Pure preprocessor implementation of the roff(7) .ec and .eo requests

(escape character control), touching nothing after the preprocessing
stage and keeping even the state variable local to the preprocessor.
Since the escape character is also used for line continuation, this
requires pulling the implementation of line continuation from the
input reader to the preprocessor, which also considerably shortens
the code required for that.

When the escape character is changed, simply let the preprocessor
replace bare by escaped backslashes and instances of the non-standard
escape character with bare backslashes - that's all we need.

Oh, and if anybody dares to use these requests in OpenBSD manuals,
sending a medium-sized pack of axe-murderers after them might be a
worthwhile part of the punishment, but probably insuffient on its own.

1 files changed, 4 insertions, 70 deletions

diff --git a/read.c b/read.c
index 43b55ba3..efc840bf 100644
--- a/read.c
+++ b/read.c
@@ -1,4 +1,4 @@
-/*	$Id: read.c,v 1.169 2017/06/03 15:55:24 schwarze Exp $ */
+/*	$Id: read.c,v 1.170 2017/06/04 00:13:15 schwarze Exp $ */
 /*
  * Copyright (c) 2008, 2009, 2010, 2011 Kristaps Dzonsons <kristaps@bsd.lv>
  * Copyright (c) 2010-2017 Ingo Schwarze <schwarze@openbsd.org>
@@ -326,7 +326,6 @@ mparse_buf_r(struct mparse *curp, struct buf blk, size_t i, int start)
 	const char	*save_file;
 	char		*cp;
 	size_t		 pos; /* byte number in the ln buffer */
-	size_t		 j;  /* auxiliary byte number in the blk buffer */
 	enum rofferr	 rr;
 	int		 of;
 	int		 lnn; /* line number in the real file */
@@ -408,79 +407,14 @@ mparse_buf_r(struct mparse *curp, struct buf blk, size_t i, int start)
 				continue;
 			}
 
-			/* Trailing backslash = a plain char. */
-
-			if (blk.buf[i] != '\\' || i + 1 == blk.sz) {
-				ln.buf[pos++] = blk.buf[i++];
-				continue;
-			}
-
-			/*
-			 * Found escape and at least one other character.
-			 * When it's a newline character, skip it.
-			 * When there is a carriage return in between,
-			 * skip that one as well.
-			 */
-
-			if ('\r' == blk.buf[i + 1] && i + 2 < blk.sz &&
-			    '\n' == blk.buf[i + 2])
-				++i;
-			if ('\n' == blk.buf[i + 1]) {
-				i += 2;
-				++lnn;
-				continue;
-			}
-
-			if ('"' == blk.buf[i + 1] || '#' == blk.buf[i + 1]) {
-				j = i;
-				i += 2;
-				/* Comment, skip to end of line */
-				for (; i < blk.sz; ++i) {
-					if (blk.buf[i] != '\n')
-						continue;
-					if (blk.buf[i - 1] == ' ' ||
-					    blk.buf[i - 1] == '\t')
-						mandoc_msg(
-						    MANDOCERR_SPACE_EOL,
-						    curp, curp->line,
-						    pos + i-1 - j, NULL);
-					++i;
-					++lnn;
-					break;
-				}
-
-				/* Backout trailing whitespaces */
-				for (; pos > 0; --pos) {
-					if (ln.buf[pos - 1] != ' ')
-						break;
-					if (pos > 2 && ln.buf[pos - 2] == '\\')
-						break;
-				}
-				break;
-			}
-
-			/* Catch escaped bogus characters. */
-
-			c = (unsigned char) blk.buf[i+1];
-
-			if ( ! (isascii(c) &&
-			    (isgraph(c) || isblank(c)))) {
-				mandoc_vmsg(MANDOCERR_CHAR_BAD, curp,
-				    curp->line, pos, "0x%x", c);
-				i += 2;
-				ln.buf[pos++] = '?';
-				continue;
-			}
-
-			/* Some other escape sequence, copy & cont. */
-
-			ln.buf[pos++] = blk.buf[i++];
 			ln.buf[pos++] = blk.buf[i++];
 		}
 
-		if (pos >= ln.sz)
+		if (pos + 1 >= ln.sz)
 			resize_buf(&ln, 256);
 
+		if (i == blk.sz || blk.buf[i] == '\0')
+			ln.buf[pos++] = '\n';
 		ln.buf[pos] = '\0';
 
 		/*