minix/lib/libpuffs/path.c

   1 /*
   2  * This file contains the procedures that look up path names in the directory
   3  * system and determine the pnode number that goes with a given path name.
   4  *
   5  * Created (based on MFS):
   6  *   June 2011 (Evgeniy Ivanov)
   7  */
   8
   9 #include "fs.h"
  10
  11 #include <sys/cdefs.h>
  12 #include <sys/stat.h>
  13 #include <sys/types.h>
  14
  15 /*===========================================================================*
  16  *                              fs_lookup                                    *
  17  *===========================================================================*/
  18 int fs_lookup(ino_t dir_nr, char *name, struct fsdriver_node *node,
  19         int *is_mountpt)
  20 {
  21   struct puffs_node *pn, *pn_dir;
  22
  23   /* Find the pnode of the directory node. */
  24   if ((pn_dir = puffs_pn_nodewalk(global_pu, find_inode_cb, &dir_nr)) == NULL) {
  25         lpuffs_debug("nodewalk failed\n");
  26         return(EINVAL);
  27   }
  28
  29   if (!S_ISDIR(pn_dir->pn_va.va_mode))
  30         return ENOTDIR;
  31
  32   if ((pn = advance(pn_dir, name)) == NULL)
  33         return err_code;
  34
  35   pn->pn_count++; /* open pnode */
  36
  37   node->fn_ino_nr = pn->pn_va.va_fileid;
  38   node->fn_mode = pn->pn_va.va_mode;
  39   node->fn_size = pn->pn_va.va_size;
  40   node->fn_uid = pn->pn_va.va_uid;
  41   node->fn_gid = pn->pn_va.va_gid;
  42   node->fn_dev = pn->pn_va.va_rdev;
  43
  44   *is_mountpt = pn->pn_mountpoint;
  45
  46   return OK;
  47 }
  48
  49
  50 /*===========================================================================*
  51  *                              advance                                      *
  52  *===========================================================================*/
  53 struct puffs_node *advance(
  54         struct puffs_node *pn_dir,      /* pnode for directory to be searched */
  55         char string[NAME_MAX + 1]       /* component name to look for */
  56 )
  57 {
  58 /* Given a directory and a component of a path, look up the component in
  59  * the directory, find the pnode, open it, and return a pointer to its pnode
  60  * slot.
  61  * TODO: instead of string, should get pcn.
  62  */
  63   struct puffs_node *pn;
  64
  65   struct puffs_newinfo pni;
  66
  67   struct puffs_kcn pkcnp;
  68   PUFFS_MAKECRED(pcr, &global_kcred);
  69   struct puffs_cn pcn = {&pkcnp, (struct puffs_cred *) __UNCONST(pcr), {0,0,0}};
  70
  71   enum vtype node_vtype;
  72   voff_t size;
  73   dev_t rdev;
  74   int error;
  75
  76   assert(pn_dir != NULL);
  77
  78   err_code = OK;
  79
  80   /* If 'string' is empty, return an error. */
  81   if (string[0] == '\0') {
  82         err_code = ENOENT;
  83         return(NULL);
  84   }
  85
  86   /* If dir has been removed return ENOENT. */
  87   if (pn_dir->pn_va.va_nlink == NO_LINK) {
  88         err_code = ENOENT;
  89         return(NULL);
  90   }
  91
  92   if (strcmp(string, ".") == 0) {
  93         /* Otherwise we will fall into trouble: path for pnode to be looked up
  94          * will be parent path (same pnode as the one to be looked up) +
  95          * requested path. E.g. after several lookups we might get advance
  96          * for "." with parent path "/././././././././.".
  97          * FIXME: how is ".." handled then?
  98          *
  99          * Another problem is that after lookup pnode will be added
 100          * to the pu_pnodelst, which already contains pnode instance for this
 101          * pnode. It will cause lot of troubles.
 102          * FIXME: check if this is actually correct, because if it is, we are
 103          * in lots of trouble; there are many ways to reach already-open pnodes
 104          */
 105         return pn_dir;
 106   }
 107
 108   pni.pni_cookie = (void** )&pn;
 109   pni.pni_vtype = &node_vtype;
 110   pni.pni_size = &size;
 111   pni.pni_rdev = &rdev;
 112
 113   pcn.pcn_namelen = strlen(string);
 114   assert(pcn.pcn_namelen <= MAXPATHLEN);
 115   strcpy(pcn.pcn_name, string);
 116
 117   if (buildpath) {
 118         if (puffs_path_pcnbuild(global_pu, &pcn, pn_dir) != 0) {
 119                 lpuffs_debug("pathbuild error\n");
 120                 err_code = ENOENT;
 121                 return(NULL);
 122         }
 123   }
 124
 125   /* lookup *must* be present */
 126   error = global_pu->pu_ops.puffs_node_lookup(global_pu, pn_dir, &pni, &pcn);
 127
 128   if (buildpath) {
 129         if (error) {
 130                 global_pu->pu_pathfree(global_pu, &pcn.pcn_po_full);
 131                 err_code = ENOENT;
 132                 return(NULL);
 133         } else {
 134                 struct puffs_node *_pn;
 135
 136                 /*
 137                  * did we get a new node or a
 138                  * recycled node?
 139                  */
 140                 _pn = PU_CMAP(global_pu, pn);
 141                 if (_pn->pn_po.po_path == NULL)
 142                         _pn->pn_po = pcn.pcn_po_full;
 143                 else
 144                         global_pu->pu_pathfree(global_pu, &pcn.pcn_po_full);
 145         }
 146   }
 147
 148   if (error) {
 149         err_code = error < 0 ? error : -error;
 150         return(NULL);
 151   }
 152
 153   err_code = OK;
 154
 155   assert(pn != NULL);
 156
 157   return(pn);
 158 }