From 3a43ce11ac1aec9b2c00d7c5f966919b71f5eda7 Mon Sep 17 00:00:00 2001
From: Ingo Schwarze <schwarze@openbsd.org>
Date: Sun, 5 Jun 2022 13:54:09 +0000
Subject: With the improved escape sequence parser, it becomes easy to also
 improve diagnostics.  Distinguish "incomplete escape sequence", "invalid
 special character", and "unknown special character" from the generic "invalid
 escape sequence", also promoting them from WARNING to ERROR because
 incomplete escape sequences are severe syntax violations and because
 encountering an invalid or unknown special character makes it likely that
 part of the document content intended by the authors gets lost.

---
 roff_escape.c | 33 ++++++++++++++++++++++-----------
 1 file changed, 22 insertions(+), 11 deletions(-)

(limited to 'roff_escape.c')

diff --git a/roff_escape.c b/roff_escape.c
index 8145a9dd..777d753b 100644
--- a/roff_escape.c
+++ b/roff_escape.c
@@ -310,13 +310,12 @@ roff_escape(const char *buf, const int ln, const int aesc,
 	iendarg = iarg;
 	while (maxl > 0) {
 		if (buf[iendarg] == '\0') {
+			err = MANDOCERR_ESC_INCOMPLETE;
+			if (rval != ESCAPE_EXPAND)
+				rval = ESCAPE_ERROR;
 			/* Ignore an incomplete argument except for \w. */
 			if (buf[inam] != 'w')
 				iendarg = iarg;
-			if (rval == ESCAPE_EXPAND)
-				err = MANDOCERR_ESC_BAD;
-			else
-				rval = ESCAPE_ERROR;
 			break;
 		}
 		if (buf[iendarg] == term) {
@@ -401,6 +400,7 @@ roff_escape(const char *buf, const int ln, const int aesc,
 		 */
 
 		if (term != '\0' && argl == 1 && buf[iarg] != '-') {
+			err = MANDOCERR_ESC_BADCHAR;
 			rval = ESCAPE_ERROR;
 			break;
 		}
@@ -416,8 +416,10 @@ roff_escape(const char *buf, const int ln, const int aesc,
 			c = 0;
 			for (i = iarg; i < iendarg; i++)
 				c = 10 * c + (buf[i] - '0');
-			if (c < 0x21 || (c > 0x7e && c < 0xa0) || c > 0xff)
+			if (c < 0x21 || (c > 0x7e && c < 0xa0) || c > 0xff) {
+				err = MANDOCERR_ESC_BADCHAR;
 				break;
+			}
 			iarg += 4;
 			rval = ESCAPE_NUMBERED;
 			break;
@@ -433,13 +435,19 @@ roff_escape(const char *buf, const int ln, const int aesc,
 		if (buf[iarg] != 'u' || argl < 5 || argl > 7)
 			break;
 		if (argl == 7 &&
-		    (buf[iarg + 1] != '1' || buf[iarg + 2] != '0'))
+		    (buf[iarg + 1] != '1' || buf[iarg + 2] != '0')) {
+			err = MANDOCERR_ESC_BADCHAR;
 			break;
-		if (argl == 6 && buf[iarg + 1] == '0')
+		}
+		if (argl == 6 && buf[iarg + 1] == '0') {
+			err = MANDOCERR_ESC_BADCHAR;
 			break;
+		}
 		if (argl == 5 && buf[iarg + 1] == 'D' &&
-		    strchr("89ABCDEF", buf[iarg + 2]) != NULL)
+		    strchr("89ABCDEF", buf[iarg + 2]) != NULL) {
+			err = MANDOCERR_ESC_BADCHAR;
 			break;
+		}
 		if ((int)strspn(buf + iarg + 1, "0123456789ABCDEFabcdef")
 		    + 1 == argl)
 			rval = ESCAPE_UNICODE;
@@ -477,7 +485,8 @@ out:
 	*resc = iesc;
 	switch (rval) {
 	case ESCAPE_ERROR:
-		err = MANDOCERR_ESC_BAD;
+		if (err == MANDOCERR_OK)
+			err = MANDOCERR_ESC_BAD;
 		break;
 	case ESCAPE_UNSUPP:
 		err = MANDOCERR_ESC_UNSUPP;
@@ -487,8 +496,10 @@ out:
 			err = MANDOCERR_ESC_UNDEF;
 		break;
 	case ESCAPE_SPECIAL:
-		if (mchars_spec2cp(buf + iarg, argl) < 0)
-			err = MANDOCERR_ESC_BAD;
+		if (mchars_spec2cp(buf + iarg, argl) >= 0)
+			err = MANDOCERR_OK;
+		else if (err == MANDOCERR_OK)
+			err = MANDOCERR_ESC_UNKCHAR;
 		break;
 	default:
 		break;
-- 
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