lesskey: don't ignore HAVE_SNPRINTF

While defines.h is included at lesskey.h, and it does define
HAVE_SNPRINTF, till now it was ignored while building lesskey, which
resulted in snprintf being used even when HAVE_SNPRINTF is 0.

Now we have the SNPRINTF<N> macros, copied from less.h, and used
instead of snprintf in lesskey source files.

Note that lesstest also ignores HAVE_SNPRINTF, but it's not mandatory
so currently not handled.

TODO: maybe add lesscommon.h with unified handling of snprintf.

lesskey.h

@@ -61,3 +61,17 @@ struct lesskey_tables
 };
 
 extern int parse_lesskey(char *infile, struct lesskey_tables *tables);
+
+/* keep in sync with less.h */
+#if HAVE_SNPRINTF
+#define SNPRINTF1(str, size, fmt, v1) snprintf((str), (size), (fmt), (v1))
+#define SNPRINTF2(str, size, fmt, v1, v2) snprintf((str), (size), (fmt), (v1), (v2))
+#define SNPRINTF3(str, size, fmt, v1, v2, v3) snprintf((str), (size), (fmt), (v1), (v2), (v3))
+#define SNPRINTF4(str, size, fmt, v1, v2, v3, v4) snprintf((str), (size), (fmt), (v1), (v2), (v3), (v4))
+#else
+/* Use unsafe sprintf if we don't have snprintf. */
+#define SNPRINTF1(str, size, fmt, v1) sprintf((str), (fmt), (v1))
+#define SNPRINTF2(str, size, fmt, v1, v2) sprintf((str), (fmt), (v1), (v2))
+#define SNPRINTF3(str, size, fmt, v1, v2, v3) sprintf((str), (fmt), (v1), (v2), (v3))
+#define SNPRINTF4(str, size, fmt, v1, v2, v3, v4) sprintf((str), (fmt), (v1), (v2), (v3), (v4))
+#endif

lesskey_parse.c

@@ -130,9 +130,9 @@ static struct lesskey_cmdname editnames[] =
 static void parse_error(char *fmt, char *arg1)
 {
  char buf[1024];
- int n = snprintf(buf, sizeof(buf), "%s: line %d: ", lesskey_file, linenum);
+ int n = SNPRINTF2(buf, sizeof(buf), "%s: line %d: ", lesskey_file, linenum);
  if (n >= 0 && n < sizeof(buf))
- snprintf(buf+n, sizeof(buf)-n, fmt, arg1);
+ SNPRINTF1(buf+n, sizeof(buf)-n, fmt, arg1);
  ++errors;
  lesskey_parse_error(buf);
 }
@@ -167,7 +167,7 @@ static char * char_string(char *buf, int ch, int lit)
  buf[1] = '\0';
  } else
  {
- snprintf(buf, CHAR_STRING_LEN, "\\x%02x", ch);
+ SNPRINTF1(buf, CHAR_STRING_LEN, "\\x%02x", ch);
  }
  return buf;
 }