ifupdown: reread state file before rewriting it.

Fixes "ifup started another ifup" state corruption bug.
Patch by Natanael Copa <natanael.copa@gmail.com>.

1 files changed, 37 insertions, 36 deletions

diff --git a/networking/ifupdown.c b/networking/ifupdown.c
index 887c2eea5..ff4f7855b 100644
--- a/networking/ifupdown.c
+++ b/networking/ifupdown.c
@@ -1083,15 +1083,33 @@ static llist_t *find_iface_state(llist_t *state_list, const char *iface)
         return NULL;
 }
 
+/* read the previous state from the state file */
+static llist_t *read_iface_state(void)
+{
+        llist_t *state_list = NULL;
+        FILE *state_fp = fopen("/var/run/ifstate", "r");
+
+        if (state_fp) {
+                char *start, *end_ptr;
+                while ((start = xmalloc_fgets(state_fp)) != NULL) {
+                        /* We should only need to check for a single character */
+                        end_ptr = start + strcspn(start, " \t\n");
+                        *end_ptr = '\0';
+                        llist_add_to(&state_list, start);
+                }
+                fclose(state_fp);
+        }
+        return state_list;
+}
+
+
 int ifupdown_main(int argc, char **argv);
 int ifupdown_main(int argc, char **argv)
 {
         int (*cmds)(struct interface_defn_t *) = NULL;
         struct interfaces_file_t *defn;
-        llist_t *state_list = NULL;
         llist_t *target_list = NULL;
         const char *interfaces = "/etc/network/interfaces";
-        FILE *state_fp;
         bool any_failures = 0;
 
         cmds = iface_down;
@@ -1118,32 +1136,9 @@ int ifupdown_main(int argc, char **argv)
         startup_PATH = getenv("PATH");
         if (!startup_PATH) startup_PATH = "";
 
-        /* Read the previous state from the state file */
-        state_fp = fopen("/var/run/ifstate", "r");
-        if (state_fp) {
-                char *start, *end_ptr;
-                while ((start = xmalloc_fgets(state_fp)) != NULL) {
-                        /* We should only need to check for a single character */
-                        end_ptr = start + strcspn(start, " \t\n");
-                        *end_ptr = '\0';
-                        llist_add_to(&state_list, start);
-                }
-                fclose(state_fp);
-        }
-
         /* Create a list of interfaces to work on */
         if (DO_ALL) {
-                if (cmds == iface_up) {
-                        target_list = defn->autointerfaces;
-                } else {
-                        /* iface_down */
-                        const llist_t *list = state_list;
-                        while (list) {
-                                llist_add_to_end(&target_list, xstrdup(list->data));
-                                list = list->link;
-                        }
-                        target_list = defn->autointerfaces;
-                }
+                target_list = defn->autointerfaces;
         } else {
                 llist_add_to_end(&target_list, argv[optind]);
         }
@@ -1170,6 +1165,7 @@ int ifupdown_main(int argc, char **argv)
                 }
 
                 if (!FORCE) {
+                        llist_t *state_list = read_iface_state();
                         const llist_t *iface_state = find_iface_state(state_list, iface);
 
                         if (cmds == iface_up) {
@@ -1185,6 +1181,7 @@ int ifupdown_main(int argc, char **argv)
                                         continue;
                                 }
                         }
+                        llist_free(state_list, free);
                 }
 
 #if ENABLE_FEATURE_IFUPDOWN_MAPPING
@@ -1239,6 +1236,8 @@ int ifupdown_main(int argc, char **argv)
                         bb_error_msg("ignoring unknown interface %s", liface);
                         any_failures = 1;
                 } else {
+                        /* update the state file */
+                        llist_t *state_list = read_iface_state();
                         llist_t *iface_state = find_iface_state(state_list, iface);
 
                         if (cmds == iface_up) {
@@ -1254,19 +1253,21 @@ int ifupdown_main(int argc, char **argv)
                                 llist_unlink(&state_list, iface_state);
                                 free(llist_pop(&iface_state));
                         }
-                }
-        }
 
-        /* Actually write the new state */
-        if (!NO_ACT) {
-                state_fp = xfopen("/var/run/ifstate", "w");
-                while (state_list) {
-                        if (state_list->data) {
-                                fprintf(state_fp, "%s\n", state_list->data);
+                        /* Actually write the new state */
+                        if (!NO_ACT) {
+                                FILE *state_fp = xfopen("/var/run/ifstate", "w");
+                                llist_t *state = state_list;
+                                while (state) {
+                                        if (state->data) {
+                                                fprintf(state_fp, "%s\n", state->data);
+                                        }
+                                        state = state->link;
+                                }
+                                fclose(state_fp);
                         }
-                        state_list = state_list->link;
+                        llist_free(state_list, free);
                 }
-                fclose(state_fp);
         }
 
         return any_failures;