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path: root/src/core/file_sys/vfs_concat.cpp
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-rw-r--r--src/core/file_sys/vfs_concat.cpp161
1 files changed, 101 insertions, 60 deletions
diff --git a/src/core/file_sys/vfs_concat.cpp b/src/core/file_sys/vfs_concat.cpp
index d23623aa0..853b893a1 100644
--- a/src/core/file_sys/vfs_concat.cpp
+++ b/src/core/file_sys/vfs_concat.cpp
@@ -10,84 +10,105 @@
namespace FileSys {
-static bool VerifyConcatenationMapContinuity(const std::multimap<u64, VirtualFile>& map) {
- const auto last_valid = --map.end();
- for (auto iter = map.begin(); iter != last_valid;) {
- const auto old = iter++;
- if (old->first + old->second->GetSize() != iter->first) {
+ConcatenatedVfsFile::ConcatenatedVfsFile(ConcatenationMap&& concatenation_map_, std::string&& name_)
+ : concatenation_map(std::move(concatenation_map_)), name(std::move(name_)) {
+ DEBUG_ASSERT(this->VerifyContinuity());
+}
+
+bool ConcatenatedVfsFile::VerifyContinuity() const {
+ u64 last_offset = 0;
+ for (auto& entry : concatenation_map) {
+ if (entry.offset != last_offset) {
return false;
}
- }
-
- return map.begin()->first == 0;
-}
-ConcatenatedVfsFile::ConcatenatedVfsFile(std::vector<VirtualFile> files_, std::string name_)
- : name(std::move(name_)) {
- std::size_t next_offset = 0;
- for (const auto& file : files_) {
- files.emplace(next_offset, file);
- next_offset += file->GetSize();
+ last_offset = entry.offset + entry.file->GetSize();
}
-}
-ConcatenatedVfsFile::ConcatenatedVfsFile(std::multimap<u64, VirtualFile> files_, std::string name_)
- : files(std::move(files_)), name(std::move(name_)) {
- ASSERT(VerifyConcatenationMapContinuity(files));
+ return true;
}
ConcatenatedVfsFile::~ConcatenatedVfsFile() = default;
-VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(std::vector<VirtualFile> files,
- std::string name) {
- if (files.empty())
+VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(const std::vector<VirtualFile>& files,
+ std::string&& name) {
+ // Fold trivial cases.
+ if (files.empty()) {
return nullptr;
- if (files.size() == 1)
- return files[0];
+ }
+ if (files.size() == 1) {
+ return files.front();
+ }
+
+ // Make the concatenation map from the input.
+ std::vector<ConcatenationEntry> concatenation_map;
+ concatenation_map.reserve(files.size());
+ u64 last_offset = 0;
+
+ for (auto& file : files) {
+ concatenation_map.emplace_back(ConcatenationEntry{
+ .offset = last_offset,
+ .file = file,
+ });
+
+ last_offset += file->GetSize();
+ }
- return VirtualFile(new ConcatenatedVfsFile(std::move(files), std::move(name)));
+ return VirtualFile(new ConcatenatedVfsFile(std::move(concatenation_map), std::move(name)));
}
VirtualFile ConcatenatedVfsFile::MakeConcatenatedFile(u8 filler_byte,
- std::multimap<u64, VirtualFile> files,
- std::string name) {
- if (files.empty())
+ const std::multimap<u64, VirtualFile>& files,
+ std::string&& name) {
+ // Fold trivial cases.
+ if (files.empty()) {
return nullptr;
- if (files.size() == 1)
+ }
+ if (files.size() == 1) {
return files.begin()->second;
+ }
- const auto last_valid = --files.end();
- for (auto iter = files.begin(); iter != last_valid;) {
- const auto old = iter++;
- if (old->first + old->second->GetSize() != iter->first) {
- files.emplace(old->first + old->second->GetSize(),
- std::make_shared<StaticVfsFile>(filler_byte, iter->first - old->first -
- old->second->GetSize()));
+ // Make the concatenation map from the input.
+ std::vector<ConcatenationEntry> concatenation_map;
+
+ concatenation_map.reserve(files.size());
+ u64 last_offset = 0;
+
+ // Iteration of a multimap is ordered, so offset will be strictly non-decreasing.
+ for (auto& [offset, file] : files) {
+ if (offset > last_offset) {
+ concatenation_map.emplace_back(ConcatenationEntry{
+ .offset = last_offset,
+ .file = std::make_shared<StaticVfsFile>(filler_byte, offset - last_offset),
+ });
}
- }
- // Ensure the map starts at offset 0 (start of file), otherwise pad to fill.
- if (files.begin()->first != 0)
- files.emplace(0, std::make_shared<StaticVfsFile>(filler_byte, files.begin()->first));
+ concatenation_map.emplace_back(ConcatenationEntry{
+ .offset = offset,
+ .file = file,
+ });
+
+ last_offset = offset + file->GetSize();
+ }
- return VirtualFile(new ConcatenatedVfsFile(std::move(files), std::move(name)));
+ return VirtualFile(new ConcatenatedVfsFile(std::move(concatenation_map), std::move(name)));
}
std::string ConcatenatedVfsFile::GetName() const {
- if (files.empty()) {
+ if (concatenation_map.empty()) {
return "";
}
if (!name.empty()) {
return name;
}
- return files.begin()->second->GetName();
+ return concatenation_map.front().file->GetName();
}
std::size_t ConcatenatedVfsFile::GetSize() const {
- if (files.empty()) {
+ if (concatenation_map.empty()) {
return 0;
}
- return files.rbegin()->first + files.rbegin()->second->GetSize();
+ return concatenation_map.back().offset + concatenation_map.back().file->GetSize();
}
bool ConcatenatedVfsFile::Resize(std::size_t new_size) {
@@ -95,10 +116,10 @@ bool ConcatenatedVfsFile::Resize(std::size_t new_size) {
}
VirtualDir ConcatenatedVfsFile::GetContainingDirectory() const {
- if (files.empty()) {
+ if (concatenation_map.empty()) {
return nullptr;
}
- return files.begin()->second->GetContainingDirectory();
+ return concatenation_map.front().file->GetContainingDirectory();
}
bool ConcatenatedVfsFile::IsWritable() const {
@@ -110,25 +131,45 @@ bool ConcatenatedVfsFile::IsReadable() const {
}
std::size_t ConcatenatedVfsFile::Read(u8* data, std::size_t length, std::size_t offset) const {
- auto entry = --files.end();
- for (auto iter = files.begin(); iter != files.end(); ++iter) {
- if (iter->first > offset) {
- entry = --iter;
+ const ConcatenationEntry key{
+ .offset = offset,
+ .file = nullptr,
+ };
+
+ // Read nothing if the map is empty.
+ if (concatenation_map.empty()) {
+ return 0;
+ }
+
+ // Binary search to find the iterator to the first position we can check.
+ // It must exist, since we are not empty and are comparing unsigned integers.
+ auto it = std::prev(std::upper_bound(concatenation_map.begin(), concatenation_map.end(), key));
+ u64 cur_length = length;
+ u64 cur_offset = offset;
+
+ while (cur_length > 0 && it != concatenation_map.end()) {
+ // Check if we can read the file at this position.
+ const auto& file = it->file;
+ const u64 file_offset = it->offset;
+ const u64 file_size = file->GetSize();
+
+ if (cur_offset >= file_offset + file_size) {
+ // Entirely out of bounds read.
break;
}
- }
- if (entry->first + entry->second->GetSize() <= offset)
- return 0;
+ // Read the file at this position.
+ const u64 intended_read_size = std::min<u64>(cur_length, file_size);
+ const u64 actual_read_size =
+ file->Read(data + (cur_offset - offset), intended_read_size, cur_offset - file_offset);
- const auto read_in =
- std::min<u64>(entry->first + entry->second->GetSize() - offset, entry->second->GetSize());
- if (length > read_in) {
- return entry->second->Read(data, read_in, offset - entry->first) +
- Read(data + read_in, length - read_in, offset + read_in);
+ // Update tracking.
+ cur_offset += actual_read_size;
+ cur_length -= actual_read_size;
+ it++;
}
- return entry->second->Read(data, std::min<u64>(read_in, length), offset - entry->first);
+ return cur_offset - offset;
}
std::size_t ConcatenatedVfsFile::Write(const u8* data, std::size_t length, std::size_t offset) {
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-02 10:22:05 +0200