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

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/*-
* 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[] =
"$Id: fileupd.c,v 1.6 1998/07/16 17:18:24 nate Exp $";
#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)
errno = EINVAL;
else {
int infd = open(filename, O_RDWR | O_CREAT, 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;
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)
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, 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
* Unfortunately, it will lose the inode
* and hence the lock.
*/
if (fflush(infp) == EOF || ferror(infp)) {
rc = errno; /* Preserve errno for return */
rename(file, filename);
}
else
ftruncate(infd, ftell(infp));
}
}
free(line);
fclose(outfp);
}
remove(file);
}
fclose(infp);
}
}
}
return rc;
}