Support '*' (suppress assignment) in scanf() check.

diff --git a/format_check.c b/format_check.c
index 39d2334..d77b588 100644 (file)
--- a/format_check.c
+++ b/format_check.c
@@ -622,6 +622,12 @@ static void check_scanf_format(const call_argument_t *arg,
 
                ++num_fmt;
 
+               bool suppress_assignment = false;
+               if (fmt == '*') {
+                       fmt = *++c;
+                       suppress_assignment = true;
+               }
+
                /* look for length modifiers */
                format_length_modifier_t fmt_mod = FMT_MOD_NONE;
                switch (fmt) {
@@ -803,7 +809,11 @@ static void check_scanf_format(const call_argument_t *arg,
                        expected_type = type_void_ptr;
                        break;
 
-               case 'n':
+               case 'n': {
+                       if (suppress_assignment) {
+                               warningf(WARN_FORMAT, pos, "conversion '%n' cannot be suppressed with '*' at format %u", num_fmt);
+                       }
+
                        switch (fmt_mod) {
                        case FMT_MOD_NONE: expected_type = type_int;         break;
                        case FMT_MOD_hh:   expected_type = type_signed_char; break;
@@ -819,14 +829,20 @@ static void check_scanf_format(const call_argument_t *arg,
                                goto next_arg;
                        }
                        break;
+               }
 
                default:
                        warningf(WARN_FORMAT, pos, "encountered unknown conversion specifier '%%%c' at format %u", fmt, num_fmt);
+                       if (suppress_assignment)
+                               continue;
                        if (arg == NULL)
                                goto too_few_args;
                        goto next_arg;
                }
 
+               if (suppress_assignment)
+                       continue;
+
                if (arg == NULL) {
 too_few_args:
                        warningf(WARN_FORMAT, pos, "too few arguments for format string");