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 //config:config PWD
  10 //config:       bool "pwd (4 kb)"
  11 //config:       default y
  12 //config:       help
  13 //config:       pwd is used to print the current directory.
  14
  15 //applet:IF_PWD(APPLET_NOFORK(pwd, pwd, BB_DIR_BIN, BB_SUID_DROP, pwd))
  16
  17 //kbuild:lib-$(CONFIG_PWD) += pwd.o
  18
  19 //usage:#define pwd_trivial_usage
  20 //usage:       ""
  21 //usage:#define pwd_full_usage "\n\n"
  22 //usage:       "Print the full filename of the current working directory"
  23 //usage:
  24 //usage:#define pwd_example_usage
  25 //usage:       "$ pwd\n"
  26 //usage:       "/root\n"
  27
  28 #include "libbb.h"
  29
  30 static int logical_getcwd(void)
  31 {
  32         struct stat st1;
  33         struct stat st2;
  34         char *wd;
  35         char *p;
  36
  37         wd = getenv("PWD");
  38         if (!wd || wd[0] != '/')
  39                 return 0;
  40
  41         p = wd;
  42         while (*p) {
  43                 /* doing strstr(p, "/.") by hand is smaller and faster... */
  44                 if (*p++ != '/')
  45                         continue;
  46                 if (*p != '.')
  47                         continue;
  48                 /* we found "/.", skip to next char */
  49                 p++;
  50                 if (*p == '.')
  51                         p++; /* we found "/.." */
  52                 if (*p == '\0' || *p == '/')
  53                         return 0; /* "/./" or "/../" component: bad */
  54         }
  55
  56         if (stat(wd, &st1) != 0)
  57                 return 0;
  58         if (stat(".", &st2) != 0)
  59                 return 0;
  60         if (st1.st_ino != st2.st_ino)
  61                 return 0;
  62         if (st1.st_dev != st2.st_dev)
  63                 return 0;
  64
  65         puts(wd);
  66         return 1;
  67 }
  68
  69 int pwd_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  70 int pwd_main(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
  71 {
  72         char *buf;
  73
  74         if (ENABLE_DESKTOP) {
  75                 /* TODO: assume -L if $POSIXLY_CORRECT? (coreutils does that)
  76                  * Rationale:
  77                  * POSIX requires a default of -L, but most scripts expect -P
  78                  */
  79                 unsigned opt = getopt32(argv, "LP");
  80                 if ((opt & 1) && logical_getcwd())
  81                         return fflush_all();
  82         }
  83
  84         buf = xrealloc_getcwd_or_warn(NULL);
  85
  86         if (buf) {
  87                 puts(buf);
  88                 free(buf);
  89                 return fflush_all();
  90         }
  91
  92         return EXIT_FAILURE;
  93 }