Support "bind" mounts: local loopback mounts without using symlinks.

5 files changed, 190 insertions, 96 deletions

diff --git a/NEWS b/NEWS
index 5c83bd7..54a4e82 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,10 @@
+Since autofs-3.1.4:
+-------------------
+* Support "bind" mounts introduced in linux-2.3.99-pre7.7 instead of
+  using symlinks.  If you are using a version of the Linux kernel
+  which supports "bind" mounts, you will no longer see symlinks when
+  mounting local filesystems.
+  
 Since autofs-3.1.3:
 -------------------
 * Merge in documentation changes from RedHat RPM.
diff --git a/daemon/mount.c b/daemon/mount.c
index 1978463..11d5dbd 100644
--- a/daemon/mount.c
+++ b/daemon/mount.c
@@ -26,7 +26,7 @@
 /* These filesystems are known not to work with the "generic" module */
 /* Note: starting with Samba 2.0.6, smbfs is handled generically.    */
 static char *not_generic[] = { "nfs", "ncpfs", "userfs", "afs",
-			       "autofs", "changer", NULL };
+			       "autofs", "changer", "bind", NULL };
 
 int do_mount(const char *root, const char *name, int name_len,
 	     const char *what, const char *fstype, const char *options)
diff --git a/modules/Makefile b/modules/Makefile
index 20980f8..5d398a1 100644
--- a/modules/Makefile
+++ b/modules/Makefile
@@ -10,13 +10,13 @@ SRCS :=	lookup_yp.c  lookup_file.c  lookup_program.c  lookup_userhome.c \
 	lookup_multi.c \
 	parse_sun.c    \
 	mount_generic.c  mount_nfs.c  mount_afs.c  mount_autofs.c \
-	mount_changer.c
+	mount_changer.c  mount_bind.c
 
 MODS :=	lookup_yp.so lookup_file.so lookup_program.so lookup_userhome.so \
 	lookup_multi.so \
 	parse_sun.so \
 	mount_generic.so mount_nfs.so mount_afs.so mount_autofs.so \
-	mount_changer.so
+	mount_changer.so mount_bind.so
 
 ifeq ($(EXT2FS), 1)
   SRCS += mount_ext2.c
diff --git a/modules/mount_bind.c b/modules/mount_bind.c
new file mode 100644
index 0000000..18ed071
--- /dev/null
+++ b/modules/mount_bind.c
@@ -0,0 +1,94 @@
+#ident "$Id$"
+/* ----------------------------------------------------------------------- *
+ *   
+ *  mount_bind.c      - module to mount a local filesystem if possible;
+ *			otherwise create a symlink.
+ *
+ *   Copyright 2000 Transmeta Corporation - All Rights Reserved
+ *
+ *   This program 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, Inc., 675 Mass Ave, Cambridge MA 02139,
+ *   USA; either version 2 of the License, or (at your option) any later
+ *   version; incorporated herein by reference.
+ *
+ * ----------------------------------------------------------------------- */
+
+#include <stdio.h>
+#include <malloc.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <syslog.h>
+#include <string.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#define MODULE_MOUNT
+#include "automount.h"
+
+#define MODPREFIX "mount(bind): "
+int mount_version = AUTOFS_MOUNT_VERSION; /* Required by protocol */
+
+int mount_init(void **context)
+{
+  return 0;
+}
+
+int mount_mount(const char *root, const char *name, int name_len,
+		const char *what, const char *fstype, const char *options,
+		void *context)
+{
+  char *fullpath;
+  int err;
+
+  fullpath = alloca(strlen(root)+name_len+2);
+  if ( !fullpath ) {
+    syslog(LOG_ERR, MODPREFIX "alloca: %m");
+    return 1;
+  }
+  sprintf(fullpath, "%s/%s", root, name);
+    
+  syslog(LOG_DEBUG, MODPREFIX "calling mkdir %s", fullpath);
+  if ( mkdir(fullpath, 0555) && errno != EEXIST ) {
+    syslog(LOG_NOTICE, MODPREFIX "mkdir %s failed: %m", name);
+    return 1;
+  }
+    
+  if ( options ) {
+    syslog(LOG_DEBUG, MODPREFIX "calling mount -t %s " SLOPPY "-o %s %s %s",
+	   fstype, options, what, fullpath);
+    err = spawnl(LOG_NOTICE, PATH_MOUNT, PATH_MOUNT, "-t", fstype,
+		 SLOPPYOPT "-o", options, what, fullpath, NULL);
+  } else {
+    syslog(LOG_DEBUG, MODPREFIX "calling mount -t %s %s %s",
+	   fstype, what, fullpath);
+      err = spawnl(LOG_NOTICE, PATH_MOUNT, PATH_MOUNT, "-t", fstype,
+		   what, fullpath, NULL);
+  }
+  if ( err ) {
+    if ( rmdir(fullpath) && errno == EBUSY )
+      return 0;
+
+    syslog(LOG_DEBUG, MODPREFIX "failed to mount %s (type %s) on %s, trying symlink",
+	   what, fstype, fullpath);
+    if ( symlink(what, fullpath) && errno != EEXIST ) {
+      syslog(LOG_NOTICE, MODPREFIX "failed to create local mount %s -> %s", fullpath, what);
+      
+      return 1;
+    } else {
+      syslog(LOG_DEBUG, MODPREFIX "symlinked %s -> %s", fullpath, what);
+      return 0;
+    }
+  } else {
+    syslog(LOG_DEBUG, MODPREFIX "mounted %s type %s on %s",
+	   what, fstype, fullpath);
+    return 0;
+  }
+}
+
+int mount_done(void *context)
+{
+  return 0;
+}
diff --git a/modules/mount_nfs.c b/modules/mount_nfs.c
index 1996972..e1d9e6b 100644
--- a/modules/mount_nfs.c
+++ b/modules/mount_nfs.c
@@ -4,7 +4,7 @@
  * mount_nfs.c - Module for Linux automountd to mount an NFS filesystem,
  *               with fallback to symlinking if the path is local
  *
- *   Copyright 1997 Transmeta Corporation - All Rights Reserved
+ *   Copyright 1997-2000 Transmeta Corporation - All Rights Reserved
  *
  *   This program is free software; you can redistribute it and/or modify
  *   it under the terms of the GNU General Public License as published by
@@ -37,6 +37,8 @@ int mount_version = AUTOFS_MOUNT_VERSION; /* Required by protocol */
 static int udpproto;
 static short port_discard;
 
+static struct mount_mod *mount_bind = NULL;
+
 int mount_init(void **context)
 {
   struct protoent *udp;
@@ -51,14 +53,18 @@ int mount_init(void **context)
   else
     port_discard = htons(9);    /* 9 is the standard discard port */
 
-  return 0;
+  /* Make sure we have the local mount method available */
+  if ( !mount_bind )
+    mount_bind = open_mount("bind", MODPREFIX);
+
+  return !mount_bind;
 }
 
 int mount_mount(const char *root, const char *name, int name_len,
 		const char *what, const char *fstype,
 		const char *options, void *context)
 {
-  char *colon, **haddr, *fullpath;
+  char *colon, *localname, **haddr, *fullpath;
   char *whatstr, *hostname, *comma, *paren;
   struct hostent *he;
   struct sockaddr_in saddr, laddr;
@@ -74,106 +80,93 @@ int mount_mount(const char *root, const char *name, int name_len,
 
   colon = strchr(whatstr, ':');
   if ( !colon ) {
-    /* No colon, take this as a symlink (local) entry */
-    syslog(LOG_DEBUG, MODPREFIX "entry %s -> %s: no colon, assume local",
-	   name, whatstr);
-    chdir(root);
-    err = symlink(whatstr, name);
-    if ( err && errno == EEXIST )
-      err = 0;
-    if ( err )
-      syslog(LOG_NOTICE, MODPREFIX "symlink %s: %m", name);
-    chdir("/");
-    return err ? 1 : 0;
-  }
-
-  *colon = '\0';
-
-  /* The host part may actually be a comma-separated list of hosts with 
-     parenthesized weights.  We want to check each host, ignoring any 
-     weights, until we either find the localhost or reach the end of the 
-     list. */
-  local = 0;
-  hostname = whatstr;
-  do {
-    comma = strchr(hostname, ',');
-    if ( comma )
-      *comma = '\0';
-    
-    paren = strchr(hostname, '(');
-    if ( paren )
-      *paren = '\0';
-    
-    if ( !(he = gethostbyname(hostname)) ) {
-      syslog(LOG_NOTICE, MODPREFIX "entry %s: host %s: lookup failure",
-	     name, hostname);
-      return 1;			/* No such host */
-    }
-    
-    /* Probe to see if we are the local host.  Open a UDP socket and see
-       if the local address is the same as the remote one */
-    
-    for ( haddr = he->h_addr_list ; *haddr ; haddr++ ) {
-      sock = socket(AF_INET, SOCK_DGRAM, udpproto);
-      if ( sock < 0 ) {
-	syslog(LOG_ERR, MODPREFIX "socket: %m");
-	return 1;
+    /* No colon, take this as a bind (local) entry */
+    local = 1;
+    localname = whatstr;
+  } else {
+    *colon = '\0';
+
+    /* The host part may actually be a comma-separated list of hosts with 
+       parenthesized weights.  We want to check each host, ignoring any 
+       weights, until we either find the localhost or reach the end of the 
+       list. */
+    local = 0;
+    localname = colon+1;
+    hostname = whatstr;
+    do {
+      comma = strchr(hostname, ',');
+      if ( comma )
+	*comma = '\0';
+      
+      paren = strchr(hostname, '(');
+      if ( paren )
+	*paren = '\0';
+      
+      if ( !(he = gethostbyname(hostname)) ) {
+	syslog(LOG_NOTICE, MODPREFIX "entry %s: host %s: lookup failure",
+	       name, hostname);
+	return 1;			/* No such host */
       }
-      saddr.sin_family = AF_INET;
-      memcpy(&saddr.sin_addr, *haddr, he->h_length);
-      saddr.sin_port = port_discard;
       
-      len = sizeof(laddr);
-
-      if ( connect(sock, (struct sockaddr *) &saddr, sizeof(saddr)) < 0 )
-	continue;		/* Assume it wasn't local */
-
-      if ( getsockname(sock, (struct sockaddr *) &laddr, &len) < 0 ) {
-	syslog(LOG_ERR, MODPREFIX "getsockname failed for %s: %m", name);
+      /* Probe to see if we are the local host.  Open a UDP socket and see
+	 if the local address is the same as the remote one */
+      
+      for ( haddr = he->h_addr_list ; *haddr ; haddr++ ) {
+	sock = socket(AF_INET, SOCK_DGRAM, udpproto);
+	if ( sock < 0 ) {
+	  syslog(LOG_ERR, MODPREFIX "socket: %m");
+	  return 1;
+	}
+	saddr.sin_family = AF_INET;
+	memcpy(&saddr.sin_addr, *haddr, he->h_length);
+	saddr.sin_port = port_discard;
+	
+	len = sizeof(laddr);
+	
+	if ( connect(sock, (struct sockaddr *) &saddr, sizeof(saddr)) < 0 )
+	  continue;		/* Assume it wasn't local */
+	
+	if ( getsockname(sock, (struct sockaddr *) &laddr, &len) < 0 ) {
+	  syslog(LOG_ERR, MODPREFIX "getsockname failed for %s: %m", name);
+	  close(sock);
+	  return 1;
+	}
 	close(sock);
-	return 1;
+	
+	if ( !memcmp(&saddr.sin_addr,&laddr.sin_addr,he->h_length) ) {
+	  local = 1;
+	  break;
+	}
       }
-      close(sock);
       
-      if ( !memcmp(&saddr.sin_addr,&laddr.sin_addr,he->h_length) ) {
-	local = 1;
-	break;
+      if ( paren )
+	*paren = '(';
+      
+      if ( comma ) {
+	*comma = ',';
+	hostname = comma + 1;
+      } else {
+	hostname += strlen(hostname);
       }
-    }
+    } while (*hostname && !local);
+  }
 
-    if ( paren )
-      *paren = '(';
+  fullpath = alloca(strlen(root)+name_len+2);
+  if ( !fullpath ) {
+    syslog(LOG_ERR, MODPREFIX "alloca: %m");
+    return 1;
+  }
+  sprintf(fullpath, "%s/%s", root, name);
+  
+  if ( local ) {
+    /* Local host -- do a "bind" */
 
-    if ( comma ) {
-      *comma = ',';
-      hostname = comma + 1;
-    } else {
-      hostname += strlen(hostname);
-    }
-  } while (*hostname && !local);
+    syslog(LOG_DEBUG, MODPREFIX "%s is local, doing bind", name);
 
-  if ( local ) {
-    /* Local host -- do a symlink */
-    
-    syslog(LOG_DEBUG, MODPREFIX "%s is local, symlinking", name);
-    chdir(root);
-    err = symlink(colon+1, name);
-    if ( err && errno == EEXIST )
-      err = 0;
-    if ( err )
-      syslog(LOG_NOTICE, MODPREFIX "symlink %s: %m", name);
-    chdir("/");
-    return err ? 1 : 0;
+    return mount_bind->mount_mount(root,name,name_len,localname,"bind",NULL,mount_bind->context);
   } else {
-    /* Not a local host - do a mount */
+    /* Not a local host - do an NFS mount */
 
-    fullpath = alloca(strlen(root)+name_len+2);
-    if ( !fullpath ) {
-      syslog(LOG_ERR, MODPREFIX "alloca: %m");
-      return 1;
-    }
-    sprintf(fullpath, "%s/%s", root, name);
-    
     *colon = ':';
     syslog(LOG_DEBUG, MODPREFIX "calling mkdir %s", fullpath);
     if ( mkdir(fullpath, 0555) && errno != EEXIST ) {
@@ -205,5 +198,5 @@ int mount_mount(const char *root, const char *name, int name_len,
 
 int mount_done(void *context)
 {
-  return 0;
+  return mount_bind->mount_done(mount_bind->context);
 }