# AUTHOR <EMAIL@ADDRESS>, YEAR.
# 
# Translators:
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"Project-Id-Version: Defensive Coding Guide\n"
"POT-Creation-Date: 2013-03-12T03:19:44\n"
"PO-Revision-Date: 2013-03-19 15:29+0000\n"
"Last-Translator: Automatically generated\n"
"Language-Team: German <trans-de@lists.fedoraproject.org>\n"
"MIME-Version: 1.0\n"
"Content-Type: text/plain; charset=UTF-8\n"
"Content-Transfer-Encoding: 8bit\n"
"Language: de\n"
"Plural-Forms: nplurals=2; plural=(n != 1);\n"

#. Tag: title
#, no-c-format
msgid "Library Design"
msgstr ""

#. Tag: para
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msgid ""
"Throught this section, the term <emphasis>client code</emphasis> refers to "
"applications and other libraries using the library."
msgstr ""

#. Tag: title
#, no-c-format
msgid "State management"
msgstr ""

#. Tag: title
#, no-c-format
msgid "Global state"
msgstr ""

#. Tag: para
#, no-c-format
msgid "Global state should be avoided."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"If this is impossible, the global state must be protected with a lock. For "
"C/C++, you can use the <function>pthread_mutex_lock</function> and "
"<function>pthread_mutex_unlock</function> functions without linking against "
"<literal>-lpthread</literal> because the system provides stubs for non-"
"threaded processes."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"For compatibility with <function>fork</function>, these locks should be "
"acquired and released in helpers registered with "
"<function>pthread_atfork</function>. This function is not available without "
"<literal>-lpthread</literal>, so you need to use <function>dlsym</function> "
"or a weak symbol to obtain its address."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"If you need <function>fork</function> protection for other reasons, you "
"should store the process ID and compare it to the value returned by "
"<function>getpid</function> each time you access the global state. "
"(<function>getpid</function> is not implemented as a system call and is "
"fast.) If the value changes, you know that you have to re-create the state "
"object. (This needs to be combined with locking, of course.)"
msgstr ""

#. Tag: title
#, no-c-format
msgid "Handles"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Library state should be kept behind a curtain. Client code should receive "
"only a handle. In C, the handle can be a pointer to an incomplete "
"<literal>struct</literal>. In C++, the handle can be a pointer to an "
"abstract base class, or it can be hidden using the pointer-to-implementation"
" idiom."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"The library should provide functions for creating and destroying handles. "
"(In C++, it is possible to use virtual destructors for the latter.) "
"Consistency between creation and destruction of handles is strongly "
"recommended: If the client code created a handle, it is the responsibility "
"of the client code to destroy it. (This is not always possible or "
"convenient, so sometimes, a transfer of ownership has to happen.)"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Using handles ensures that it is possible to change the way the library "
"represents state in a way that is transparent to client code. This is "
"important to facilitate security updates and many other code changes."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"It is not always necessary to protect state behind a handle with a lock. "
"This depends on the level of thread safety the library provides."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Object orientation"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Classes should be either designed as base classes, or it should be "
"impossible to use them as base classes (like <literal>final</literal> "
"classes in Java). Classes which are not designed for inheritance and are "
"used as base classes nevertheless create potential maintenance hazards "
"because it is difficult to predict how client code will react when calls to "
"virtual methods are added, reordered or removed."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Virtual member functions can be used as callbacks. See <xref linkend=\"sect-"
"Defensive_Coding-Tasks-Library_Design-Callbacks\" /> for some of the "
"challenges involved."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Callbacks"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Higher-order code is difficult to analyze for humans and computers alike, so"
" it should be avoided. Often, an iterator-based interface (a library "
"function which is called repeatedly by client code and returns a stream of "
"events) leads to a better design which is easier to document and use."
msgstr ""

#. Tag: para
#, no-c-format
msgid "If callbacks are unavoidable, some guidelines for them follow."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"In modern C++ code, <literal>std::function</literal> objects should be used "
"for callbacks."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"In older C++ code and in C code, all callbacks must have an additional "
"closure parameter of type <literal>void *</literal>, the value of which can "
"be specified by client code. If possible, the value of the closure parameter"
" should be provided by client code at the same time a specific callback is "
"registered (or specified as a function argument). If a single closure "
"parameter is shared by multiple callbacks, flexibility is greatly reduced, "
"and conflicts between different pieces of client code using the same library"
" object could be unresolvable. In some cases, it makes sense to provide a "
"de-registration callback which can be used to destroy the closure parameter "
"when the callback is no longer used."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Callbacks can throw exceptions or call <function>longjmp</function>. If "
"possible, all library objects should remain in a valid state. (All further "
"operations on them can fail, but it should be possible to deallocate them "
"without causing resource leaks.)"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"The presence of callbacks raises the question if functions provided by the "
"library are <emphasis>reentrant</emphasis>. Unless a library was designed "
"for such use, bad things will happen if a callback function uses functions "
"in the same library (particularly if they are invoked on the same objects "
"and manipulate the same state). When the callback is invoked, the library "
"can be in an inconsistent state. Reentrant functions are more difficult to "
"write than thread-safe functions (by definition, simple locking would "
"immediately lead to deadlocks). It is also difficult to decide what to do "
"when destruction of an object which is currently processing a callback is "
"requested."
msgstr ""

#. Tag: title
#, no-c-format
msgid "Process attributes"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Several attributes are global and affect all code in the process, not just "
"the library that manipulates them."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"environment variables (see <xref linkend=\"sect-Defensive_Coding-Tasks-"
"secure_getenv\" />)"
msgstr ""

#. Tag: para
#, no-c-format
msgid "umask"
msgstr ""

#. Tag: para
#, no-c-format
msgid "user IDs, group IDs and capabilities"
msgstr ""

#. Tag: para
#, no-c-format
msgid "current working directory"
msgstr ""

#. Tag: para
#, no-c-format
msgid "signal handlers, signal masks and signal delivery"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"file locks (especially <function>fcntl</function> locks behave in surprising"
" ways, not just in a multi-threaded environment)"
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"Library code should avoid manipulating these global process attributes. It "
"should not rely on environment variables, umask, the current working "
"directory and signal masks because these attributes can be inherted from an "
"untrusted source."
msgstr ""

#. Tag: para
#, no-c-format
msgid ""
"In addition, there are obvious process-wide aspects such as the virtual "
"memory layout, the set of open files and dynamic shared objects, but with "
"the exception of shared objects, these can be manipulated in a relatively "
"isolated way."
msgstr ""
