From eedbed42d6733444d48314653f40cf61df8dd0d5 Mon Sep 17 00:00:00 2001
From: Marcus Holland-Moritz <github@mhxnet.de>
Date: Fri, 26 May 2023 13:52:44 +0200
Subject: [PATCH] folly::Range -> std::span in filesystem_v2 / mmif

---
 include/dwarfs/filesystem_v2.h | 12 ++++++++----
 include/dwarfs/mmif.h          |  7 +++----
 src/dwarfs/filesystem_v2.cpp   | 21 ++++++++++-----------
 3 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/include/dwarfs/filesystem_v2.h b/include/dwarfs/filesystem_v2.h
index 9239a6e9..804b5877 100644
--- a/include/dwarfs/filesystem_v2.h
+++ b/include/dwarfs/filesystem_v2.h
@@ -28,6 +28,7 @@
 #include <iosfwd>
 #include <memory>
 #include <optional>
+#include <span>
 #include <string>
 #include <utility>
 
@@ -70,9 +71,10 @@ class filesystem_v2 {
                       int detail_level = 0, size_t num_readers = 1,
                       bool check_integrity = false, off_t image_offset = 0);
 
-  static std::optional<folly::ByteRange> header(std::shared_ptr<mmif> mm);
+  static std::optional<std::span<uint8_t const>>
+  header(std::shared_ptr<mmif> mm);
 
-  static std::optional<folly::ByteRange>
+  static std::optional<std::span<uint8_t const>>
   header(std::shared_ptr<mmif> mm, off_t image_offset);
 
   void dump(std::ostream& os, int detail_level) const {
@@ -150,7 +152,9 @@ class filesystem_v2 {
     return impl_->readv(inode, size, offset);
   }
 
-  std::optional<folly::ByteRange> header() const { return impl_->header(); }
+  std::optional<std::span<uint8_t const>> header() const {
+    return impl_->header();
+  }
 
   void set_num_workers(size_t num) { return impl_->set_num_workers(num); }
   void set_cache_tidy_config(cache_tidy_config const& cfg) {
@@ -190,7 +194,7 @@ class filesystem_v2 {
                           off_t offset) const = 0;
     virtual folly::Expected<std::vector<std::future<block_range>>, int>
     readv(uint32_t inode, size_t size, off_t offset) const = 0;
-    virtual std::optional<folly::ByteRange> header() const = 0;
+    virtual std::optional<std::span<uint8_t const>> header() const = 0;
     virtual void set_num_workers(size_t num) = 0;
     virtual void set_cache_tidy_config(cache_tidy_config const& cfg) = 0;
   };
diff --git a/include/dwarfs/mmif.h b/include/dwarfs/mmif.h
index fb243ba7..8e121dde 100644
--- a/include/dwarfs/mmif.h
+++ b/include/dwarfs/mmif.h
@@ -21,13 +21,12 @@
 
 #pragma once
 
+#include <span>
 #include <string>
 #include <system_error>
 
 #include <boost/noncopyable.hpp>
 
-#include <folly/Range.h>
-
 namespace dwarfs {
 
 class mmif : public boost::noncopyable {
@@ -40,8 +39,8 @@ class mmif : public boost::noncopyable {
         reinterpret_cast<char const*>(this->addr()) + offset);
   }
 
-  folly::ByteRange range(off_t offset, size_t length) const {
-    return folly::ByteRange(this->as<uint8_t>(offset), length);
+  std::span<uint8_t const> span(off_t offset, size_t length) const {
+    return std::span(this->as<uint8_t>(offset), length);
   }
 
   virtual void const* addr() const = 0;
diff --git a/src/dwarfs/filesystem_v2.cpp b/src/dwarfs/filesystem_v2.cpp
index 06032948..498af1b8 100644
--- a/src/dwarfs/filesystem_v2.cpp
+++ b/src/dwarfs/filesystem_v2.cpp
@@ -28,8 +28,6 @@
 #include <sys/mman.h>
 #include <sys/statvfs.h>
 
-#include <folly/Range.h>
-
 #include <fmt/format.h>
 
 #include "dwarfs/block_cache.h"
@@ -180,11 +178,11 @@ class filesystem_parser {
     return std::nullopt;
   }
 
-  std::optional<folly::ByteRange> header() const {
+  std::optional<std::span<uint8_t const>> header() const {
     if (image_offset_ == 0) {
       return std::nullopt;
     }
-    return folly::ByteRange(mm_->as<uint8_t>(), image_offset_);
+    return mm_->span(0, image_offset_);
   }
 
   void rewind() {
@@ -250,7 +248,7 @@ get_uncompressed_section_size(std::shared_ptr<mmif> mm, fs_section const& sec) {
   return bd.uncompressed_size();
 }
 
-folly::ByteRange
+std::span<uint8_t const>
 get_section_data(std::shared_ptr<mmif> mm, fs_section const& section,
                  std::vector<uint8_t>& buffer, bool force_buffer) {
   auto compression = section.compression();
@@ -258,7 +256,7 @@ get_section_data(std::shared_ptr<mmif> mm, fs_section const& section,
   auto length = section.length();
 
   if (!force_buffer && compression == compression_type::NONE) {
-    return mm->range(start, length);
+    return mm->span(start, length);
   }
 
   buffer = block_decompressor::decompress(compression, mm->as<uint8_t>(start),
@@ -346,7 +344,7 @@ class filesystem_ final : public filesystem_v2::impl {
                 off_t offset) const override;
   folly::Expected<std::vector<std::future<block_range>>, int>
   readv(uint32_t inode, size_t size, off_t offset) const override;
-  std::optional<folly::ByteRange> header() const override;
+  std::optional<std::span<uint8_t const>> header() const override;
   void set_num_workers(size_t num) override { ir_.set_num_workers(num); }
   void set_cache_tidy_config(cache_tidy_config const& cfg) override {
     ir_.set_cache_tidy_config(cfg);
@@ -362,7 +360,7 @@ class filesystem_ final : public filesystem_v2::impl {
   mutable std::mutex mx_;
   mutable filesystem_parser parser_;
   std::vector<uint8_t> meta_buffer_;
-  std::optional<folly::ByteRange> header_;
+  std::optional<std::span<uint8_t const>> header_;
   mutable std::unique_ptr<filesystem_info const> fsinfo_;
 };
 
@@ -575,7 +573,8 @@ filesystem_<LoggerPolicy>::readv(uint32_t inode, size_t size,
 }
 
 template <typename LoggerPolicy>
-std::optional<folly::ByteRange> filesystem_<LoggerPolicy>::header() const {
+std::optional<std::span<uint8_t const>>
+filesystem_<LoggerPolicy>::header() const {
   return header_;
 }
 
@@ -743,12 +742,12 @@ int filesystem_v2::identify(logger& lgr, std::shared_ptr<mmif> mm,
   return errors;
 }
 
-std::optional<folly::ByteRange>
+std::optional<std::span<uint8_t const>>
 filesystem_v2::header(std::shared_ptr<mmif> mm) {
   return header(std::move(mm), filesystem_options::IMAGE_OFFSET_AUTO);
 }
 
-std::optional<folly::ByteRange>
+std::optional<std::span<uint8_t const>>
 filesystem_v2::header(std::shared_ptr<mmif> mm, off_t image_offset) {
   return filesystem_parser(mm, image_offset).header();
 }