libbb/simplify_path.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * bb_simplify_path implementation for busybox
   4  *
   5  * Copyright (C) 2001  Manuel Novoa III  <mjn3@codepoet.org>
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   8  */
   9
  10 #include <stdlib.h>
  11 #include "libbb.h"
  12
  13 char *bb_simplify_path(const char *path)
  14 {
  15         char *s, *start, *p;
  16
  17         if (path[0] == '/')
  18                 start = bb_xstrdup(path);
  19         else {
  20                 s = xgetcwd(NULL);
  21                 start = concat_path_file(s, path);
  22                 free(s);
  23         }
  24         p = s = start;
  25
  26         do {
  27                 if (*p == '/') {
  28                         if (*s == '/') {        /* skip duplicate (or initial) slash */
  29                                 continue;
  30                         } else if (*s == '.') {
  31                                 if (s[1] == '/' || s[1] == 0) { /* remove extra '.' */
  32                                         continue;
  33                                 } else if ((s[1] == '.') && (s[2] == '/' || s[2] == 0)) {
  34                                         ++s;
  35                                         if (p > start) {
  36                                                 while (*--p != '/');    /* omit previous dir */
  37                                         }
  38                                         continue;
  39                                 }
  40                         }
  41                 }
  42                 *++p = *s;
  43         } while (*++s);
  44
  45         if ((p == start) || (*p != '/')) {      /* not a trailing slash */
  46                 ++p;                                    /* so keep last character */
  47         }
  48         *p = 0;
  49
  50         return start;
  51 }