mergerfs/src/fuse_statx_supported.icpp

/*
  ISC License

  Copyright (c) 2025, 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 "fuse_statx.hpp"

#include "config.hpp"
#include "errno.hpp"
#include "fileinfo.hpp"
#include "fs_inode.hpp"
#include "fs_path.hpp"
#include "fs_statx.hpp"
#include "state.hpp"
#include "str.hpp"
#include "symlinkify.hpp"
#include "ugid.hpp"

#include "fmt/core.h"

#include "fuse.h"

#include <string>


static
void
_set_stat_if_leads_to_dir(const fs::path    &path_,
                          struct fuse_statx *st_)
{
  int rv;
  struct fuse_statx st;

  rv = fs::statx(AT_FDCWD,path_,AT_SYMLINK_FOLLOW,STATX_TYPE,&st);
  if(rv < 0)
    return;

  if(S_ISDIR(st.mode))
    *st_ = st;

  return;
}

static
void
_set_stat_if_leads_to_reg(const fs::path    &path_,
                          struct fuse_statx *st_)
{
  int rv;
  struct fuse_statx st;

  rv = fs::statx(AT_FDCWD,path_,AT_SYMLINK_FOLLOW,STATX_TYPE,&st);
  if(rv < 0)
    return;

  if(S_ISREG(st.mode))
    *st_ = st;

  return;
}

static
int
_statx_fake_root(struct fuse_statx *st_)
{
  st_->ino     = 0;
  st_->mode    = (S_IFDIR|S_IRWXU|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH);
  st_->nlink   = 2;
  st_->uid     = 0;
  st_->gid     = 0;
  st_->size    = 0;
  st_->blocks  = 0;
  st_->atime.tv_sec = 0;
  st_->mtime.tv_sec = 0;
  st_->ctime.tv_sec = 0;

  return 0;
}

static
int
_statx_controlfile(struct fuse_statx *st_)
{
  static const uid_t  uid = ::getuid();
  static const gid_t  gid = ::getgid();
  static const time_t now = ::time(NULL);

  st_->ino     = 0;
  st_->mode    = (S_IFREG|S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP|S_IROTH);
  st_->nlink   = 1;
  st_->uid     = uid;
  st_->gid     = gid;
  st_->size    = 0;
  st_->blocks  = 0;
  st_->atime.tv_sec = now;
  st_->mtime.tv_sec = now;
  st_->ctime.tv_sec = now;

  return 0;
}

static
int
_statx(const Policy::Search &searchFunc_,
       const Branches       &branches_,
       const fs::path       &fusepath_,
       const uint32_t        flags_,
       const uint32_t        mask_,
       struct fuse_statx    *st_,
       const bool            symlinkify_,
       const time_t          symlinkify_timeout_,
       FollowSymlinks        followsymlinks_)
{
  int rv;
  fs::path fullpath;
  std::vector<Branch*> branches;

  rv = searchFunc_(branches_,fusepath_,branches);
  if(rv < 0)
    return rv;

  fullpath = branches[0]->path / fusepath_;

  switch(followsymlinks_)
    {
    case FollowSymlinks::ENUM::NEVER:
      rv = fs::statx(AT_FDCWD,fullpath,flags_|AT_SYMLINK_NOFOLLOW,mask_,st_);
      break;
    case FollowSymlinks::ENUM::DIRECTORY:
      rv = fs::statx(AT_FDCWD,fullpath,flags_|AT_SYMLINK_NOFOLLOW,mask_,st_);
      if((rv >= 0) && S_ISLNK(st_->mode))
        ::_set_stat_if_leads_to_dir(fullpath,st_);
      break;
    case FollowSymlinks::ENUM::REGULAR:
      rv = fs::statx(AT_FDCWD,fullpath,flags_|AT_SYMLINK_NOFOLLOW,mask_,st_);
      if((rv >= 0) && S_ISLNK(st_->mode))
        ::_set_stat_if_leads_to_reg(fullpath,st_);
      break;
    case FollowSymlinks::ENUM::ALL:
      rv = fs::statx(AT_FDCWD,fullpath,flags_|AT_SYMLINK_FOLLOW,mask_,st_);
      if(rv < 0)
        rv = fs::statx(AT_FDCWD,fullpath,flags_|AT_SYMLINK_NOFOLLOW,mask_,st_);
      break;
    }

  if(rv < 0)
    return rv;

  if(symlinkify_ && symlinkify::can_be_symlink(*st_,symlinkify_timeout_))
    symlinkify::convert(fullpath,st_);

  fs::inode::calc(branches[0]->path,
                  fusepath_,
                  st_);

  return 0;
}

static
int
_statx(const fs::path    &fusepath_,
       const uint32_t     flags_,
       const uint32_t     mask_,
       struct fuse_statx *st_,
       fuse_timeouts_t   *timeout_)
{
  int rv;

  rv = ::_statx(cfg.func.getattr.policy,
                cfg.branches,
                fusepath_,
                flags_,
                mask_,
                st_,
                cfg.symlinkify,
                cfg.symlinkify_timeout,
                cfg.follow_symlinks);
  if((rv < 0) && Config::is_rootdir(fusepath_))
    return ::_statx_fake_root(st_);

  timeout_->entry = ((rv >= 0) ?
                     cfg.cache_entry :
                     cfg.cache_negative_entry);
  timeout_->attr  = cfg.cache_attr;

  return rv;
}

int
FUSE::statx(const fuse_req_ctx_t *ctx_,
            const char           *fusepath_,
            const uint32_t        flags_,
            const uint32_t        mask_,
            struct fuse_statx    *st_,
            fuse_timeouts_t      *timeout_)
{
  const fs::path fusepath{fusepath_};

  if(Config::is_ctrl_file(fusepath))
    return ::_statx_controlfile(st_);

  const ugid::Set ugid(ctx_);

  return ::_statx(fusepath,
                  flags_|AT_STATX_DONT_SYNC,
                  mask_,
                  st_,
                  timeout_);
}

int
FUSE::statx_fh(const fuse_req_ctx_t *ctx_,
               const uint64_t        fh_,
               const uint32_t        flags_,
               const uint32_t        mask_,
               struct fuse_statx    *st_,
               fuse_timeouts_t      *timeout_)
{
  uint64_t fh;

  fh = fh_;
  if(fh == 0)
    {
      state.open_files.cvisit(ctx_->nodeid,
                              [&](auto &val_)
                              {
                                fh = val_.second.fi->to_fh();
                              });
    }

  if(fh == 0)
    return -ENOENT;

  FileInfo *fi = FileInfo::from_fh(fh);

  const ugid::Set ugid(ctx_);

  return ::_statx(fi->fusepath,
                  flags_|AT_STATX_DONT_SYNC,
                  mask_,
                  st_,
                  timeout_);
}