tiny.tldr.formats.elf.ehframe.header.reservation

1const std = @import("std");2const root = @import("../../../../root.zig");3const elf = @import("../../root.zig");4const ehframe = @import("../root.zig");56const model = root.model;7const format = elf.format;8const layout = elf.layout;9const output_section = elf.output_section;10const parser = elf.parser;11const ObjectFile = parser.ObjectFile;12const ObjectLayout = layout.ObjectLayout;13const OutputSection = layout.OutputSection;14const Rela = format.Rela;15const OutputSectionKind = output_section.OutputSectionKind;16const output_section_count = output_section.output_section_count;17const eh_frame_hdr_fixed_size = format.eh_frame_hdr_fixed_size;18const eh_frame_hdr_entry_size = format.eh_frame_hdr_entry_size;19const contributionAt = layout.contributionAt;20const ehFrameSectionLayout = layout.ehFrameSection;21const sectionBytes = format.sectionBytes;22const readU32 = format.readU32;23const record = ehframe.record;24const section = ehframe.section;2526pub fn reserve(27    output_sections: *[output_section_count]OutputSection,28    objects: []const ObjectFile,29    layouts: []const ObjectLayout,30    options: model.LinkOptions,31) model.Error!void {32    if (!options.eh_frame_header) return;33    const count = try countEntries(objects, layouts);34    if (count == 0) return;35    const header_size = try size(count);36    var output = &output_sections[@backingInt(OutputSectionKind.eh_frame_hdr)];37    output.file_size = header_size;38    output.memory_size = header_size;39    output.alignment = @max(output.alignment, 4);40}4142pub fn size(entry_count: usize) model.Error!u64 {43    const count = std.math.cast(u64, entry_count) orelse return error.InvalidRange;44    if (count > (std.math.maxInt(u64) - eh_frame_hdr_fixed_size) / eh_frame_hdr_entry_size) return error.InvalidRange;45    return eh_frame_hdr_fixed_size + count * eh_frame_hdr_entry_size;46}4748fn countEntries(49    objects: []const ObjectFile,50    layouts: []const ObjectLayout,51) model.Error!usize {52    var count: usize = 0;53    for (objects, 0..) |object, object_index| {54        const object_layout = layouts[object_index];55        for (object.sections, 0..) |input_section, section_index| {56            if (contributionAt(object_layout.sections, section_index) == null) continue;57            if (!section.is(object, section_index, input_section)) continue;58            const bytes = try sectionBytes(object.bytes, input_section);59            if (ehFrameSectionLayout(object_layout, section_index)) |eh_frame_section| {60                var cursor = record.Cursor.init(eh_frame_section.relocations);61                for (eh_frame_section.pieces) |piece| {62                    if (try record.hasHeaderEntry(bytes, piece.input_offset, piece.size, piece.output_offset, &cursor)) count += 1;63                }64                continue;65            }66            try countRawEntries(bytes, object.relocationsForSection(section_index), &count);67        }68    }69    return count;70}7172fn countRawEntries(73    bytes: []const u8,74    relocations: []const Rela,75    count: *usize,76) model.Error!void {77    var cursor = record.Cursor.init(relocations);78    var input_offset: u64 = 0;79    while (input_offset < bytes.len) {80        const record_start: usize = @intCast(input_offset);81        if (bytes.len - record_start < 4) return error.InvalidObject;82        const record_length = readU32(bytes, record_start);83        if (record_length == 0xffffffff) return error.UnsupportedFormat;84        const record_size = @as(u64, record_length) + 4;85        if (record_size < 4) return error.InvalidObject;86        if (input_offset > std.math.maxInt(u64) - record_size) return error.InvalidObject;87        const record_end = input_offset + record_size;88        if (record_end > bytes.len) return error.InvalidObject;89        if (try record.hasHeaderEntry(bytes, input_offset, record_size, input_offset, &cursor)) count.* += 1;90        if (record_length == 0) break;91        input_offset = record_end;92    }93}

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