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LibCore: Define and use a fallible, OS-independent getpwent(_r) wrapper
Rather than maintaining a list of #ifdef guards to check systems that do not provide the reentrant version of getpwent, we can use C++ concepts to let the compiler perform this check for us. While we're at it, we can also provide this wrapper as fallible to let the caller TRY calling it.
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b367da592c
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1ee808fae6
3 changed files with 58 additions and 27 deletions
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@ -128,40 +128,31 @@ ErrorOr<Account> Account::from_uid(uid_t uid, [[maybe_unused]] Read options)
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ErrorOr<Vector<Account>> Account::all([[maybe_unused]] Read options)
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{
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Vector<Account> accounts;
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#ifndef AK_OS_MACOS
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struct passwd pwd;
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struct passwd* ptr = nullptr;
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char buffer[1024] = { 0 };
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#endif
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ScopeGuard pwent_guard([] { endpwent(); });
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setpwent();
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errno = 0;
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#ifndef AK_OS_MACOS
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while (getpwent_r(&pwd, buffer, sizeof(buffer), &ptr) == 0 && ptr) {
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#else
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while (auto const* ptr = getpwent()) {
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#endif
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while (true) {
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auto pwd = TRY(Core::System::getpwent({ buffer, sizeof(buffer) }));
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if (!pwd.has_value())
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break;
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spwd spwd = {};
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#ifndef AK_OS_BSD_GENERIC
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ScopeGuard spent_guard([] { endspent(); });
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if (options != Read::PasswdOnly) {
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auto maybe_spwd = TRY(Core::System::getspnam({ ptr->pw_name, strlen(ptr->pw_name) }));
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auto maybe_spwd = TRY(Core::System::getspnam({ pwd->pw_name, strlen(pwd->pw_name) }));
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if (!maybe_spwd.has_value())
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return Error::from_string_literal("No shadow entry for user");
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spwd = maybe_spwd.release_value();
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}
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#endif
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accounts.append({ *ptr, spwd, get_extra_gids(*ptr) });
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accounts.append({ *pwd, spwd, get_extra_gids(*pwd) });
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}
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if (errno)
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return Error::from_errno(errno);
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return accounts;
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}
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@ -226,13 +217,17 @@ Account::Account(passwd const& pwd, spwd const& spwd, Vector<gid_t> extra_gids)
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ErrorOr<DeprecatedString> Account::generate_passwd_file() const
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{
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StringBuilder builder;
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char buffer[1024] = { 0 };
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ScopeGuard pwent_guard([] { endpwent(); });
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setpwent();
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struct passwd* p;
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errno = 0;
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while ((p = getpwent())) {
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if (p->pw_name == m_username) {
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while (true) {
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auto pwd = TRY(Core::System::getpwent({ buffer, sizeof(buffer) }));
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if (!pwd.has_value())
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break;
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if (pwd->pw_name == m_username) {
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builder.appendff("{}:!:{}:{}:{}:{}:{}\n",
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m_username,
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m_uid, m_gid,
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@ -242,15 +237,11 @@ ErrorOr<DeprecatedString> Account::generate_passwd_file() const
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} else {
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builder.appendff("{}:!:{}:{}:{}:{}:{}\n",
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p->pw_name, p->pw_uid,
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p->pw_gid, p->pw_gecos, p->pw_dir,
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p->pw_shell);
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pwd->pw_name, pwd->pw_uid,
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pwd->pw_gid, pwd->pw_gecos, pwd->pw_dir,
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pwd->pw_shell);
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}
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}
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endpwent();
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if (errno)
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return Error::from_errno(errno);
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return builder.to_deprecated_string();
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}
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@ -52,6 +52,40 @@ static int memfd_create(char const* name, unsigned int flags)
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} \
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return success_value;
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// clang-format off
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template<typename T>
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concept SupportsReentrantGetpwent = requires(T passwd, T* ptr)
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{
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getpwent_r(&passwd, nullptr, 0, &ptr);
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};
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// clang-format on
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// Note: This has to be in the global namespace for the extern declaration to trick the compiler
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// into finding a declaration of getpwent_r when it doesn't actually exist.
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static ErrorOr<Optional<struct passwd>> getpwent_impl(Span<char> buffer)
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{
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if constexpr (SupportsReentrantGetpwent<struct passwd>) {
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struct passwd passwd;
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struct passwd* ptr = nullptr;
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extern int getpwent_r(struct passwd*, char*, size_t, struct passwd**);
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auto result = getpwent_r(&passwd, buffer.data(), buffer.size(), &ptr);
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if (result == 0 && ptr)
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return passwd;
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if (result != 0 && result != ENOENT)
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return Error::from_errno(result);
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} else {
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errno = 0;
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if (auto const* passwd = ::getpwent())
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return *passwd;
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if (errno)
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return Error::from_errno(errno);
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}
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return Optional<struct passwd> {};
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}
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namespace Core::System {
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#ifndef HOST_NAME_MAX
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@ -627,6 +661,11 @@ ErrorOr<void> chown(StringView pathname, uid_t uid, gid_t gid)
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#endif
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}
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ErrorOr<Optional<struct passwd>> getpwent(Span<char> buffer)
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{
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return getpwent_impl(buffer);
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}
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ErrorOr<Optional<struct passwd>> getpwuid(uid_t uid)
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{
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errno = 0;
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@ -122,6 +122,7 @@ ErrorOr<int> tcsetpgrp(int fd, pid_t pgrp);
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ErrorOr<void> chmod(StringView pathname, mode_t mode);
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ErrorOr<void> lchown(StringView pathname, uid_t uid, gid_t gid);
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ErrorOr<void> chown(StringView pathname, uid_t uid, gid_t gid);
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ErrorOr<Optional<struct passwd>> getpwent(Span<char> buffer);
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ErrorOr<Optional<struct passwd>> getpwnam(StringView name);
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ErrorOr<Optional<struct group>> getgrnam(StringView name);
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ErrorOr<Optional<struct passwd>> getpwuid(uid_t);
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