freebsd-skq/usr.sbin/pw/fileupd.c
kensmith 7d850e0369 Shift file locking to source file instead of temp file. This fixes
data buffering issue that corrupts files if two pw(8)'s run at the
same time as well as changing pw(8) so it uses the same locking
mechanism as PAM, vipw(8), pwd_mkdb(8), etc.

PR:		bin/23501
Submitted by:	Alex Kapranoff <alex (at) kapran (dot) bitmcnit (dot) bryansk (dot) su>
Approved by:	rwatson (mentor)
MFC after:	5 days
2004-03-08 20:31:37 +00:00

204 lines
5.2 KiB
C

/*-
* 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.
*/
#ifndef lint
static const char rcsid[] =
"$FreeBSD$";
#endif /* not lint */
#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;
}