coreutils/pwd.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Mini pwd implementation for busybox
   4  *
   5  * Copyright (C) 1995, 1996 by Bruce Perens <bruce@pixar.com>.
   6  *
   7  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   8  */
   9
  10 //usage:#define pwd_trivial_usage
  11 //usage:       ""
  12 //usage:#define pwd_full_usage "\n\n"
  13 //usage:       "Print the full filename of the current working directory"
  14 //usage:
  15 //usage:#define pwd_example_usage
  16 //usage:       "$ pwd\n"
  17 //usage:       "/root\n"
  18
  19 #include "libbb.h"
  20
  21 /* This is a NOFORK applet. Be very careful! */
  22
  23 static int logical_getcwd(void)
  24 {
  25         struct stat st1;
  26         struct stat st2;
  27         char *wd;
  28         char *p;
  29
  30         wd = getenv("PWD");
  31         if (!wd || wd[0] != '/')
  32                 return 0;
  33
  34         p = wd;
  35         while (*p) {
  36                 /* doing strstr(p, "/.") by hand is smaller and faster... */
  37                 if (*p++ != '/')
  38                         continue;
  39                 if (*p != '.')
  40                         continue;
  41                 /* we found "/.", skip to next char */
  42                 p++;
  43                 if (*p == '.')
  44                         p++; /* we found "/.." */
  45                 if (*p == '\0' || *p == '/')
  46                         return 0; /* "/./" or "/../" component: bad */
  47         }
  48
  49         if (stat(wd, &st1) != 0)
  50                 return 0;
  51         if (stat(".", &st2) != 0)
  52                 return 0;
  53         if (st1.st_ino != st2.st_ino)
  54                 return 0;
  55         if (st1.st_dev != st2.st_dev)
  56                 return 0;
  57
  58         puts(wd);
  59         return 1;
  60 }
  61
  62 int pwd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  63 int pwd_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
  64 {
  65         char *buf;
  66
  67         if (ENABLE_DESKTOP) {
  68                 /* TODO: assume -L if $POSIXLY_CORRECT? (coreutils does that)
  69                  * Rationale:
  70                  * POSIX requires a default of -L, but most scripts expect -P
  71                  */
  72                 unsigned opt = getopt32(argv, "LP");
  73                 if ((opt & 1) && logical_getcwd())
  74                         return fflush_all();
  75         }
  76
  77         buf = xrealloc_getcwd_or_warn(NULL);
  78
  79         if (buf) {
  80                 puts(buf);
  81                 free(buf);
  82                 return fflush_all();
  83         }
  84
  85         return EXIT_FAILURE;
  86 }