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