Function to find .zip appended to a IoBuffer-wrapped executable file

1 files changed, 97 insertions, 0 deletions

diff --git a/zenserver/frontend/frontend.cpp b/zenserver/frontend/frontend.cpp
index 4bd3ec90a..0611f068c 100644
--- a/zenserver/frontend/frontend.cpp
+++ b/zenserver/frontend/frontend.cpp
@@ -5,8 +5,105 @@
 #include <zencore/filesystem.h>
 #include <zencore/string.h>
 
+ZEN_THIRD_PARTY_INCLUDES_START
+#if ZEN_PLATFORM_WINDOWS
+#	include <Windows.h>
+#endif
+ZEN_THIRD_PARTY_INCLUDES_END
+
 namespace zen {
 
+//////////////////////////////////////////////////////////////////////////
+static IoBuffer FindZipFsInBinary(const IoBuffer& BinBuffer)
+{
+	if (BinBuffer.GetSize() < 4)
+	{
+		return {};
+	}
+
+	uintptr_t Cursor = uintptr_t(BinBuffer.GetData());
+	size_t BinSize = 0;
+
+	uint32_t Magic = *(uint32_t*)(BinBuffer.GetData());
+#if ZEN_PLATFORM_LINUX
+	if (Magic == 0x464c457f)
+	{
+		struct Elf64Header
+		{
+			char		Ident[16];
+			uint16_t	Type;
+			uint16_t	Machine;
+			uint32_t	Version;
+			uint64_t	Entry;
+			uint64_t	ProgHeaderOffset;
+			uint64_t	SectionHeaderOffset;
+			uint32_t	Flags;
+			uint16_t	EhSize;
+			uint16_t	ProgHeaderEntrySize;
+			uint16_t	ProgHeaderCount;
+			uint16_t	SectionHeaderEntrySize;
+			uint16_t	SectionHeaderCount;
+			uint16_t	SectionStringIndex;
+		};
+
+		struct SectionHeader
+		{
+			uint32_t	NameIndex;
+			uint32_t	Type;
+			uint64_t	Flags;
+			uint64_t	Address;
+			uint64_t	Offset;
+			uint64_t	Size;
+			uint64_t	_Other[3];
+		};
+
+		const auto* Elf = (Elf64Header*)Cursor;
+		if (Elf->Ident[4] != 0x02) // Elf64
+		{
+			return {};
+		}
+
+		const auto* Section = (SectionHeader*)(Cursor + Elf->SectionHeaderOffset);
+
+		/*
+		size_t BinSize = 0;
+		for (int i = 0, n = Elf->SectionHeaderCount; i < n; ++i, ++Section)
+		{
+			uint32_t SectionEnd = Section->Offset + Section->Size;
+			BinSize = (SectionEnd > BinSize) ? SectionEnd : BinSize;
+		}
+		*/
+
+		// What if the section headers aren't the last thing in the fiile though?
+		BinSize  = Elf->SectionHeaderEntrySize;
+		BinSize *= Elf->SectionHeaderCount;
+		BinSize += Elf->SectionHeaderOffset;
+	}
+#elif ZEN_PLATFORM_WINDOWS
+	if ((Magic & 0xffff) == 0x5a4d)
+	{
+		const auto* Dos = (IMAGE_DOS_HEADER*)Cursor;
+		const auto* Nt = (IMAGE_NT_HEADERS64*)(Cursor + Dos->e_lfanew);
+		const auto* Section = (IMAGE_SECTION_HEADER*)(uintptr_t(&Nt->OptionalHeader) + Nt->FileHeader.SizeOfOptionalHeader);
+
+		for (int i = 0, n = Nt->FileHeader.NumberOfSections; i < n; ++i, ++Section)
+		{
+			uint32_t SectionEnd = Section->PointerToRawData + Section->SizeOfRawData;
+			BinSize = (SectionEnd > BinSize) ? SectionEnd : BinSize;
+		}
+	}
+#elif ZEN_PLATFORM_MAC
+#	error "needs to be implemented!"
+#endif // win/linux/mac
+
+	if (!BinSize || BinSize > BinBuffer.GetSize())
+	{
+		return {};
+	}
+
+	return IoBuffer(BinBuffer, BinSize);
+}
+
 namespace html {
 
 	constexpr std::string_view Index = R"(