refactor: simpler ways to construct filesystem_v2

include/dwarfs/filesystem_v2.h

@@ -59,6 +59,14 @@ class filesystem_v2 {
  public:
   filesystem_v2() = default;
 
+  filesystem_v2(logger& lgr, os_access const& os,
+                std::filesystem::path const& path);
+
+  filesystem_v2(logger& lgr, os_access const& os,
+                std::filesystem::path const& path,
+                filesystem_options const& options,
+                std::shared_ptr<performance_monitor const> perfmon = nullptr);
+
   filesystem_v2(logger& lgr, os_access const& os, std::shared_ptr<mmif> mm);
 
   filesystem_v2(logger& lgr, os_access const& os, std::shared_ptr<mmif> mm,

src/dwarfs/filesystem_v2.cpp

@@ -43,6 +43,7 @@
 #include <dwarfs/logger.h>
 #include <dwarfs/mmif.h>
 #include <dwarfs/options.h>
+#include <dwarfs/os_access.h>
 #include <dwarfs/performance_monitor.h>
 #include <dwarfs/util.h>
 #include <dwarfs/writer_progress.h>
@@ -1177,6 +1178,17 @@ filesystem_<LoggerPolicy>::header() const {
 
 } // namespace internal
 
+filesystem_v2::filesystem_v2(logger& lgr, os_access const& os,
+                             std::filesystem::path const& path)
+    : filesystem_v2(lgr, os, os.map_file(os.canonical(path))) {}
+
+filesystem_v2::filesystem_v2(logger& lgr, os_access const& os,
+                             std::filesystem::path const& path,
+                             filesystem_options const& options,
+                             std::shared_ptr<performance_monitor const> perfmon)
+    : filesystem_v2(lgr, os, os.map_file(os.canonical(path)), options,
+                    std::move(perfmon)) {}
+
 filesystem_v2::filesystem_v2(logger& lgr, os_access const& os,
                              std::shared_ptr<mmif> mm)
     : filesystem_v2(lgr, os, std::move(mm), filesystem_options()) {}

src/dwarfs_main.cpp

@@ -1462,9 +1462,8 @@ void load_filesystem(dwarfs_userdata& userdata) {
 
   LOG_DEBUG << "attempting to load filesystem from " << fsimage;
 
-  userdata.fs =
-      filesystem_v2(userdata.lgr, *userdata.iol.os,
-                    std::make_shared<mmap>(fsimage), fsopts, userdata.perfmon);
+  userdata.fs = filesystem_v2(userdata.lgr, *userdata.iol.os, fsimage, fsopts,
+                              userdata.perfmon);
 
   ti << "file system initialized";
 }

src/dwarfsbench_main.cpp

@@ -99,8 +99,7 @@ int dwarfsbench_main(int argc, sys_char** argv, iolayer const& iol) {
     fsopts.block_cache.num_workers = num_workers;
     fsopts.block_cache.decompress_ratio = to<double>(decompress_ratio_str);
 
-    dwarfs::filesystem_v2 fs(
-        lgr, *iol.os, std::make_shared<dwarfs::mmap>(filesystem), fsopts);
+    dwarfs::filesystem_v2 fs(lgr, *iol.os, filesystem, fsopts);
 
     thread_pool pool(lgr, *iol.os, "reader", num_readers);
 

src/dwarfsextract_main.cpp

@@ -56,7 +56,7 @@ constexpr std::string_view kDash{"-"};
 } // namespace
 
 int dwarfsextract_main(int argc, sys_char** argv, iolayer const& iol) {
-  sys_string filesystem, output, trace_file;
+  sys_string fs_image, output, trace_file;
   std::string format, cache_size_str, image_offset;
   logger_options logopts;
 #if DWARFS_PERFMON_ENABLED
@@ -70,7 +70,7 @@ int dwarfsextract_main(int argc, sys_char** argv, iolayer const& iol) {
   po::options_description opts("Command line options");
   opts.add_options()
     ("input,i",
-        po_sys_value<sys_string>(&filesystem),
+        po_sys_value<sys_string>(&fs_image),
         "input filesystem file")
     ("output,o",
         po_sys_value<sys_string>(&output),
@@ -164,9 +164,7 @@ int dwarfsextract_main(int argc, sys_char** argv, iolayer const& iol) {
     std::shared_ptr<performance_monitor> perfmon = performance_monitor::create(
         perfmon_enabled, iol.file, perfmon_trace_file);
 
-    auto fs_path = iol.os->canonical(filesystem);
-
-    filesystem_v2 fs(lgr, *iol.os, iol.os->map_file(fs_path), fsopts, perfmon);
+    filesystem_v2 fs(lgr, *iol.os, fs_image, fsopts, perfmon);
     filesystem_extractor fsx(lgr, *iol.os);
 
     if (format.empty()) {

src/mkdwarfs_main.cpp

@@ -1159,14 +1159,14 @@ int mkdwarfs_main(int argc, sys_char** argv, iolayer const& iol) {
     }
   }
 
-  std::unique_ptr<filesystem_v2> input_filesystem;
+  std::optional<filesystem_v2> input_filesystem;
   std::shared_ptr<category_resolver> cat_resolver;
 
   if (recompress) {
-    filesystem_options fsopts;
-    fsopts.image_offset = filesystem_options::IMAGE_OFFSET_AUTO;
-    input_filesystem = std::make_unique<filesystem_v2>(
-        lgr, *iol.os, iol.os->map_file(path), fsopts);
+    input_filesystem.emplace(
+        lgr, *iol.os, path,
+        filesystem_options{.image_offset =
+                               filesystem_options::IMAGE_OFFSET_AUTO});
 
     LOG_INFO << "checking input filesystem...";