Add fsck.mergerfs tool (#1483)

DEPENDENCIES

@@ -8,6 +8,7 @@
 * concurrentqueue: https://github.com/cameron314/concurrentqueue
 * scope_guard: https://github.com/Neargye/scope_guard
 * subprocess: https://github.com/arun11299/cpp-subprocess
+* CLI11: https://github.com/CLIUtils/CLI11
 * boost
   * download boost
   * ./bootstrap.sh

Makefile

@@ -22,7 +22,7 @@ LN        = ln
 FIND 	  = find
 INSTALL   = install
 MKTEMP    = mktemp
-STRIP     = strip
+STRIP    ?= strip
 SED       = sed
 GIT2DEBCL = ./buildtools/git2debcl
 PKGCONFIG = pkg-config
@@ -136,6 +136,7 @@ build/tests: build/mergerfs tests-objects
 	$(CXX) $(CXXFLAGS) $(TESTS_FLAGS) $(FUSE_FLAGS) $(MFS_FLAGS) $(CPPFLAGS) $(TESTS_OBJS) -o $@ libfuse/build/libfuse.a $(LDFLAGS)
 
 mergerfs: build/mergerfs
+	ln -fs "mergerfs" "build/fsck.mergerfs"
 
 tests: build/tests
 
@@ -181,7 +182,8 @@ install: install-base install-mount-tools install-preload install-man
 
 install-base: build/mergerfs
 	$(MKDIR) -p "$(INSTALLBINDIR)"
-	$(INSTALL) -v -m 0755 build/mergerfs "$(INSTALLBINDIR)/mergerfs"
+	$(INSTALL) -v -m 0755 "build/mergerfs" "$(INSTALLBINDIR)/mergerfs"
+	ln -s "mergerfs" "${INSTALLBINDIR}/fsck.mergerfs"
 
 install-mount-tools: install-base
 	$(MKDIR) -p "$(INSTALLBINDIR)"
@@ -231,14 +233,14 @@ endif
 signed-deb:
 	$(MAKE) distclean
 	$(MAKE) debian-changelog
-#	dpkg-source -b .
-	dpkg-buildpackage -nc
+	fakeroot dpkg-buildpackage -nc
 
 deb:
 	$(MAKE) distclean
 	$(MAKE) debian-changelog
-#	dpkg-source -b .
-	dpkg-buildpackage -nc -uc -us
+	fakeroot dpkg-buildpackage -nc -uc -us
+	mkdir -p ./build/pkgs/
+	mv -v ../mergerfs*deb ./build/pkgs/
 
 .PHONY: rpm-clean
 rpm-clean:
@@ -268,6 +270,11 @@ release:
 		--target=all \
 		--cleanup \
 		--branch=$(shell git branch --show-current)
+release-sample:
+	./buildtools/build-release \
+		--target=debian.12.amd64 \
+		--cleanup \
+		--branch=$(shell git branch --show-current)
 release-amd64:
 	./buildtools/build-release \
 		--target=amd64 \

buildtools/install-build-pkgs

@@ -7,7 +7,7 @@ if [ -e /usr/bin/apt-get ]; then
 	    install \
             ca-certificates \
             build-essential \
-            dpkg \
+            dpkg-dev \
             git \
             g++ \
             debhelper \

debian/compat

@@ -1 +0,0 @@
-9

debian/control

@@ -2,7 +2,7 @@ Source: mergerfs
 Section: utils
 Priority: optional
 Maintainer: Antonio SJ Musumeci <trapexit@spawn.link>
-Build-Depends: debhelper (>= 8.0.0)
+Build-Depends: debhelper-compat (= 10)
 Standards-Version: 3.9.4
 Homepage: http://github.com/trapexit/mergerfs
 

debian/rules

@@ -1,11 +1,13 @@
 #!/usr/bin/make -f
 # -*- makefile -*-
 
-# Uncomment this to turn on verbose mode.
 export DH_VERBOSE=1
 
 %:
-	dh $@ --parallel
+	dh $@ --parallel --max-parallel=6
+
+override_dh_strip:
+	dh_strip --no-automatic-dbgsym
 
 override_dh_auto_install:
 	$(MAKE) DESTDIR=$(CURDIR)/debian/mergerfs PREFIX=/usr install

libfuse/Makefile

@@ -137,7 +137,7 @@ strip:
 install-utils: mergerfs-fusermount mount.mergerfs strip
 	install -D build/mergerfs-fusermount "$(INSTALLBINDIR)/mergerfs-fusermount"
 	install -D build/mount.mergerfs "$(INSTALLSBINDIR)/mount.mergerfs"
-	chown root "$(INSTALLBINDIR)/mergerfs-fusermount"
+	chown root:root "$(INSTALLBINDIR)/mergerfs-fusermount"
 	chmod u+s "$(INSTALLBINDIR)/mergerfs-fusermount"
 
 install: $(INSTALLUTILS)

mergerfs.spec

@@ -34,6 +34,7 @@ make install PREFIX=%{_prefix} DESTDIR=%{buildroot}
 %files
 /usr/bin/mergerfs
 /usr/bin/mergerfs-fusermount
+/usr/bin/fsck.mergerfs
 /sbin/mount.mergerfs
 /usr/lib/mergerfs/preload.so
 %doc %{_mandir}/*

src/fs_clonefile.cpp

@@ -60,6 +60,7 @@ namespace fs
     if(rv == -1)
       return -1;
 
+    // TODO: should not copy "immutable" flag till last
     rv = fs::attr::copy(src_fd_,dst_fd_);
     if((rv == -1) && !l::ignorable_error(errno))
       return -1;

src/fs_copydata_copy_file_range.cpp

@@ -41,6 +41,8 @@ namespace l
         rv = fs::copy_file_range(src_fd_,&src_off,dst_fd_,&dst_off,nleft,0);
         if((rv == -1) && (errno == EINTR))
           continue;
+        if((rv == -1) && (errno == EAGAIN))
+          continue;
         if(rv == -1)
           return -1;
 

src/fs_copydata_readwrite.cpp

@@ -42,6 +42,8 @@ namespace l
         rv = fs::write(fd_,buf_,nleft);
         if((rv == -1) && (errno == EINTR))
           continue;
+        if((rv == -1) && (errno == EAGAIN))
+          continue;
         if(rv == -1)
           return -1;
 
@@ -76,6 +78,8 @@ namespace l
           return totalwritten;
         if((nr == -1) && (errno == EINTR))
           continue;
+        if((nr == -1) && (errno == EAGAIN))
+          continue;
         if(nr == -1)
           return -1;
 

src/fs_copyfile.cpp

@@ -0,0 +1,39 @@
+#include "fs_copyfile.hpp"
+
+#include "fs_clonefile.hpp"
+#include "fs_close.hpp"
+#include "fs_mktemp.hpp"
+#include "fs_open.hpp"
+#include "fs_rename.hpp"
+#include "scope_guard.hpp"
+
+#include <fcntl.h>
+
+
+int
+fs::copyfile(const std::filesystem::path &src_,
+             const std::filesystem::path &dst_)
+{
+  int rv;
+  int src_fd;
+  int dst_fd;
+  std::string dst_tmppath;
+
+  src_fd = fs::open(src_,O_RDONLY|O_NOFOLLOW);
+  if(src_fd < 0)
+    return src_fd;
+  DEFER { fs::close(src_fd); };
+
+  std::tie(dst_fd,dst_tmppath) = fs::mktemp(dst_,O_RDWR);
+  if(dst_fd < 0)
+    return dst_fd;
+  DEFER { fs::close(dst_fd); };
+
+  rv = fs::clonefile(src_fd,dst_fd);
+  if(rv < 0)
+    return rv;
+
+  rv = fs::rename(dst_tmppath,dst_);
+
+  return rv;
+}

src/fs_copyfile.hpp

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <filesystem>
+
+namespace fs
+{
+  int copyfile(const std::filesystem::path &src,
+               const std::filesystem::path &dst);
+}

src/fs_is_rofs.hpp

@@ -52,7 +52,7 @@ namespace fs
     int fd;
     std::string tmp_filepath;
 
-    std::tie(fd,tmp_filepath) = fs::mktemp_in_dir(path_,O_WRONLY);
+    std::tie(fd,tmp_filepath) = fs::mktemp_in_dir(path_,"",O_WRONLY);
     if(fd < 0)
       return (fd == -EROFS);
 

src/fs_mktemp.cpp

@@ -22,12 +22,14 @@
 #include "rnd.hpp"
 
 #include <limits.h>
+#include <unistd.h>
 
+#include <algorithm>
 #include <cstdlib>
 #include <string>
 #include <tuple>
 
-#define PAD_LEN             16
+#define PAD_LEN             6ULL
 #define MAX_ATTEMPTS        3
 
 static char const CHARS[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
@@ -38,16 +40,28 @@ namespace l
 {
   static
   std::string
-  generate_tmp_path(std::string const base_)
+  generate_tmp_path(const std::string &dirpath_,
+                    const std::string &filename_)
   {
+    long name_max;
+    size_t substr_len;
     fs::Path path;
     std::string filename;
 
-    filename  = '.';
-    for(int i = 0; i < PAD_LEN; i++)
+    name_max = pathconf(dirpath_.c_str(),_PC_NAME_MAX);
+    if(name_max == -1)
+      name_max = NAME_MAX;
+
+    substr_len = std::min(filename_.size(),
+                          (size_t)(name_max - PAD_LEN - 2ULL));
+
+    filename = '.';
+    filename += filename_.substr(0,substr_len);
+    filename += '_';
+    for(size_t i = 0; i < PAD_LEN; i++)
       filename += CHARS[RND::rand64(CHARS_SIZE)];
 
-    path = base_;
+    path = dirpath_;
     path /= filename;
 
     return path.string();
@@ -57,7 +71,8 @@ namespace l
 namespace fs
 {
   std::tuple<int,std::string>
-  mktemp_in_dir(const std::string dirpath_,
+  mktemp_in_dir(const std::string &dirpath_,
+                const std::string &filename_,
                 const int         flags_)
   {
     int fd;
@@ -67,12 +82,12 @@ namespace fs
 
     fd    = -1;
     count = MAX_ATTEMPTS;
-    flags = (flags_ | O_EXCL | O_CREAT | O_TRUNC);
+    flags = (flags_ | O_EXCL | O_CREAT);
     while(count-- > 0)
       {
-        tmp_filepath = l::generate_tmp_path(dirpath_);
+        tmp_filepath = l::generate_tmp_path(dirpath_,filename_);
 
-        fd = fs::open(tmp_filepath,flags,S_IWUSR);
+        fd = fs::open(tmp_filepath,flags,S_IRUSR|S_IWUSR);
         if((fd == -1) && (errno == EEXIST))
           continue;
         if(fd == -1)
@@ -85,11 +100,13 @@ namespace fs
   }
 
   std::tuple<int,std::string>
-  mktemp(const std::string filepath_,
-         const int         flags_)
+  mktemp(const std::string &filepath_,
+         const int          flags_)
   {
     fs::Path filepath{filepath_};
 
-    return fs::mktemp_in_dir(filepath.parent_path(),flags_);
+    return fs::mktemp_in_dir(filepath.parent_path(),
+                             filepath.filename(),
+                             flags_);
   }
 }

src/fs_mktemp.hpp

@@ -23,11 +23,13 @@
 
 namespace fs
 {
-  std::tuple<int,std::string>
-  mktemp(std::string const filepath,
-         int const         flags);
 
   std::tuple<int,std::string>
-  mktemp_in_dir(std::string const dirpath,
+  mktemp_in_dir(const std::string &dirpath,
+                const std::string &filename,
                 int const         flags);
+
+  std::tuple<int,std::string>
+  mktemp(const std::string &filepath,
+         const int          flags);
 }

src/fsck_mergerfs.cpp

@@ -0,0 +1,454 @@
+#include "fsck_mergerfs.hpp"
+
+#include "fs_lchmod.hpp"
+#include "fs_lchown.hpp"
+#include "fs_close.hpp"
+#include "fs_ioctl.hpp"
+#include "fs_lgetxattr.hpp"
+#include "fs_lstat.hpp"
+#include "fs_open.hpp"
+#include "int_types.h"
+#include "mergerfs_ioctl.hpp"
+#include "str.hpp"
+#include "fs_copyfile.hpp"
+
+#include "fmt/core.h"
+#include "fmt/chrono.h"
+#include "CLI11.hpp"
+
+#include <filesystem>
+
+namespace FS = std::filesystem;
+
+struct PathStat
+{
+  PathStat(const std::string &path_)
+    : path(path_),
+      st{}
+  {
+  }
+
+  std::string path;
+  struct stat st;
+};
+
+using PathStatVec = std::vector<PathStat>;
+using FixFunc = std::function<void(const PathStatVec&,const bool)>;
+
+static
+bool
+_files_differ(const PathStatVec &paths_,
+              const bool         check_size_)
+{
+  if(paths_.size() <= 1)
+    return false;
+
+  const struct stat &st0 = paths_[0].st;
+  for(u64 i = 1; i < paths_.size(); i++)
+    {
+      const struct stat &st = paths_[i].st;
+
+      if(st.st_mode != st0.st_mode)
+        return true;
+      if(st.st_uid != st0.st_uid)
+        return true;
+      if(st.st_gid != st0.st_gid)
+        return true;
+      if(check_size_ &&
+         S_ISREG(st0.st_mode) &&
+         (st.st_size != st0.st_size))
+        return true;
+    }
+
+  return false;
+}
+
+static
+bool
+_files_same_type(const PathStatVec &paths_)
+{
+  mode_t type;
+
+  if(paths_.size() <= 1)
+    return true;
+
+  type = (paths_[0].st.st_mode & S_IFMT);
+  for(u64 i = 1; i < paths_.size(); i++)
+    {
+      if((paths_[i].st.st_mode & S_IFMT) != type)
+        return false;
+    }
+
+  return true;
+}
+
+static
+const char*
+_file_type(const mode_t mode_)
+{
+  switch(mode_ & S_IFMT)
+    {
+    case S_IFBLK:
+      return "block dev";
+    case S_IFCHR:
+      return "char dev";
+    case S_IFDIR:
+      return "directory";
+    case S_IFIFO:
+      return "fifo";
+    case S_IFLNK:
+      return "symlink";
+    case S_IFSOCK:
+      return "socket";
+    case S_IFREG:
+      return "regular";
+    }
+
+  return "unknown";
+}
+
+static
+void
+_compare_files(const std::string &mergerfs_path_,
+               PathStatVec       &pathstats_,
+               const FixFunc      fix_func_,
+               const bool         check_size_,
+               const bool         copy_file_)
+{
+  int rv;
+
+  if(pathstats_.size() <= 1)
+    return;
+
+  for(auto &pathstat : pathstats_)
+    {
+      rv = fs::lstat(pathstat.path,&pathstat.st);
+      if(rv == -1)
+        pathstat.st.st_size = -errno;
+    }
+
+  if(!::_files_differ(pathstats_,check_size_))
+    return;
+
+  fmt::println("* {}",mergerfs_path_);
+  for(u64 i = 0; i < pathstats_.size(); i++)
+    {
+      const auto &path = pathstats_[i].path;
+      const auto &st   = pathstats_[i].st;
+
+      fmt::println("  {}: {}",i,path);
+      if(st.st_size < 0)
+        fmt::println("    - err: {}",strerror(-st.st_size));
+      fmt::println("    -"
+                   " uid: {};"
+                   " gid: {};"
+                   " mode: {:05o};"
+                   " type: {};"
+                   " size: {};"
+                   " mtime: {:%Y-%m-%dT%H:%M:%S%z}",
+                   st.st_uid,
+                   st.st_gid,
+                   st.st_mode,
+                   ::_file_type(st.st_mode),
+                   st.st_size,
+                   *std::localtime(&st.st_mtime));
+    }
+
+  if(!fix_func_)
+    return;
+
+  if(::_files_same_type(pathstats_))
+    fix_func_(pathstats_,copy_file_);
+  else
+    fmt::println("  X: WARNING - files are of different types."
+                 " Requires manual intervention.");
+}
+
+static
+int
+_get_allpaths(const std::string &mergerfs_path_,
+              PathStatVec       &pathstats_)
+{
+  int fd;
+  int rv;
+  IOCTL_BUF buf;
+  std::vector<std::string> allpaths;
+
+  strcpy(buf,"allpaths");
+
+  fd = fs::open(mergerfs_path_,O_RDONLY|O_NOFOLLOW);
+  if(fd == -1)
+    return -errno;
+
+  rv = fs::ioctl(fd,IOCTL_FILE_INFO,buf);
+
+  fs::close(fd);
+
+  str::split_on_null(buf,rv,&allpaths);
+  for(const auto &path : allpaths)
+    pathstats_.emplace_back(path);
+
+  return 0;
+}
+
+static
+u64
+_read_u64(const u64 min_,
+          const u64 max_)
+{
+  u64 rv;
+  while(true)
+    {
+      fmt::print("Select correct file: ");
+      std::cin >> rv;
+      if((rv >= min_) && (rv <= max_))
+        return rv;
+      std::cin.clear();
+      std::cin.ignore(100, '\n');
+    }
+}
+
+static
+void
+_setattr(const struct stat &st_,
+         const PathStatVec &pathstats_)
+{
+  int rv;
+
+  for(const auto &path : pathstats_)
+    {
+      rv  = fs::lchmod(path.path,st_.st_mode);
+      rv |= fs::lchown(path.path,st_.st_uid,st_.st_gid);
+      if(rv)
+        fmt::println("ERROR: problem setting mode or owner - {}",
+                     strerror(errno));
+    }
+}
+
+static
+void
+_copy_files(const std::string &src_,
+            const PathStatVec &dsts_)
+{
+  for(const auto &dst : dsts_)
+    {
+      int rv;
+
+      // TODO: Additional protection to confirm not the literal same
+      // file. fs::is_same_file(src,dst);
+      if(src_ == dst.path)
+        continue;
+
+      rv = fs::copyfile(src_,dst.path);
+      if(rv < 0)
+        fmt::print(stderr,
+                   "ERROR: failed copying to {} - {}",
+                   dst.path,
+                   strerror(errno));
+    }
+}
+
+static
+bool
+_mtime_cmp(const struct stat &a_,
+           const struct stat &b_)
+{
+  if(a_.st_mtim.tv_sec == b_.st_mtim.tv_sec)
+    return (a_.st_mtim.tv_nsec < b_.st_mtim.tv_nsec);
+  return (a_.st_mtim.tv_sec < b_.st_mtim.tv_sec);
+}
+
+static
+bool
+_pathstat_cmp(const PathStatVec::value_type &a_,
+              const PathStatVec::value_type &b_)
+{
+  return ::_mtime_cmp(a_.st,b_.st);
+}
+
+static
+const
+PathStatVec::value_type*
+_find_latest_mtime(const PathStatVec &pathstats_)
+{
+  PathStatVec::const_iterator i;
+
+  i = std::max_element(pathstats_.begin(),
+                       pathstats_.end(),
+                       ::_pathstat_cmp);
+
+  return &(*i);
+}
+
+static
+const
+PathStatVec::value_type*
+_find_largest(const PathStatVec &pathstats_)
+{
+  PathStatVec::const_iterator i;
+
+  i = std::max_element(pathstats_.begin(),
+                       pathstats_.end(),
+                       [](const PathStatVec::value_type &a_,
+                          const PathStatVec::value_type &b_)
+                       {
+                         return (a_.st.st_size < b_.st.st_size);
+                       });
+
+  return &(*i);
+}
+
+static
+void
+_fix_func_manual(const PathStatVec &pathstats_,
+                 const bool         copy_file_)
+{
+  u64 idx;
+
+  idx = ::_read_u64(0ULL,pathstats_.size()-1);
+
+  if(copy_file_ && S_ISREG(pathstats_[idx].st.st_mode))
+    ::_copy_files(pathstats_[idx].path,pathstats_);
+  else
+    ::_setattr(pathstats_[idx].st,pathstats_);
+}
+
+static
+void
+_fix_func_newest(const PathStatVec &pathstats_,
+                 const bool         copy_file_)
+{
+  const PathStatVec::value_type *pathst;
+
+  pathst = _find_latest_mtime(pathstats_);
+  if(!pathst)
+    return;
+
+  if(copy_file_ && S_ISREG(pathst->st.st_mode))
+    ::_copy_files(pathst->path,pathstats_);
+  else
+    ::_setattr(pathst->st,pathstats_);
+};
+
+static
+void
+_fix_func_largest(const PathStatVec &pathstats_,
+                  const bool         copy_file_)
+{
+  const PathStatVec::value_type *pathst;
+
+  pathst = ::_find_largest(pathstats_);
+  if(!pathst)
+    return;
+
+  if(copy_file_ && S_ISREG(pathst->st.st_mode))
+    ::_copy_files(pathst->path,pathstats_);
+  else
+    ::_setattr(pathst->st,pathstats_);
+}
+
+static
+FixFunc
+_select_fix_func(const std::string &fix_)
+{
+  if(fix_ == "none")
+    return {};
+  else if(fix_ == "manual")
+    return ::_fix_func_manual;
+  else if(fix_ == "newest")
+    return ::_fix_func_newest;
+  else if(fix_ == "largest")
+    return ::_fix_func_largest;
+  else
+    abort();
+
+  return {};
+}
+
+static
+void
+_fsck(const FS::path &path_,
+      const FixFunc   fix_func_,
+      const bool      check_size_,
+      const bool      copy_file_)
+{
+  int rv;
+  PathStatVec paths;
+
+  ::_get_allpaths(path_,paths);
+  ::_compare_files(path_,paths,fix_func_,check_size_,copy_file_);
+
+  auto opts = FS::directory_options::skip_permission_denied;
+  auto rdi = FS::recursive_directory_iterator(path_,opts);
+  for(const auto &de : rdi)
+    {
+      paths.clear();
+      rv = ::_get_allpaths(de.path(),paths);
+      if(rv == -1)
+        continue;
+
+      ::_compare_files(de.path(),
+                       paths,
+                       fix_func_,
+                       check_size_,
+                       copy_file_);
+    }
+}
+
+int
+fsck::main(int    argc_,
+           char **argv_)
+{
+  CLI::App app;
+  FS::path path;
+  std::string fix;
+  bool check_size;
+  bool copy_file;
+  FixFunc fix_func;
+
+  app.description("fsck.mergerfs:"
+                  " A tool to help diagnose and solve mergerfs pool issues");
+  app.name("USAGE: fsck.mergerfs");
+
+  app.add_option("path",path)
+    ->description("mergerfs path")
+    ->check(CLI::ExistingDirectory)
+    ->required();
+  app.add_option("--fix",fix)
+    ->description("Will attempt to 'fix' the problem by chown+chmod or copying files based on a selected file.\n"
+                  " * none: Do nothing. Just print details.\n"
+                  " * manual: User selects source file.\n"
+                  " * newest: Use file with most recent mtime.\n"
+                  " * largest: Use file with largest size.")
+    ->check(CLI::IsMember({"none","manual","newest","largest"}))
+    ->default_val("none");
+  app.add_option("--check-size",check_size)
+    ->description("Considers file size in calculating differences")
+    ->default_val(false)
+    ->default_str("false");
+  app.add_option("--copy-file",copy_file)
+    ->description("Copy file rather than chown/chmod to fix")
+    ->default_val(false)
+    ->default_str("false");
+
+  try
+    {
+      app.parse(argc_,argv_);
+    }
+  catch(const CLI::ParseError &e)
+    {
+      return app.exit(e);
+    }
+
+  if((geteuid() != 0) && (fix != "none"))
+    fmt::println(stderr,"WARNING: fsck.mergerfs should be run as root to apply fixes");
+
+  fix_func = ::_select_fix_func(fix);
+
+  ::_fsck(path,
+          fix_func,
+          check_size,
+          copy_file);
+
+  return 0;
+}

src/fsck_mergerfs.hpp

@@ -0,0 +1,6 @@
+#pragma once
+
+namespace fsck
+{
+  int main(int argc, char **argv);
+}

src/fuse_ioctl.cpp

@@ -25,6 +25,7 @@
 #include "fs_open.hpp"
 #include "fs_path.hpp"
 #include "gidcache.hpp"
+#include "mergerfs_ioctl.hpp"
 #include "str.hpp"
 #include "ugid.hpp"
 
@@ -34,19 +35,6 @@
 #include <fcntl.h>
 #include <string.h>
 
-#ifndef _IOC_TYPE
-#define _IOC_TYPE(X) (((X) >> 8) & 0xFF)
-#endif
-
-typedef char IOCTL_BUF[4096];
-#define IOCTL_APP_TYPE             0xDF
-#define IOCTL_FILE_INFO            _IOWR(IOCTL_APP_TYPE,0,IOCTL_BUF)
-#define IOCTL_GC                   _IO(IOCTL_APP_TYPE,1)
-#define IOCTL_GC1                  _IO(IOCTL_APP_TYPE,2)
-#define IOCTL_INVALIDATE_ALL_NODES _IO(IOCTL_APP_TYPE,3)
-#define IOCTL_INVALIDATE_GID_CACHE _IO(IOCTL_APP_TYPE,4)
-
-
 // From linux/btrfs.h
 #define BTRFS_IOCTL_MAGIC 0x94
 

src/mergerfs.cpp

@@ -15,6 +15,7 @@
 */
 
 #include "mergerfs.hpp"
+#include "fsck_mergerfs.hpp"
 
 #include "fs_path.hpp"
 #include "fs_readahead.hpp"
@@ -327,9 +328,25 @@ namespace l
   }
 }
 
+static
+int
+_pick_app_and_run(int    argc_,
+                  char **argv_)
+{
+  std::filesystem::path appname;
+
+  appname = argv_[0];
+  appname = appname.filename();
+
+  if(appname == "fsck.mergerfs")
+    return fsck::main(argc_,argv_);
+
+  return l::main(argc_,argv_);
+}
+
 int
 main(int    argc_,
      char **argv_)
 {
-  return l::main(argc_,argv_);
+  return ::_pick_app_and_run(argc_,argv_);
 }

src/mergerfs_ioctl.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+#include <sys/ioctl.h>
+
+#ifndef _IOC_TYPE
+#define _IOC_TYPE(X) (((X) >> 8) & 0xFF)
+#endif
+
+typedef char IOCTL_BUF[4096];
+#define IOCTL_APP_TYPE             0xDF
+#define IOCTL_FILE_INFO            _IOWR(IOCTL_APP_TYPE,0,IOCTL_BUF)
+#define IOCTL_GC                   _IO(IOCTL_APP_TYPE,1)
+#define IOCTL_GC1                  _IO(IOCTL_APP_TYPE,2)
+#define IOCTL_INVALIDATE_ALL_NODES _IO(IOCTL_APP_TYPE,3)
+#define IOCTL_INVALIDATE_GID_CACHE _IO(IOCTL_APP_TYPE,4)

src/str.cpp

@@ -68,6 +68,23 @@ namespace str
     return str::split(str_.c_str(),delimiter_,result_);
   }
 
+  void
+  split_on_null(const char   *str_,
+                const size_t  len_,
+                std::vector<std::string> *result_)
+  {
+    const char *start;
+    const char *end;
+
+    start = str_;
+    end   = start + len_;
+    while(start < end)
+      {
+        result_->emplace_back(start);
+        start += (result_->back().size() + 1);
+      }
+  }
+
   void
   rsplit1(const string   &str_,
           const char      delimiter_,

src/str.hpp

@@ -40,6 +40,11 @@ namespace str
         const char             delimiter,
         std::set<std::string> *result);
 
+  void
+  split_on_null(const char               *str,
+                const size_t              len,
+                std::vector<std::string> *result);
+
   void
   rsplit1(const std::string        &str,
           const char                delimiter,