted or unquoted roff-style request or macro argument.
+ * Return a pointer to the parsed argument, which is either the original
+ * pointer or advanced by one byte in case the argument is quoted.
+ * Null-terminate the argument in place.
+ * Collapse pairs of quotes inside quoted arguments.
+ * Advance the argument pointer to the next argument,
+ * or to the null byte terminating the argument line.
+ */
+char *
+mandoc_getarg(char **cpp, mandocmsg msg, void *data, int ln, int *pos)
+{
+	char	 *start, *cp;
+	int	  quoted, pairs, white;
+
+	/* Quoting can only start with a new word. */
+	start = *cpp;
+	if ('"' == *start) {
+		quoted = 1;
+		start++;
+	} else
+		quoted = 0;
+
+	pairs = 0;
+	white = 0;
+	for (cp = start; '\0' != *cp; cp++) {
+		/* Move left after quoted quotes and escaped backslashes. */
+		if (pairs)
+			cp[-pairs] = cp[0];
+		if ('\\' == cp[0]) {
+			if ('\\' == cp[1]) {
+				/* Poor man's copy mode. */
+				pairs++;
+				cp++;
+			} else if (0 == quoted && ' ' == cp[1])
+				/* Skip escaped blanks. */
+				cp++;
+		} else if (0 == quoted) {
+			if (' ' == cp[0]) {
+				/* Unescaped blanks end unquoted args. */
+				white = 1;
+				break;
+			}
+		} else if ('"' == cp[0]) {
+			if ('"' == cp[1]) {
+				/* Quoted quotes collapse. */
+				pairs++;
+				cp++;
+			} else {
+				/* Unquoted quotes end quoted args. */
+				quoted = 2;
+				break;
+			}
+		}
+	}
+
+	/* Quoted argument without a closing quote. */
+	if (1 == quoted && msg)
+		(*msg)(MANDOCERR_BADQUOTE, data, ln, *pos, NULL);
+
+	/* Null-terminate this argument and move to the next one. */
+	if (pairs)
+		cp[-pairs] = '\0';
+	if ('\0' != *cp) {
+		*cp++ = '\0';
+		while (' ' == *cp)
+			cp++;
+	}
+	*pos += (cp - start) + (quoted ? 1 : 0);
+	*cpp = cp;
+
+	if ('\0' == *cp && msg && (white || ' ' == cp[-1]))
+		(*msg)(MANDOCERR_EOLNSPACE, data, ln, *pos, NULL);
+
+	return(start);
+}
+
 
 static int
 a2time(time_t *t, const char *fmt, const char *p)
diff --git a/roff.c b/roff.c
index c84077b8..35e227d7 100644
--- a/roff.c
+++ b/roff.c
@@ -1,7 +1,7 @@
 /*	$Id$ */
 /*
- * Copyright (c) 2010 Kristaps Dzonsons <kristaps@bsd.lv>
- * Copyright (c) 2010 Ingo Schwarze <schwarze@openbsd.org>
+ * Copyright (c) 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
+ * Copyright (c) 2010, 2011 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
@@ -1201,53 +1201,16 @@ roff_userdef(ROFF_ARGS)
 {
 	const char	 *arg[9];
 	char		 *cp, *n1, *n2;
-	int		  i, quoted, pairs;
+	int		  i;
 
 	/*
 	 * Collect pointers to macro argument strings
 	 * and null-terminate them.
 	 */
 	cp = *bufp + pos;
-	for (i = 0; i < 9; i++) {
-		/* Quoting can only start with a new word. */
-		if ('"' == *cp) {
-			quoted = 1;
-			cp++;
-		} else
-			quoted = 0;
-		arg[i] = cp;
-		for (pairs = 0; '\0' != *cp; cp++) {
-			/* Unquoted arguments end at blanks. */
-			if (0 == quoted) {
-				if (' ' == *cp)
-					break;
-				continue;
-			}
-			/* After pairs of quotes, move left. */
-			if (pairs)
-				cp[-pairs] = cp[0];
-			/* Pairs of quotes do not end words, ... */
-			if ('"' == cp[0] && '"' == cp[1]) {
-				pairs++;
-				cp++;
-				continue;
-			}
-			/* ... but solitary quotes do. */
-			if ('"' != *cp)
-				continue;
-			if (pairs)
-				cp[-pairs] = '\0';
-			*cp = ' ';
-			break;
-		}
-		/* Last argument; the remaining ones are empty strings. */
-		if ('\0' == *cp)
-			continue;
-		/* Null-terminate argument and move to the next one. */
-		*cp++ = '\0';
-		while (' ' == *cp)
-			cp++;
-	}
+	for (i = 0; i < 9; i++)
+		arg[i] = '\0' == *cp ? NULL :
+		    mandoc_getarg(&cp, r->msg, r->data, ln, &pos);
 
 	/*
 	 * Expand macro arguments.