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/* $Id$
**
** File handling for the wallet client.
**
** Written by Russ Allbery <rra@stanford.edu>
** Copyright 2007 Board of Trustees, Leland Stanford Jr. University
**
** See LICENSE for licensing terms.
*/
#include <config.h>
#include <system.h>
#include <fcntl.h>
#include <client/internal.h>
#include <util/util.h>
/*
** Given a filename, some data, and a length, write that data to the given
** file safely and atomically by creating file.new, writing the data, linking
** file to file.bak, and then renaming file.new to file.
*/
void
write_file(const char *name, const void *data, size_t length)
{
int fd;
ssize_t status;
char *temp, *backup;
temp = concat(name, ".new", (char *) 0);
backup = concat(name, ".bak", (char *) 0);
fd = open(temp, O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (fd < 0)
sysdie("open of %s failed", temp);
status = write(fd, data, length);
if (status < 0)
sysdie("write to %s failed", temp);
else if (status != (ssize_t) length)
die("write to %s truncated", temp);
if (close(fd) < 0)
sysdie("close of %s failed (file probably truncated)", temp);
if (access(name, F_OK) == 0) {
if (access(backup, F_OK) == 0)
if (unlink(backup) < 0)
sysdie("unlink of old backup %s failed", backup);
if (link(name, backup) < 0)
sysdie("link of %s to %s failed", name, backup);
}
if (rename(temp, name) < 0)
sysdie("rename of %s to %s failed", temp, name);
free(temp);
free(backup);
}
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