Initial checkin

1 files changed, 492 insertions, 0 deletions

diff --git a/usermux/mux.c b/usermux/mux.c
new file mode 100644
index 00000000..932361fd
--- /dev/null
+++ b/usermux/mux.c
@@ -0,0 +1,492 @@
+/* Root usermux node
+
+   Copyright (C) 1997 Free Software Foundation, Inc.
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation; either version 2, or (at
+   your option) any later version.
+
+   The GNU Hurd is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+
+#include <stddef.h>
+#include <string.h>
+#include <dirent.h>
+#include <pwd.h>
+
+#include "usermux.h"
+
+/* The granularity with which we allocate space to return our result.  */
+#define DIRENTS_CHUNK_SIZE	(128*1024)/* Enough for perhaps 8000 names.  */
+
+/* The number seconds we cache our directory return value, in seconds.  */
+#define DIRENTS_CACHE_TIME	90
+
+/* Returned directory entries are aligned to blocks this many bytes long.
+   Must be a power of two.  */
+#define DIRENT_ALIGN 4
+#define DIRENT_NAME_OFFS offsetof (struct dirent, d_name)
+
+/* Length is structure before the name + the name + '\0', all
+   padded to a four-byte alignment.  */
+#define DIRENT_LEN(name_len)						      \
+  ((DIRENT_NAME_OFFS + (name_len) + 1 + (DIRENT_ALIGN - 1))		      \
+   & ~(DIRENT_ALIGN - 1))
+
+static error_t lookup_user (struct usermux *mux, const char *user,
+			    struct node **node); /* fwd decl */
+
+/* [root] Directory operations.  */
+
+/* Lookup NAME in DIR for USER; set *NODE to the found name upon return.  If
+   the name was not found, then return ENOENT.  On any error, clear *NODE.
+   (*NODE, if found, should be locked, this call should unlock DIR no matter
+   what.) */
+error_t
+netfs_attempt_lookup (struct iouser *user, struct node *dir, 
+		      char *name, struct node **node)
+{
+  error_t err;
+
+  if (dir->nn->name)
+    err = ENOTDIR;
+  else
+    err = lookup_user (dir->nn->mux, name, node);
+
+  fshelp_touch (&dir->nn_stat, TOUCH_ATIME, usermux_maptime);
+
+  mutex_unlock (&dir->lock);
+
+  if (! err)
+    mutex_lock (&(*node)->lock);
+
+  return err;
+}
+
+/* Fetch a directory of user entries, as for netfs_get_dirents (that function
+   is actually a wrapper that caches the results for a while).  */
+static error_t
+get_dirents (struct node *dir,
+	     int first_entry, int max_entries, char **data,
+	     mach_msg_type_number_t *data_len,
+	     vm_size_t max_data_len, int *data_entries)
+{
+  error_t err = 0;
+
+  if (dir->nn->name)
+    return ENOTDIR;
+
+  /* Start scanning.  */
+  setpwent ();
+
+  /* Find the first entry.  */
+  while (first_entry-- > 0)
+    if (! getpwent ())
+      {
+	max_entries = 0;
+	break;
+      }
+
+  if (max_entries != 0)
+    {
+      size_t size = (max_data_len == 0 ? DIRENTS_CHUNK_SIZE : max_data_len);
+
+      err = vm_allocate (mach_task_self (), (vm_address_t *) data, size, 1);
+
+      if (! err)
+	{
+	  struct passwd *pw;
+	  char *p = *data;
+	  int count = 0; 
+	  int entry_type =
+	    (S_ISLNK (dir->nn->mux->stat_template.st_mode) ? DT_LNK : DT_REG);
+
+	  /* See how much space we need for the result.  */
+	  while ((max_entries == -1 || count < max_entries)
+		 && (pw = getpwent ()))
+	    {
+	      struct dirent hdr;
+	      size_t name_len = strlen (pw->pw_name);
+	      size_t sz = DIRENT_LEN (name_len);
+
+	      if ((p - *data) + sz > size)
+		if (max_data_len > 0)
+		  break;
+		else
+		  /* Try to grow our return buffer.  */
+		  {
+		    vm_address_t extension = (vm_address_t)(*data + size);
+		    err = vm_allocate (mach_task_self (), &extension,
+				       DIRENTS_CHUNK_SIZE, 0);
+		    if (err)
+		      break;
+		    size += DIRENTS_CHUNK_SIZE;
+		  }
+
+	      hdr.d_namlen = name_len;
+	      hdr.d_fileno = pw->pw_uid + USERMUX_FILENO_UID_OFFSET;
+	      hdr.d_reclen = sz;
+	      hdr.d_type = entry_type;
+
+	      memcpy (p, &hdr, DIRENT_NAME_OFFS);
+	      strcpy (p + DIRENT_NAME_OFFS, pw->pw_name);
+	      p += sz;
+
+	      count++;
+	    }
+
+	  if (err)
+	    vm_deallocate (mach_task_self (), (vm_address_t)*data, size);
+	  else
+	    {
+	      vm_address_t alloc_end = (vm_address_t)(*data + size);
+	      vm_address_t real_end = round_page (p);
+	      if (alloc_end > real_end)
+		vm_deallocate (mach_task_self (),
+			       real_end, alloc_end - real_end);
+	      *data_len = p - *data;
+	      *data_entries = count;
+	    }
+	}
+    }
+
+  endpwent ();
+
+  return err;
+}
+
+/* Implement the netfs_get_directs callback as described in
+   <hurd/netfs.h>. */
+error_t
+netfs_get_dirents (struct iouser *cred, struct node *dir,
+		   int first_entry, int max_entries, char **data,
+		   mach_msg_type_number_t *data_len,
+		   vm_size_t max_data_len, int *data_entries)
+{
+  error_t err;
+  static time_t cache_timestamp = 0;
+  static struct rwlock cache_lock = RWLOCK_INITIALIZER;
+  static char *cached_data = 0;
+  static mach_msg_type_number_t cached_data_len = 0;
+  static int cached_data_entries = 0;
+  struct timeval tv;
+  char *first;
+  size_t bytes_left, entries_left;
+
+  maptime_read (usermux_maptime, &tv);
+  if (tv.tv_sec > cache_timestamp + DIRENTS_CACHE_TIME)
+    {
+      rwlock_writer_lock (&cache_lock);
+
+      if (cached_data_len > 0)
+	/* Free the old cache.  */
+	{
+	  vm_deallocate (mach_task_self (),
+			 (vm_address_t)cached_data, cached_data_len);
+	  cached_data = 0;
+	  cached_data_len = 0;
+	}
+
+      err = get_dirents (dir, 0, -1, &cached_data, &cached_data_len, 0,
+			 &cached_data_entries);
+
+      if (! err)
+	cache_timestamp = tv.tv_sec;
+
+      rwlock_writer_unlock (&cache_lock);
+
+      if (err)
+	return err;
+    }
+
+  rwlock_reader_lock (&cache_lock);
+
+  first = cached_data;
+  bytes_left = cached_data_len;
+  entries_left = cached_data_entries;
+
+  while (first_entry > 0)
+    {
+      struct dirent *e = (struct dirent *)first;
+
+      if (entries_left == 0)
+	{
+	  rwlock_reader_unlock (&cache_lock);
+	  return EINVAL;
+	}
+      
+      first += e->d_reclen;
+      bytes_left -= e->d_reclen;
+      entries_left--;
+    }
+
+  if ((max_data_len > 0 && max_data_len < bytes_left)
+      || (max_entries > 0 && max_entries < entries_left))
+    /* If there's some limit on the return value, we can't just use our
+       values representing the whole cache, so we have to explicitly count
+       how much we're going to return.  */
+    {
+      char *lim = first;
+      int entries = 0;
+
+      while (entries_left > 0
+	     && max_entries > 0
+	     && max_data_len > ((struct dirent *)lim)->d_reclen)
+	{
+	  size_t reclen = ((struct dirent *)lim)->d_reclen;
+	  max_data_len -= reclen;
+	  max_entries--;
+	  entries++;
+	  lim += reclen;
+	}
+
+      bytes_left = (lim - first);
+      entries_left = entries;
+    }
+
+  *data_len = bytes_left;
+  *data_entries = entries_left;
+  
+  err = vm_allocate (mach_task_self (), (vm_address_t *)data, bytes_left, 1);
+  if (! err)
+    bcopy (cached_data, *data, bytes_left);
+
+  rwlock_reader_unlock (&cache_lock);
+
+  fshelp_touch (&dir->nn_stat, TOUCH_ATIME, usermux_maptime);
+
+  return err;
+}
+
+/* User lookup.  */
+
+/* Free storage allocated consumed by the host mux name NM, but not the node
+   it points to.  */
+static void
+free_name (struct usermux_name *nm)
+{
+  free ((char *)nm->name);
+  free (nm);
+}
+
+/* See if there's an existing entry for the name USER, and if so, return its
+   node in NODE with an additional references.  True is returned iff the
+   lookup succeeds.  If PURGE is true, then any nodes with a null node are
+   removed.  */
+static int
+lookup_cached (struct usermux *mux, const char *user, int purge,
+	       struct node **node)
+{
+  struct usermux_name *nm = mux->names, **prevl = &mux->names;
+
+  while (nm)
+    {
+      struct usermux_name *next = nm->next;
+
+      if (strcasecmp (user, nm->name) == 0)
+	{
+	  spin_lock (&netfs_node_refcnt_lock);
+	  if (nm->node)
+	    nm->node->references++;
+	  spin_unlock (&netfs_node_refcnt_lock);
+
+	  if (nm->node)
+	    {
+	      *node = nm->node;
+	      return 1;
+	    }
+	}
+
+      if (purge && !nm->node)
+	{
+	  *prevl = nm->next;
+	  free_name (nm);
+	}
+      else
+	prevl = &nm->next;
+
+      nm = next;
+    }
+
+  return 0;
+}
+
+/* See if there's an existing entry for the name USER, and if so, return its
+   node in NODE, with an additional reference, otherwise, create a new node
+   for the user HE as referred to by USER, and return that instead, with a
+   single reference.  The type of node created is either a translator node,
+   if USER refers to the official name of the user, or a symlink node to the
+   official name, if it doesn't.  */
+static error_t
+lookup_pwent (struct usermux *mux, const char *user, struct passwd *pw,
+		struct node **node)
+{
+  error_t err;
+  struct usermux_name *nm = malloc (sizeof (struct usermux_name));
+
+  if (! nm)
+    return ENOMEM;
+
+  nm->name = strdup (user);
+  err = create_user_node (mux, nm, pw, node);
+  if (err)
+    {
+      free_name (nm);
+      return err;
+    }
+
+  rwlock_writer_lock (&mux->names_lock);
+  if (lookup_cached (mux, user, 1, node))
+    /* An entry for USER has already been created between the time we last
+       looked and now (which is possible because we didn't lock MUX).
+       Just throw away our version and return the one already in the cache.  */
+    {
+      rwlock_writer_unlock (&mux->names_lock);
+      nm->node->nn->name = 0;	/* Avoid touching the mux name list.  */
+      netfs_nrele (nm->node);	/* Free the tentative new node.  */
+      free_name (nm);		/* And the name it was under.  */
+    }
+  else
+    /* Enter NM into MUX's list of names, and return the new node.  */
+    {
+      nm->next = mux->names;
+      mux->names = nm;
+      rwlock_writer_unlock (&mux->names_lock);
+    }
+
+  return 0;
+}  
+
+/* Lookup the user USER in MUX, and return the resulting node in NODE, with
+   an additional reference, or an error.  */
+static error_t
+lookup_user (struct usermux *mux, const char *user, struct node **node)
+{
+  int was_cached;
+  struct passwd _pw, *pw;
+  char pwent_data[2048];	/* XXX what size should this be???? */
+
+  rwlock_reader_lock (&mux->names_lock);
+  was_cached = lookup_cached (mux, user, 0, node);
+  rwlock_reader_unlock (&mux->names_lock);
+
+  if (was_cached)
+    return 0;
+  else if (getpwnam_r (user, &_pw, pwent_data, sizeof pwent_data, &pw) == 0)
+    return lookup_pwent (mux, user, pw, node);
+  else
+    return ENOENT;
+}
+
+/* This should sync the entire remote filesystem.  If WAIT is set, return
+   only after sync is completely finished.  */
+error_t
+netfs_attempt_syncfs (struct iouser *cred, int wait)
+{
+  return 0;
+}
+
+/* This should attempt a chmod call for the user specified by CRED on node
+   NODE, to change the owner to UID and the group to GID. */
+error_t
+netfs_attempt_chown (struct iouser *cred, struct node *node, uid_t uid, uid_t gid)
+{
+  if (node->nn->name)
+    return EOPNOTSUPP;
+  else
+    {
+      struct usermux *mux = node->nn->mux;
+      error_t err = file_chown (mux->underlying, uid, gid);
+
+      if (! err)
+	{
+	  struct usermux_name *nm;
+
+	  /* Change NODE's owner.  */
+	  mux->stat_template.st_uid = uid;
+	  mux->stat_template.st_gid = gid;
+	  node->nn_stat.st_uid = uid;
+	  node->nn_stat.st_gid = gid;
+
+	  /* Change the owner of each leaf node.  */
+	  rwlock_reader_lock (&mux->names_lock);
+	  for (nm = mux->names; nm; nm = nm->next)
+	    if (nm->node)
+	      {
+		nm->node->nn_stat.st_uid = uid;
+		nm->node->nn_stat.st_gid = gid;
+	      }
+	  rwlock_reader_unlock (&mux->names_lock);
+
+	  fshelp_touch (&node->nn_stat, TOUCH_CTIME, usermux_maptime);
+	}
+
+      return err;
+    }
+}
+
+/* This should attempt a chauthor call for the user specified by CRED on node
+   NODE, to change the author to AUTHOR. */
+error_t
+netfs_attempt_chauthor (struct iouser *cred, struct node *node, uid_t author)
+{
+  if (node->nn->name)
+    return EOPNOTSUPP;
+  else
+    {
+      struct usermux *mux = node->nn->mux;
+      error_t err = file_chauthor (mux->underlying, author);
+
+      if (! err)
+	{
+	  struct usermux_name *nm;
+
+	  /* Change NODE's owner.  */
+	  mux->stat_template.st_author = author;
+	  node->nn_stat.st_author = author;
+
+	  /* Change the owner of each leaf node.  */
+	  rwlock_reader_lock (&mux->names_lock);
+	  for (nm = mux->names; nm; nm = nm->next)
+	    if (nm->node)
+	      nm->node->nn_stat.st_author = author;
+	  rwlock_reader_unlock (&mux->names_lock);
+
+	  fshelp_touch (&node->nn_stat, TOUCH_CTIME, usermux_maptime);
+	}
+
+      return err;
+    }
+}
+
+/* This should attempt a chmod call for the user specified by CRED on node
+   NODE, to change the mode to MODE.  Unlike the normal Unix and Hurd meaning
+   of chmod, this function is also used to attempt to change files into other
+   types.  If such a transition is attempted which is impossible, then return
+   EOPNOTSUPP.  */
+error_t
+netfs_attempt_chmod (struct iouser *cred, struct node *node, mode_t mode)
+{
+  mode &= ~S_ITRANS;
+  if (node->nn->name || ((mode & S_IFMT) != (node->nn_stat.st_mode & S_IFMT)))
+    return EOPNOTSUPP;
+  else
+    {
+      error_t err = file_chmod (node->nn->mux->underlying, mode & ~S_IFMT);
+      if (! err)
+	{
+	  node->nn_stat.st_mode = mode;
+	  fshelp_touch (&node->nn_stat, TOUCH_CTIME, usermux_maptime);
+	}
+      return err;
+    }
+}