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https://github.com/SerenityOS/serenity
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d8b514873f
Using the kernel stack is preferable, especially when the examined strings should be limited to a reasonable length. This is a small improvement, because if we don't actually move these strings then we don't need to own heap allocations for them during the syscall handler function scope. In addition to that, some kernel strings are known to be limited, like the hostname string, for these strings we also can use FixedStringBuffer to store and copy to and from these buffers, without using any heap allocations at all.
47 lines
1.6 KiB
C++
47 lines
1.6 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Tasks/Process.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$gethostname(Userspace<char*> buffer, size_t size)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::stdio));
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if (size > NumericLimits<ssize_t>::max())
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return EINVAL;
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return hostname().with_shared([&](auto const& name) -> ErrorOr<FlatPtr> {
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// NOTE: To be able to copy a null-terminated string, we need at most
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// 65 characters to store and copy and not 64 here, to store the whole
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// hostname string + null terminator.
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FixedStringBuffer<UTSNAME_ENTRY_LEN> current_hostname {};
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current_hostname.store_characters(name.representable_view());
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auto name_view = current_hostname.representable_view();
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if (size < (name_view.length() + 1))
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return ENAMETOOLONG;
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TRY(copy_to_user(buffer, name_view.characters_without_null_termination(), name_view.length() + 1));
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return 0;
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});
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}
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ErrorOr<FlatPtr> Process::sys$sethostname(Userspace<char const*> buffer, size_t length)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_no_promises());
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auto credentials = this->credentials();
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if (!credentials->is_superuser())
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return EPERM;
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auto new_hostname = TRY(get_syscall_name_string_fixed_buffer<UTSNAME_ENTRY_LEN - 1>(buffer, length));
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hostname().with_exclusive([&](auto& name) {
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name.store_characters(new_hostname.representable_view());
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});
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return 0;
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}
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}
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