pw/fileupd.c

   1 /*-
   2  * Copyright (C) 1996
   3  *      David L. Nugent.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY DAVID L. NUGENT AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL DAVID L. NUGENT OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  *      $Id: fileupd.c,v 1.1.1.1 1996/12/09 14:05:35 joerg Exp $
  27  */
  28
  29 #include <stdio.h>
  30 #include <fcntl.h>
  31 #include <stdlib.h>
  32 #include <string.h>
  33 #include <sys/types.h>
  34 #include <sys/stat.h>
  35 #include <sys/param.h>
  36 #include <errno.h>
  37 #include <unistd.h>
  38
  39 #include "pwupd.h"
  40
  41 int
  42 fileupdate(char const * filename, mode_t fmode, char const * newline, char const * prefix, int pfxlen, int updmode)
  43 {
  44         int             rc = 0;
  45
  46         if (pfxlen <= 1)
  47                 errno = EINVAL;
  48         else {
  49                 int             infd = open(filename, O_RDWR | O_CREAT | O_EXLOCK, fmode);
  50
  51                 if (infd != -1) {
  52                         FILE           *infp = fdopen(infd, "r+");
  53
  54                         if (infp == NULL)
  55                                 close(infd);
  56                         else {
  57                                 int             outfd;
  58                                 char            file[MAXPATHLEN];
  59
  60                                 strcpy(file, filename);
  61                                 strcat(file, ".new");
  62                                 outfd = open(file, O_RDWR | O_CREAT | O_TRUNC | O_EXLOCK, fmode);
  63                                 if (outfd != -1) {
  64                                         FILE           *outfp = fdopen(outfd, "w+");
  65
  66                                         if (outfp == NULL)
  67                                                 close(outfd);
  68                                         else {
  69                                                 int             updated = UPD_CREATE;
  70                                                 char            line[2048];
  71
  72                                                 while (fgets(line, sizeof(line), infp) != NULL) {
  73                                                         char           *p = strchr(line, '\n');
  74
  75                                                         if (p == NULL) {        /* Line too long */
  76                                                                 int             ch;
  77
  78                                                                 fputs(line, outfp);
  79                                                                 while ((ch = fgetc(infp)) != EOF) {
  80                                                                         fputc(ch, outfp);
  81                                                                         if (ch == '\n')
  82                                                                                 break;
  83                                                                 }
  84                                                                 continue;
  85                                                         }
  86                                                         if (*line != '#' && *line != '\n') {
  87                                                                 if (!updated && strncmp(line, prefix, pfxlen) == 0) {
  88                                                                         updated = updmode == UPD_REPLACE ? UPD_REPLACE : UPD_DELETE;
  89
  90                                                                         /*
  91                                                                          * Only actually write changes if updating
  92                                                                          */
  93                                                                         if (updmode == UPD_REPLACE)
  94                                                                                 strcpy(line, newline);
  95                                                                         else if (updmode == UPD_DELETE)
  96                                                                                 continue;
  97                                                                 }
  98                                                         }
  99                                                         fputs(line, outfp);
 100                                                 }
 101
 102                                                 /*
 103                                                  * Now, we need to decide what to do: If we are in
 104                                                  * update mode, and no record was updated, then error If
 105                                                  * we are in insert mode, and record already exists,
 106                                                  * then error
 107                                                  */
 108                                                 if (updmode != updated)
 109                                                         errno = (updmode == UPD_CREATE) ? EEXIST : ENOENT;
 110                                                 else {
 111
 112                                                         /*
 113                                                          * If adding a new record, append it to the end
 114                                                          */
 115                                                         if (updmode == UPD_CREATE)
 116                                                                 fputs(newline, outfp);
 117
 118                                                         /*
 119                                                          * Flush the file and check for the result
 120                                                          */
 121                                                         rc = fflush(outfp) != EOF;
 122                                                         if (rc) {
 123
 124                                                                 /*
 125                                                                  * Copy data back into the
 126                                                                  * original file and truncate
 127                                                                  */
 128                                                                 rewind(infp);
 129                                                                 rewind(outfp);
 130                                                                 while (fgets(line, sizeof(line), outfp) != NULL)
 131                                                                         fputs(line, infp);
 132
 133                                                                 /*
 134                                                                  * This is a gross hack, but we may have
 135                                                                  * corrupted the original file
 136                                                                  * Unfortunately, it will lose the inode.
 137                                                                  */
 138                                                                 if (fflush(infp) == EOF || ferror(infp))
 139                                                                         rc = rename(file, filename) == 0;
 140                                                                 else
 141                                                                         ftruncate(infd, ftell(infp));
 142                                                         }
 143                                                 }
 144                                                 fclose(outfp);
 145                                         }
 146                                         remove(file);
 147                                 }
 148                                 fclose(infp);
 149                         }
 150                 }
 151         }
 152         return rc;
 153 }