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 "libbb.h"
  11
  12 char *bb_simplify_path(const char *path)
  13 {
  14         char *s, *start, *p;
  15
  16         if (path[0] == '/')
  17                 start = xstrdup(path);
  18         else {
  19                 s = xgetcwd(NULL);
  20                 start = concat_path_file(s, path);
  21                 free(s);
  22         }
  23         p = s = start;
  24
  25         do {
  26                 if (*p == '/') {
  27                         if (*s == '/') {        /* skip duplicate (or initial) slash */
  28                                 continue;
  29                         } else if (*s == '.') {
  30                                 if (s[1] == '/' || s[1] == 0) { /* remove extra '.' */
  31                                         continue;
  32                                 } else if ((s[1] == '.') && (s[2] == '/' || s[2] == 0)) {
  33                                         ++s;
  34                                         if (p > start) {
  35                                                 while (*--p != '/');    /* omit previous dir */
  36                                         }
  37                                         continue;
  38                                 }
  39                         }
  40                 }
  41                 *++p = *s;
  42         } while (*++s);
  43
  44         if ((p == start) || (*p != '/')) {      /* not a trailing slash */
  45                 ++p;                                    /* so keep last character */
  46         }
  47         *p = 0;
  48
  49         return start;
  50 }