From c5657b5cf6e72df9f573f149fe027374bf634fa7 Mon Sep 17 00:00:00 2001
From: Aki <please@ignore.pl>
Date: Sun, 7 Aug 2022 22:38:21 +0200
Subject: Added method to expand stored files

---
 ArchiveEx/Archive.cpp | 37 ++++++++++++++++++++++++++++++++++---
 ArchiveEx/Archive.h   |  1 +
 2 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/ArchiveEx/Archive.cpp b/ArchiveEx/Archive.cpp
index d714e46..3eea0fe 100644
--- a/ArchiveEx/Archive.cpp
+++ b/ArchiveEx/Archive.cpp
@@ -1,5 +1,6 @@
 #include "Archive.h"
 
+#include <cstdint>
 #include <cstdio>
 #include <memory>
 #include <vector>
@@ -28,7 +29,7 @@ Archive::Archive(const char* p) :
 	UniqueFileHandle file {std::fopen(path, "rb"), &std::fclose};
 	if (!file)
 		throw "could not open archive";
-	std::size_t length = fread(&header, sizeof(Header), 1, file.get());
+	std::size_t length = std::fread(&header, sizeof(Header), 1, file.get());
 	if (1 != length)
 		throw "could not read";
 	if (VERSION != header.version)
@@ -36,7 +37,7 @@ Archive::Archive(const char* p) :
 	int err = std::fseek(file.get(), sizeof(Header) + header.directory.offset, SEEK_SET);
 	if (-1 == err)
 		throw "could not find directory in archive";
-	std::vector<std::uint8_t> compressed(header.directory.compressed_size);
+	std::vector<Bytef> compressed(header.directory.compressed_size);
 	length = std::fread(compressed.data(), 1, header.directory.compressed_size, file.get());
 	if (header.directory.compressed_size != length)
 		throw "could not read compressed directory";
@@ -44,7 +45,7 @@ Archive::Archive(const char* p) :
 	entries.resize(header.total_entries);
 	entries.reserve(total_entries);  // In original impl entries were switched on/off with their uncompressed size value.
 	uLongf uncompressed_size = sizeof(Entry) * total_entries;
-	err = ::uncompress(
+	err = uncompress(
 		reinterpret_cast<Bytef*>(entries.data()),
 		&uncompressed_size,
 		compressed.data(),
@@ -54,6 +55,36 @@ Archive::Archive(const char* p) :
 }
 
 
+int
+Archive::Expand(const int index, std::uint8_t*& buffer, const bool null_terminated) const
+{
+	if (0 > index && static_cast<int>(header.total_entries) <= index)
+		return -1;  // Can be replaced by error-checked access to std::vector holding entries.
+	UniqueFileHandle file {std::fopen(path, "rb"), &std::fclose};
+	if (!file)
+		return -1;
+	const auto& entry = entries[index];
+	std::vector<Bytef> compressed(entry.compressed_size);
+	int err = std::fseek(file.get(), sizeof(Header) + entry.offset, SEEK_SET);
+	if (-1 == err)
+		return -1;
+	std::size_t length = std::fread(compressed.data(), 1, entry.compressed_size, file.get());
+	if (entry.compressed_size != length)
+		return -1;
+	uLongf output_length = entry.original_size + static_cast<uLongf>(null_terminated);
+	std::unique_ptr<std::uint8_t[]> uncompressed(new std::uint8_t[output_length]);
+	if (!uncompressed)
+		return -1;
+	err = uncompress(uncompressed.get(), &output_length, compressed.data(), entry.compressed_size);
+	if (Z_OK != err)
+		return -1;
+	buffer = uncompressed.release();
+	if (null_terminated)
+		buffer[output_length - 1] = 0;
+	return output_length;
+}
+
+
 void
 Archive::PrintNamesOfEntries() const
 {
diff --git a/ArchiveEx/Archive.h b/ArchiveEx/Archive.h
index cc06dc4..6870194 100644
--- a/ArchiveEx/Archive.h
+++ b/ArchiveEx/Archive.h
@@ -39,6 +39,7 @@ class Archive
 {
 public:
 	explicit Archive(const char* path);
+	int Expand(int index, std::uint8_t*& buffer, bool null_terminated=false) const;
 	void PrintNamesOfEntries() const;
 	std::size_t DirectoryBlocks() const;
 private:
-- 
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