tiny.tldr.formats.elf.image.zero

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

1const std = @import("std");2const root = @import("../../../root.zig");3const elf = @import("../root.zig");45const model = root.model;6const ObjectFile = elf.parser.ObjectFile;7const ObjectLayout = elf.layout.ObjectLayout;8const OutputSection = elf.layout.OutputSection;9const output_section_count = elf.output_section.output_section_count;10const contributionAt = elf.layout.contributionAt;1112pub fn unwrittenFileRanges(13    image: []u8,14    objects: []const ObjectFile,15    layouts: []const ObjectLayout,16    output_sections: []const OutputSection,17    metadata_start: u64,18    metadata_end: u64,19    section_header_offset: u64,20) model.Error!void {21    var section_cursors = @as([output_section_count]u64, @splat(0));22    var file_cursor: u64 = 0;23    for (output_sections, 0..) |section, output_index| {24        if (section.logicalSize() == 0) continue;25        try range(image, file_cursor, section.file_offset);26        if (section.kind.isNoBits()) {27            file_cursor = section.file_offset;28            continue;29        }3031        const section_end = section.file_offset + section.fileLoadSize();32        section_cursors[output_index] = section.file_offset;33        file_cursor = section_end;34    }3536    try contributionGaps(image, objects, layouts, output_sections, &section_cursors);3738    for (output_sections, 0..) |section, output_index| {39        if (section.logicalSize() == 0) continue;40        if (section.kind.isNoBits()) continue;41        try range(image, section_cursors[output_index], section.file_offset + section.fileLoadSize());42    }4344    try range(image, file_cursor, metadata_start);45    try range(image, metadata_end, section_header_offset);46}4748fn contributionGaps(49    image: []u8,50    objects: []const ObjectFile,51    layouts: []const ObjectLayout,52    output_sections: []const OutputSection,53    section_cursors: *[output_section_count]u64,54) model.Error!void {55    for (objects, 0..) |object, object_index| {56        const object_layout = layouts[object_index];57        for (object.sections, 0..) |section, section_index| {58            if (section.section_type == std.elf.SHT_NOBITS) continue;59            const contribution = contributionAt(object_layout.sections, section_index) orelse continue;60            const output_index = contribution.outputIndex();61            const output = output_sections[output_index];6263            const payload_start = output.file_offset + contribution.offset;64            const payload_end = payload_start + contribution.size;65            const reserve_end = output.file_offset + contribution.offset + contribution.reserved_size;66            try range(image, section_cursors[output_index], payload_start);67            try range(image, payload_end, reserve_end);68            section_cursors[output_index] = reserve_end;69        }70    }71}7273pub fn range(image: []u8, start: u64, end: u64) model.Error!void {74    if (end < start) return error.InvalidRange;75    if (start == end) return;76    const image_len: u64 = @intCast(image.len);77    if (end > image_len) return error.InvalidRange;78    const first: usize = @intCast(start);79    const last: usize = @intCast(end);80    @memset(image[first..last], 0);81}