feat: support case-insensitive lookups (fixes gh #232)

.maintainer-scripts/unicode-case-fold.pl

@@ -0,0 +1,38 @@
+#!/usr/bin/perl -w
+use strict;
+use warnings;
+
+# Input data: https://www.unicode.org/Public/UCD/latest/ucd/CaseFolding.txt
+
+my %map;
+
+while (<>) {
+    chomp;
+    next if /^(#|\s*$)/;
+    my($char, $status, $fold, $comment) = split /\s*;\s*/;
+    if ($status =~ /^[CS]$/) {
+        $comment =~ s/^#\s*//;
+        # print "    case 0x$char: return 0x$fold; // [$status] $comment\n";
+        $map{hex($char)} = hex($fold);
+    }
+}
+
+my @valid_code_points = (0..0xD7FF, 0xE000..0x10FFFF);
+
+sub cp_to_str {
+  my $cp = shift;
+  my $fmt = $cp < 0x10000 ? "\\u%04X" : "\\U%08X";
+  return sprintf $fmt, $cp;
+}
+
+while (@valid_code_points) {
+  my @cps = splice @valid_code_points, 0, 256;
+  my $orig;
+  my $folded;
+  for my $cp (@cps) {
+    my $fold = $map{$cp} // $cp;
+    $orig .= cp_to_str($cp);
+    $folded .= cp_to_str($fold);
+  }
+  print "    {u8\"$orig\"sv, u8\"$folded\"sv},\n" if $orig ne $folded;
+}

CMakeLists.txt

@@ -450,6 +450,7 @@ if(WITH_TESTS)
       pcmaudio_categorizer_test
       speedometer_test
       terminal_test
+      unicode_test
       utils_test
       file_utils_test
       worker_group_test

cmake/libdwarfs.cmake

@@ -49,6 +49,7 @@ add_library(
   src/internal/fs_section.cpp
   src/internal/glob_to_regex.cpp
   src/internal/string_table.cpp
+  src/internal/unicode_case_folding.cpp
   src/internal/wcwidth.c
   src/internal/worker_group.cpp
 

doc/dwarfs.md

@@ -104,6 +104,17 @@ options:
   overlays and want the file system to reflect its read-only
   state, you can set this option.
 
+- `-o case_insensitive`:
+  Perform case-insensitive lookups in the mounted file system,
+  i.e. an entry orignally named `ReadMe.txt` can be accessed as
+  `readme.txt`, `README.TXT`, or `rEaDmE.tXt`. This works across
+  all platforms. When mounting a file system with many files, this
+  may be slightly slower and consume slightly more memory as case-
+  insensitive lookup requires an additional mapping table that is
+  built on-demand. Note that this is not supported if the file
+  system contains directories with entries that only differ in
+  case.
+
 - `-o (no_)cache_image`:
   By default, `dwarfs` tries to ensure that the compressed file
   system image will not be cached by the kernel (i.e. the default

include/dwarfs/internal/unicode_case_folding.h

@@ -0,0 +1,32 @@
+/* vim:set ts=2 sw=2 sts=2 et: */
+/**
+ * \author     Marcus Holland-Moritz (github@mhxnet.de)
+ * \copyright  Copyright (c) Marcus Holland-Moritz
+ *
+ * This file is part of dwarfs.
+ *
+ * dwarfs is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * dwarfs is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with dwarfs.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <string>
+#include <string_view>
+
+namespace dwarfs::internal {
+
+std::string utf8_case_fold(std::string_view in);
+std::string utf8_case_fold_unchecked(std::string_view in);
+
+} // namespace dwarfs::internal

include/dwarfs/reader/metadata_options.h

@@ -32,6 +32,7 @@ struct metadata_options {
   bool enable_nlink{false};
   bool readonly{false};
   bool check_consistency{false};
+  bool case_insensitive_lookup{false};
   size_t block_size{512};
   std::optional<file_stat::uid_type> fs_uid{};
   std::optional<file_stat::gid_type> fs_gid{};

src/reader/internal/metadata_v2.cpp

@@ -32,19 +32,28 @@
 
 #include <boost/algorithm/string.hpp>
 
+#include <boost/sort/flat_stable_sort/flat_stable_sort.hpp>
+
 #include <thrift/lib/cpp2/frozen/FrozenUtil.h>
 #include <thrift/lib/cpp2/protocol/DebugProtocol.h>
 #include <thrift/lib/cpp2/protocol/Serializer.h>
 
 #include <fmt/chrono.h>
 #include <fmt/format.h>
+#if FMT_VERSION >= 110000
+#include <fmt/ranges.h>
+#endif
 
 #include <folly/container/F14Set.h>
 #include <folly/portability/Stdlib.h>
 #include <folly/portability/Unistd.h>
+#include <folly/small_vector.h>
 #include <folly/stats/Histogram.h>
 
+#include <parallel_hashmap/phmap.h>
+
 #include <range/v3/view/enumerate.hpp>
+#include <range/v3/view/transform.hpp>
 
 #include <dwarfs/error.h>
 #include <dwarfs/file_stat.h>
@@ -60,6 +69,7 @@
 #include <dwarfs/internal/features.h>
 #include <dwarfs/internal/packed_int_vector.h>
 #include <dwarfs/internal/string_table.h>
+#include <dwarfs/internal/unicode_case_folding.h>
 #include <dwarfs/reader/internal/metadata_v2.h>
 
 #include <dwarfs/gen-cpp2/metadata_layouts.h>
@@ -415,7 +425,7 @@ class metadata_ final : public metadata_v2::impl {
       , symlinks_(meta_.compact_symlinks()
                       ? string_table(lgr, "symlinks", *meta_.compact_symlinks())
                       : string_table(meta_.symlinks()))
-      // clang-format off
+      , dir_icase_cache_{build_dir_icase_cache()} // clang-format off
       PERFMON_CLS_PROXY_INIT(perfmon, "metadata_v2")
       PERFMON_CLS_TIMER_INIT(find)
       PERFMON_CLS_TIMER_INIT(getattr)
@@ -661,6 +671,10 @@ class metadata_ final : public metadata_v2::impl {
   nlohmann::json as_json(dir_entry_view entry) const;
   nlohmann::json as_json(directory_view dir, dir_entry_view entry) const;
 
+  std::optional<dir_entry_view>
+  find_impl(directory_view dir, auto const& range, auto const& name,
+            auto const& index_map, auto const& entry_name_transform) const;
+
   std::optional<dir_entry_view>
   find(directory_view dir, std::string_view name) const;
 
@@ -920,6 +934,79 @@ class metadata_ final : public metadata_v2::impl {
     return packed_nlinks;
   }
 
+  std::vector<packed_int_vector<uint32_t>> build_dir_icase_cache() const {
+    std::vector<packed_int_vector<uint32_t>> cache;
+
+    if (options_.case_insensitive_lookup) {
+      auto ti = LOG_TIMED_INFO;
+      size_t num_cached_dirs = 0;
+      size_t num_cached_files = 0;
+      size_t total_cache_size = 0;
+
+      cache.resize(meta_.directories().size());
+
+      for (uint32_t inode = 0; inode < meta_.directories().size() - 1;
+           ++inode) {
+        directory_view dir{inode, global_};
+        auto range = dir.entry_range();
+
+        // Cache the folded names of the directory entries; this significantly
+        // speeds up the sorting code.
+        std::vector<std::string> names(range.size());
+        std::transform(range.begin(), range.end(), names.begin(), [&](auto ix) {
+          return utf8_case_fold_unchecked(
+              dir_entry_view_impl::name(ix, global_));
+        });
+
+        // Check and report any collisions in the directory
+        phmap::flat_hash_map<std::string_view, folly::small_vector<uint32_t, 1>>
+            collisions;
+        collisions.reserve(range.size());
+        for (size_t i = 0; i < names.size(); ++i) {
+          collisions[names[i]].push_back(i);
+        }
+        for (auto& [name, indices] : collisions) {
+          if (indices.size() > 1) {
+            LOG_WARN << fmt::format(
+                "case-insensitive collision in directory \"{}\" (inode={}): {}",
+                dir.self_entry_view().unix_path(), inode,
+                fmt::join(indices | ranges::views::transform([&](auto i) {
+                            return dir_entry_view_impl::name(range[i], global_);
+                          }),
+                          ", "));
+          }
+        }
+
+        // It's faster to check here if the folded names are sorted than to
+        // check later if the indices in `entries` are sorted.
+        if (!std::is_sorted(names.begin(), names.end())) {
+          std::vector<uint32_t> entries(range.size());
+          std::iota(entries.begin(), entries.end(), 0);
+          boost::sort::flat_stable_sort(
+              entries.begin(), entries.end(),
+              [&](auto a, auto b) { return names[a] < names[b]; });
+          auto& pv = cache[inode];
+          pv.reset(std::bit_width(entries.size()), entries.size());
+          for (size_t i = 0; i < entries.size(); ++i) {
+            pv.set(i, entries[i]);
+          }
+          ++num_cached_dirs;
+          num_cached_files += entries.size();
+          total_cache_size += pv.size_in_bytes();
+        }
+      }
+
+      ti << "built case-insensitive directory cache for " << num_cached_files
+         << " entries in " << num_cached_dirs << " out of "
+         << meta_.directories().size() - 1 << " directories ("
+         << size_with_unit(total_cache_size +
+                           sizeof(decltype(cache)::value_type) * cache.size())
+         << ")";
+    }
+
+    return cache;
+  }
+
   size_t total_file_entries() const {
     return (dev_inode_offset_ - file_inode_offset_) +
            (meta_.dir_entries()
@@ -943,6 +1030,7 @@ class metadata_ final : public metadata_v2::impl {
   const int unique_files_;
   const metadata_options options_;
   const string_table symlinks_;
+  std::vector<packed_int_vector<uint32_t>> const dir_icase_cache_;
   PERFMON_CLS_PROXY_DECL
   PERFMON_CLS_TIMER_DECL(find)
   PERFMON_CLS_TIMER_DECL(getattr)
@@ -1687,6 +1775,31 @@ void metadata_<LoggerPolicy>::walk_data_order_impl(
   }
 }
 
+template <typename LoggerPolicy>
+std::optional<dir_entry_view>
+metadata_<LoggerPolicy>::find_impl(directory_view dir, auto const& range,
+                                   auto const& name, auto const& index_map,
+                                   auto const& entry_name_transform) const {
+  auto entry_name = [&](auto ix) {
+    return entry_name_transform(dir_entry_view_impl::name(ix, global_));
+  };
+
+  auto it = std::lower_bound(range.begin(), range.end(), name,
+                             [&](auto ix, auto const& name) {
+                               return entry_name(index_map(ix)) < name;
+                             });
+
+  if (it != range.end()) {
+    auto ix = index_map(*it);
+    if (entry_name(ix) == name) {
+      return dir_entry_view{dir_entry_view_impl::from_dir_entry_index_shared(
+          ix, global_.self_dir_entry(dir.inode()), global_)};
+    }
+  }
+
+  return std::nullopt;
+}
+
 template <typename LoggerPolicy>
 std::optional<dir_entry_view>
 metadata_<LoggerPolicy>::find(directory_view dir, std::string_view name) const {
@@ -1694,19 +1807,21 @@ metadata_<LoggerPolicy>::find(directory_view dir, std::string_view name) const {
 
   auto range = dir.entry_range();
 
-  auto it = std::lower_bound(
-      range.begin(), range.end(), name, [&](auto ix, std::string_view name) {
-        return internal::dir_entry_view_impl::name(ix, global_) < name;
-      });
-
-  if (it != range.end()) {
-    if (internal::dir_entry_view_impl::name(*it, global_) == name) {
-      return dir_entry_view{dir_entry_view_impl::from_dir_entry_index_shared(
-          *it, global_.self_dir_entry(dir.inode()), global_)};
-    }
+  if (!options_.case_insensitive_lookup) {
+    return find_impl(dir, range, name, std::identity{}, std::identity{});
   }
 
-  return std::nullopt;
+  auto const& cache = dir_icase_cache_[dir.inode()];
+
+  return find_impl(
+      dir, boost::irange(range.size()), utf8_case_fold(name),
+      [&cache, &range](auto ix) {
+        if (!cache.empty()) {
+          ix = cache[ix];
+        }
+        return range[ix];
+      },
+      utf8_case_fold_unchecked);
 }
 
 template <typename LoggerPolicy>

test/dwarfs_test.cpp

@@ -28,6 +28,7 @@
 #include <sstream>
 #include <vector>
 
+#include <gmock/gmock.h>
 #include <gtest/gtest.h>
 
 // This needs to be included *after* gtest.h
@@ -2054,3 +2055,183 @@ TEST(filesystem, multi_image) {
     EXPECT_EQ("baz", fs.read_string(fs.open(baz->inode())));
   }
 }
+
+TEST(filesystem, case_insensitive_lookup) {
+  auto input = std::make_shared<test::os_access_mock>();
+
+  input->add_dir("");
+  input->add_dir(u8"hEllÖwÖrLD");
+  input->add_dir(u8"FÜñKÿStrÍñg");
+  input->add_dir(u8"unícødérøcks");
+  input->add_dir(u8"JÄLAPEÑOPEPPÉR");
+  input->add_dir(u8"SpIcYsÜsHiRoLL");
+  input->add_dir(u8"CAFÉMØCHAlatte");
+  input->add_dir(u8"ČhàŧGƤŦ");
+  input->add_dir(u8"lõREMÏpSüM");
+  input->add_dir(u8"ŠåmpŁËŠTrInG");
+  input->add_dir(u8"pythonprogramming");
+  input->add_dir(u8"DÃTâScïÊNcË");
+  input->add_dir(u8"AIISFÛTÛRË");
+  input->add_dir(u8"readability");
+  input->add_file(u8"TëStCãSeSçÉNâRïÖ", "testcasescenario");
+  input->add_file(u8"lõREMÏpSüM/ÆSTHETÎCcøding", "aestheticcoding");
+  input->add_file(u8"lõREMÏpSüM/smîLëyFÀÇë😊", "smileyface");
+  input->add_file(u8"lõREMÏpSüM/NØRTHèast", "northeast");
+  input->add_file(u8"lõREMÏpSüM/SPACEadventure", "spaceadventure");
+  input->add_file(u8"lõREMÏpSüM/cõMPLEXïTy🚀", "complexity");
+  input->add_file(u8"lõREMÏpSüM/thisisatest", "thisisatest");
+  input->add_file(u8"lõREMÏpSüM/thisISaTEST", "thisisatest");
+
+  std::vector<std::u8string> case_sensitive_dirs{
+      u8"/hEllÖwÖrLD",        u8"/FÜñKÿStrÍñg",    u8"/unícødérøcks",
+      u8"/JÄLAPEÑOPEPPÉR",    u8"/SpIcYsÜsHiRoLL", u8"/CAFÉMØCHAlatte",
+      u8"/ČhàŧGƤŦ",           u8"/lõREMÏpSüM",     u8"/ŠåmpŁËŠTrInG",
+      u8"/pythonprogramming", u8"/DÃTâScïÊNcË",    u8"/AIISFÛTÛRË",
+      u8"/readability",
+  };
+
+  std::vector<std::pair<std::u8string, std::string>> case_sensitive_files{
+      {u8"/TëStCãSeSçÉNâRïÖ", "testcasescenario"},
+      {u8"/lõREMÏpSüM/ÆSTHETÎCcøding", "aestheticcoding"},
+      {u8"/lõREMÏpSüM/smîLëyFÀÇë😊", "smileyface"},
+      {u8"/lõREMÏpSüM/NØRTHèast", "northeast"},
+      {u8"/lõREMÏpSüM/SPACEadventure", "spaceadventure"},
+      {u8"/lõREMÏpSüM/cõMPLEXïTy🚀", "complexity"},
+      {u8"/lõREMÏpSüM/thisisatest", "thisisatest"},
+      {u8"/lõREMÏpSüM/thisISaTEST", "thisisatest"},
+  };
+
+  std::vector<std::u8string> case_insensitive_dirs{
+      u8"/HELlÖwÖRLD",        u8"/FÜÑKÿSTríÑg",    u8"/uNÍcødéRøcks",
+      u8"/JÄLApeñOPePPÉR",    u8"/SpiCysÜshiRoLL", u8"/CAféMØchAlatte",
+      u8"/čhàŧgƥŧ",           u8"/lõremÏpsüM",     u8"/šåmpŁëšTrInG",
+      u8"/pyTHonproGRamming", u8"/DãtÂScïêNcË",    u8"/AiisFÛTÛRË",
+      u8"/reADabiLIty",
+  };
+
+  std::vector<std::pair<std::u8string, std::string>> case_insensitive_files{
+      {u8"/TësTcãSeSçéNâRïÖ", "testcasescenario"},
+      {u8"/lõRemïpSüM/ÆstHETÎCcØDing", "aestheticcoding"},
+      {u8"/lõremïPSüM/smîlËYfàÇë😊", "smileyface"},
+      {u8"/lõREMÏPsÜM/NØRthÈAst", "northeast"},
+      {u8"/lõRemïPsüM/SPACEadvENTure", "spaceadventure"},
+      {u8"/LÕREMÏpSüM/CõMPlexïTy🚀", "complexity"},
+      {u8"/lõrEMÏpSüM/thiSISatest", "thisisatest"},
+  };
+
+  std::vector<std::u8string> non_matching_entries{
+      u8"/HELlÖwÖRLDx",
+      u8"/FÜÑKÿSTríÑj",
+      u8"/uNÍcødéRcks",
+      u8"/JÄLApeñOPePPÉ",
+      u8"/SpiCysÜshiRoLLx",
+      u8"/CAféMØchAltte",
+      u8"/čhàŧgƥŧx",
+      u8"/lõremÏpsü",
+      u8"/šåmpŁëšTrnG",
+      u8"/pyTHonproGRammin",
+      u8"/DãtÂScïêNcËx",
+      u8"/AiisFÛTÛTË",
+      u8"/reADabiLItx",
+      u8"/TësRcãSeSçéNâRïÖ",
+      u8"/lõRemïpüM/ÆstHETÎCcØDing",
+      u8"/lõremïPSüM/mîlËYfàÇë😊",
+      u8"/lõRMÏPsÜM/NØRthÈAst",
+      u8"/lõRemïPsüM/SPACEadvENTurex",
+      u8"/LÕREMÏpSüM/CõMPexïTy🚀",
+      u8"/lõrEMÏpSüM/thiSISatesy",
+  };
+
+  test::test_logger lgr;
+  auto fsimage = build_dwarfs(lgr, input, "null");
+
+  auto mm = std::make_shared<test::mmap_mock>(std::move(fsimage));
+
+  lgr.clear();
+
+  {
+    reader::filesystem_v2 fs(lgr, *input, mm,
+                             {.metadata = {.case_insensitive_lookup = false}});
+
+    EXPECT_TRUE(lgr.empty());
+
+    for (auto const& dir : case_sensitive_dirs) {
+      auto name = u8string_to_string(dir);
+      auto dev = fs.find(name);
+      EXPECT_TRUE(dev) << name;
+    }
+
+    for (auto const& [file, content] : case_sensitive_files) {
+      auto name = u8string_to_string(file);
+      auto dev = fs.find(name);
+      EXPECT_TRUE(dev) << name;
+      EXPECT_EQ(content, fs.read_string(fs.open(dev->inode()))) << name;
+    }
+
+    for (auto const& dir : case_insensitive_dirs) {
+      auto name = u8string_to_string(dir);
+      auto dev = fs.find(name);
+      EXPECT_FALSE(dev) << name;
+    }
+
+    for (auto const& [file, content] : case_insensitive_files) {
+      auto name = u8string_to_string(file);
+      auto dev = fs.find(name);
+      EXPECT_FALSE(dev) << name;
+    }
+
+    for (auto const& ent : non_matching_entries) {
+      auto name = u8string_to_string(ent);
+      auto dev = fs.find(name);
+      EXPECT_FALSE(dev) << name;
+    }
+  }
+
+  lgr.clear();
+
+  {
+    reader::filesystem_v2 fs(lgr, *input, mm,
+                             {.metadata = {.case_insensitive_lookup = true}});
+
+    EXPECT_THAT(
+        lgr.get_log(),
+        testing::Contains(testing::ResultOf(
+            [](const auto& entry) { return entry.output; },
+            testing::AllOf(testing::HasSubstr(u8string_to_string(
+                               u8"case-insensitive collision in directory "
+                               u8"\"lõREMÏpSüM\" (inode=")),
+                           testing::HasSubstr("thisISaTEST, thisisatest")))));
+
+    for (auto const& dir : case_sensitive_dirs) {
+      auto name = u8string_to_string(dir);
+      auto dev = fs.find(name);
+      EXPECT_TRUE(dev) << name;
+    }
+
+    for (auto const& [file, content] : case_sensitive_files) {
+      auto name = u8string_to_string(file);
+      auto dev = fs.find(name);
+      EXPECT_TRUE(dev) << name;
+      EXPECT_EQ(content, fs.read_string(fs.open(dev->inode()))) << name;
+    }
+
+    for (auto const& dir : case_insensitive_dirs) {
+      auto name = u8string_to_string(dir);
+      auto dev = fs.find(name);
+      EXPECT_TRUE(dev) << name;
+    }
+
+    for (auto const& [file, content] : case_insensitive_files) {
+      auto name = u8string_to_string(file);
+      auto dev = fs.find(name);
+      EXPECT_TRUE(dev) << name;
+      EXPECT_EQ(content, fs.read_string(fs.open(dev->inode()))) << name;
+    }
+
+    for (auto const& ent : non_matching_entries) {
+      auto name = u8string_to_string(ent);
+      auto dev = fs.find(name);
+      EXPECT_FALSE(dev) << name;
+    }
+  }
+}

test/tools_test.cpp

@@ -1053,6 +1053,7 @@ TEST_P(tools_test, end_to_end) {
 
     std::vector<std::string> all_options{
         "-s",
+        "-ocase_insensitive",
 #ifndef _WIN32
         "-oenable_nlink",
         "-oreadonly",
@@ -1074,6 +1075,7 @@ TEST_P(tools_test, end_to_end) {
 
     for (unsigned bitmask = 0; bitmask < combinations; ++bitmask) {
       std::vector<std::string> args;
+      bool case_insensitive{false};
 #ifndef _WIN32
       bool enable_nlink{false};
       bool readonly{false};
@@ -1083,6 +1085,9 @@ TEST_P(tools_test, end_to_end) {
       for (size_t i = 0; i < all_options.size(); ++i) {
         if ((1 << i) & bitmask) {
           auto const& opt = all_options[i];
+          if (opt == "-ocase_insensitive") {
+            case_insensitive = true;
+          }
 #ifndef _WIN32
           if (opt == "-oreadonly") {
             readonly = true;
@@ -1139,6 +1144,12 @@ TEST_P(tools_test, end_to_end) {
           EXPECT_EQ(st.st_gid, 3456) << runner.cmdline();
         }
 #endif
+        EXPECT_TRUE(fs::exists(mountpoint / "format.sh")) << runner.cmdline();
+        EXPECT_EQ(case_insensitive, fs::exists(mountpoint / "FORMAT.SH"))
+            << runner.cmdline();
+        EXPECT_EQ(case_insensitive, fs::exists(mountpoint / "fOrMaT.Sh"))
+            << runner.cmdline();
+
         auto perfmon =
             dwarfs::getxattr(mountpoint, "user.dwarfs.driver.perfmon");
 #if DWARFS_PERFMON_ENABLED

tools/src/dwarfs_main.cpp

@@ -179,6 +179,7 @@ struct options {
 #endif
   int enable_nlink{0};
   int readonly{0};
+  int case_insensitive{0};
   int cache_image{0};
   int cache_files{0};
   size_t cachesize{0};
@@ -258,6 +259,7 @@ constexpr struct ::fuse_opt dwarfs_opts[] = {
     DWARFS_OPT("seq_detector=%s", seq_detector_thresh_str, 0),
     DWARFS_OPT("enable_nlink", enable_nlink, 1),
     DWARFS_OPT("readonly", readonly, 1),
+    DWARFS_OPT("case_insensitive", case_insensitive, 1),
     DWARFS_OPT("cache_image", cache_image, 1),
     DWARFS_OPT("no_cache_image", cache_image, 0),
     DWARFS_OPT("cache_files", cache_files, 1),
@@ -1224,6 +1226,7 @@ void usage(std::ostream& os, std::filesystem::path const& progname) {
      << "    -o imagesize=NUM       filesystem image size in bytes\n"
      << "    -o enable_nlink        show correct hardlink numbers\n"
      << "    -o readonly            show read-only file system\n"
+     << "    -o case_insensitive    perform case-insensitive lookups\n"
      << "    -o (no_)cache_image    (don't) keep image in kernel cache\n"
      << "    -o (no_)cache_files    (don't) keep files in kernel cache\n"
      << "    -o debuglevel=NAME     " << logger::all_level_names() << "\n"
@@ -1464,6 +1467,7 @@ void load_filesystem(dwarfs_userdata& userdata) {
   fsopts.inode_reader.readahead = opts.readahead;
   fsopts.metadata.enable_nlink = bool(opts.enable_nlink);
   fsopts.metadata.readonly = bool(opts.readonly);
+  fsopts.metadata.case_insensitive_lookup = bool(opts.case_insensitive);
   fsopts.metadata.block_size = opts.blocksize;
 #ifndef _WIN32
   fsopts.metadata.fs_uid = opts.fs_uid;

vcpkg.json

@@ -11,6 +11,7 @@
     "boost-multi-index",
     "boost-process",
     "boost-program-options",
+    "boost-sort",
     "boost-thread",
     "boost-uuid",
     "boost-variant",