mirror of
git://sourceware.org/git/lvm2.git
synced 2024-12-21 13:34:40 +03:00
102 lines
2.0 KiB
C
102 lines
2.0 KiB
C
/*
|
|
* Copyright (C) 2001 Sistina Software (UK) Limited.
|
|
*
|
|
* This file is released under the LGPL.
|
|
*/
|
|
|
|
#include "log.h"
|
|
#include "lvm-file.h"
|
|
#include "lvm-string.h"
|
|
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <sys/types.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/file.h>
|
|
#include <fcntl.h>
|
|
|
|
/*
|
|
* Creates a temporary filename, and opens a descriptor to the
|
|
* file. Both the filename and descriptor are needed so we can
|
|
* rename the file after successfully writing it. Grab
|
|
* NFS-supported exclusive fcntl discretionary lock.
|
|
*/
|
|
int create_temp_name(const char *dir, char *buffer, size_t len,
|
|
int *fd)
|
|
{
|
|
int i, num;
|
|
pid_t pid;
|
|
char hostname[255];
|
|
struct flock lock = {
|
|
l_type: F_WRLCK,
|
|
l_whence: 0,
|
|
l_start: 0,
|
|
l_len: 0
|
|
};
|
|
|
|
num = rand();
|
|
pid = getpid();
|
|
if (gethostname(hostname, sizeof(hostname)) < 0) {
|
|
log_sys_error("gethostname", "");
|
|
strcpy(hostname, "nohostname");
|
|
}
|
|
|
|
for (i = 0; i < 20; i++, num++) {
|
|
|
|
if (lvm_snprintf(buffer, len, "%s/.lvm_%s_%d_%d",
|
|
dir, hostname, pid, num) == -1) {
|
|
log_err("Not enough space to build temporary file "
|
|
"string.");
|
|
return 0;
|
|
}
|
|
|
|
*fd = open(buffer, O_CREAT | O_EXCL | O_WRONLY | O_APPEND,
|
|
S_IRUSR | S_IRGRP | S_IROTH |
|
|
S_IWUSR | S_IWGRP | S_IWOTH);
|
|
if (*fd < 0)
|
|
continue;
|
|
|
|
if (!fcntl(*fd, F_SETLK, &lock))
|
|
return 1;
|
|
|
|
close(*fd);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* NFS-safe rename of a temporary file to a common name, designed
|
|
* to avoid race conditions and not overwrite the destination if
|
|
* it exists.
|
|
*
|
|
* Try to create the new filename as a hard link to the original.
|
|
* Check the link count of the original file to see if it worked.
|
|
* (Assumes nothing else touches our temporary file!) If it
|
|
* worked, unlink the old filename.
|
|
*/
|
|
int lvm_rename(const char *old, const char *new)
|
|
{
|
|
struct stat buf;
|
|
|
|
link(old, new);
|
|
|
|
if (stat(old, &buf)) {
|
|
log_sys_error("stat", old);
|
|
return 0;
|
|
}
|
|
|
|
if (buf.st_nlink != 2) {
|
|
log_error("%s: rename to %s failed", old, new);
|
|
return 0;
|
|
}
|
|
|
|
if (unlink(old)) {
|
|
log_sys_error("unlink", old);
|
|
return 0;
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|