/*-
 * Copyright (C) 1996
 *      David L. Nugent.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * $FreeBSD: src/usr.sbin/pw/fileupd.c,v 1.10 2004/03/08 20:31:37 kensmith Exp $
 */

#include <stdio.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <errno.h>
#include <unistd.h>

#include "pwupd.h"

int
extendline(char **buf, int * buflen, int needed)
{
        if (needed > *buflen) {
                char    *tmp = realloc(*buf, needed);
                if (tmp == NULL)
                        return -1;
                *buf = tmp;
                *buflen = needed;
        }
        return *buflen;
}

int
extendarray(char ***buf, int * buflen, int needed)
{
        if (needed > *buflen) {
                char    **tmp = realloc(*buf, needed * sizeof(char *));
                if (tmp == NULL)
                        return -1;
                *buf = tmp;
                *buflen = needed;
        }
        return *buflen;
}


int
fileupdate(char const * filename, mode_t fmode, char const * newline, char const * prefix, int pfxlen, int updmode)
{
        int     rc = 0;

        if (pfxlen <= 1)
                rc = EINVAL;
        else {
                int    infd = open(filename, O_RDWR | O_CREAT | O_EXLOCK, fmode);

                if (infd == -1)
                        rc = errno;
                else {
                        FILE   *infp = fdopen(infd, "r+");

                        if (infp == NULL) {
                                rc = errno;             /* Assumes fopen(3) sets errno from open(2) */
                                close(infd);
                        } else {
                                int       outfd;
                                char      file[MAXPATHLEN];

                                strcpy(file, filename);
                                strcat(file, ".new");
                                outfd = open(file, O_RDWR | O_CREAT | O_TRUNC, fmode);
                                if (outfd == -1)
                                        rc = errno;
                                else {
                                        FILE    *outfp = fdopen(outfd, "w+");

                                        if (outfp == NULL) {
                                                rc = errno;
                                                close(outfd);
                                        } else {
                                                int   updated = UPD_CREATE;
                                                int             linesize = PWBUFSZ;
                                                char  *line = malloc(linesize);

                                        nextline:
                                                while (fgets(line, linesize, infp) != NULL) {
                                                        char  *p = strchr(line, '\n');

                                                        while ((p = strchr(line, '\n')) == NULL) {
                                                                int     l;
                                                                if (extendline(&line, &linesize, linesize + PWBUFSZ) == -1) {
                                                                        int     ch;
                                                                        fputs(line, outfp);
                                                                        while ((ch = fgetc(infp)) != EOF) {
                                                                                fputc(ch, outfp);
                                                                                if (ch == '\n')
                                                                                        break;
                                                                        }
                                                                        goto nextline;
                                                                }
                                                                l = strlen(line);
                                                                if (fgets(line + l, linesize - l, infp) == NULL)
                                                                        break;
                                                        }
                                                        if (*line != '#' && *line != '\n') {
                                                                if (!updated && strncmp(line, prefix, pfxlen) == 0) {
                                                                        updated = updmode == UPD_REPLACE ? UPD_REPLACE : UPD_DELETE;

                                                                        /*
                                                                         * Only actually write changes if updating
                                                                         */
                                                                        if (updmode == UPD_REPLACE)
                                                                                strcpy(line, newline);
                                                                        else if (updmode == UPD_DELETE)
                                                                                continue;
                                                                }
                                                        }
                                                        fputs(line, outfp);
                                                }

                                                /*
                                                 * Now, we need to decide what to do: If we are in
                                                 * update mode, and no record was updated, then error If
                                                 * we are in insert mode, and record already exists,
                                                 * then error
                                                 */
                                                if (updmode != updated)
                                                        /* -1 return means:
                                                         * update,delete=no user entry
                                                         * create=entry exists
                                                         */
                                                        rc = -1;
                                                else {

                                                        /*
                                                         * If adding a new record, append it to the end
                                                         */
                                                        if (updmode == UPD_CREATE)
                                                                fputs(newline, outfp);

                                                        /*
                                                         * Flush the file and check for the result
                                                         */
                                                        if (fflush(outfp) == EOF)
                                                                rc = errno;     /* Failed to update */
                                                        else {
                                                                /*
                                                                 * Copy data back into the
                                                                 * original file and truncate
                                                                 */
                                                                rewind(infp);
                                                                rewind(outfp);
                                                                while (fgets(line, linesize, outfp) != NULL)
                                                                        fputs(line, infp);

                                                                /*
                                                                 * If there was a problem with copying
                                                                 * we will just rename 'file.new' 
                                                                 * to 'file'.
                                                                 * This is a gross hack, but we may have
                                                                 * corrupted the original file
                                                                 */
                                                                if (fflush(infp) == EOF || ferror(infp))
                                                                        rename(file, filename);
                                                                else
                                                                        ftruncate(infd, ftell(infp));
                                                        }
                                                }
                                                free(line);
                                                fclose(outfp);
                                        }
                                        remove(file);
                                }
                                fclose(infp);
                        }
                }
        }
        return rc;
}