New upstream version 1.39.90 upstream/1.39.90

1 files changed, 444 insertions, 159 deletions

diff --git a/src/c-stdaux/src/c-stdaux.h b/src/c-stdaux/src/c-stdaux.h
index 1cdbbbcf..80db7f9a 100644
--- a/src/c-stdaux/src/c-stdaux.h
+++ b/src/c-stdaux/src/c-stdaux.h
@@ -1,12 +1,23 @@
 #pragma once
 
 /*
- * Auxiliary macros and functions for the C standard library
+ * c-stdaux: Auxiliary macros and functions for the C standard library
  *
- * The `c-stdaux.h` header contains a collection of auxiliary macros and helper
- * functions around the functionality provided by the different C standard
- * library implementations, as well as other specifications implemented by
- * them.
+ * Main public header of the c-stdaux library. All includes of this header are
+ * part of the API!
+ */
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * DOC:
+ *
+ * The ``c-stdaux.h`` header contains a collection of auxiliary macros and
+ * helper functions around the functionality provided by the different C
+ * standard library implementations, as well as other specifications
+ * implemented by them.
  *
  * Most of the helpers provided here provide aliases for common library and
  * compiler features. Furthermore, several helpers simply provide other calling
@@ -16,17 +27,27 @@
  *
  * The namespace used by this project is:
  *
- *  * `c_*` for all common C symbols or definitions that behave like proper C
+ * -  ``c_*`` for all common C symbols or definitions that behave like proper C
  *    entities (e.g., macros that protect against double-evaluation would use
- *    lower-case names)
+ *    lower-case names).
  *
- *  * `C_*` for all constants, as well as macros that may not be safe against
+ * -  ``C_*`` for all constants, as well as macros that may not be safe against
  *    double evaluation.
+ *
+ * -  ``c_internal_*`` and ``C_INTERNAL_*`` for all internal symbols that
+ *    should not be invoked by the caller and are not part of the API
+ *    guarantees.
  */
+/**/
 
-#ifdef __cplusplus
-extern "C" {
-#endif
+/**
+ * DOC: Guaranteed Includes
+ *
+ * The ``c-stdaux.h`` header includes a set of C Standard Library headers as
+ * well as UNIX headers. All those includes are guaranteed and part of the API.
+ * See the actual header for a comprehensive list.
+ */
+/**/
 
 #include <assert.h>
 #include <dirent.h>
@@ -36,9 +57,6 @@ extern "C" {
 #include <limits.h>
 #include <stdalign.h>
 #include <stdarg.h>
-#if 0 /* NM_IGNORED */
-#include <stdatomic.h>
-#endif /* NM_IGNORED */
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdio.h>
@@ -50,44 +68,152 @@ extern "C" {
 #include <time.h>
 #include <unistd.h>
 
-/*
- * Shortcuts for gcc attributes. See GCC manual for details. They're 1-to-1
- * mappings to the GCC equivalents. No additional magic here. They are
- * supported by other compilers as well.
+/**
+ * DOC: Compiler Attributes
+ *
+ * The GCC compiler uses the ``__attribute__((__xyz__()))`` syntax to annotate
+ * language entities with special attributes. Aliases are provided by this
+ * header which map one-to-one to the respective compiler attributes.
+ *
+ * These attributes are not supported by all compilers, but are always provided
+ * by this header. They are pre-processor macros and do not affect the
+ * compilation, unless used. Note that most compilers support these, not just
+ * GCC.
+ */
+/**/
+
+/**
+ * _c_cleanup_() - Cleanup attribute
+ * @_x:                 Cleanup function to use
+ *
+ * Alias for ``__attribute__((__cleanup__(_x)))``.
  */
 #define _c_cleanup_(_x) __attribute__((__cleanup__(_x)))
+
+/**
+ * _c_const_() - Const attribute
+ *
+ * Alias for ``__attribute__((__const__))``.
+ */
 #define _c_const_ __attribute__((__const__))
+
+/**
+ * _c_deprecated_() - Deprecated attribute
+ *
+ * Alias for ``__attribute__((__deprecated__))``.
+ */
 #define _c_deprecated_ __attribute__((__deprecated__))
+
+/**
+ * _c_hidden_() - Hidden attribute
+ *
+ * Alias for ``__attribute__((__visibility__("hidden")))``.
+ */
 #define _c_hidden_ __attribute__((__visibility__("hidden")))
-#define _c_likely_(_x) (__builtin_expect(!!(_x), 1))
+
+/**
+ * _c_packed_() - Packed attribute
+ *
+ * Alias for ``__attribute__((__packed__))``.
+ */
 #define _c_packed_ __attribute__((__packed__))
+
+/**
+ * _c_printf_() - Printf attribute
+ * @_a:                 Format expression argument index
+ * @_b:                 First format-parameter argument index
+ *
+ * Alias for ``__attribute__((__format__(printf, _a, _b)))``.
+ */
 #define _c_printf_(_a, _b) __attribute__((__format__(printf, _a, _b)))
+
+/**
+ * _c_public_() - Public attribute
+ *
+ * Alias for ``__attribute__((__visibility__("default")))``.
+ */
 #define _c_public_ __attribute__((__visibility__("default")))
+
+/**
+ * _c_pure_() - Pure attribute
+ *
+ * Alias for ``__attribute__((__pure__))``.
+ */
 #define _c_pure_ __attribute__((__pure__))
+
+/**
+ * _c_sentinel_() - Sentinel attribute
+ *
+ * Alias for ``__attribute__((__sentinel__))``.
+ */
 #define _c_sentinel_ __attribute__((__sentinel__))
-#define _c_unlikely_(_x) (__builtin_expect(!!(_x), 0))
+
+/**
+ * _c_unused_() - Unused attribute
+ *
+ * Alias for ``__attribute__((__unused__))``.
+ */
 #define _c_unused_ __attribute__((__unused__))
 
 /**
- * C_EXPR_ASSERT() - create expression with assertion
- * @_expr:              expression to evaluate to
- * @_assertion:         arbitrary assertion
- * @_message:           message associated with the assertion
+ * DOC: Compiler Intrinsics
+ *
+ * Aliases for common compiler extensions and intrinsics are provided similar
+ * to the compiler attributes. They are pure preprocessor aliases and do not
+ * affect compilation unless used.
+ */
+/**/
+
+/**
+ * _c_likely_() - Likely attribute
+ * @_x:                 Expression to evaluate
  *
- * This macro simply evaluates to @_expr. That is, it can be used in any
- * context that expects an expression like @_expr. Additionally, it takes an
- * assertion as @_assertion and evaluates it through _Static_assert(), using
- * @_message as debug message.
+ * Alias for ``__builtin_expect(!!(_x), 1)``.
  *
- * The _Static_assert() builtin of C11 is defined as statement and thus cannot
- * be used in expressions. This macro circumvents this restriction.
+ * Return: The expression ``_x`` is evaluated and returned.
+ */
+#define _c_likely_(_x) (__builtin_expect(!!(_x), 1))
+
+/**
+ * _c_unlikely_() - Unlikely attribute
+ * @_x:                 Expression to evaluate
  *
- * Return: Evaluates to @_expr.
+ * Alias for ``__builtin_expect(!!(_x), 0)``.
+ *
+ * Return: The expression ``_x`` is evaluated and returned.
  */
+#define _c_unlikely_(_x) (__builtin_expect(!!(_x), 0))
+
+/**
+ * DOC: Utility Macros
+ *
+ * A set of utility macros is provided which aids in creating safe macros
+ * suitable for use in other pre-processor statements as well as in C
+ * expressions.
+ */
+/**/
+
+/**
+ * C_EXPR_ASSERT() - Create expression with assertion
+ * @_expr:              Expression to evaluate to
+ * @_assertion:         Arbitrary assertion
+ * @_message:           Message associated with the assertion
+ *
+ * This macro simply evaluates to ``_expr``. That is, it can be used in any
+ * context that expects an expression like ``_expr``. Additionally, it takes an
+ * assertion as ``_assertion`` and evaluates it through ``_Static_assert()``,
+ * using ``_message`` as debug message.
+ *
+ * The ``_Static_assert()`` builtin of C11 is defined as statement and thus
+ * cannot be used in expressions. This macro circumvents this restriction.
+ *
+ * Return: Evaluates to ``_expr``.
+ */
+#define C_EXPR_ASSERT(_expr, _assertion, _message) C_INTERNAL_EXPR_ASSERT((_expr), (_assertion), _message)
 #if defined(__COVERITY__) // Coverity cannot const-fold __builtin_choose_expr()
-#  define C_EXPR_ASSERT(_expr, _assertion, _message) (_expr)
+#  define C_INTERNAL_EXPR_ASSERT(_expr, _assertion, _message) (_expr)
 #else
-#  define C_EXPR_ASSERT(_expr, _assertion, _message)                    \
+#  define C_INTERNAL_EXPR_ASSERT(_expr, _assertion, _message)           \
         /* indentation and line-split to get better diagnostics */      \
         (__builtin_choose_expr(                                         \
                 !!(1 + 0 * sizeof(                                      \
@@ -101,8 +227,8 @@ _Static_assert(_assertion, _message); \
 #endif
 
 /**
- * C_STRINGIFY() - stringify a token, but evaluate it first
- * @_x:         token to evaluate and stringify
+ * C_STRINGIFY() - Stringify a token, but evaluate it first
+ * @_x:         Token to evaluate and stringify
  *
  * Return: Evaluates to a constant string literal
  */
@@ -110,9 +236,9 @@ _Static_assert(_assertion, _message); \
 #define C_INTERNAL_STRINGIFY(_x) #_x
 
 /**
- * C_CONCATENATE() - concatenate two tokens, but evaluate them first
- * @_x:         first token
- * @_y:         second token
+ * C_CONCATENATE() - Concatenate two tokens, but evaluate them first
+ * @_x:         First token
+ * @_y:         Second token
  *
  * Return: Evaluates to a constant identifier
  */
@@ -120,8 +246,8 @@ _Static_assert(_assertion, _message); \
 #define C_INTERNAL_CONCATENATE(_x, _y) _x ## _y
 
 /**
- * C_EXPAND() - expand a tuple to a series of its values
- * @_x:         tuple to expand
+ * C_EXPAND() - Expand a tuple to a series of its values
+ * @_x:         Tuple to expand
  *
  * Return: Evaluates to the expanded tuple
  */
@@ -129,29 +255,32 @@ _Static_assert(_assertion, _message); \
 #define C_INTERNAL_EXPAND(...) __VA_ARGS__
 
 /**
- * C_VAR() - generate unique variable name
- * @_x:         name of variable, optional
- * @_uniq:      unique prefix, usually provided by __COUNTER__, optional
+ * C_VAR() - Generate unique variable name
+ * @_x:         Name of variable, optional
+ * @_uniq:      Unique prefix, usually provided by ``__COUNTER__``, optional
  *
  * This macro shall be used to generate unique variable names, that will not be
  * shadowed by recursive macro invocations. It is effectively a
- * C_CONCATENATE of both arguments, but also provides a globally separated
- * prefix and makes the code better readable.
+ * :c:macro:`C_CONCATENATE` of both arguments, but also provides a globally
+ * separated prefix and makes the code better readable.
  *
- * The second argument is optional. If not given, __LINE__ is implied, and as
- * such the macro will generate the same identifier if used multiple times on
- * the same code-line (or within a macro). This should be used if recursive
+ * The second argument is optional. If not given, ``__LINE__`` is implied, and
+ * as such the macro will generate the same identifier if used multiple times
+ * on the same code-line (or within a macro). This should be used if recursive
  * calls into the macro are not expected. In fact, no argument is necessary in
- * this case, as a mere `C_VAR` will evaluate to a valid variable name.
+ * this case, as a mere ``C_VAR`` will evaluate to a valid variable name.
  *
  * This helper may be used by macro implementations that might reasonable well
  * be called in a stacked fasion, like:
  *
+ * .. code-block:: c
+ *
  *     c_max(foo, c_max(bar, baz))
  *
- * Such a stacked call of c_max() might cause compiler warnings of shadowed
- * variables in the definition of c_max(). By using C_VAR(), such warnings
- * can be silenced as each evaluation of c_max() uses unique variable names.
+ * Such a stacked call of :c:macro:`c_max()` might cause compiler warnings of
+ * shadowed variables in the definition of :c:macro:`c_max()`. By using
+ * ``C_VAR()``, such warnings can be silenced as each evaluation of
+ * :c:macro:`c_max()` uses unique variable names.
  *
  * Return: This evaluates to a constant identifier.
  */
@@ -161,28 +290,28 @@ _Static_assert(_assertion, _message); \
 #define C_VAR2(_x, _uniq) C_CONCATENATE(c_internal_var_unique_, C_CONCATENATE(_uniq, _x))
 
 /**
- * C_CC_MACRO1() - provide safe environment to a macro
- * @_call:      macro to call
- * @_x1:        first argument
- * @...:        further arguments to forward unmodified to @_call
+ * C_CC_MACRO1() - Provide safe environment to a macro
+ * @_call:      Macro to call
+ * @_x1:        First argument
+ * @...:        Further arguments to forward unmodified to ``_call``
  *
  * This function simplifies the implementation of macros. Whenever you
- * implement a macro, provide the internal macro name as @_call and its
- * argument as @_x1. Inside of your internal macro, you...
+ * implement a macro, provide the internal macro name as ``_call`` and its
+ * argument as ``_x1``. Inside of your internal macro, you...
  *
- *  - ...are safe against multiple evaluation errors, since C_CC_MACRO1 will
- *       store the initial parameters in temporary variables.
+ * -  are safe against multiple evaluation errors, since ``C_CC_MACRO1``
+ *    will store the initial parameters in temporary variables.
  *
- *  - ...support constant folding, as C_CC_MACRO1 takes care to invoke your
- *       macro with the original values, if they are compile-time constant.
+ * -  support constant folding, as ``C_CC_MACRO1`` takes care to invoke your
+ *    macro with the original values, if they are compile-time constant.
  *
- *  - ...have unique variable names for recursive callers and will not run into
- *       variable-shadowing-warnings accidentally.
+ * -  have unique variable names for recursive callers and will not run into
+ *    variable-shadowing-warnings accidentally.
  *
- *  - ...have properly typed arguments as C_CC_MACRO1 stores the original
- *       arguments in an `__auto_type` temporary variable.
+ * -  have properly typed arguments as ``C_CC_MACRO1`` stores the original
+ *    arguments in an ``__auto_type`` temporary variable.
  *
- * Return: Result of @_call is returned.
+ * Return: Result of ``_call`` is returned.
  */
 #define C_CC_MACRO1(_call, _x1, ...) C_INTERNAL_CC_MACRO1(_call, __COUNTER__, (_x1), ## __VA_ARGS__)
 #define C_INTERNAL_CC_MACRO1(_call, _x1q, _x1, ...)                     \
@@ -195,15 +324,15 @@ _Static_assert(_assertion, _message); \
                 }))
 
 /**
- * C_CC_MACRO2() - provide safe environment to a macro
- * @_call:      macro to call
- * @_x1:        first argument
- * @_x2:        second argument
- * @...:        further arguments to forward unmodified to @_call
+ * C_CC_MACRO2() - Provide safe environment to a macro
+ * @_call:      Macro to call
+ * @_x1:        First argument
+ * @_x2:        Second argument
+ * @...:        Further arguments to forward unmodified to ``_call``
  *
- * This is the 2-argument equivalent of C_CC_MACRO1().
+ * This is the 2-argument equivalent of :c:macro:`C_CC_MACRO1()`.
  *
- * Return: Result of @_call is returned.
+ * Return: Result of ``_call`` is returned.
  */
 #define C_CC_MACRO2(_call, _x1, _x2, ...) C_INTERNAL_CC_MACRO2(_call, __COUNTER__, (_x1), __COUNTER__, (_x2), ## __VA_ARGS__)
 #define C_INTERNAL_CC_MACRO2(_call, _x1q, _x1, _x2q, _x2, ...)                          \
@@ -217,16 +346,16 @@ _Static_assert(_assertion, _message); \
                 }))
 
 /**
- * C_CC_MACRO3() - provide safe environment to a macro
- * @_call:      macro to call
- * @_x1:        first argument
- * @_x2:        second argument
- * @_x3:        third argument
- * @...:        further arguments to forward unmodified to @_call
+ * C_CC_MACRO3() - Provide safe environment to a macro
+ * @_call:      Macro to call
+ * @_x1:        First argument
+ * @_x2:        Second argument
+ * @_x3:        Third argument
+ * @...:        Further arguments to forward unmodified to ``_call``
  *
- * This is the 3-argument equivalent of C_CC_MACRO1().
+ * This is the 3-argument equivalent of :c:macro:`C_CC_MACRO1()`.
  *
- * Return: Result of @_call is returned.
+ * Return: Result of ``_call`` is returned.
  */
 #define C_CC_MACRO3(_call, _x1, _x2, _x3, ...) C_INTERNAL_CC_MACRO3(_call, __COUNTER__, (_x1), __COUNTER__, (_x2), __COUNTER__, (_x3), ## __VA_ARGS__)
 #define C_INTERNAL_CC_MACRO3(_call, _x1q, _x1, _x2q, _x2, _x3q, _x3, ...)                               \
@@ -241,8 +370,17 @@ _Static_assert(_assertion, _message); \
                 }))
 
 /**
- * C_ARRAY_SIZE() - calculate number of array elements at compile time
- * @_x:         array to calculate size of
+ * DOC: Standard Library Utilities
+ *
+ * The C Standard Library lacks some crucial and basic support functions. This
+ * section describes the set of helpers provided as extension to the standard
+ * library.
+ */
+/**/
+
+/**
+ * C_ARRAY_SIZE() - Calculate number of array elements at compile time
+ * @_x:         Array to calculate size of
  *
  * Return: Evaluates to a constant integer expression.
  */
@@ -260,9 +398,8 @@ _Static_assert(_assertion, _message); \
         )
 
 /**
- * C_DECIMAL_MAX() - calculate maximum length of the decimal
- *                   representation of an integer
- * @_type: integer variable/type
+ * C_DECIMAL_MAX() - Calculate maximum length of a decimal representation
+ * @_type: Integer variable/type
  *
  * This calculates the bytes required for the decimal representation of an
  * integer of the given type. It accounts for a possible +/- prefix, but it
@@ -294,28 +431,41 @@ _Static_assert(_assertion, _message); \
         )
 
 /**
- * c_container_of() - cast a member of a structure out to the containing structure
- * @_ptr:       pointer to the member or NULL
- * @_type:      type of the container struct this is embedded in
- * @_member:    name of the member within the struct
+ * c_container_of() - Cast a member of a structure out to the containing type
+ * @_ptr:       Pointer to the member or NULL
+ * @_type:      Type of the container struct this is embedded in
+ * @_member:    Name of the member within the struct
  *
- * This uses `offsetof(3)` to turn a pointer to a structure-member into a
+ * This uses ``offsetof(3)`` to turn a pointer to a structure-member into a
  * pointer to the surrounding structure.
  *
  * Return: Pointer to the surrounding object.
  */
 #define c_container_of(_ptr, _type, _member) C_CC_MACRO1(C_CONTAINER_OF, (_ptr), _type, _member)
 #define C_CONTAINER_OF(_ptr, _type, _member)                                            \
-        __extension__ ({                                                                \
-                /* trigger warning if types do not match */                             \
-                (void)(&((_type *)0)->_member == (_ptr));                               \
-                _ptr ? (_type*)( (char*)_ptr - offsetof(_type, _member) ) : NULL;       \
-        })
+        C_EXPR_ASSERT(                                                                  \
+                (_ptr ? (_type*)c_internal_container_of((void *)_ptr, offsetof(_type, _member)) : NULL),     \
+                __builtin_types_compatible_p(                                           \
+                        __typeof__(*(_ptr)),                                            \
+                        __typeof__(((_type){})._member)                                 \
+                ) || __builtin_types_compatible_p(                                      \
+                        __typeof__(_ptr),                                               \
+                        __typeof__(NULL)                                                \
+                ),                                                                      \
+                "Invalid use of C_CONTAINER_OF()"                                       \
+        )
+static inline void *c_internal_container_of(void *ptr, size_t offset) {
+        /*
+         * Arithmetic on NULL is UB, even if in dead-code. Hide it in a proper
+         * C function, so the macro never emits it as code.
+         */
+        return (char *)ptr - offset;
+}
 
 /**
- * c_max() - compute maximum of two values
- * @_a:         value A
- * @_b:         value B
+ * c_max() - Compute maximum of two values
+ * @_a:         Value A
+ * @_b:         Value B
  *
  * Calculate the maximum of both passed values. Both arguments are evaluated
  * exactly once, under all circumstances. Furthermore, if both values are
@@ -331,9 +481,9 @@ _Static_assert(_assertion, _message); \
 #define C_MAX(_a, _b) ((_a) > (_b) ? (_a) : (_b))
 
 /**
- * c_min() - compute minimum of two values
- * @_a:         value A
- * @_b:         value B
+ * c_min() - Compute minimum of two values
+ * @_a:         Value A
+ * @_b:         Value B
  *
  * Calculate the minimum of both passed values. Both arguments are evaluated
  * exactly once, under all circumstances. Furthermore, if both values are
@@ -349,32 +499,32 @@ _Static_assert(_assertion, _message); \
 #define C_MIN(_a, _b) ((_a) < (_b) ? (_a) : (_b))
 
 /**
- * c_less_by() - calculate clamped difference of two values
- * @_a:         minuend
- * @_b:         subtrahend
+ * c_less_by() - Calculate clamped difference of two values
+ * @_a:         Minuend
+ * @_b:         Subtrahend
  *
- * Calculate [_a - _b], but clamp the result to 0. Both arguments are evaluated
- * exactly once, under all circumstances. Furthermore, if both values are
- * constant expressions, the result will be constant as well.
+ * Calculate ``_a - _b``, but clamp the result to 0. Both arguments are
+ * evaluated exactly once, under all circumstances. Furthermore, if both values
+ * are constant expressions, the result will be constant as well.
  *
  * The comparison of their values is performed with the types given by the
  * caller. It is the caller's responsibility to convert them to suitable types
  * if necessary.
  *
- * Return: This computes [_a - _b], if [_a > _b]. Otherwise, 0 is returned.
+ * Return: This computes ``_a - _b``, if ``_a > _b``. Otherwise, 0 is returned.
  */
 #define c_less_by(_a, _b) C_CC_MACRO2(C_LESS_BY, (_a), (_b))
 #define C_LESS_BY(_a, _b) ((_a) > (_b) ? (_a) - (_b) : 0)
 
 /**
- * c_clamp() - clamp value to lower and upper boundary
- * @_x:         value to clamp
- * @_low:       lower boundary
- * @_high:      higher boundary
+ * c_clamp() - Clamp value to lower and upper boundary
+ * @_x:         Value to clamp
+ * @_low:       Lower boundary
+ * @_high:      Higher boundary
  *
- * This clamps @_x to the lower and higher bounds given as @_low and @_high.
- * All arguments are evaluated exactly once, and yield a constant expression if
- * all arguments are constant as well.
+ * This clamps ``_x`` to the lower and higher bounds given as ``_low`` and
+ * ``_high``. All arguments are evaluated exactly once, and yield a constant
+ * expression if all arguments are constant as well.
  *
  * The comparison of their values is performed with the types given by the
  * caller. It is the caller's responsibility to convert them to suitable types
@@ -386,18 +536,18 @@ _Static_assert(_assertion, _message); \
 #define C_CLAMP(_x, _low, _high) ((_x) > (_high) ? (_high) : (_x) < (_low) ? (_low) : (_x))
 
 /**
- * c_div_round_up() - calculate integer quotient but round up
- * @_x:         dividend
- * @_y:         divisor
+ * c_div_round_up() - Calculate integer quotient but round up
+ * @_x:         Dividend
+ * @_y:         Divisor
  *
- * Calculates [x / y] but rounds up the result to the next integer. All
+ * Calculates ``x / y`` but rounds up the result to the next integer. All
  * arguments are evaluated exactly once, and yield a constant expression if all
  * arguments are constant.
  *
- * Note:
- * [(x + y - 1) / y] suffers from an integer overflow, even though the
+ * **Note:**
+ * ``(x + y - 1) / y`` suffers from an integer overflow, even though the
  * computation should be possible in the given type. Therefore, we use
- * [x / y + !!(x % y)]. Note that on most CPUs a division returns both the
+ * ``x / y + !!(x % y)``. Note that on most CPUs a division returns both the
  * quotient and the remainder, so both should be equally fast. Furthermore, if
  * the divisor is a power of two, the compiler will optimize it, anyway.
  *
@@ -411,34 +561,35 @@ _Static_assert(_assertion, _message); \
 #define C_DIV_ROUND_UP(_x, _y) ((_x) / (_y) + !!((_x) % (_y)))
 
 /**
- * c_align_to() - align value to a multiple
- * @_val:       value to align
- * @_to:        align to multiple of this
+ * c_align_to() - Align value to a multiple
+ * @_val:       Value to align
+ * @_to:        Align to multiple of this
  *
- * This aligns @_val to a multiple of @_to. If @_val is already a multiple of
- * @_to, @_val is returned unchanged. This function operates within the
- * boundaries of the type of @_val and @_to. Make sure to cast them if needed.
+ * This aligns ``_val`` to a multiple of ``_to``. If ``_val`` is already a
+ * multiple of ``_to``, ``_val`` is returned unchanged. This function operates
+ * within the boundaries of the type of ``_val`` and ``_to``. Make sure to cast
+ * them if needed.
  *
  * The arguments of this macro are evaluated exactly once. If both arguments
  * are a constant expression, this also yields a constant return value.
  *
- * Note that @_to must be a power of 2, otherwise the behavior will not match
- * expectations.
+ * Note that ``_to`` must be a power of 2, otherwise the behavior will not
+ * match expectations.
  *
- * Return: @_val aligned to a multiple of @_to
+ * Return: ``_val`` aligned to a multiple of ``_to``.
  */
 #define c_align_to(_val, _to) C_CC_MACRO2(C_ALIGN_TO, (_val), (_to))
 #define C_ALIGN_TO(_val, _to) (((_val) + (_to) - 1) & ~((_to) - 1))
 
 /**
- * c_assert() - runtime assertions
- * @expr_result:                result of an expression
+ * c_assert() - Runtime assertions
+ * @expr_result:                Result of an expression
  *
- * This function behaves like the standard `assert(3)` macro. That is, if
- * `NDEBUG` is defined, it is a no-op. In all other cases it will assert that
+ * This function behaves like the standard ``assert(3)`` macro. That is, if
+ * ``NDEBUG`` is defined, it is a no-op. In all other cases it will assert that
  * the result of the passed expression is true.
  *
- * Unlike the standard `assert(3)` macro, this function always evaluates its
+ * Unlike the standard ``assert(3)`` macro, this function always evaluates its
  * argument. This means side-effects will always be evaluated! However, if the
  * macro is used with constant expressions, the compiler will be able to
  * optimize it away.
@@ -449,13 +600,13 @@ _Static_assert(_assertion, _message); \
         })
 
 /**
- * c_errno() - return valid errno
+ * c_errno() - Return valid errno
  *
- * This helper should be used to shut up gcc if you know 'errno' is valid (ie.,
- * errno is > 0). Instead of "return -errno;", use
- * "return -c_errno();" It will suppress bogus gcc warnings in case it assumes
- * 'errno' might be 0 (or <0) and thus the caller's error-handling might not be
- * triggered.
+ * This helper should be used to shut up gcc if you know ``errno`` is valid
+ * (ie., ``errno`` is greater than 0). Instead of ``return -errno;``, use
+ * ``return -c_errno();`` It will suppress bogus gcc warnings in case it
+ * assumes ``errno`` might be 0 (or smaller than 0) and thus the caller's
+ * error-handling might not be triggered.
  *
  * This helper should be avoided whenever possible. However, occasionally we
  * really want to shut up gcc (especially with static/inline functions). In
@@ -472,62 +623,196 @@ static inline int c_errno(void) {
         return _c_likely_(errno > 0) ? errno : ENOTRECOVERABLE;
 }
 
-/*
- * Common Destructors
+/**
+ * c_memset() - Fill memory region with constant byte
+ * @p:          Pointer to memory region, if non-empty
+ * @c:          Value to fill with
+ * @n:          Size of the memory region in bytes
+ *
+ * This function works like ``memset(3)`` if ``n`` is non-zero. If ``n`` is
+ * zero, this function is a no-op. Therefore, unlike ``memset(3)`` it is safe
+ * to call this function with ``NULL`` as ``p`` if ``n`` is 0.
+ *
+ * Return: ``p`` is returned.
+ */
+static inline void *c_memset(void *p, int c, size_t n) {
+        if (n > 0)
+                memset(p, c, n);
+        return p;
+}
+
+/**
+ * c_memzero() - Clear memory area
+ * @p:          Pointer to memory region, if non-empty
+ * @n:          Size of the memory region in bytes
+ *
+ * Clear a memory area to 0. If the memory area is empty, this is a no-op.
+ * Similar to ``c_memset()``, this function allows ``p`` to be ``NULL`` if the
+ * area is empty.
+ *
+ * Return: ``p`` is returned.
+ */
+static inline void *c_memzero(void *p, size_t n) {
+        return c_memset(p, 0, n);
+}
+
+/**
+ * c_memcpy() - Copy memory area
+ * @dst:        Pointer to target area
+ * @src:        Pointer to source area
+ * @n:          Length of area to copy
+ *
+ * Copy the memory of size ``n`` from ``src`` to ``dst``, just as ``memcpy(3)``
+ * does, except this function allows either to be ``NULL`` if ``n`` is zero. In
+ * the latter case, the operation is a no-op.
+ *
+ * Return: ``p`` is returned.
+ */
+static inline void *c_memcpy(void *dst, const void *src, size_t n) {
+        if (n > 0)
+                memcpy(dst, src, n);
+        return dst;
+}
+
+/**
+ * c_memcmp() - Compare memory areas
+ * @s1:         Pointer to one area
+ * @s2:         Pointer to other area
+ * @n:          Length of area to compare
+ *
+ * Compare the memory of size ``n`` of ``s1`` and ``s2``, just as ``memcmp(3)``
+ * does, except this function allows either to be ``NULL`` if ``n`` is zero.
  *
- * Followingly, there're a bunch of common 'static inline' destructors, which
- * simply call the function that they're named after, but return "INVALID"
- * instead of "void". This allows direct assignment to any member-field and/or
- * variable they're defined in, like:
+ * Return: Comparison result for ordering is returned.
+ */
+static inline int c_memcmp(const void *s1, const void *s2, size_t n) {
+        if (n > 0)
+                return memcmp(s1, s2, n);
+        return 0;
+}
+
+/**
+ * DOC: Common Destructors
  *
- *   foo = c_free(foo);
+ * A set of destructors is provided which extends standard library destructors
+ * to adhere to some adjuvant rules. In particular, they return an invalid
+ * value of the particular object, rather than void. This allows direct
+ * assignment to any member-field and/or variable they are defined in, like:
  *
- * or
+ * .. code-block:: c
  *
- *   foo->bar = c_close(foo->bar);
+ *     foo = c_free(foo);
+ *     foo->bar = c_close(foo->bar);
  *
  * Furthermore, all those destructors can be safely called with the "INVALID"
  * value as argument, and they will be a no-op.
  */
+/**/
 
+/**
+ * c_free() - Destructor-wrapper for free()
+ * @p:          Value to pass to destructor, or NULL
+ *
+ * Wrapper around ``free()``, but always returns ``NULL``.
+ *
+ * Return: NULL is returned.
+ */
 static inline void *c_free(void *p) {
         free(p);
         return NULL;
 }
 
+/**
+ * c_close() - Destructor-wrapper for close()
+ * @fd:         File-descriptor to pass to destructor, or negative value
+ *
+ * Wrapper around ``close()``, but a no-op if a negative value is provided.
+ * Always returns ``-1``.
+ *
+ * Return: -1 is returned.
+ */
 static inline int c_close(int fd) {
         if (fd >= 0)
                 close(fd);
         return -1;
 }
 
+/**
+ * c_fclose() - Destructor-wrapper for fclose()
+ * @f:          File handle to pass to destructor, or NULL
+ *
+ * Wrapper around ``fclose()``, but a no-op if ``NULL`` is passed. Always
+ * returns ``NULL``.
+ *
+ * Return: NULL is returned.
+ */
 static inline FILE *c_fclose(FILE *f) {
         if (f)
                 fclose(f);
         return NULL;
 }
 
+/**
+ * c_closedir() - Destructor-wrapper for closedir)
+ * @d:          Directory handle to pass to destructor, or NULL
+ *
+ * Wrapper around ``closedir()``, but a no-op if ``NULL`` is passed. Always
+ * returns ``NULL``.
+ *
+ * Return: NULL is returned.
+ */
 static inline DIR *c_closedir(DIR *d) {
         if (d)
                 closedir(d);
         return NULL;
 }
 
-/*
- * Common Cleanup Helpers
+/**
+ * DOC: Common Cleanup Helpers
  *
- * A bunch of _c_cleanup_(foobarp) helpers that are used all over the place.
- * Note that all of those have the "if (IS_INVALID(foobar))" check inline, so
- * compilers can optimize most of the cleanup-paths in a function. However, if
- * the function they call already does this _inline_, then it might be skipped.
+ * A set of helpers that aid in creating functions suitable for use with
+ * :c:macro:`_c_cleanup_()`. Furthermore, a collection of predefined cleanup
+ * functions of a set of standard library objects ready for use with
+ * :c:macro:`_c_cleanup_()`.
+ * Those cleanup helpers are always suffixed with a ``p``.
+ *
+ * The helpers that are provided are:
+ *
+ * - ``c_freep()``: Wrapper around :c:func:`c_free()`.
+ * - ``c_closep()``: Wrapper around :c:func:`c_close()`.
+ * - ``c_fclosep()``: Wrapper around :c:func:`c_fclose()`.
+ * - ``c_closedirp()``: Wrapper around :c:func:`c_closedir()`.
  */
+/**/
 
+/**
+ * C_DEFINE_CLEANUP() - Define cleanup helper
+ * @_type:                      Type of object to cleanup
+ * @_func:                      Destructor of the respective type
+ *
+ * Define a C static inline function that takes a single argument of type
+ * `_type` and calls `_func` on it, if its dereferenced value of its argument
+ * evaluates to true. Otherwise, it is a no-op.
+ *
+ * This macro allows for very simple and fast creation of cleanup helpers for
+ * use with ``_c_cleanup_()``, based on any destructor and type you provide to
+ * it.
+ */
 #define C_DEFINE_CLEANUP(_type, _func)                                          \
         static inline void _func ## p(_type *p) {                               \
                 if (*p)                                                         \
                         _func(*p);                                              \
         } struct c_internal_trailing_semicolon
 
+/**
+ * C_DEFINE_DIRECT_CLEANUP() - Define direct cleanup helper
+ * @_type:                      Type of object to cleanup
+ * @_func:                      Destructor of the respective type
+ *
+ * This works like :c:macro:`C_DEFINE_CLEANUP()` but does not check the
+ * dereferenced value of its argument. It always unconditionally invokes the
+ * destructor.
+ */
 #define C_DEFINE_DIRECT_CLEANUP(_type, _func)                                   \
         static inline void _func ## p(_type *p) {                               \
                 _func(*p);                                                      \