box/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 = xrealloc_getcwd_or_warn(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                         }
  30                         if (*s == '.') {
  31                                 if (s[1] == '/' || !s[1]) {     /* remove extra '.' */
  32                                         continue;
  33                                 }
  34                                 if ((s[1] == '.') && (s[2] == '/' || !s[2])) {
  35                                         ++s;
  36                                         if (p > start) {
  37                                                 while (*--p != '/')     /* omit previous dir */
  38                                                         continue;
  39                                         }
  40                                         continue;
  41                                 }
  42                         }
  43                 }
  44                 *++p = *s;
  45         } while (*++s);
  46
  47         if ((p == start) || (*p != '/')) {      /* not a trailing slash */
  48                 ++p;                                    /* so keep last character */
  49         }
  50         *p = 0;
  51
  52         return start;
  53 }