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 source tree.
   8  */
   9 #include "libbb.h"
  10
  11 char* FAST_FUNC bb_simplify_abs_path_inplace(char *start)
  12 {
  13         char *s, *p;
  14
  15         p = s = start;
  16         do {
  17                 if (*p == '/') {
  18                         if (*s == '/') {  /* skip duplicate (or initial) slash */
  19                                 continue;
  20                         }
  21                         if (*s == '.') {
  22                                 if (s[1] == '/' || !s[1]) {  /* remove extra '.' */
  23                                         continue;
  24                                 }
  25                                 if ((s[1] == '.') && (s[2] == '/' || !s[2])) {
  26                                         ++s;
  27                                         if (p > start) {
  28                                                 while (*--p != '/')  /* omit previous dir */
  29                                                         continue;
  30                                         }
  31                                         continue;
  32                                 }
  33                         }
  34                 }
  35                 *++p = *s;
  36         } while (*++s);
  37
  38         if ((p == start) || (*p != '/')) {  /* not a trailing slash */
  39                 ++p;  /* so keep last character */
  40         }
  41         *p = '\0';
  42         return p;
  43 }
  44
  45 char* FAST_FUNC bb_simplify_path(const char *path)
  46 {
  47         char *s, *p;
  48
  49         if (path[0] == '/')
  50                 s = xstrdup(path);
  51         else {
  52                 p = xrealloc_getcwd_or_warn(NULL);
  53                 s = concat_path_file(p, path);
  54                 free(p);
  55         }
  56
  57         bb_simplify_abs_path_inplace(s);
  58         return s;
  59 }