Traditional roff(7) explicitly allows certain control characters

in the input stream (SOH, STX, ETX, ENQ, ACK, BEL, BS) for specific
purposes (leaders, backspace, delimiters, .tr), but making sure
these don't leak through to the output is tricky, so mark them as
unsupported for now.

2 files changed, 10 insertions, 7 deletions

diff --git a/mandoc.h b/mandoc.h
index 18b496a4..61aa5428 100644
--- a/mandoc.h
+++ b/mandoc.h
@@ -145,7 +145,7 @@ enum	mandocerr {
 	/* related to document structure and macros */
 	MANDOCERR_FILE, /* cannot open file */
 	MANDOCERR_ROFFLOOP, /* input stack limit exceeded, infinite loop? */
-	MANDOCERR_BADCHAR, /* skipping bad character: number */
+	MANDOCERR_CHAR_BAD, /* skipping bad character: number */
 	MANDOCERR_MACRO, /* skipping unknown macro: macro */
 	MANDOCERR_REQ_INSEC, /* skipping insecure request: request */
 	MANDOCERR_IT_STRAY, /* skipping item outside list: It ... */
@@ -172,6 +172,7 @@ enum	mandocerr {
 	MANDOCERR_UNSUPP, /* ===== start of unsupported features ===== */
 
 	MANDOCERR_TOOLARGE, /* input too large */
+	MANDOCERR_CHAR_UNSUPP, /* unsupported control character: number */
 	MANDOCERR_REQ_UNSUPP, /* unsupported roff request: request */
 	MANDOCERR_TBL, /* unsupported table syntax */
 	MANDOCERR_TBLOPT, /* unsupported table option */
diff --git a/read.c b/read.c
index 07e6ce50..c0b390a6 100644
--- a/read.c
+++ b/read.c
@@ -215,6 +215,7 @@ static	const char * const	mandocerrs[MANDOCERR_MAX] = {
 
 	"unsupported feature",
 	"input too large",
+	"unsupported control character",
 	"unsupported roff request",
 	"unsupported table syntax",
 	"unsupported table option",
@@ -369,9 +370,8 @@ mparse_buf_r(struct mparse *curp, struct buf blk, size_t i, int start)
 			if (c & 0x80) {
 				if ( ! (curp->filenc && preconv_encode(
 				    &blk, &i, &ln, &pos, &curp->filenc))) {
-					mandoc_vmsg(MANDOCERR_BADCHAR,
-					    curp, curp->line, pos,
-					    "0x%x", c);
+					mandoc_vmsg(MANDOCERR_CHAR_BAD, curp,
+					    curp->line, pos, "0x%x", c);
 					ln.buf[pos++] = '?';
 					i++;
 				}
@@ -383,8 +383,10 @@ mparse_buf_r(struct mparse *curp, struct buf blk, size_t i, int start)
 			 */
 
 			if (c == 0x7f || (c < 0x20 && c != 0x09)) {
-				mandoc_vmsg(MANDOCERR_BADCHAR, curp,
-				    curp->line, pos, "0x%x", c);
+				mandoc_vmsg(c == 0x00 || c == 0x04 ||
+				    c > 0x0a ? MANDOCERR_CHAR_BAD :
+				    MANDOCERR_CHAR_UNSUPP,
+				    curp, curp->line, pos, "0x%x", c);
 				i++;
 				ln.buf[pos++] = '?';
 				continue;
@@ -440,7 +442,7 @@ mparse_buf_r(struct mparse *curp, struct buf blk, size_t i, int start)
 
 			if ( ! (isascii(c) &&
 			    (isgraph(c) || isblank(c)))) {
-				mandoc_vmsg(MANDOCERR_BADCHAR, curp,
+				mandoc_vmsg(MANDOCERR_CHAR_BAD, curp,
 				    curp->line, pos, "0x%x", c);
 				i += 2;
 				ln.buf[pos++] = '?';