struct Coff [src]

Fields

data: []const u8
is_loaded: bool
is_image: bool
coff_header_offset: usize
guid: [16]u8 = undefined
age: u32 = undefined
Members

getCoffHeader (Function)
getDataDirectories (Function)
getImageBase (Function)
getNumberOfDataDirectories (Function)
getOptionalHeader (Function)
getOptionalHeader32 (Function)
getOptionalHeader64 (Function)
getPdbPath (Function)
getSectionByName (Function)
getSectionData (Function)
getSectionDataAlloc (Function)
getSectionHeaders (Function)
getSectionHeadersAlloc (Function)
getSectionName (Function)
getStrtab (Function)
getSymtab (Function)
init (Function)
strtabRequired (Function)
Source

  pub const Coff = struct {
    data: []const u8,
    // Set if `data` is backed by the image as loaded by the loader
    is_loaded: bool,
    is_image: bool,
    coff_header_offset: usize,

    guid: [16]u8 = undefined,
    age: u32 = undefined,

    // The lifetime of `data` must be longer than the lifetime of the returned Coff
    pub fn init(data: []const u8, is_loaded: bool) !Coff {
        const pe_pointer_offset = 0x3C;
        const pe_magic = "PE\x00\x00";

        var stream = std.io.fixedBufferStream(data);
        const reader = stream.reader();
        try stream.seekTo(pe_pointer_offset);
        const coff_header_offset = try reader.readInt(u32, .little);
        try stream.seekTo(coff_header_offset);
        var buf: [4]u8 = undefined;
        try reader.readNoEof(&buf);
        const is_image = mem.eql(u8, pe_magic, &buf);

        var coff = @This(){
            .data = data,
            .is_image = is_image,
            .is_loaded = is_loaded,
            .coff_header_offset = coff_header_offset,
        };

        // Do some basic validation upfront
        if (is_image) {
            coff.coff_header_offset = coff.coff_header_offset + 4;
            const coff_header = coff.getCoffHeader();
            if (coff_header.size_of_optional_header == 0) return error.MissingPEHeader;
        }

        // JK: we used to check for architecture here and throw an error if not x86 or derivative.
        // However I am willing to take a leap of faith and let aarch64 have a shot also.

        return coff;
    }

    pub fn getPdbPath(self: *Coff) !?[]const u8 {
        assert(self.is_image);

        const data_dirs = self.getDataDirectories();
        if (@intFromEnum(DirectoryEntry.DEBUG) >= data_dirs.len) return null;

        const debug_dir = data_dirs[@intFromEnum(DirectoryEntry.DEBUG)];
        var stream = std.io.fixedBufferStream(self.data);
        const reader = stream.reader();

        if (self.is_loaded) {
            try stream.seekTo(debug_dir.virtual_address);
        } else {
            // Find what section the debug_dir is in, in order to convert the RVA to a file offset
            for (self.getSectionHeaders()) |*sect| {
                if (debug_dir.virtual_address >= sect.virtual_address and debug_dir.virtual_address < sect.virtual_address + sect.virtual_size) {
                    try stream.seekTo(sect.pointer_to_raw_data + (debug_dir.virtual_address - sect.virtual_address));
                    break;
                }
            } else return error.InvalidDebugDirectory;
        }

        // Find the correct DebugDirectoryEntry, and where its data is stored.
        // It can be in any section.
        const debug_dir_entry_count = debug_dir.size / @sizeOf(DebugDirectoryEntry);
        var i: u32 = 0;
        while (i < debug_dir_entry_count) : (i += 1) {
            const debug_dir_entry = try reader.readStruct(DebugDirectoryEntry);
            if (debug_dir_entry.type == .CODEVIEW) {
                const dir_offset = if (self.is_loaded) debug_dir_entry.address_of_raw_data else debug_dir_entry.pointer_to_raw_data;
                try stream.seekTo(dir_offset);
                break;
            }
        } else return null;

        var cv_signature: [4]u8 = undefined; // CodeView signature
        try reader.readNoEof(cv_signature[0..]);
        // 'RSDS' indicates PDB70 format, used by lld.
        if (!mem.eql(u8, &cv_signature, "RSDS"))
            return error.InvalidPEMagic;
        try reader.readNoEof(self.guid[0..]);
        self.age = try reader.readInt(u32, .little);

        // Finally read the null-terminated string.
        const start = reader.context.pos;
        const len = std.mem.indexOfScalar(u8, self.data[start..], 0) orelse return null;
        return self.data[start .. start + len];
    }

    pub fn getCoffHeader(self: Coff) CoffHeader {
        return @as(*align(1) const CoffHeader, @ptrCast(self.data[self.coff_header_offset..][0..@sizeOf(CoffHeader)])).*;
    }

    pub fn getOptionalHeader(self: Coff) OptionalHeader {
        assert(self.is_image);
        const offset = self.coff_header_offset + @sizeOf(CoffHeader);
        return @as(*align(1) const OptionalHeader, @ptrCast(self.data[offset..][0..@sizeOf(OptionalHeader)])).*;
    }

    pub fn getOptionalHeader32(self: Coff) OptionalHeaderPE32 {
        assert(self.is_image);
        const offset = self.coff_header_offset + @sizeOf(CoffHeader);
        return @as(*align(1) const OptionalHeaderPE32, @ptrCast(self.data[offset..][0..@sizeOf(OptionalHeaderPE32)])).*;
    }

    pub fn getOptionalHeader64(self: Coff) OptionalHeaderPE64 {
        assert(self.is_image);
        const offset = self.coff_header_offset + @sizeOf(CoffHeader);
        return @as(*align(1) const OptionalHeaderPE64, @ptrCast(self.data[offset..][0..@sizeOf(OptionalHeaderPE64)])).*;
    }

    pub fn getImageBase(self: Coff) u64 {
        const hdr = self.getOptionalHeader();
        return switch (hdr.magic) {
            IMAGE_NT_OPTIONAL_HDR32_MAGIC => self.getOptionalHeader32().image_base,
            IMAGE_NT_OPTIONAL_HDR64_MAGIC => self.getOptionalHeader64().image_base,
            else => unreachable, // We assume we have validated the header already
        };
    }

    pub fn getNumberOfDataDirectories(self: Coff) u32 {
        const hdr = self.getOptionalHeader();
        return switch (hdr.magic) {
            IMAGE_NT_OPTIONAL_HDR32_MAGIC => self.getOptionalHeader32().number_of_rva_and_sizes,
            IMAGE_NT_OPTIONAL_HDR64_MAGIC => self.getOptionalHeader64().number_of_rva_and_sizes,
            else => unreachable, // We assume we have validated the header already
        };
    }

    pub fn getDataDirectories(self: *const Coff) []align(1) const ImageDataDirectory {
        const hdr = self.getOptionalHeader();
        const size: usize = switch (hdr.magic) {
            IMAGE_NT_OPTIONAL_HDR32_MAGIC => @sizeOf(OptionalHeaderPE32),
            IMAGE_NT_OPTIONAL_HDR64_MAGIC => @sizeOf(OptionalHeaderPE64),
            else => unreachable, // We assume we have validated the header already
        };
        const offset = self.coff_header_offset + @sizeOf(CoffHeader) + size;
        return @as([*]align(1) const ImageDataDirectory, @ptrCast(self.data[offset..]))[0..self.getNumberOfDataDirectories()];
    }

    pub fn getSymtab(self: *const Coff) ?Symtab {
        const coff_header = self.getCoffHeader();
        if (coff_header.pointer_to_symbol_table == 0) return null;

        const offset = coff_header.pointer_to_symbol_table;
        const size = coff_header.number_of_symbols * Symbol.sizeOf();
        return .{ .buffer = self.data[offset..][0..size] };
    }

    pub fn getStrtab(self: *const Coff) error{InvalidStrtabSize}!?Strtab {
        const coff_header = self.getCoffHeader();
        if (coff_header.pointer_to_symbol_table == 0) return null;

        const offset = coff_header.pointer_to_symbol_table + Symbol.sizeOf() * coff_header.number_of_symbols;
        const size = mem.readInt(u32, self.data[offset..][0..4], .little);
        if ((offset + size) > self.data.len) return error.InvalidStrtabSize;

        return Strtab{ .buffer = self.data[offset..][0..size] };
    }

    pub fn strtabRequired(self: *const Coff) bool {
        for (self.getSectionHeaders()) |*sect_hdr| if (sect_hdr.getName() == null) return true;
        return false;
    }

    pub fn getSectionHeaders(self: *const Coff) []align(1) const SectionHeader {
        const coff_header = self.getCoffHeader();
        const offset = self.coff_header_offset + @sizeOf(CoffHeader) + coff_header.size_of_optional_header;
        return @as([*]align(1) const SectionHeader, @ptrCast(self.data.ptr + offset))[0..coff_header.number_of_sections];
    }

    pub fn getSectionHeadersAlloc(self: *const Coff, allocator: mem.Allocator) ![]SectionHeader {
        const section_headers = self.getSectionHeaders();
        const out_buff = try allocator.alloc(SectionHeader, section_headers.len);
        for (out_buff, 0..) |*section_header, i| {
            section_header.* = section_headers[i];
        }

        return out_buff;
    }

    pub fn getSectionName(self: *const Coff, sect_hdr: *align(1) const SectionHeader) error{InvalidStrtabSize}![]const u8 {
        const name = sect_hdr.getName() orelse blk: {
            const strtab = (try self.getStrtab()).?;
            const name_offset = sect_hdr.getNameOffset().?;
            break :blk strtab.get(name_offset);
        };
        return name;
    }

    pub fn getSectionByName(self: *const Coff, comptime name: []const u8) ?*align(1) const SectionHeader {
        for (self.getSectionHeaders()) |*sect| {
            const section_name = self.getSectionName(sect) catch |e| switch (e) {
                error.InvalidStrtabSize => continue, //ignore invalid(?) strtab entries - see also GitHub issue #15238
            };
            if (mem.eql(u8, section_name, name)) {
                return sect;
            }
        }
        return null;
    }

    pub fn getSectionData(self: *const Coff, sec: *align(1) const SectionHeader) []const u8 {
        const offset = if (self.is_loaded) sec.virtual_address else sec.pointer_to_raw_data;
        return self.data[offset..][0..sec.virtual_size];
    }

    pub fn getSectionDataAlloc(self: *const Coff, sec: *align(1) const SectionHeader, allocator: mem.Allocator) ![]u8 {
        const section_data = self.getSectionData(sec);
        return allocator.dupe(u8, section_data);
    }
}  