lib/libsffs/path.c

   1 /* This file contains routines for creating and manipulating path strings.
   2  *
   3  * The entry points into this file are:
   4  *   make_path          construct a path string for an inode
   5  *   push_path          add a path component to the end of a path string
   6  *   pop_path           remove the last path component from a path string
   7  *
   8  * Created:
   9  *   April 2009 (D.C. van Moolenbroek)
  10  */
  11
  12 #include "inc.h"
  13
  14 /*===========================================================================*
  15  *                              make_path                                    *
  16  *===========================================================================*/
  17 int make_path(path, ino)
  18 char path[PATH_MAX];
  19 struct inode *ino;
  20 {
  21 /* Given an inode, construct the path identifying that inode.
  22  */
  23   char buf[PATH_MAX], *p, *prefix;
  24   size_t len, plen, total;
  25
  26   p = &buf[sizeof(buf) - 1];
  27   p[0] = 0;
  28
  29   dprintf(("%s: make_path: constructing path for inode %d\n",
  30         sffs_name, ino->i_num));
  31
  32   /* Get the length of the prefix, skipping any leading slashes. */
  33   for (prefix = sffs_params->p_prefix; prefix[0] == '/'; prefix++);
  34   plen = strlen(prefix);
  35
  36   /* Construct the path right-to-left in a temporary buffer first. */
  37   for (total = plen; ino != NULL && !IS_ROOT(ino); ino = ino->i_parent) {
  38         len = strlen(ino->i_name);
  39
  40         total += len + 1;
  41         p -= len + 1;
  42
  43         if (total >= sizeof(buf))
  44                 return ENAMETOOLONG;
  45
  46         p[0] = '/';
  47         memcpy(p + 1, ino->i_name, len);
  48   }
  49
  50   /* If any of the intermediate inodes has no parent, the final inode is no
  51    * longer addressable by name.
  52    */
  53   if (ino == NULL)
  54         return ENOENT;
  55
  56   /* Put the result in the actual buffer. We need the leading slash in the
  57    * temporary buffer only when the prefix is not empty.
  58    */
  59   if (!prefix[0] && p[0] == '/') p++;
  60
  61   strlcpy(path, prefix, PATH_MAX);
  62   strlcpy(&path[plen], p, PATH_MAX - plen);
  63
  64   dprintf(("%s: make_path: resulting path is '%s'\n", sffs_name, path));
  65
  66   return OK;
  67 }
  68
  69 /*===========================================================================*
  70  *                              push_path                                    *
  71  *===========================================================================*/
  72 int push_path(path, name)
  73 char path[PATH_MAX];
  74 char *name;
  75 {
  76 /* Add a component to the end of a path.
  77  */
  78   size_t len, add;
  79
  80   len = strlen(path);
  81   add = strlen(name);
  82   if (len > 0) add++;
  83
  84   if (len + add >= PATH_MAX)
  85         return ENAMETOOLONG;
  86
  87   if (len > 0) path[len++] = '/';
  88   strlcpy(&path[len], name, PATH_MAX - len);
  89
  90   return OK;
  91 }
  92
  93 /*===========================================================================*
  94  *                              pop_path                                     *
  95  *===========================================================================*/
  96 void pop_path(path)
  97 char path[PATH_MAX];
  98 {
  99 /* Remove the last component from a path.
 100  */
 101   char *p;
 102
 103   p = strrchr(path, '/');
 104
 105   if (p == NULL) {
 106         p = path;
 107
 108         /* Can't pop the root component */
 109         assert(p[0] != 0);
 110   }
 111
 112   p[0] = 0;
 113 }