From c8cdc23dd605e08382028d103f06d34563196973 Mon Sep 17 00:00:00 2001
From: Kristaps Dz <kristaps@bsd.lv>
Date: Wed, 25 Dec 2024 11:57:31 -0800
Subject: [PATCH] Make --template escaperoff() escape initial delim.

Make escaperoff() escape its roff delimiters whether they appear
after a newline OR at the start of the string.  This is more in line
with how the transform would be used in practice.
---
 man/lowdown-diff.1               |  2 ++
 man/lowdown.1                    |  2 ++
 nroff_escape.c                   | 14 +++++++++-----
 regress/template/escaperoff.html |  3 +++
 regress/template/escaperoff.md   |  6 ++++++
 regress/template/escaperoff.xml  |  2 ++
 template.c                       |  2 +-
 7 files changed, 25 insertions(+), 6 deletions(-)
 create mode 100644 regress/template/escaperoff.html
 create mode 100644 regress/template/escaperoff.md
 create mode 100644 regress/template/escaperoff.xml

diff --git a/man/lowdown-diff.1 b/man/lowdown-diff.1
index a04b7ab..caf1d4a 100644
--- a/man/lowdown-diff.1
+++ b/man/lowdown-diff.1
@@ -959,6 +959,8 @@ body content.
 Escape list items for roff
 .Pq Fl t Ns Ar ms , Fl t Ns Ar man ,
 either for multiple lines or compressed to a single line.
+.Cm escaperoff
+also escapes initial roff delimiters and those after newlines.
 .It Cm join
 Join a list into a singleton list using two spaces as a join delimiter.
 .It Cm lowercase
diff --git a/man/lowdown.1 b/man/lowdown.1
index 5e5a0f3..2debc3a 100644
--- a/man/lowdown.1
+++ b/man/lowdown.1
@@ -952,6 +952,8 @@ body content.
 Escape list items for roff
 .Pq Fl t Ns Ar ms , Fl t Ns Ar man ,
 either for multiple lines or compressed to a single line.
+.Cm escaperoff
+also escapes initial roff delimiters and those after newlines.
 .It Cm join
 Join a list into a singleton list using two spaces as a join delimiter.
 .It Cm lowercase
diff --git a/nroff_escape.c b/nroff_escape.c
index 50e34b1..c5d7454 100644
--- a/nroff_escape.c
+++ b/nroff_escape.c
@@ -34,7 +34,10 @@
 /*
  * Escape unsafe text into roff output such that no roff features are
  * invoked by the text (macros, escapes, etc.).
- * If "oneline" is non-zero, newlines are replaced with spaces.
+ * If "oneline" is >0, newlines are replaced with spaces; if =0,
+ * newlines are retained and roff delimiters after the newline are
+ * escaped; if <0, like =0 except that the first character if a
+ * delimiter is also escaped.
  * If "literal", doesn't strip leading space.
  * Return zero on failure, non-zero on success.
  */
@@ -81,7 +84,7 @@ lowdown_nroff_esc(struct lowdown_buf *ob, const char *data, size_t size,
 				return 0;
 			break;
 		case '\n':
-			if (!hbuf_putc(ob, oneline ? ' ' : '\n'))
+			if (!hbuf_putc(ob, oneline > 0 ? ' ' : '\n'))
 				return 0;
 			if (literal)
 				break;
@@ -99,9 +102,10 @@ lowdown_nroff_esc(struct lowdown_buf *ob, const char *data, size_t size,
 			break;
 		case '\'':
 		case '.':
-			if (!oneline &&
-			    ob->size > 0 && 
-			    ob->data[ob->size - 1] == '\n' &&
+			if (((oneline < 0 && i == 0) ||
+			     (oneline <= 0 &&
+			      ob->size > 0 &&
+			      ob->data[ob->size - 1] == '\n')) &&
 			    !HBUF_PUTSL(ob, "\\&"))
 				return 0;
 			/* FALLTHROUGH */
diff --git a/regress/template/escaperoff.html b/regress/template/escaperoff.html
new file mode 100644
index 0000000..d8da307
--- /dev/null
+++ b/regress/template/escaperoff.html
@@ -0,0 +1,3 @@
+\&.HT \e(ac \ee bc  
+\&.HT foo
+.AT hello \eethere .HT multiline
diff --git a/regress/template/escaperoff.md b/regress/template/escaperoff.md
new file mode 100644
index 0000000..ba05f08
--- /dev/null
+++ b/regress/template/escaperoff.md
@@ -0,0 +1,6 @@
+title: .HT \(ac \e bc  
+.HT foo
+author: .AT hello \ethere
+   .HT multiline
+
+asdf
diff --git a/regress/template/escaperoff.xml b/regress/template/escaperoff.xml
new file mode 100644
index 0000000..a33a6b7
--- /dev/null
+++ b/regress/template/escaperoff.xml
@@ -0,0 +1,2 @@
+$title.escaperoff()$
+$author.escaperoffline()$
diff --git a/template.c b/template.c
index 77785ed..b4a4121 100644
--- a/template.c
+++ b/template.c
@@ -840,7 +840,7 @@ op_eval_function(struct op_out *out, const char *expr, size_t exprsz,
 	else if (exprsz == 11 && strncasecmp(expr, "escapelatex", 11) == 0)
 		nq = op_eval_function_escape_latex(out, input);
 	else if (exprsz == 10 && strncasecmp(expr, "escaperoff", 10) == 0)
-		nq = op_eval_function_escape_roff(out, input, 0);
+		nq = op_eval_function_escape_roff(out, input, -1);
 	else if (exprsz == 14 && strncasecmp(expr, "escaperoffline", 14) == 0)
 		nq = op_eval_function_escape_roff(out, input, 1);
 	else {