minix/lib/libsffs/lookup.c

   1 /* This file provides path-to-inode lookup functionality.
   2  *
   3  * The entry points into this file are:
   4  *   do_lookup          perform the LOOKUP file system call
   5  *
   6  * Created:
   7  *   April 2009 (D.C. van Moolenbroek)
   8  */
   9
  10 #include "inc.h"
  11
  12 /*===========================================================================*
  13  *                              go_up                                        *
  14  *===========================================================================*/
  15 static int go_up(
  16         char path[PATH_MAX],    /* path to take the last part from */
  17         struct inode *ino,      /* inode of the current directory */
  18         struct inode **res_ino, /* place to store resulting inode */
  19         struct sffs_attr *attr  /* place to store inode attributes */
  20 )
  21 {
  22 /* Given an inode, progress into the parent directory.
  23  */
  24   struct inode *parent;
  25   int r;
  26
  27   pop_path(path);
  28
  29   parent = ino->i_parent;
  30   assert(parent != NULL);
  31
  32   if ((r = verify_path(path, parent, attr, NULL)) != OK)
  33         return r;
  34
  35   get_inode(parent);
  36
  37   *res_ino = parent;
  38
  39   return r;
  40 }
  41
  42 /*===========================================================================*
  43  *                              go_down                                      *
  44  *===========================================================================*/
  45 static int go_down(
  46         char path[PATH_MAX],    /* path to add the name to */
  47         struct inode *parent,   /* inode of the current directory */
  48         char *name,             /* name of the directory entry */
  49         struct inode **res_ino, /* place to store resulting inode */
  50         struct sffs_attr *attr  /* place to store inode attributes */
  51 )
  52 {
  53 /* Given a directory inode and a name, progress into a directory entry.
  54  */
  55   struct inode *ino;
  56   int r, stale = 0;
  57
  58   if ((r = push_path(path, name)) != OK)
  59         return r;
  60
  61   dprintf(("%s: go_down: name '%s', path now '%s'\n", sffs_name, name, path));
  62
  63   ino = lookup_dentry(parent, name);
  64
  65   dprintf(("%s: lookup_dentry('%s') returned %p\n", sffs_name, name, ino));
  66
  67   if (ino != NULL)
  68         r = verify_path(path, ino, attr, &stale);
  69   else
  70         r = sffs_table->t_getattr(path, attr);
  71
  72   dprintf(("%s: path query returned %d\n", sffs_name, r));
  73
  74   if (r != OK) {
  75         if (ino != NULL) {
  76                 put_inode(ino);
  77
  78                 ino = NULL;
  79         }
  80
  81         if (!stale)
  82                 return r;
  83   }
  84
  85   dprintf(("%s: name '%s'\n", sffs_name, name));
  86
  87   if (ino == NULL) {
  88         if ((ino = get_free_inode()) == NULL)
  89                 return ENFILE;
  90
  91         dprintf(("%s: inode %p ref %d\n", sffs_name, ino, ino->i_ref));
  92
  93         ino->i_flags = MODE_TO_DIRFLAG(attr->a_mode);
  94
  95         add_dentry(parent, name, ino);
  96   }
  97
  98   *res_ino = ino;
  99   return OK;
 100 }
 101
 102 /*===========================================================================*
 103  *                              do_lookup                                    *
 104  *===========================================================================*/
 105 int do_lookup(ino_t dir_nr, char *name, struct fsdriver_node *node,
 106         int *is_mountpt)
 107 {
 108 /* Resolve a path string to an inode.
 109  */
 110   struct inode *dir_ino, *ino = NULL;
 111   struct sffs_attr attr;
 112   char path[PATH_MAX];
 113   int r;
 114
 115   dprintf(("%s: lookup: got query for %"PRIu64", '%s'\n",
 116         sffs_name, dir_nr, name));
 117
 118   if ((dir_ino = find_inode(dir_nr)) == NULL)
 119         return EINVAL;
 120
 121   attr.a_mask = SFFS_ATTR_MODE | SFFS_ATTR_SIZE;
 122
 123   if ((r = verify_inode(dir_ino, path, &attr)) != OK)
 124         return r;
 125
 126   if (!IS_DIR(dir_ino))
 127         return ENOTDIR;
 128
 129   r = OK;
 130   if (!strcmp(name, "."))
 131         get_inode(ino = dir_ino);
 132   else if (!strcmp(name, ".."))
 133         r = go_up(path, dir_ino, &ino, &attr);
 134   else
 135         r = go_down(path, dir_ino, name, &ino, &attr);
 136
 137   if (r != OK)
 138         return r;
 139
 140   node->fn_ino_nr = INODE_NR(ino);
 141   node->fn_mode = get_mode(ino, attr.a_mode);
 142   node->fn_size = attr.a_size;
 143   node->fn_uid = sffs_params->p_uid;
 144   node->fn_gid = sffs_params->p_gid;
 145   node->fn_dev = NO_DEV;
 146
 147   *is_mountpt = FALSE;
 148
 149   return OK;
 150 }