#include <stdlib.h>
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <string.h>

static int has_dot_or_dotdot(char *path) {
	if (!path) return 0;

	while (*path) {
		if (*path == '/') {
			path++;
			continue;
		}
		if (*path == '.') {
			path++;
			if (*path == '.') path++;
			switch (path[0]) {
				case '/':
				case 0:
					return 1;
				default:
					break;
			}
		}
		while (*path && *path != '/') {
			path++;
		}
	}
	return 0;
}

static void fillcwd(char *s, size_t n) {
	if (!getcwd(s, n)) {
		switch (errno) {
			case ERANGE:
				fprintf(stderr, "pwd: path too long\n");
				exit(1);
			default:
				perror("pwd");
				exit(1);
		}
	}
}

int main(int ac, char *av[]) {
	int cleansym = 0;
	char cwd[PATH_MAX];
	char *pwd;
	char *envpwd;
	int arg;

	for (arg=1; arg < ac; arg++) {
		if (av[arg][0] == '-') {
		       if (av[arg][1] == 'P' && av[arg][2] == 0) {
			       cleansym = 1;
		       } else if (av[arg][1] == 'L' && av[arg][2] == 0) {
			       cleansym = 0;
		       }
		} else {
			fprintf(stderr, "usage: pwd [-L|-P]\n");
			exit(1);
		}
	}

	if (!getcwd(cwd, sizeof cwd)) {
		switch (errno) {
			case ERANGE:
				fprintf(stderr, "pwd: path too long\n");
				exit(1);
			default:
				perror("pwd");
				exit(1);
		}
	}
	pwd = cwd;

	if (!cleansym) {
		envpwd = getenv("PWD");
		if (envpwd && !has_dot_or_dotdot(envpwd)) {
			if (chdir(envpwd) != -1) {
				fillcwd(cwd, sizeof cwd);
				if (strcmp(cwd, envpwd)) {
					pwd = envpwd;
				}
			}
		}
	}

	printf("%s\n", pwd);
	return 0;
}