freebsd-skq/usr.sbin/pw/fileupd.c

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/*-
* Copyright (c) 1996 by David L. Nugent <davidn@blaze.net.au>.
* 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 as
* the first lines of this file unmodified.
* 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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by David L. Nugent.
* 4. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE DAVID L. NUGENT ``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 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.
*
* $Id$
*/
#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
fileupdate(char const * filename, mode_t fmode, char const * newline, char const * prefix, int pfxlen, int updmode)
{
int rc = 0;
if (pfxlen <= 1)
errno = EINVAL;
else {
int infd = open(filename, O_RDWR | O_CREAT | O_EXLOCK, fmode);
if (infd != -1) {
FILE *infp = fdopen(infd, "r+");
if (infp == NULL)
close(infd);
else {
int outfd;
char file[MAXPATHLEN];
strcpy(file, filename);
strcat(file, ".new");
outfd = open(file, O_RDWR | O_CREAT | O_TRUNC | O_EXLOCK, fmode);
if (outfd != -1) {
FILE *outfp = fdopen(outfd, "w+");
if (outfp == NULL)
close(outfd);
else {
int updated = UPD_CREATE;
char line[2048];
while (fgets(line, sizeof(line), infp) != NULL) {
char *p = strchr(line, '\n');
if (p == NULL) { /* Line too long */
int ch;
fputs(line, outfp);
while ((ch = fgetc(infp)) != EOF) {
fputc(ch, outfp);
if (ch == '\n')
break;
}
continue;
}
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)
errno = (updmode == UPD_CREATE) ? EEXIST : ENOENT;
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
*/
rc = fflush(outfp) != EOF;
if (rc) {
/*
* Copy data back into the
* original file and truncate
*/
rewind(infp);
rewind(outfp);
while (fgets(line, sizeof(line), outfp) != NULL)
fputs(line, infp);
/*
* This is a gross hack, but we may have
* corrupted the original file
* Unfortunately, it will lose the inode.
*/
if (fflush(infp) == EOF || ferror(infp))
rc = rename(file, filename) == 0;
else
ftruncate(infd, ftell(infp));
}
}
fclose(outfp);
}
remove(file);
}
fclose(infp);
}
}
}
return rc;
}