getpreroot.c revision 7c2fbfb345896881c631598ee3852ce9ce33fb07
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin/***********************************************************************
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* This software is part of the ast package *
7c2fbfb345896881c631598ee3852ce9ce33fb07April Chin* Copyright (c) 1985-2008 AT&T Intellectual Property *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* and is licensed under the *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* Common Public License, Version 1.0 *
7c2fbfb345896881c631598ee3852ce9ce33fb07April Chin* by AT&T Intellectual Property *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* A copy of the License is available at *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* (with md5 checksum 059e8cd6165cb4c31e351f2b69388fd9) *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* Information and Software Systems Research *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* AT&T Research *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* Florham Park NJ *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* Glenn Fowler <gsf@research.att.com> *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* David Korn <dgk@research.att.com> *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin* Phong Vo <kpv@research.att.com> *
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin***********************************************************************/
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin * AT&T Bell Laboratories
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin * return the real absolute pathname of the preroot dir for cmd
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin * if cmd==0 then current preroot path returned
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin register int c;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin register char* p;
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin sfsprintf(buf, sizeof(buf), "set x `%s= %s - </dev/null 2>&1`\nwhile :\ndo\nshift\ncase $# in\n[012]) break ;;\nesac\ncase \"$1 $2\" in\n\"+ %s\") echo $3; exit ;;\nesac\ndone\necho\n", PR_SILENT, cmd, PR_COMMAND);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin for (p = path; (c = getc(fp)) != EOF && c != '\n'; *p++ = c);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin if (path == p) return(0);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin if ((ruid = getuid()) != (euid = geteuid())) setuid(ruid);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin if (stat(PR_REAL, cur) || stat("/", par) || cur->st_dev == par->st_dev && cur->st_ino == par->st_ino) ERROR(ENOTDIR);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin * like getcwd() but starting at the preroot
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin *d++ = '/';
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin *d++ = '.';
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin *d++ = '.';
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin *d++ = '/';
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin *--p = '/';
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin while (*d++ = *p++);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin * this fallthrough handles logical naming
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin if ((d - dots) > (PATH_MAX - 1 - namlen)) ERROR(ERANGE);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin } while (tstst.st_ino != cur->st_ino || tstst.st_dev != cur->st_dev);
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin if (*p) *--p = '/';
da2e3ebdc1edfbc5028edf1354e7dd2fa69a7968chin return(0);