tiny.tldr.formats.elf.note

1const std = @import("std");2const root = @import("../../root.zig");3const format = @import("format.zig");4const layout = @import("layout/root.zig");5const output_section = @import("section.zig");67const model = root.model;8const OutputSection = layout.OutputSection;9const OutputSectionKind = output_section.OutputSectionKind;10const SectionHeader = format.SectionHeader;11const output_section_count = output_section.output_section_count;12const requireRange = format.requireRange;13const writeU32 = format.writeU32;14const writeU64 = format.writeU64;1516pub const section_name = ".note.gnu.build-id";17pub const desc_offset = format.build_id_note_desc_offset;18pub const fast_desc_size = format.build_id_fast_desc_size;19pub const sha1_desc_size = format.build_id_sha1_desc_size;2021pub fn reserveBuildId(22    output_sections: *[output_section_count]OutputSection,23    options: model.LinkOptions,24) void {25    if (options.build_id == .none) return;26    var output = &output_sections[@backingInt(OutputSectionKind.build_id_note)];27    const note_size = size(options.build_id);28    output.file_size = note_size;29    output.memory_size = note_size;30    output.alignment = @max(output.alignment, 4);31}3233pub fn writeBuildIdHeader(image: []u8, offset: u64) model.Error!void {34    try requireRange(image, offset, desc_offset);35    const start: usize = @intCast(offset);36    writeU32(image, start + 0, 4);37    writeU32(image, start + 8, std.elf.NT_GNU_BUILD_ID);38    image[start + 12] = 'G';39    image[start + 13] = 'N';40    image[start + 14] = 'U';41    image[start + 15] = 0;42}4344pub fn finishBuildId(45    image: []u8,46    output_sections: []const OutputSection,47    options: model.LinkOptions,48) model.Error!void {49    if (options.build_id == .none) return;50    const section = output_sections[@backingInt(OutputSectionKind.build_id_note)];51    const note_size = size(options.build_id);52    try requireRange(image, section.file_offset, note_size);53    try finishBuildIdAt(image, section.file_offset, options.build_id);54}5556pub fn finishBuildIdSection(57    image: []u8,58    section: SectionHeader,59    mode: model.BuildIdMode,60) model.Error!void {61    if (mode == .none) return;62    if (section.section_type != std.elf.SHT_NOTE) return error.InvalidElfHeader;63    if (section.size != size(mode)) return error.InvalidElfHeader;64    try requireRange(image, section.offset, section.size);65    try finishBuildIdAt(image, section.offset, mode);66}6768fn finishBuildIdAt(69    image: []u8,70    file_offset: u64,71    mode: model.BuildIdMode,72) model.Error!void {73    const desc_size = descSize(mode);74    const start: usize = @intCast(file_offset);75    const desc_start = start + desc_offset;76    writeU32(image, start + 4, @intCast(desc_size));77    @memset(image[desc_start..][0..desc_size], 0);78    switch (mode) {79        .none => unreachable,80        .fast => {81            var hasher = std.hash.XxHash64.init(0);82            hasher.update(image);83            writeU64(image, desc_start, hasher.final());84        },85        .sha1 => {86            var digest: [sha1_desc_size]u8 = undefined;87            std.crypto.hash.Sha1.hash(image, &digest, .{});88            @memcpy(image[desc_start..][0..sha1_desc_size], &digest);89        },90    }91}9293pub fn patchGenerated(94    image: []u8,95    candidate_image: []const u8,96    section: SectionHeader,97    candidate_section: SectionHeader,98) model.Error!void {99    if (section.offset != candidate_section.offset) return error.InvalidElfHeader;100    if (section.size != candidate_section.size) return error.InvalidElfHeader;101    if (section.section_type != std.elf.SHT_NOTE or candidate_section.section_type != std.elf.SHT_NOTE) return error.InvalidElfHeader;102    try requireRange(image, section.offset, section.size);103    try requireRange(candidate_image, candidate_section.offset, candidate_section.size);104    const start: usize = @intCast(section.offset);105    const note_size: usize = @intCast(section.size);106    @memcpy(image[start..][0..note_size], candidate_image[start..][0..note_size]);107}108109pub fn size(mode: model.BuildIdMode) u64 {110    return desc_offset + descSize(mode);111}112113fn descSize(mode: model.BuildIdMode) u64 {114    return switch (mode) {115        .none => 0,116        .fast => fast_desc_size,117        .sha1 => sha1_desc_size,118    };119}

1pub const note = @import("note.zig");