mtab: support moving mount points

Also fix canonical_path function; it fails to parse some paths

servers/vfs/misc.c

@@ -92,6 +92,7 @@ int do_getsysinfo()
 	break;
 #endif
     case SI_VMNT_TAB:
+	fetch_vmnt_paths();
 	src_addr = (vir_bytes) vmnt;
 	len = sizeof(struct vmnt) * NR_MNTS;
 	break;

servers/vfs/path.c

@@ -656,7 +656,8 @@ struct fproc *rfp;
   char temp_path[PATH_MAX];
   struct lookup resolve;
 
-  dir_vp = NULL;
+  parent_dir = dir_vp = NULL;
+  parent_vmp = dir_vmp = NULL;
   strlcpy(temp_path, orig_path, PATH_MAX);
   temp_path[PATH_MAX - 1] = '\0';
 
@@ -678,6 +679,9 @@ struct fproc *rfp;
 	 */
 	strlcpy(orig_path, temp_path, NAME_MAX+1);	/* Store file name */
 
+	/* If we're just crossing a mount point, our name has changed to '.' */
+	if (!strcmp(orig_path, ".")) orig_path[0] = '\0';
+
 	/* check if the file is a symlink, if so resolve it */
 	r = rdlink_direct(orig_path, temp_path, rfp);
 
@@ -706,6 +710,10 @@ struct fproc *rfp;
 
 	/* check if we're at the root node of the file system */
 	if (dir_vp->v_vmnt->m_root_node == dir_vp) {
+		if (dir_vp->v_vmnt->m_mounted_on == NULL) {
+			/* Bail out, we can't go any higher */
+			break;
+		}
 		unlock_vnode(dir_vp);
 		unlock_vmnt(dir_vmp);
 		put_vnode(dir_vp);
@@ -769,18 +777,23 @@ struct fproc *rfp;
 	unlock_vmnt(dir_vmp);
 	put_vnode(dir_vp);
 	dir_vp = parent_dir;
+	dir_vmp = parent_vmp;
+	parent_vmp = NULL;
   }
 
+  unlock_vmnt(dir_vmp);
   unlock_vnode(dir_vp);
-  unlock_vmnt(parent_vmp);
-
   put_vnode(dir_vp);
 
   /* add the leading slash */
+  len = strlen(orig_path);
   if (strlen(orig_path) >= PATH_MAX) return(ENAMETOOLONG);
-  memmove(orig_path+1, orig_path, strlen(orig_path));
+  memmove(orig_path+1, orig_path, len);
   orig_path[0] = '/';
 
+  /* remove trailing slash if there is any */
+  if (len > 1 && orig_path[len] == '/') orig_path[len] = '\0';
+
   return(OK);
 }
 

servers/vfs/proto.h

@@ -315,6 +315,7 @@ void init_vmnts(void);
 int lock_vmnt(struct vmnt *vp, tll_access_t locktype);
 void unlock_vmnt(struct vmnt *vp);
 void vmnt_unmap_by_endpt(endpoint_t proc_e);
+void fetch_vmnt_paths(void);
 
 /* vnode.c */
 void check_vnode_locks(void);

servers/vfs/vmnt.c

@@ -6,6 +6,7 @@
 #include "threads.h"
 #include "vmnt.h"
 #include <assert.h>
+#include <string.h>
 #include "fproc.h"
 
 static int is_vmnt_locked(struct vmnt *vmp);
@@ -214,3 +215,54 @@ void unlock_vmnt(struct vmnt *vmp)
 #endif
 
 }
+
+/*===========================================================================*
+ *                             fetch_vmnt_paths				     *
+ *===========================================================================*/
+void fetch_vmnt_paths(void)
+{
+  struct vmnt *vmp;
+  struct vnode *cur_wd;
+  char orig_path[PATH_MAX];
+
+  cur_wd = fp->fp_wd;
+
+  for (vmp = &vmnt[0]; vmp < &vmnt[NR_MNTS]; vmp++) {
+	if (vmp->m_dev == NO_DEV)
+		continue;
+	if (vmp->m_fs_e == PFS_PROC_NR)
+		continue;
+
+	strlcpy(orig_path, vmp->m_mount_path, PATH_MAX);
+
+	/* Find canonical path */
+	if (canonical_path(vmp->m_mount_path, fp) != OK) {
+		/* We failed to find it (moved somewhere else?). Let's try
+		 * again by starting at the node on which we are mounted:
+		 * pretend that node is our working directory and look for the
+		 * canonical path of the relative path to the mount point
+		 * (which should be in our 'working directory').
+		 */
+		char *mp;
+		int len;
+
+		fp->fp_wd = vmp->m_mounted_on;	/* Change our working dir */
+
+		/* Isolate the mount point name of the full path */
+		len = strlen(vmp->m_mount_path);
+		if (vmp->m_mount_path[len - 1] == '/') {
+			vmp->m_mount_path[len - 1] = '\0';
+		}
+		mp = strrchr(vmp->m_mount_path, '/');
+		strlcpy(vmp->m_mount_path, mp+1, NAME_MAX+1);
+
+		if (canonical_path(vmp->m_mount_path, fp) != OK) {
+			/* Our second try failed too. Maybe an FS has crashed
+			 * and we're missing part of the tree. Revert path.
+			 */
+			strlcpy(vmp->m_mount_path, orig_path, PATH_MAX);
+		}
+		fp->fp_wd = cur_wd;		/* Revert working dir */
+	}
+  }
+}