Switch mtab_list to doubly linked so we can traverse in either order. Convert umount and df. Add dlist_terminate() to break lists for traversal in either direction.

3 files changed, 28 insertions, 10 deletions

diff --git a/lib/getmountlist.c b/lib/getmountlist.c
index d5a392d6..0b7ff06b 100644
--- a/lib/getmountlist.c
+++ b/lib/getmountlist.c
@@ -11,25 +11,28 @@
 
 struct mtab_list *xgetmountlist(char *path)
 {
-  struct mtab_list *mtlist, *mt;
+  struct mtab_list *mtlist = 0, *mt;
   struct mntent *me;
   FILE *fp;
+  char *p = path ? path : "/proc/mounts";
 
-  if (!path) path = "/proc/mounts";
-  if (!(fp = setmntent(path, "r"))) perror_exit("bad %s", path);
+  if (!(fp = setmntent(p, "r"))) perror_exit("bad %s", p);
 
   // The "test" part of the loop is done before the first time through and
   // again after each "increment", so putting the actual load there avoids
   // duplicating it. If the load was NULL, the loop stops.
 
-  for (mtlist = 0; (me = getmntent(fp)); mtlist = mt) {
+  while ((me = getmntent(fp))) {
     mt = xzalloc(sizeof(struct mtab_list) + strlen(me->mnt_fsname) +
       strlen(me->mnt_dir) + strlen(me->mnt_type) + strlen(me->mnt_opts) + 4);
-    mt->next = mtlist;
-
-    // Collect details about mounted filesystem (don't bother for /etc/fstab).
-    if (stat(me->mnt_dir, &(mt->stat)) || statvfs(me->mnt_dir, &(mt->statvfs)))
-      perror_msg("stat '%s'");
+    dlist_add_nomalloc((void *)&mtlist, (void *)mt);
+
+    // Collect details about mounted filesystem
+    // Don't report errors, just leave data zeroed
+    if (!path) {
+      stat(me->mnt_dir, &(mt->stat));
+      statvfs(me->mnt_dir, &(mt->statvfs));
+    }
 
     // Remember information from /proc/mounts
     mt->dir = stpcpy(mt->type, me->mnt_type)+1;
diff --git a/lib/lib.h b/lib/lib.h
index bbb1488d..09af2837 100644
--- a/lib/lib.h
+++ b/lib/lib.h
@@ -31,6 +31,7 @@ void *llist_pop(void *list);  // actually void **list
 void *dlist_pop(void *list);  // actually struct double_list **list
 void dlist_add_nomalloc(struct double_list **list, struct double_list *new);
 struct double_list *dlist_add(struct double_list **list, char *data);
+void *dlist_terminate(void *list);
 
 // args.c
 void get_optflags(void);
@@ -162,7 +163,7 @@ int xsocket(int domain, int type, int protocol);
 
 // getmountlist.c
 struct mtab_list {
-  struct mtab_list *next;
+  struct mtab_list *next, *prev;
   struct stat stat;
   struct statvfs statvfs;
   char *dir;
diff --git a/lib/llist.c b/lib/llist.c
index 2d5bc97a..6b4b8f2c 100644
--- a/lib/llist.c
+++ b/lib/llist.c
@@ -85,3 +85,17 @@ struct double_list *dlist_add(struct double_list **list, char *data)
 
   return new;
 }
+
+// Terminate circular list for traversal in either direction. Returns end *.
+void *dlist_terminate(void *list)
+{
+  struct double_list *end = list;
+
+  if (!list) return 0;
+
+  end = end->prev;
+  end->next->prev = 0;
+  end->next = 0;
+
+  return end;
+}