fuse.hpp

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#pragma once
 
#include <cstring>
#include <filesystem>
#include <expected>
#include <sys/vfs.h>
#include <sys/mount.h>
#include <thread>
 
#include "subprocess.hpp"
#include "env.hpp"
#include "../std/expected.hpp"
 
// Other codes available here:
// https://man7.org/linux/man-pages/man2/statfs.2.html
#define FUSE_SUPER_MAGIC 0x65735546

namespace ns_fuse
{
 
namespace
{
 
namespace fs = std::filesystem;
 
} // namespace

inline Value<bool> is_fuse(fs::path const& path_dir_mount)
{
  struct statfs buf;
 
  if ( statfs(path_dir_mount.c_str(), &buf) < 0 )
  {
    return Error("E::{}", strerror(errno));
  }
 
  return buf.f_type == FUSE_SUPER_MAGIC;
}

inline void wait_fuse(fs::path const& path_dir_filesystem)
{
  using namespace std::chrono_literals;
  auto time_beg = std::chrono::system_clock::now();
  while ( true )
  {
    auto expected_is_fuse = ns_fuse::is_fuse(path_dir_filesystem);
    break_if(not expected_is_fuse, "E::Could not check if filesystem is fuse");
    break_if(*expected_is_fuse, "D::Filesystem '{}' is fuse", path_dir_filesystem.string());
    auto time_cur = std::chrono::system_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::seconds>(time_cur - time_beg);
    break_if(elapsed.count() > 60, "E::Reached timeout to wait for fuse filesystems");
  } // while
} // function: wait_fuse
 

inline Value<int> unmount(fs::path const& path_dir_mount)
{
  using namespace std::chrono_literals;
 
  // Find fusermount
  auto path_file_fusermount = Pop(ns_env::search_path("fusermount"));
 
  // Un-mount filesystem
  using enum ns_subprocess::Stream;
  auto child = ns_subprocess::Subprocess(path_file_fusermount)
    .with_args("-zu", path_dir_mount)
    .spawn();
 
  // Check if process was started
  return_if(not child, Error("E::Could not spawn fusermount"));
 
  // Retrieve return code
  int code = Pop(child->wait());
 
  // Check for successful un-mount
  if(code == 0)
  {
    logger("D::Un-mounted filesystem '{}'", path_dir_mount.string());
  }
  else
  {
    logger("D::Failed to un-mount filesystem '{}'", path_dir_mount.string());
  }
 
  // Filesystem could be busy for a bit after un-mount
  while(Pop(ns_fuse::is_fuse(path_dir_mount)))
  {
    std::this_thread::sleep_for(100ms);
  }
 
  return code;
} // function: unmount
 
} // namespace ns_fuse
 
/* vim: set expandtab fdm=marker ts=2 sw=2 tw=100 et :*/