usr/src/lib/libc/gen/getcwd.c

/*
 * Copyright (c) 1989 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)getcwd.c    5.4 (Berkeley) %G%";
#endif /* LIBC_SCCS and not lint */

#include <sys/param.h>
#include <sys/stat.h>
#include <dirent.h>

char *
getwd(store)
        char *store;
{
        extern int errno;
        register DIR *dir;
        register struct dirent *dp;
        register int first;
        register char *pp, *pu;
        struct stat s, tmp;
        dev_t root_dev;
        ino_t root_ino;
        char path[MAXPATHLEN], up[MAXPATHLEN], *strerror();

        if (stat("/", &s))
                goto err;
        root_dev = s.st_dev;
        root_ino = s.st_ino;
        if (stat(".", &s))
                goto err;
        pp = path + sizeof(path) - 1;
        *pp = '\0';
        for (pu = up, first = 1;; first = 0) {
                if (root_dev == s.st_dev && root_ino == s.st_ino) {
                        *store = '/';
                        (void)strcpy(store + 1, pp);
                        return(store);
                }
                *pu++ = '.';
                *pu++ = '.';
                *pu = '\0';
                if (!(dir = opendir(up))) {
                        (void)strcpy(path, "getwd: opendir failed.");
                        return((char *)NULL);
                }
                *pu++ = '/';
                while (dp = readdir(dir)) {
                        if (dp->d_name[0] == '.' && (!dp->d_name[1] ||
                            dp->d_name[1] == '.' && !dp->d_name[2]))
                                continue;
                        bcopy(dp->d_name, pu, dp->d_namlen + 1);
                        if (lstat(up, &tmp))
                                goto err;
                        if (tmp.st_dev == s.st_dev && tmp.st_ino == s.st_ino) {
                                if (!first)
                                        *--pp = '/';
                                pp -= dp->d_namlen;
                                bcopy(dp->d_name, pp, dp->d_namlen);
                                break;
                        }
                }
                closedir(dir);
                *pu = '\0';
                if (lstat(up, &s)) {
err:                    (void)sprintf(path, "getwd: %s", strerror(errno));
                        return((char *)NULL);
                }
        }
}