Move ELFLoader code into Kernel/.

1 files changed, 211 insertions, 0 deletions

diff --git a/Kernel/ELFImage.cpp b/Kernel/ELFImage.cpp
new file mode 100644
index 0000000000..e7d7574066
--- /dev/null
+++ b/Kernel/ELFImage.cpp
@@ -0,0 +1,211 @@
+#include "ELFImage.h"
+#include <AK/kstdio.h>
+
+ELFImage::ELFImage(const byte* buffer)
+    : m_buffer(buffer)
+{
+    m_valid = parse();
+}
+
+ELFImage::~ELFImage()
+{
+}
+
+static const char* objectFileTypeToString(Elf32_Half type)
+{
+    switch (type) {
+    case ET_NONE: return "None";
+    case ET_REL: return "Relocatable";
+    case ET_EXEC: return "Executable";
+    case ET_DYN: return "Shared object";
+    case ET_CORE: return "Core";
+    default: return "(?)";
+    }
+}
+
+const char* ELFImage::section_index_to_string(unsigned index)
+{
+    if (index == SHN_UNDEF)
+        return "Undefined";
+    if (index >= SHN_LORESERVE)
+        return "Reserved";
+    return section(index).name();
+}
+
+unsigned ELFImage::symbol_count() const
+{
+    return section(m_symbol_table_section_index).entry_count();
+}
+
+void ELFImage::dump()
+{
+    kprintf("ELFImage{%p} {\n", this);
+    kprintf("    isValid: %u\n", is_valid());
+
+    if (!is_valid()) {
+        kprintf("}\n");
+        return;
+    }
+
+    kprintf("    type:    %s\n", objectFileTypeToString(header().e_type));
+    kprintf("    machine: %u\n", header().e_machine);
+    kprintf("    entry:   %x\n", header().e_entry);
+    kprintf("    shoff:   %u\n", header().e_shoff);
+    kprintf("    shnum:   %u\n", header().e_shnum);
+    kprintf(" shstrndx:   %u\n", header().e_shstrndx);
+
+    for (unsigned i = 0; i < header().e_shnum; ++i) {
+        auto& section = this->section(i);
+        kprintf("    Section %u: {\n", i);
+        kprintf("        name: %s\n", section.name());
+        kprintf("        type: %x\n", section.type());
+        kprintf("      offset: %x\n", section.offset());
+        kprintf("        size: %u\n", section.size());
+        kprintf("        \n");
+        kprintf("    }\n");
+    }
+
+    kprintf("Symbol count: %u (table is %u)\n", symbol_count(), m_symbol_table_section_index);
+    for (unsigned i = 1; i < symbol_count(); ++i) {
+        auto& sym = symbol(i);
+        kprintf("Symbol @%u:\n", i);
+        kprintf("    Name: %s\n", sym.name());
+        kprintf("    In section: %s\n", section_index_to_string(sym.section_index()));
+        kprintf("    Value: %x\n", sym.value());
+        kprintf("    Size: %u\n", sym.size());
+    }
+
+    kprintf("}\n");
+}
+
+unsigned ELFImage::section_count() const
+{
+    return header().e_shnum;
+}
+
+unsigned ELFImage::program_header_count() const
+{
+    return header().e_phnum;
+}
+
+bool ELFImage::parse()
+{
+    // We only support i386.
+    if (header().e_machine != 3)
+        return false;
+
+    // First locate the string tables.
+    for (unsigned i = 0; i < section_count(); ++i) {
+        auto& sh = section_header(i);
+        if (sh.sh_type == SHT_SYMTAB) {
+            ASSERT(!m_symbol_table_section_index);
+            m_symbol_table_section_index = i;
+        }
+        if (sh.sh_type == SHT_STRTAB && i != header().e_shstrndx) {
+            ASSERT(!m_string_table_section_index);
+            m_string_table_section_index = i;
+        }
+    }
+
+#ifdef SUPPORT_RELOCATIONS
+    // Then create a name-to-index map.
+    for (unsigned i = 0; i < section_count(); ++i) {
+        auto& section = this->section(i);
+        m_sections.set(section.name(), move(i));
+    }
+#endif
+    return true;
+}
+
+const char* ELFImage::section_header_table_string(unsigned offset) const
+{
+    auto& sh = section_header(header().e_shstrndx);
+    if (sh.sh_type != SHT_STRTAB)
+        return nullptr;
+    return raw_data(sh.sh_offset + offset);
+}
+
+const char* ELFImage::table_string(unsigned offset) const
+{
+    auto& sh = section_header(m_string_table_section_index);
+    if (sh.sh_type != SHT_STRTAB)
+        return nullptr;
+    return raw_data(sh.sh_offset + offset);
+}
+
+const char* ELFImage::raw_data(unsigned offset) const
+{
+    return reinterpret_cast<const char*>(m_buffer) + offset;
+}
+
+const Elf32_Ehdr& ELFImage::header() const
+{
+    return *reinterpret_cast<const Elf32_Ehdr*>(raw_data(0));
+}
+
+const Elf32_Phdr& ELFImage::program_header_internal(unsigned index) const
+{
+    ASSERT(index < header().e_phnum);
+    return *reinterpret_cast<const Elf32_Phdr*>(raw_data(header().e_phoff + (index * sizeof(Elf32_Phdr))));
+}
+
+const Elf32_Shdr& ELFImage::section_header(unsigned index) const
+{
+    ASSERT(index < header().e_shnum);
+    return *reinterpret_cast<const Elf32_Shdr*>(raw_data(header().e_shoff + (index * sizeof(Elf32_Shdr))));
+}
+
+const ELFImage::Symbol ELFImage::symbol(unsigned index) const
+{
+    ASSERT(index < symbol_count());
+    auto* rawSyms = reinterpret_cast<const Elf32_Sym*>(raw_data(section(m_symbol_table_section_index).offset()));
+    return Symbol(*this, index, rawSyms[index]);
+}
+
+const ELFImage::Section ELFImage::section(unsigned index) const
+{
+    ASSERT(index < section_count());
+    return Section(*this, index);
+}
+
+const ELFImage::ProgramHeader ELFImage::program_header(unsigned index) const
+{
+    ASSERT(index < program_header_count());
+    return ProgramHeader(*this, index);
+}
+
+#ifdef SUPPORT_RELOCATIONS
+const ELFImage::Relocation ELFImage::RelocationSection::relocation(unsigned index) const
+{
+    ASSERT(index < relocation_count());
+    auto* rels = reinterpret_cast<const Elf32_Rel*>(m_image.raw_data(offset()));
+    return Relocation(m_image, rels[index]);
+}
+
+const ELFImage::RelocationSection ELFImage::Section::relocations() const
+{
+    // FIXME: This is ugly.
+    char relocationSectionName[128];
+    ksprintf(relocationSectionName, ".rel%s", name());
+
+#ifdef ELFIMAGE_DEBUG
+    kprintf("looking for '%s'\n", relocationSectionName);
+#endif
+    auto relocationSection = m_image.lookupSection(relocationSectionName);
+    if (relocationSection.type() != SHT_REL)
+        return static_cast<const RelocationSection>(m_image.section(0));
+
+#ifdef ELFIMAGE_DEBUG
+    kprintf("Found relocations for %s in %s\n", name(), relocationSection.name());
+#endif
+    return static_cast<const RelocationSection>(relocationSection);
+}
+
+const ELFImage::Section ELFImage::lookupSection(const char* name) const
+{
+    if (auto it = m_sections.find(name); it != m_sections.end())
+        return section((*it).value);
+    return section(0);
+}
+#endif
+