basic/time-util: make parsing of dual_timestamp more strict

*scanf functions set errno on i/o error. For sscanf, this doesn't really apply,
so (based on the man page), it seems that errno is unlikely to be ever set to a
useful value. So just ignore errno. The error message includes the string that
was parsed, so it should be always pretty clear why parsing failed.

On the other hand, detect trailing characters and minus prefix that weren't
converted properly. This matches what our safe_ato* functions do. Add tests to
elucidate various edge cases.

diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index a2b57f872716a37ecdb6de7adbbaf5f998c431cb..f6d5621ed34f1839ec86fc11b3e9e6a4e3bdbc52 100644 (file)
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -566,15 +566,29 @@ void dual_timestamp_serialize(FILE *f, const char *name, dual_timestamp *t) {
 
 int dual_timestamp_deserialize(const char *value, dual_timestamp *t) {
         uint64_t a, b;
 
 int dual_timestamp_deserialize(const char *value, dual_timestamp *t) {
         uint64_t a, b;

+        int r, pos;

 
         assert(value);
         assert(t);
 
 
         assert(value);
         assert(t);
 

-        if (sscanf(value, "%" PRIu64 "%" PRIu64, &a, &b) != 2) {
-                log_debug("Failed to parse dual timestamp value \"%s\": %m", value);
+        pos = strspn(value, WHITESPACE);
+        if (value[pos] == '-')
+                return -EINVAL;
+        pos += strspn(value + pos, DIGITS);
+        pos += strspn(value + pos, WHITESPACE);
+        if (value[pos] == '-')
+                return -EINVAL;
+
+        r = sscanf(value, "%" PRIu64 "%" PRIu64 "%n", &a, &b, &pos);
+        if (r != 2) {
+                log_debug("Failed to parse dual timestamp value \"%s\".", value);

                 return -EINVAL;
         }
 
                 return -EINVAL;
         }
 

+        if (value[pos] != '\0')
+                /* trailing garbage */
+                return -EINVAL;
+

         t->realtime = a;
         t->monotonic = b;
 
         t->realtime = a;
         t->monotonic = b;