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-rw-r--r--client/file.c50
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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 README 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 (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);
+}