--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toys/lsb/umount.c	Wed Sep 04 01:40:41 2013 -0500
@@ -0,0 +1,151 @@
+/* umount.c - Unmount a mount point.
+ *
+ * Copyright 2012 Rob Landley <rob@landley.net>
+ *
+ * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/umount.html
+ *
+ * Note: -n (/etc/mtab) is obsolete, /proc/mounts replaced it. Neither chroot
+ * nor per-process mount namespaces can work sanely with mtab. The kernel
+ * tracks mount points now, a userspace application can't do so anymore.
+
+USE_UMOUNT(NEWTOY(umount, "ndDflrat*v", TOYFLAG_BIN|TOYFLAG_STAYROOT))
+
+config UMOUNT
+  bool "umount"
+  default y
+  help
+    usage: umount [-a [-t TYPE[,TYPE...]]] [-vrfD] [DIR...]
+
+    Unmount the listed filesystems.
+
+    -a	Unmount all mounts in /proc/mounts instead of command line list
+    -t	Restrict "all" to mounts of TYPE (or use "noTYPE" to skip)
+    -D  Don't free loopback device(s).
+    -f  Force unmount.
+    -l  Lazy unmount (detach from filesystem now, close when last user does).
+    -r  Remount read only if unmounting fails.
+    -v	Verbose
+*/
+
+#define FOR_umount
+#include "toys.h"
+
+GLOBALS(
+  struct arg_list *t;
+
+  char *types;
+)
+
+// todo
+//   borrow df code to identify filesystem?
+//   umount -a from fstab
+//   umount when getpid() not 0, according to fstab
+//   lookup mount: losetup -d, bind, file, block
+
+// TODO
+// loopback delete
+// fstab -o user
+
+// Realloc *old with oldstring,newstring
+
+void comma_collate(char **old, char *new)
+{
+  char *temp, *atold = *old;
+
+  // Only add a comma if old string didn't end with one
+  if (atold && *atold) {
+    char *comma = ",";
+
+    if (atold[strlen(atold)-1] == ',') comma = "";
+    temp = xmsprintf("%s%s%s", atold, comma, new);
+  } else temp = xstrdup(new);
+  free (atold);
+  *old = temp;
+}
+
+void arg_comma_collate(char **old, struct arg_list *arg)
+{
+  while (arg) {
+    comma_collate(old, arg->arg);
+    arg = arg->next;
+  }
+}
+
+char *comma_iterate(char **list, int *len)
+{
+  char *start = *list, *end;
+
+  if (!*list) return 0;
+  if (!(end = strchr(*list, ','))) {
+    *len = strlen(*list);
+    *list = 0;
+  } else *list += (*len = end-start)+1;
+
+  return start;
+}
+
+static void do_umount(char *dir, int flags)
+{
+  if (!umount2(dir, flags)) {
+    if (toys.optflags & FLAG_v) printf("%s unmounted", dir);
+    return;
+  }
+  if (toys.optflags & FLAG_r) {
+    if (!mount("", *toys.optargs, "", MS_REMOUNT|MS_RDONLY, "")) {
+      if (toys.optflags & FLAG_v) printf("%s remounted ro", dir);
+      return;
+    }
+  }
+  perror_msg("%s", dir);
+}
+
+void umount_main(void)
+{
+  int flags=0;
+
+  if (!toys.optc && !(toys.optflags & FLAG_a))
+    error_exit("Need 1 arg or -a");
+
+  if (toys.optflags & FLAG_f) flags |= MNT_FORCE;
+  if (toys.optflags & FLAG_l) flags |= MNT_DETACH;
+
+  for (; *toys.optargs; toys.optargs++) do_umount(*toys.optargs, flags);
+
+  if (toys.optflags & FLAG_a) {
+    struct mtab_list *mlsave, *ml;
+    char *typestr = 0;
+
+    if (TT.t) arg_comma_collate(&typestr, TT.t);
+
+    // Loop through mounted filesystems
+    for (mlsave = ml = xgetmountlist(0); ml; ml = ml->next) {
+      if (TT.t) {
+        char *type, *types = typestr;
+        int len, skip = strncmp(types, "no", 2);
+
+        // Loop through -t filters
+        for (;;) {
+          if (!(type = comma_iterate(&types, &len))) break;
+          if (!skip) {
+            if (strncmp(type, "no", 2)) error_exit("bad -t");
+            if (!strncmp(type+2, ml->type, len-2)) {
+              skip = 1;
+              break;
+            }
+          } else if (!strncmp(type, ml->type, len) && !ml->type[len]) {
+            skip = 0;
+            break;
+          }
+        }
+        if (skip) continue;
+      }
+      do_umount(ml->dir, flags);
+    }
+    if (CFG_TOYBOX_FREE) {
+      free(typestr);
+      llist_traverse(mlsave, free);
+    }
+
+    return;
+  }
+}