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mergerfs/src/fs.cpp

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/*
The MIT License (MIT)
Copyright (c) 2014 Antonio SJ Musumeci <trapexit@spawn.link>
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/
#include <string>
#include <vector>
#include <map>
#include <sstream>
#include <cstdlib>
#include <iterator>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/fs.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/statvfs.h>
#include <sys/types.h>
#include <attr/xattr.h>
#include <unistd.h>
#include "fs.hpp"
using std::string;
using std::vector;
using std::map;
using std::istringstream;
template<typename Container>
Container&
split(Container &result,
const typename Container::value_type &s,
typename Container::value_type::value_type delimiter)
{
string str;
istringstream ss(s);
while(std::getline(ss,str,delimiter))
result.push_back(str);
return result;
}
template <typename Iter>
Iter
random_element(Iter begin,
Iter end)
{
const unsigned long n = std::distance(begin, end);
std::advance(begin, (std::rand() % n));
return begin;
}
namespace fs
{
string
dirname(const string path)
{
string parent = path;
string::reverse_iterator i;
string::reverse_iterator bi;
bi = parent.rend();
i = parent.rbegin();
while(*i == '/' && i != bi)
i++;
while(*i != '/' && i != bi)
i++;
while(*i == '/' && i != bi)
i++;
parent.erase(i.base(),parent.end());
return parent;
}
string
basename(const string path)
{
return path.substr(path.find_last_of('/')+1);
}
bool
dir_is_empty(const string path)
{
DIR *dir;
struct dirent *de;
dir = ::opendir(path.c_str());
if(!dir)
return false;
while((de = ::readdir(dir)))
{
const char *d_name = de->d_name;
if(d_name[0] == '.' &&
((d_name[1] == '\0') ||
(d_name[1] == '.' && d_name[2] == '\0')))
continue;
::closedir(dir);
return false;
}
::closedir(dir);
return true;
}
string
make_path(const string base,
const string suffix)
{
return base + suffix;
}
bool
path_exists(vector<string>::const_iterator begin,
vector<string>::const_iterator end,
const string fusepath)
{
for(vector<string>::const_iterator
iter = begin; iter != end; ++iter)
{
int rv;
struct stat st;
string path;
path = make_path(*iter,fusepath);
rv = ::lstat(path.c_str(),&st);
if(rv == 0)
return true;
}
return false;
}
bool
path_exists(const vector<string> &srcmounts,
const string fusepath)
{
return path_exists(srcmounts.begin(),
srcmounts.end(),
fusepath);
}
Path
find_first(vector<string>::const_iterator beginiter,
vector<string>::const_iterator enditer,
const string suffix)
{
for(vector<string>::const_iterator
iter = beginiter; iter != enditer; ++iter)
{
int rv;
struct stat st;
string path;
path = fs::make_path(*iter,suffix);
rv = ::lstat(path.c_str(),&st);
if(rv == 0 || (rv == -1 && errno == EACCES))
return Path(*iter,path);
}
return Path();
}
Path
find_first(const vector<string> &basepaths,
const string suffix)
{
return find_first(basepaths.begin(),
basepaths.end(),
suffix);
}
void
find_first(const vector<string> &basepaths,
const string suffix,
vector<Path> &paths)
{
paths.push_back(find_first(basepaths,suffix));
}
Path
find_first_with_permission(vector<string>::const_iterator beginiter,
vector<string>::const_iterator enditer,
const string suffix)
{
for(vector<string>::const_iterator
iter = beginiter; iter != enditer; ++iter)
{
int rv;
struct stat st;
string path;
path = make_path(*iter,suffix);
rv = ::lstat(path.c_str(),&st);
if(rv == 0)
return Path(*iter,path);
}
return Path();
}
Path
find_first_with_permission(const vector<string> &basepaths,
const string suffix)
{
return find_first_with_permission(basepaths.begin(),
basepaths.end(),
suffix);
}
void
find_first_with_permission(const vector<string> &basepaths,
const string suffix,
vector<Path> &paths)
{
paths.push_back(find_first_with_permission(basepaths,suffix));
}
Path
find_newest(vector<string>::const_iterator beginiter,
vector<string>::const_iterator enditer,
const string suffix)
{
time_t newest;
string npath;
vector<string>::const_iterator niter;
newest = 0;
for(vector<string>::const_iterator
iter = beginiter; iter != enditer; ++iter)
{
int rv;
struct stat st;
const string path = make_path(*iter,suffix);
rv = ::lstat(path.c_str(),&st);
if(rv == 0 && st.st_mtime > newest)
{
newest = st.st_mtime;
niter = iter;
npath = path;
}
}
if(newest)
return Path(*niter,npath);
return Path();
}
Path
find_newest(const vector<string> &basepaths,
const string suffix)
{
return find_newest(basepaths.begin(),
basepaths.end(),
suffix);
}
void
find_newest(const vector<string> &basepaths,
const string suffix,
vector<Path> &paths)
{
paths.push_back(find_newest(basepaths,suffix));
}
void
find_all(const vector<string> &basepaths,
const string suffix,
vector<Path> &paths)
{
for(vector<string>::const_iterator
i = basepaths.begin(), ei = basepaths.end(); i != ei; ++i)
{
int rv;
struct stat st;
string path;
path = fs::make_path(*i,suffix);
rv = ::lstat(path.c_str(),&st);
if(rv == 0 || (rv == -1 && errno == EACCES))
paths.push_back(Path(*i,path));
}
}
Path
find_mfs(vector<string>::const_iterator iter,
vector<string>::const_iterator enditer,
const string fusepath)
{
fsblkcnt_t mfs = 0;
string mfspath;
string fullmfspath;
for(;iter != enditer; ++iter)
{
int rv;
struct statvfs fsstats;
const string mountpoint = *iter;
rv = ::statvfs(mountpoint.c_str(),&fsstats);
if(rv == 0)
{
fsblkcnt_t spaceavail;
spaceavail = (fsstats.f_bsize * fsstats.f_bavail);
if(spaceavail > mfs)
{
mfs = spaceavail;
mfspath = mountpoint;
}
}
}
fullmfspath = make_path(mfspath,fusepath);
return Path(mfspath,fullmfspath);
}
Path
find_mfs(const vector<string> &paths,
const string fusepath)
{
return find_mfs(paths.begin(),
paths.end(),
fusepath);
}
Path
find_mfs_existing(vector<string>::const_iterator iter,
vector<string>::const_iterator enditer,
const string fusepath)
{
fsblkcnt_t existingmfs = 0;
fsblkcnt_t generalmfs = 0;
string path;
string generalmfspath;
string existingmfspath;
do
{
int rv;
struct statvfs fsstats;
const string mountpoint = *iter;
rv = ::statvfs(mountpoint.c_str(),&fsstats);
if(rv == 0)
{
struct stat filestats;
fsblkcnt_t spaceavail;
spaceavail = (fsstats.f_bsize * fsstats.f_bavail);
if(spaceavail > generalmfs)
{
generalmfs = spaceavail;
generalmfspath = mountpoint;
}
path = make_path(mountpoint,fusepath);
rv = ::lstat(path.c_str(),&filestats);
if(rv == 0)
{
if(spaceavail > existingmfs)
{
existingmfs = spaceavail;
existingmfspath = mountpoint;
}
}
}
++iter;
}
while(iter != enditer);
if(existingmfspath.empty())
existingmfspath = generalmfspath;
return Path(existingmfspath,path);
}
Path
find_mfs_existing(const vector<string> &paths,
const string fusepath)
{
return find_mfs_existing(paths.begin(),
paths.end(),
fusepath);
}
Path
find_random(vector<string>::const_iterator iter,
vector<string>::const_iterator enditer,
string fusepath)
{
string randombasepath;
string randomfullpath;
randombasepath = *random_element(iter,enditer);
randomfullpath = make_path(randombasepath,fusepath);
return Path(randombasepath,randomfullpath);
}
Path
find_random(const vector<string> &paths,
const string fusepath)
{
return find_random(paths.begin(),
paths.end(),
fusepath);
}
int
listxattr(const string path,
vector<char> &attrs)
{
int rv;
int size;
rv = -1;
errno = ERANGE;
while(rv == -1 && errno == ERANGE)
{
size = ::listxattr(path.c_str(),NULL,0);
attrs.resize(size);
rv = ::listxattr(path.c_str(),&attrs[0],size);
}
return rv;
}
int
listxattr(const string path,
vector<string> &attrvector)
{
int rv;
vector<char> attrs;
rv = listxattr(path,attrs);
if(rv != -1)
{
string tmp(attrs.begin(),attrs.end());
split(attrvector,tmp,'\0');
}
return rv;
}
int
listxattr(const string path,
string &attrstr)
{
int rv;
vector<char> attrs;
rv = listxattr(path,attrs);
if(rv != -1)
attrstr = string(attrs.begin(),attrs.end());
return rv;
}
int
getxattr(const string path,
const string attr,
vector<char> &value)
{
int rv;
int size;
rv = -1;
errno = ERANGE;
while(rv == -1 && errno == ERANGE)
{
size = ::getxattr(path.c_str(),attr.c_str(),NULL,0);
value.resize(size);
rv = ::getxattr(path.c_str(),attr.c_str(),&value[0],size);
}
return rv;
}
int
getxattr(const string path,
const string attr,
string &value)
{
int rv;
vector<char> tmpvalue;
rv = getxattr(path,attr,tmpvalue);
if(rv != -1)
value = string(tmpvalue.begin(),tmpvalue.end());
return rv;
}
int
getxattrs(const string path,
map<string,string> &attrs)
{
int rv;
string attrstr;
rv = listxattr(path,attrstr);
if(rv == -1)
return -1;
{
string key;
istringstream ss(attrstr);
while(getline(ss,key,'\0'))
{
string value;
rv = getxattr(path,key,value);
if(rv != -1)
attrs[key] = value;
}
}
return 0;
}
int
setxattr(const string path,
const string key,
const string value,
const int flags)
{
return ::setxattr(path.c_str(),
key.c_str(),
value.data(),
value.size(),
flags);
}
int
setxattr(const int fd,
const string key,
const string value,
const int flags)
{
return ::fsetxattr(fd,
key.c_str(),
value.data(),
value.size(),
flags);
}
int
setxattrs(const string path,
const map<string,string> &attrs)
{
int fd;
fd = ::open(path.c_str(),O_RDONLY|O_NONBLOCK);
if(fd == -1)
return -1;
for(map<string,string>::const_iterator
i = attrs.begin(), ei = attrs.end(); i != ei; ++i)
{
setxattr(fd,i->first,i->second,0);
}
return ::close(fd);
}
int
copyxattrs(const string from,
const string to)
{
int rv;
map<string,string> attrs;
rv = getxattrs(from,attrs);
if(rv == -1)
return -1;
return setxattrs(to,attrs);
}
int
copyattr(const string from,
const string to)
{
int fd;
int rv;
int flags;
int error;
const int openflags = O_RDONLY|O_NONBLOCK;
fd = ::open(from.c_str(),openflags);
if(fd == -1)
return -1;
rv = ::ioctl(fd,FS_IOC_GETFLAGS,&flags);
if(rv == -1)
{
error = errno;
::close(fd);
errno = error;
return -1;
}
fd = ::open(to.c_str(),openflags);
if(fd == -1)
return -1;
rv = ::ioctl(fd,FS_IOC_SETFLAGS,&flags);
if(rv == -1)
{
error = errno;
::close(fd);
errno = error;
return -1;
}
return ::close(fd);
}
int
clonepath(const string fromsrc,
const string tosrc,
const string relative)
{
int rv;
struct stat st;
string topath;
string frompath;
string dirname;
dirname = fs::dirname(relative);
if(!dirname.empty())
{
rv = clonepath(fromsrc,tosrc,dirname);
if(rv == -1)
return -1;
}
frompath = make_path(fromsrc,relative);
rv = ::stat(frompath.c_str(),&st);
if(rv == -1)
return -1;
else if(!S_ISDIR(st.st_mode))
return (errno = ENOTDIR,-1);
topath = make_path(tosrc,relative);
rv = ::mkdir(topath.c_str(),st.st_mode);
if(rv == -1)
return -1;
rv = ::chown(topath.c_str(),st.st_uid,st.st_gid);
if(rv == -1)
return -1;
// It may not support it... it's fine...
rv = copyattr(frompath,topath);
if(rv == -1 && errno != ENOTTY)
return -1;
rv = copyxattrs(frompath,topath);
if(rv == -1 && errno != ENOTTY)
return -1;
return (errno = 0);
}
};