utils: Detect machine_id corruption and fill out a dummy value

Signed-off-by: Hiroshi Hatake <[email protected]>

Author: cosmo0920

src/flb_utils.c

@@ -1479,6 +1479,7 @@ int flb_utils_get_machine_id(char **out_id, size_t *out_size)
     char *id;
     size_t bytes;
     char *uuid;
+    int fallback = FLB_FALSE;
 
 #ifdef __linux__
     char *dbus_var = "/var/lib/dbus/machine-id";
@@ -1488,6 +1489,11 @@ int flb_utils_get_machine_id(char **out_id, size_t *out_size)
     if (access(dbus_var, F_OK) == 0) { /* check if the file exists first */
         ret = machine_id_read_and_sanitize(dbus_var, &id, &bytes);
         if (ret == 0) {
+            if (bytes == 0) {
+                /* guid is somewhat corrupted */
+                fallback = FLB_TRUE;
+                goto fallback;
+            }
             *out_id = id;
             *out_size = bytes;
             return 0;
@@ -1498,6 +1504,11 @@ int flb_utils_get_machine_id(char **out_id, size_t *out_size)
     if (access(dbus_etc, F_OK) == 0) { /* check if the file exists first */
         ret = machine_id_read_and_sanitize(dbus_etc, &id, &bytes);
         if (ret == 0) {
+            if (bytes == 0) {
+                /* guid is somewhat corrupted */
+                fallback = FLB_TRUE;
+                goto fallback;
+            }
             *out_id = id;
             *out_size = bytes;
             return 0;
@@ -1593,6 +1604,8 @@ int flb_utils_get_machine_id(char **out_id, size_t *out_size)
     }
 #endif
 
+fallback:
+
     flb_warn("falling back on random machine UUID");
 
     /* generate a random uuid */
@@ -1605,6 +1618,9 @@ int flb_utils_get_machine_id(char **out_id, size_t *out_size)
     if (ret == 0) {
         *out_id = uuid;
         *out_size = strlen(uuid);
+        if (fallback == FLB_TRUE) {
+            return 2;
+        }
         return 0;
     }
 

tests/internal/utils.c

@@ -615,7 +615,7 @@ void test_flb_utils_get_machine_id()
     size_t size2;
 
     ret = flb_utils_get_machine_id(&id, &size);
-    TEST_CHECK(ret == 0);
+    TEST_CHECK(ret == 0 || ret == 2);
     TEST_CHECK(size != 0);
     TEST_CHECK(id != NULL);
 
@@ -626,10 +626,15 @@ void test_flb_utils_get_machine_id()
     }
 
     ret = flb_utils_get_machine_id(&id2, &size2);
-    TEST_CHECK(ret == 0);
+    TEST_CHECK(ret == 0 || ret == 2);
     TEST_CHECK(size2 != 0);
     TEST_CHECK(id2 != NULL);
-    TEST_CHECK(size2 == size);
+    if (ret == 2) {
+        TEST_CHECK(size2 != size);
+    }
+    else {
+        TEST_CHECK(size2 == size);
+    }
 
     for (idx = 0; idx < size; idx++) {
         if (!TEST_CHECK(id[idx] == id2[idx])) {