buildSymbolSearchTable

fn buildSymbolSearchTable(gpa: Allocator, endian: Endian, comptime Sym: type, symbols: []align(1) const Sym) error{
    OutOfMemory,
    BadSymtab,
}![]usize {
    var result: std.ArrayList(usize) = .empty;
    defer result.deinit(gpa);

    const swap_endian = endian != @import("builtin").cpu.arch.endian();

    for (symbols, 0..) |sym_orig, sym_index| {
        var sym = sym_orig;
        if (swap_endian) std.mem.byteSwapAllFields(Sym, &sym);
        if (sym.st_name == 0) continue;
        if (sym.st_shndx == elf.SHN_UNDEF) continue;
        try result.append(gpa, sym_index);
    }

    const SortContext = struct {
        swap_endian: bool,
        symbols: []align(1) const Sym,
        fn lessThan(ctx: @This(), lhs_sym_index: usize, rhs_sym_index: usize) bool {
            // We sort by *end* address, not start address. This matches up with logic in `searchSymtab`.
            var lhs_sym = ctx.symbols[lhs_sym_index];
            var rhs_sym = ctx.symbols[rhs_sym_index];
            if (ctx.swap_endian) {
                std.mem.byteSwapAllFields(Sym, &lhs_sym);
                std.mem.byteSwapAllFields(Sym, &rhs_sym);
            }
            const lhs_val = lhs_sym.st_value + lhs_sym.st_size;
            const rhs_val = rhs_sym.st_value + rhs_sym.st_size;
            return lhs_val < rhs_val;
        }
    };
    std.mem.sort(usize, result.items, @as(SortContext, .{
        .swap_endian = swap_endian,
        .symbols = symbols,
    }), SortContext.lessThan);

    return result.toOwnedSlice(gpa);
}