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/* $Id$
*
* File handling for the wallet client.
*
* Written by Russ Allbery <rra@stanford.edu>
* Copyright 2007, 2008 Board of Trustees, Leland Stanford Jr. University
*
* See LICENSE for licensing terms.
*/
#include <config.h>
#include <portable/system.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.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, but overwrite any existing file by that name.
*/
void
overwrite_file(const char *name, const void *data, size_t length)
{
int fd;
ssize_t status;
if (access(name, F_OK) == 0)
if (unlink(name) < 0)
sysdie("unable to delete existing file %s", name);
fd = open(name, O_WRONLY | O_CREAT | O_EXCL, 0600);
if (fd < 0)
sysdie("open of %s failed", name);
if (length > 0) {
status = write(fd, data, length);
if (status < 0)
sysdie("write to %s failed", name);
else if (status != (ssize_t) length)
die("write to %s truncated", name);
}
if (close(fd) < 0)
sysdie("close of %s failed (file probably truncated)", name);
}
/*
* 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)
{
char *temp, *backup;
temp = concat(name, ".new", (char *) 0);
backup = concat(name, ".bak", (char *) 0);
overwrite_file(temp, data, length);
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);
}
/*
* Given a remctl object, the command prefix, object type, and object name,
* and a file (which may be NULL), send a wallet get command and write the
* results to the provided file. If the file is NULL, write the results to
* standard output instead. Returns 0 on success and an exit status on
* failure.
*/
int
get_file(struct remctl *r, const char *prefix, const char *type,
const char *name, const char *file)
{
const char *command[5];
char *data = NULL;
size_t length = 0;
int status;
command[0] = prefix;
command[1] = "get";
command[2] = type;
command[3] = name;
command[4] = NULL;
status = run_command(r, command, &data, &length);
if (status != 0)
return status;
/* The empty string is valid data. */
if (data == NULL)
length = 0;
if (file != NULL)
write_file(file, data, length);
else if (length > 0) {
if (fwrite(data, length, 1, stdout) != 1)
sysdie("cannot write to standard output");
}
if (data != NULL)
free(data);
return 0;
}
/*
* Read all of a file into memory and return the contents as a newly allocated
* string. Handles a file name of "-" to mean standard input. Dies on any
* failure.
*
* This will need modification later when we want to handle nul characters.
*/
char *
read_file(const char *name)
{
char *contents;
size_t size, offset;
int fd;
struct stat st;
ssize_t status;
if (strcmp(name, "-") == 0) {
fd = fileno(stdin);
size = BUFSIZ;
contents = xmalloc(size);
} else {
fd = open(name, O_RDONLY);
if (fd < 0)
sysdie("cannot open file %s", name);
if (fstat(fd, &st) < 0)
sysdie("cannot stat file %s", name);
size = st.st_size + 1;
contents = xmalloc(size);
}
offset = 0;
do {
if (offset >= size - 1) {
size += BUFSIZ;
contents = xrealloc(contents, size);
}
do {
status = read(fd, contents + offset, size - offset - 1);
} while (status == -1 && errno == EINTR);
if (status < 0)
sysdie("cannot read from file");
offset += status;
} while (status > 0);
close(fd);
contents[offset] = '\0';
if (memchr(contents, '\0', offset) != NULL)
die("cannot yet handle file data containing nul characters");
return contents;
}
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