mergerfs/src/fuse_readdir_plus_posix.cpp

/*
  Copyright (c) 2019, 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.
*/

#define _DEFAULT_SOURCE

#include "branches.hpp"
#include "errno.hpp"
#include "fs_closedir.hpp"
#include "fs_devid.hpp"
#include "fs_dirfd.hpp"
#include "fs_fstatat.hpp"
#include "fs_inode.hpp"
#include "fs_opendir.hpp"
#include "fs_path.hpp"
#include "fs_readdir.hpp"
#include "fs_stat.hpp"
#include "hashset.hpp"

#include "fuse.h"
#include "fuse_dirents.h"

#include <string>
#include <vector>

#include <dirent.h>

using std::string;
using std::vector;

namespace l
{
  static
  uint64_t
  dirent_exact_namelen(const struct dirent *d_)
  {
#ifdef _D_EXACT_NAMLEN
    return _D_EXACT_NAMLEN(d_);
#elif defined _DIRENT_HAVE_D_NAMLEN
    return d_->d_namlen;
#else
    return strlen(d_->d_name);
#endif
  }

  static
  int
  readdir_plus(const Branches::CPtr &branches_,
               const char           *dirname_,
               const uint64_t        entry_timeout_,
               const uint64_t        attr_timeout_,
               fuse_dirents_t       *buf_)
  {
    dev_t dev;
    HashSet names;
    string basepath;
    string fullpath;
    struct stat st;
    uint64_t namelen;
    fuse_entry_t entry;

    fuse_dirents_reset(buf_);

    entry.nodeid           = 0;
    entry.generation       = 0;
    entry.entry_valid      = entry_timeout_;
    entry.attr_valid       = attr_timeout_;
    entry.entry_valid_nsec = 0;
    entry.attr_valid_nsec  = 0;
    for(auto &branch : *branches_)
      {
        int rv;
        int dirfd;
        DIR *dh;

        basepath = fs::path::make(branch.path,dirname_);

        dh = fs::opendir(basepath);
        if(!dh)
          continue;

        dirfd = fs::dirfd(dh);
        dev   = fs::devid(dirfd);

        rv = 0;
        for(struct dirent *de = fs::readdir(dh); de && !rv; de = fs::readdir(dh))
          {
            namelen = l::dirent_exact_namelen(de);

            rv = names.put(de->d_name,namelen);
            if(rv == 0)
              continue;

            rv = fs::fstatat_nofollow(dirfd,de->d_name,&st);
            if(rv == -1)
              {
                memset(&st,0,sizeof(st));
                st.st_ino  = de->d_ino;
                st.st_dev  = dev;
                st.st_mode = DTTOIF(de->d_type);
              }

            fullpath = fs::path::make(dirname_,de->d_name);
            fs::inode::calc(fullpath,&st);
            de->d_ino = st.st_ino;

            rv = fuse_dirents_add_plus(buf_,de,namelen,&entry,&st);
            if(rv)
              return (fs::closedir(dh),-ENOMEM);
          }

        fs::closedir(dh);
      }

    return 0;
  }
}

namespace FUSE
{
  int
  readdir_plus_posix(const Branches::CPtr &branches_,
                     const char           *dirname_,
                     const uint64_t        entry_timeout_,
                     const uint64_t        attr_timeout_,
                     fuse_dirents_t       *buf_)
  {
    return l::readdir_plus(branches_,dirname_,entry_timeout_,attr_timeout_,buf_);
  }
}