udev_rules_parse_file: issue diagnostics about line continuation at EOF

When udev rules file ends with a line continuation, the parser
used to silently ignore the line without any diagnostics at all.
It's time to break the vow of silence and let the parser issue some
error diagnostics.

src/udev/udev-rules.c

@@ -1279,6 +1279,7 @@ int udev_rules_parse_file(UdevRules *rules, const char *filename) {
                 line_nr++;
                 line = skip_leading_chars(buf, NULL);
 
+                /* Lines beginning with '#' are ignored regardless of line continuation. */
                 if (line[0] == '#')
                         continue;
 
@@ -1320,6 +1321,10 @@ int udev_rules_parse_file(UdevRules *rules, const char *filename) {
                 ignore_line = false;
         }
 
+        if (continuation)
+                log_line_error(rule_file, line_nr,
+                               "Unexpected EOF after line continuation, line ignored");
+
         rule_resolve_goto(rule_file);
         return 0;
 }

test/units/testsuite-17.11.sh

@@ -40,10 +40,18 @@ printf 'RUN+="/bin/true"%8175s\\\n' ' ' ' ' >sample.rules
 echo >>sample.rules
 udevadm verify sample.rules
 
-printf 'RUN+="/bin/true"%8176s\\\n' ' ' ' ' >sample.rules
+printf 'RUN+="/bin/true"%8176s\\\n #\n' ' ' ' ' >sample.rules
 echo >>sample.rules
 cat >exp <<'EOF'
-sample.rules:3 Line is too long, ignored
+sample.rules:5 Line is too long, ignored
+sample.rules: udev rules check failed
+EOF
+(! udevadm verify sample.rules 2>err)
+diff exp err
+
+printf '\\\n' >sample.rules
+cat >exp <<'EOF'
+sample.rules:1 Unexpected EOF after line continuation, line ignored
 sample.rules: udev rules check failed
 EOF
 (! udevadm verify sample.rules 2>err)