usr.sbin/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  * $FreeBSD: src/usr.sbin/pw/fileupd.c,v 1.9 1999/10/26 04:27:13 davidn Exp $
  27  * $DragonFly: src/usr.sbin/pw/fileupd.c,v 1.2 2003/06/17 04:30:01 dillon Exp $
  28  */
  29
  30 #include <stdio.h>
  31 #include <fcntl.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <sys/types.h>
  35 #include <sys/stat.h>
  36 #include <sys/param.h>
  37 #include <errno.h>
  38 #include <unistd.h>
  39
  40 #include "pwupd.h"
  41
  42 int
  43 extendline(char **buf, int * buflen, int needed)
  44 {
  45         if (needed > *buflen) {
  46                 char    *tmp = realloc(*buf, needed);
  47                 if (tmp == NULL)
  48                         return -1;
  49                 *buf = tmp;
  50                 *buflen = needed;
  51         }
  52         return *buflen;
  53 }
  54
  55 int
  56 extendarray(char ***buf, int * buflen, int needed)
  57 {
  58         if (needed > *buflen) {
  59                 char    **tmp = realloc(*buf, needed * sizeof(char *));
  60                 if (tmp == NULL)
  61                         return -1;
  62                 *buf = tmp;
  63                 *buflen = needed;
  64         }
  65         return *buflen;
  66 }
  67
  68
  69 int
  70 fileupdate(char const * filename, mode_t fmode, char const * newline, char const * prefix, int pfxlen, int updmode)
  71 {
  72         int     rc = 0;
  73
  74         if (pfxlen <= 1)
  75                 rc = EINVAL;
  76         else {
  77                 int    infd = open(filename, O_RDWR | O_CREAT, fmode);
  78
  79                 if (infd == -1)
  80                         rc = errno;
  81                 else {
  82                         FILE   *infp = fdopen(infd, "r+");
  83
  84                         if (infp == NULL) {
  85                                 rc = errno;             /* Assumes fopen(3) sets errno from open(2) */
  86                                 close(infd);
  87                         } else {
  88                                 int       outfd;
  89                                 char      file[MAXPATHLEN];
  90
  91                                 strcpy(file, filename);
  92                                 strcat(file, ".new");
  93                                 outfd = open(file, O_RDWR | O_CREAT | O_TRUNC | O_EXLOCK, fmode);
  94                                 if (outfd == -1)
  95                                         rc = errno;
  96                                 else {
  97                                         FILE    *outfp = fdopen(outfd, "w+");
  98
  99                                         if (outfp == NULL) {
 100                                                 rc = errno;
 101                                                 close(outfd);
 102                                         } else {
 103                                                 int   updated = UPD_CREATE;
 104                                                 int             linesize = PWBUFSZ;
 105                                                 char  *line = malloc(linesize);
 106
 107                                         nextline:
 108                                                 while (fgets(line, linesize, infp) != NULL) {
 109                                                         char  *p = strchr(line, '\n');
 110
 111                                                         while ((p = strchr(line, '\n')) == NULL) {
 112                                                                 int     l;
 113                                                                 if (extendline(&line, &linesize, linesize + PWBUFSZ) == -1) {
 114                                                                         int     ch;
 115                                                                         fputs(line, outfp);
 116                                                                         while ((ch = fgetc(infp)) != EOF) {
 117                                                                                 fputc(ch, outfp);
 118                                                                                 if (ch == '\n')
 119                                                                                         break;
 120                                                                         }
 121                                                                         goto nextline;
 122                                                                 }
 123                                                                 l = strlen(line);
 124                                                                 if (fgets(line + l, linesize - l, infp) == NULL)
 125                                                                         break;
 126                                                         }
 127                                                         if (*line != '#' && *line != '\n') {
 128                                                                 if (!updated && strncmp(line, prefix, pfxlen) == 0) {
 129                                                                         updated = updmode == UPD_REPLACE ? UPD_REPLACE : UPD_DELETE;
 130
 131                                                                         /*
 132                                                                          * Only actually write changes if updating
 133                                                                          */
 134                                                                         if (updmode == UPD_REPLACE)
 135                                                                                 strcpy(line, newline);
 136                                                                         else if (updmode == UPD_DELETE)
 137                                                                                 continue;
 138                                                                 }
 139                                                         }
 140                                                         fputs(line, outfp);
 141                                                 }
 142
 143                                                 /*
 144                                                  * Now, we need to decide what to do: If we are in
 145                                                  * update mode, and no record was updated, then error If
 146                                                  * we are in insert mode, and record already exists,
 147                                                  * then error
 148                                                  */
 149                                                 if (updmode != updated)
 150                                                         /* -1 return means:
 151                                                          * update,delete=no user entry
 152                                                          * create=entry exists
 153                                                          */
 154                                                         rc = -1;
 155                                                 else {
 156
 157                                                         /*
 158                                                          * If adding a new record, append it to the end
 159                                                          */
 160                                                         if (updmode == UPD_CREATE)
 161                                                                 fputs(newline, outfp);
 162
 163                                                         /*
 164                                                          * Flush the file and check for the result
 165                                                          */
 166                                                         if (fflush(outfp) == EOF)
 167                                                                 rc = errno;     /* Failed to update */
 168                                                         else {
 169                                                                 /*
 170                                                                  * Copy data back into the
 171                                                                  * original file and truncate
 172                                                                  */
 173                                                                 rewind(infp);
 174                                                                 rewind(outfp);
 175                                                                 while (fgets(line, linesize, outfp) != NULL)
 176                                                                         fputs(line, infp);
 177
 178                                                                 /*
 179                                                                  * If there was a problem with copying
 180                                                                  * we will just rename 'file.new'
 181                                                                  * to 'file'.
 182                                                                  * This is a gross hack, but we may have
 183                                                                  * corrupted the original file
 184                                                                  * Unfortunately, it will lose the inode
 185                                                                  * and hence the lock.
 186                                                                  */
 187                                                                 if (fflush(infp) == EOF || ferror(infp))
 188                                                                         rename(file, filename);
 189                                                                 else
 190                                                                         ftruncate(infd, ftell(infp));
 191                                                         }
 192                                                 }
 193                                                 free(line);
 194                                                 fclose(outfp);
 195                                         }
 196                                         remove(file);
 197                                 }
 198                                 fclose(infp);
 199                         }
 200                 }
 201         }
 202         return rc;
 203 }