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