1 files changed, 195 insertions, 0 deletions
diff --git a/tools/ramscrgen/elf.cpp b/tools/ramscrgen/elf.cpp
new file mode 100644
index 0000000..7599fe0
--- /dev/null
+++ b/tools/ramscrgen/elf.cpp
@@ -0,0 +1,195 @@
+#include <cstdio>
+#include <cstring>
+#include <cstdint>
+#include <map>
+#include <vector>
+#include <string>
+#include "ramscrgen.h"
+#include "elf.h"
+
+#define SHN_COMMON 0xFFF2
+
+static std::string s_elfPath;
+
+static FILE *s_file;
+
+static std::uint32_t s_sectionHeaderOffset;
+static int s_sectionHeaderEntrySize;
+static int s_sectionCount;
+static int s_shstrtabIndex;
+
+static std::uint32_t s_symtabOffset;
+static std::uint32_t s_strtabOffset;
+
+static std::uint32_t s_symbolCount;
+
+struct Symbol
+{
+    std::uint32_t nameOffset;
+    std::uint32_t size;
+};
+
+static void Seek(long offset)
+{
+    if (std::fseek(s_file, offset, SEEK_SET) != 0)
+        FATAL_ERROR("error: failed to seek to %ld in \"%s\"", offset, s_elfPath.c_str());
+}
+
+static void Skip(long offset)
+{
+    if (std::fseek(s_file, offset, SEEK_CUR) != 0)
+        FATAL_ERROR("error: failed to skip %ld bytes in \"%s\"", offset, s_elfPath.c_str());
+}
+
+static std::uint32_t ReadInt8()
+{
+    int c = std::fgetc(s_file);
+
+    if (c < 0)
+        FATAL_ERROR("error: unexpected EOF when reading ELF file \"%s\"\n", s_elfPath.c_str());
+
+    return c;
+}
+
+static std::uint32_t ReadInt16()
+{
+    std::uint32_t val = 0;
+    val |= ReadInt8();
+    val |= ReadInt8() << 8;
+    return val;
+}
+
+static std::uint32_t ReadInt32()
+{
+    std::uint32_t val = 0;
+    val |= ReadInt8();
+    val |= ReadInt8() << 8;
+    val |= ReadInt8() << 16;
+    val |= ReadInt8() << 24;
+    return val;
+}
+
+static std::string ReadString()
+{
+    std::string s;
+    char c;
+
+    while ((c = ReadInt8()) != 0)
+        s += c;
+
+    return s;
+}
+
+static void VerifyElfIdent()
+{
+    char expectedMagic[4] = { 0x7F, 'E', 'L', 'F' };
+    char magic[4];
+
+    if (std::fread(magic, 4, 1, s_file) != 1)
+        FATAL_ERROR("error: failed to read ELF magic from \"%s\"\n", s_elfPath.c_str());
+
+    if (std::memcmp(magic, expectedMagic, 4) != 0)
+        FATAL_ERROR("error: ELF magic did not match in \"%s\"\n", s_elfPath.c_str());
+
+    if (std::fgetc(s_file) != 1)
+        FATAL_ERROR("error: \"%s\" not 32-bit ELF\n", s_elfPath.c_str());
+
+    if (std::fgetc(s_file) != 1)
+        FATAL_ERROR("error: \"%s\" not little-endian ELF\n", s_elfPath.c_str());
+}
+
+static void ReadElfHeader()
+{
+    Seek(0x20);
+    s_sectionHeaderOffset = ReadInt32();
+    Seek(0x2E);
+    s_sectionHeaderEntrySize = ReadInt16();
+    s_sectionCount = ReadInt16();
+    s_shstrtabIndex = ReadInt16();
+}
+
+static std::string GetSectionName(std::uint32_t shstrtabOffset, int index)
+{
+    Seek(s_sectionHeaderOffset + s_sectionHeaderEntrySize * index);
+    std::uint32_t nameOffset = ReadInt32();
+    Seek(shstrtabOffset + nameOffset);
+    return ReadString();
+}
+
+static void FindTableOffsets()
+{
+    s_symtabOffset = 0;
+    s_strtabOffset = 0;
+
+    Seek(s_sectionHeaderOffset + s_sectionHeaderEntrySize * s_shstrtabIndex + 0x10);
+    std::uint32_t shstrtabOffset = ReadInt32();
+
+    for (int i = 0; i < s_sectionCount; i++)
+    {
+        std::string name = GetSectionName(shstrtabOffset, i);
+
+        if (name == ".symtab")
+        {
+            if (s_symtabOffset)
+                FATAL_ERROR("error: mutiple .symtab sections found in \"%s\"\n", s_elfPath.c_str());
+            Seek(s_sectionHeaderOffset + s_sectionHeaderEntrySize * i + 0x10);
+            s_symtabOffset = ReadInt32();
+            std::uint32_t size = ReadInt32();
+            s_symbolCount = size / 16;
+        }
+        else if (name == ".strtab")
+        {
+            if (s_strtabOffset)
+                FATAL_ERROR("error: mutiple .strtab sections found in \"%s\"\n", s_elfPath.c_str());
+            Seek(s_sectionHeaderOffset + s_sectionHeaderEntrySize * i + 0x10);
+            s_strtabOffset = ReadInt32();
+        }
+    }
+
+    if (!s_symtabOffset)
+        FATAL_ERROR("error: couldn't find .symtab section in \"%s\"\n", s_elfPath.c_str());
+
+    if (!s_strtabOffset)
+        FATAL_ERROR("error: couldn't find .strtab section in \"%s\"\n", s_elfPath.c_str());
+}
+
+std::map<std::string, std::uint32_t> GetCommonSymbols(std::string path)
+{
+    s_elfPath = path;
+
+    std::map<std::string, std::uint32_t> commonSymbols;
+
+    s_file = std::fopen(s_elfPath.c_str(), "rb");
+
+    if (s_file == NULL)
+        FATAL_ERROR("error: failed to open \"%s\" for reading\n", path.c_str());
+
+    VerifyElfIdent();
+    ReadElfHeader();
+    FindTableOffsets();
+    
+    std::vector<Symbol> commonSymbolVec;
+
+    Seek(s_symtabOffset);
+
+    for (std::uint32_t i = 0; i < s_symbolCount; i++)
+    {
+        Symbol sym;
+        sym.nameOffset = ReadInt32();
+        Skip(4);
+        sym.size = ReadInt32();
+        Skip(2);
+        std::uint16_t sectionIndex = ReadInt16();
+        if (sectionIndex == SHN_COMMON)
+            commonSymbolVec.push_back(sym);
+    }
+
+    for (const Symbol& sym : commonSymbolVec)
+    {
+        Seek(s_strtabOffset + sym.nameOffset);
+        std::string name = ReadString();
+        commonSymbols[name] = sym.size;
+    }
+
+    return commonSymbols;
+}