You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 

137 lines
3.0 KiB

/*
ISC License
Copyright (c) 2018, Antonio SJ Musumeci <trapexit@spawn.link>
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include "errno.hpp"
#include "fs_clonefile.hpp"
#include "fs_close.hpp"
#include "fs_lstat.hpp"
#include "fs_mktemp.hpp"
#include "fs_open.hpp"
#include "fs_path.hpp"
#include "fs_rename.hpp"
#include "fs_unlink.hpp"
#include <string>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
using std::string;
namespace l
{
static
int
cleanup_on_error(const int src_fd_,
const int dst_fd_ = -1,
const string &dst_fullpath_ = string())
{
int error = errno;
if(src_fd_ >= 0)
fs::close(src_fd_);
if(dst_fd_ >= 0)
fs::close(dst_fd_);
if(!dst_fullpath_.empty())
fs::unlink(dst_fullpath_);
errno = error;
return -1;
}
}
namespace fs
{
namespace cow
{
bool
is_eligible(const int flags_)
{
int accmode;
accmode = (flags_ & O_ACCMODE);
return ((accmode == O_RDWR) ||
(accmode == O_WRONLY));
}
bool
is_eligible(const struct stat &st_)
{
return ((S_ISREG(st_.st_mode)) && (st_.st_nlink > 1));
}
bool
is_eligible(const int flags_,
const struct stat &st_)
{
return (is_eligible(flags_) && is_eligible(st_));
}
bool
is_eligible(const char *fullpath_,
const int flags_)
{
int rv;
struct stat st;
if(!fs::cow::is_eligible(flags_))
return false;
rv = fs::lstat(fullpath_,&st);
if(rv == -1)
return false;
return fs::cow::is_eligible(st);
}
int
break_link(const char *src_fullpath_)
{
int rv;
int src_fd;
int dst_fd;
std::string dst_fullpath;
src_fd = fs::open(src_fullpath_,O_RDONLY|O_NOFOLLOW);
if(src_fd == -1)
return -1;
std::tie(dst_fd,dst_fullpath) = fs::mktemp(src_fullpath_,O_WRONLY);
if(dst_fd < 0)
return l::cleanup_on_error(src_fd);
rv = fs::clonefile(src_fd,dst_fd);
if(rv == -1)
return l::cleanup_on_error(src_fd,dst_fd,dst_fullpath);
rv = fs::rename(dst_fullpath,src_fullpath_);
if(rv == -1)
return l::cleanup_on_error(src_fd,dst_fd,dst_fullpath);
fs::close(src_fd);
fs::close(dst_fd);
return 0;
}
}
}