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
  27 #ifndef lint
  28 static const char rcsid[] =
  29         "$Id: fileupd.c,v 1.5 1997/10/10 06:23:31 charnier Exp $";
  30 #endif /* not lint */
  31
  32 #include <stdio.h>
  33 #include <fcntl.h>
  34 #include <stdlib.h>
  35 #include <string.h>
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <sys/param.h>
  39 #include <errno.h>
  40 #include <unistd.h>
  41
  42 #include "pwupd.h"
  43
  44 int
  45 extendline(char **buf, int * buflen, int needed)
  46 {
  47         if (needed > *buflen) {
  48                 char    *tmp = realloc(*buf, needed);
  49                 if (tmp == NULL)
  50                         return -1;
  51                 *buf = tmp;
  52                 *buflen = needed;
  53         }
  54         return *buflen;
  55 }
  56
  57 int
  58 extendarray(char ***buf, int * buflen, int needed)
  59 {
  60         if (needed > *buflen) {
  61                 char    **tmp = realloc(*buf, needed * sizeof(char *));
  62                 if (tmp == NULL)
  63                         return -1;
  64                 *buf = tmp;
  65                 *buflen = needed;
  66         }
  67         return *buflen;
  68 }
  69
  70
  71 int
  72 fileupdate(char const * filename, mode_t fmode, char const * newline, char const * prefix, int pfxlen, int updmode)
  73 {
  74         int             rc = 0;
  75
  76         if (pfxlen <= 1)
  77                 errno = EINVAL;
  78         else {
  79                 int             infd = open(filename, O_RDWR | O_CREAT, fmode);
  80
  81                 if (infd != -1) {
  82                         FILE           *infp = fdopen(infd, "r+");
  83
  84                         if (infp == NULL)
  85                                 close(infd);
  86                         else {
  87                                 int             outfd;
  88                                 char            file[MAXPATHLEN];
  89
  90                                 strcpy(file, filename);
  91                                 strcat(file, ".new");
  92                                 outfd = open(file, O_RDWR | O_CREAT | O_TRUNC | O_EXLOCK, fmode);
  93                                 if (outfd != -1) {
  94                                         FILE           *outfp = fdopen(outfd, "w+");
  95
  96                                         if (outfp == NULL)
  97                                                 close(outfd);
  98                                         else {
  99                                                 int             updated = UPD_CREATE;
 100                                                 int             linesize = PWBUFSZ;
 101                                                 char           *line = malloc(linesize);
 102
 103                                         nextline:
 104                                                 while (fgets(line, linesize, infp) != NULL) {
 105                                                         char           *p = strchr(line, '\n');
 106
 107                                                         while ((p = strchr(line, '\n')) == NULL) {
 108                                                                 int     l;
 109                                                                 if (extendline(&line, &linesize, linesize + PWBUFSZ) == -1) {
 110                                                                         int     ch;
 111                                                                         fputs(line, outfp);
 112                                                                         while ((ch = fgetc(infp)) != EOF) {
 113                                                                                 fputc(ch, outfp);
 114                                                                                 if (ch == '\n')
 115                                                                                         break;
 116                                                                         }
 117                                                                         goto nextline;
 118                                                                 }
 119                                                                 l = strlen(line);
 120                                                                 if (fgets(line + l, linesize - l, infp) == NULL)
 121                                                                         break;
 122                                                         }
 123                                                         if (*line != '#' && *line != '\n') {
 124                                                                 if (!updated && strncmp(line, prefix, pfxlen) == 0) {
 125                                                                         updated = updmode == UPD_REPLACE ? UPD_REPLACE : UPD_DELETE;
 126
 127                                                                         /*
 128                                                                          * Only actually write changes if updating
 129                                                                          */
 130                                                                         if (updmode == UPD_REPLACE)
 131                                                                                 strcpy(line, newline);
 132                                                                         else if (updmode == UPD_DELETE)
 133                                                                                 continue;
 134                                                                 }
 135                                                         }
 136                                                         fputs(line, outfp);
 137                                                 }
 138
 139                                                 /*
 140                                                  * Now, we need to decide what to do: If we are in
 141                                                  * update mode, and no record was updated, then error If
 142                                                  * we are in insert mode, and record already exists,
 143                                                  * then error
 144                                                  */
 145                                                 if (updmode != updated)
 146                                                         errno = (updmode == UPD_CREATE) ? EEXIST : ENOENT;
 147                                                 else {
 148
 149                                                         /*
 150                                                          * If adding a new record, append it to the end
 151                                                          */
 152                                                         if (updmode == UPD_CREATE)
 153                                                                 fputs(newline, outfp);
 154
 155                                                         /*
 156                                                          * Flush the file and check for the result
 157                                                          */
 158                                                         rc = fflush(outfp) != EOF;
 159                                                         if (rc) {
 160
 161                                                                 /*
 162                                                                  * Copy data back into the
 163                                                                  * original file and truncate
 164                                                                  */
 165                                                                 rewind(infp);
 166                                                                 rewind(outfp);
 167                                                                 while (fgets(line, linesize, outfp) != NULL)
 168                                                                         fputs(line, infp);
 169
 170                                                                 /*
 171                                                                  * If there was a problem with copying
 172                                                                  * we will just rename 'file.new'
 173                                                                  * to 'file'.
 174                                                                  * This is a gross hack, but we may have
 175                                                                  * corrupted the original file
 176                                                                  * Unfortunately, it will lose the inode
 177                                                                  * and hence the lock.
 178                                                                  *
 179                                                                  * The implications of this is that this invocation of pw
 180                                                                  * won't have the file locked and concurrent copies
 181                                                                  * of pw, vipw etc could clobber what this one is doing.
 182                                                                  *
 183                                                                  * It should probably just return an error instead
 184                                                                  * of going on like nothing is wrong.
 185                                                                  */
 186                                                                 if (fflush(infp) == EOF || ferror(infp))
 187                                                                         rc = rename(file, filename) == 0;
 188                                                                 else
 189                                                                         ftruncate(infd, ftell(infp));
 190                                                         }
 191                                                 }
 192                                                 free(line);
 193                                                 fclose(outfp);
 194                                         }
 195                                         remove(file);
 196                                 }
 197                                 fclose(infp);
 198                         }
 199                 }
 200         }
 201         return rc;
 202 }