pd.if.org Git - pdutils/blob - posix/pwd/pwd.c

   1 #include <stdlib.h>
   2 #include <stdio.h>
   3 #include <errno.h>
   4 #include <unistd.h>
   5 #include <limits.h>
   6 #include <string.h>
   7
   8 static int has_dot_or_dotdot(char *path) {
   9         if (!path) return 0;
  10
  11         while (*path) {
  12                 if (*path == '/') {
  13                         path++;
  14                         continue;
  15                 }
  16                 if (*path == '.') {
  17                         path++;
  18                         if (*path == '.') path++;
  19                         switch (path[0]) {
  20                                 case '/':
  21                                 case 0:
  22                                         return 1;
  23                                 default:
  24                                         break;
  25                         }
  26                 }
  27                 while (*path && *path != '/') {
  28                         path++;
  29                 }
  30         }
  31         return 0;
  32 }
  33
  34 static void fillcwd(char *s, size_t n) {
  35         if (!getcwd(s, n)) {
  36                 switch (errno) {
  37                         case ERANGE:
  38                                 fprintf(stderr, "pwd: path too long\n");
  39                                 exit(1);
  40                         default:
  41                                 perror("pwd");
  42                                 exit(1);
  43                 }
  44         }
  45 }
  46
  47 int main(int ac, char *av[]) {
  48         int cleansym = 0;
  49         char cwd[PATH_MAX];
  50         char *pwd;
  51         char *envpwd;
  52         int arg;
  53
  54         for (arg=1; arg < ac; arg++) {
  55                 if (av[arg][0] == '-') {
  56                        if (av[arg][1] == 'P' && av[arg][2] == 0) {
  57                                cleansym = 1;
  58                        } else if (av[arg][1] == 'L' && av[arg][2] == 0) {
  59                                cleansym = 0;
  60                        }
  61                 } else {
  62                         fprintf(stderr, "usage: pwd [-L|-P]\n");
  63                         exit(1);
  64                 }
  65         }
  66
  67         if (!getcwd(cwd, sizeof cwd)) {
  68                 switch (errno) {
  69                         case ERANGE:
  70                                 fprintf(stderr, "pwd: path too long\n");
  71                                 exit(1);
  72                         default:
  73                                 perror("pwd");
  74                                 exit(1);
  75                 }
  76         }
  77         pwd = cwd;
  78
  79         if (!cleansym) {
  80                 envpwd = getenv("PWD");
  81                 if (envpwd && !has_dot_or_dotdot(envpwd)) {
  82                         if (chdir(envpwd) != -1) {
  83                                 fillcwd(cwd, sizeof cwd);
  84                                 if (strcmp(cwd, envpwd)) {
  85                                         pwd = envpwd;
  86                                 }
  87                         }
  88                 }
  89         }
  90
  91         printf("%s\n", pwd);
  92         return 0;
  93 }
  94