tiny.tldr.formats.elf.addressing.boundary

1const std = @import("std");23pub const Boundary = struct {4    section_name: []const u8,5    stop: bool,6    optional: bool = false,7    match_prefix: bool = false,8    output_section: bool = false,910    pub const Context = struct {11        pub fn hash(_: Context, boundary: Boundary) u64 {12            var value = hashU64(0xd297a1b0a6e8d5f3, @intFromBool(boundary.stop));13            value = hashU64(value, @intFromBool(boundary.optional));14            value = hashU64(value, @intFromBool(boundary.match_prefix));15            value = hashU64(value, @intFromBool(boundary.output_section));16            return std.hash.Wyhash.hash(value, boundary.section_name);17        }1819        pub fn eql(_: Context, left: Boundary, right: Boundary) bool {20            return left.stop == right.stop and21                left.optional == right.optional and22                left.match_prefix == right.match_prefix and23                left.output_section == right.output_section and24                std.mem.eql(u8, left.section_name, right.section_name);25        }26    };27};2829pub fn forSymbol(symbol_name: []const u8) ?Boundary {30    if (std.mem.eql(u8, symbol_name, "__ehdr_start")) return .{ .section_name = "", .stop = false, .optional = true };31    if (std.mem.eql(u8, symbol_name, "__rela_iplt_start")) return .{ .section_name = ".rela.iplt", .stop = false, .optional = true, .output_section = true };32    if (std.mem.eql(u8, symbol_name, "__rela_iplt_end")) return .{ .section_name = ".rela.iplt", .stop = true, .optional = true, .output_section = true };33    if (arrayForSymbol(symbol_name, "__preinit_array_start", "__preinit_array_end", ".preinit_array")) |boundary| return boundary;34    if (arrayForSymbol(symbol_name, "__init_array_start", "__init_array_end", ".init_array")) |boundary| return boundary;35    if (arrayForSymbol(symbol_name, "__fini_array_start", "__fini_array_end", ".fini_array")) |boundary| return boundary;3637    const start_prefix = "__start_";38    const stop_prefix = "__stop_";39    if (std.mem.startsWith(u8, symbol_name, start_prefix)) {40        const section_name = symbol_name[start_prefix.len..];41        if (isCIdentifier(section_name)) return .{ .section_name = section_name, .stop = false };42    }43    if (std.mem.startsWith(u8, symbol_name, stop_prefix)) {44        const section_name = symbol_name[stop_prefix.len..];45        if (isCIdentifier(section_name)) return .{ .section_name = section_name, .stop = true };46    }47    return null;48}4950pub fn sectionNameMatches(boundary: Boundary, section_name: []const u8) bool {51    if (std.mem.eql(u8, section_name, boundary.section_name)) return true;52    return boundary.match_prefix and53        section_name.len > boundary.section_name.len and54        std.mem.startsWith(u8, section_name, boundary.section_name) and55        section_name[boundary.section_name.len] == '.';56}5758fn arrayForSymbol(symbol_name: []const u8, start_name: []const u8, end_name: []const u8, section_name: []const u8) ?Boundary {59    if (std.mem.eql(u8, symbol_name, start_name)) {60        return .{ .section_name = section_name, .stop = false, .optional = true, .match_prefix = true };61    }62    if (std.mem.eql(u8, symbol_name, end_name)) {63        return .{ .section_name = section_name, .stop = true, .optional = true, .match_prefix = true };64    }65    return null;66}6768fn isCIdentifier(name: []const u8) bool {69    if (name.len == 0) return false;70    if (!isCIdentifierStart(name[0])) return false;71    for (name[1..]) |byte| {72        if (!isCIdentifierContinue(byte)) return false;73    }74    return true;75}7677fn isCIdentifierStart(byte: u8) bool {78    return byte == '_' or (byte >= 'a' and byte <= 'z') or (byte >= 'A' and byte <= 'Z');79}8081fn isCIdentifierContinue(byte: u8) bool {82    return isCIdentifierStart(byte) or (byte >= '0' and byte <= '9');83}8485fn hashU64(seed: u64, value: u64) u64 {86    var bytes: [8]u8 = undefined;87    std.mem.writeInt(u64, &bytes, value, .little);88    return std.hash.Wyhash.hash(seed, &bytes);89}

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