In terminal output, unify handling of Unicode and numbered character

escape sequences just like it was earlier implemented for -Thtml.
Do not let control characters other than ASCII 9 (horizontal tab)
propagate to the output, even though groff allows them; but that
really doesn't look like a great idea.

Let mchars_num2char() return int such that we can distinguish invalid \N
syntax from \N'0'.  This also reduces the danger of signed char issues
popping up.

1 files changed, 3 insertions, 5 deletions

diff --git a/chars.c b/chars.c
index e4f3cbcf..e4f522b5 100644
--- a/chars.c
+++ b/chars.c
@@ -107,15 +107,13 @@ mchars_spec2cp(const struct mchars *arg, const char *p, size_t sz)
 	return(ln != NULL ? ln->unicode : sz == 1 ? (unsigned char)*p : -1);
 }
 
-char
+int
 mchars_num2char(const char *p, size_t sz)
 {
 	int	  i;
 
-	if ((i = mandoc_strntoi(p, sz, 10)) < 0)
-		return('\0');
-
-	return(i > 0 && i < 256 && isprint(i) ? i : '\0');
+	i = mandoc_strntoi(p, sz, 10);
+	return(i >= 0 && i < 256 ? i : -1);
 }
 
 int