/* *  sudo version 1.1 allows users to execute commands as root *  Copyright (C) 1991  The Root Group, Inc. * *  This program is free software; you can redistribute it and/or modify *  it under the terms of the GNU General Public License as published by *  the Free Software Foundation; either version 1, or (at your option) *  any later version. * *  This program is distributed in the hope that it will be useful, *  but WITHOUT ANY WARRANTY; without even the implied warranty of *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the *  GNU General Public License for more details. * *  You should have received a copy of the GNU General Public License *  along with this program; if not, write to the Free Software *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. * *  If you make modifications to the source, we would be happy to have *  them to include in future releases.  Feel free to send them to: *      Jeff Nieusma                       nieusma@rootgroup.com *      3959 Arbol CT                      (303) 447-8093 *      Boulder, CO 80301-1752              ********************************************************************************** visudo.c, sudo project* David R. Hieb* March 18, 1991** edit, lock and parse the sudoers file in a fashion similiar to /etc/vipw.*******************************************************************************/#include <sys/types.h>#include <sys/stat.h>#include <sys/file.h>#include <stdio.h>#include <errno.h>#include <signal.h>#include "sudo.h"extern	FILE *yyin, *yyout;extern	int errno, yylineno;char	buffer[BUFSIZ];char	*sudoers = SUDOERS;int	status = 0, err_line_no = 0;char	*sudoers_tmp_file = TMPSUDOERS;FILE	*sudoers_tmp_fp, *sudoers_fp;void Exit(){fclose(sudoers_tmp_fp);unlink(sudoers_tmp_file);exit(1);}main(argc, argv)int argc;char **argv;{int fd;struct stat sbuf;/* handle the signals */signal(SIGILL, Exit);signal(SIGTRAP, Exit);signal(SIGBUS, Exit);signal(SIGSEGV, Exit);signal(SIGTERM, Exit);signal(SIGHUP, SIG_IGN);signal(SIGINT, SIG_IGN);signal(SIGQUIT, SIG_IGN);setbuf(stderr, NULL);/* we only want root to be able to read/write the sudoers_tmp_file */umask(077);/* open the sudoers file read only */if ((sudoers_fp = fopen(sudoers, "r")) == NULL) {    fprintf(stderr, "%s: ", *argv);     perror(sudoers);    Exit();    }/* open the temporary sudoers file with the correct flags */if ((fd = open(sudoers_tmp_file, O_WRONLY|O_CREAT|O_EXCL, 0600)) < 0) {    if (errno == EEXIST) {        fprintf(stderr, "%s: sudoers file busy\n", *argv);        exit(1);        }    fprintf(stderr, "%s: ", *argv);     perror(sudoers_tmp_file);    exit(1);    }/* get a STREAM file pointer to the temporary sudoers file */if ((sudoers_tmp_fp = fdopen(fd, "w")) == NULL) {    fprintf(stderr, "%s: ", *argv);     perror(sudoers_tmp_file);    Exit();    }/* transfer the contents of the sudoers file to the temporary sudoers file */while (fgets(buffer, sizeof(buffer) - 1, sudoers_fp) != NULL) {    fputs(buffer, sudoers_tmp_fp);    }fclose(sudoers_fp);fclose(sudoers_tmp_fp);do {    /* build strings in buffer to be executed by system() */    sprintf(buffer, "%s +%d %s", EDITOR, err_line_no, sudoers_tmp_file);    /* edit the file */    if (system(buffer) == 0) {        /* can't stat file */        if (stat(sudoers_tmp_file, &sbuf) < 0) {            fprintf(stderr, "%s: can't stat temporary file, %s unchanged\n",                 sudoers, *argv);            Exit();            }        /* file has size == 0 */        if (sbuf.st_size == 0) {            fprintf(stderr, "%s: bad temporary file, %s unchanged\n",                 sudoers, *argv);            Exit();            }        /* re-open the sudoers file for parsing */        if ((sudoers_tmp_fp = fopen(sudoers_tmp_file, "r")) == NULL) {            fprintf(stderr, "%s: can't re-open temporary file, %s unchanged\n",                 sudoers, *argv);            Exit();            }        yyin = sudoers_tmp_fp;        yyout = stdout;                 /* parse the file */        if (yyparse()) {            fprintf(stderr, "yyparse() failed\n");            Exit();            }        /*         * the first time we get an error, set status to yylineno which         * will be the line number after the line with the error.         * then, if we have gotten an error, set err_line_no to the         * correct line so that when we edit the file err_line_no will         * be correct. at this time we also reset status and yylineno         * to their default values so that the next time yyparse() is         * called, they will be initialized correctly.         */        err_line_no = (status == 0) ? 0 : status - 1;        status = 0;        yylineno = 1;        fclose(sudoers_tmp_fp);        }    } while (err_line_no);/* once the temporary sudoers file is gramatically correct, we can  * rename it to the real sudoers file. */if (rename(sudoers_tmp_file, sudoers) != 0) {    fprintf(stderr, "%s: ", *argv), perror("rename");    }else {    if (chmod(sudoers, 0400) != 0) {        perror("chmod: failed");        }    exit(0);    }}