xmalloc.h File Reference

(37a72b0150ec36b4ea27175039afc28c62207b0c)

Declares ruby_xmalloc(). More...

#include "ruby/internal/config.h"
#include "ruby/internal/attr/alloc_size.h"
#include "ruby/internal/attr/nodiscard.h"
#include "ruby/internal/attr/noexcept.h"
#include "ruby/internal/attr/restrict.h"
#include "ruby/internal/attr/returns_nonnull.h"
#include "ruby/internal/dllexport.h"

Include dependency graph for xmalloc.h:

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Macros
#define	USE_GC_MALLOC_OBJ_INFO_DETAILS   0
#define	xmalloc   ruby_xmalloc
	Old name of ruby_xmalloc. More...
#define	xmalloc2   ruby_xmalloc2
	Old name of ruby_xmalloc2. More...
#define	xcalloc   ruby_xcalloc
	Old name of ruby_xcalloc. More...
#define	xrealloc   ruby_xrealloc
	Old name of ruby_xrealloc. More...
#define	xrealloc2   ruby_xrealloc2
	Old name of ruby_xrealloc2. More...
#define	xfree   ruby_xfree
	Old name of ruby_xfree. More...

Functions
void *	ruby_xmalloc (size_t size)
	Allocates a storage instance. More...
void *	ruby_xmalloc2 (size_t nelems, size_t elemsiz)
	Identical to ruby_xmalloc(), except it allocates nelems * elemsiz bytes. More...
void *	ruby_xcalloc (size_t nelems, size_t elemsiz)
	Identical to ruby_xmalloc2(), except it returns a zero-filled storage instance. More...
void *	ruby_xrealloc (void *ptr, size_t newsiz)
	Resize the storage instance. More...
void *	ruby_xrealloc2 (void *ptr, size_t newelems, size_t newsiz)
	Identical to ruby_xrealloc(), except it resizes the given storage instance to newelems * newsiz bytes. More...
void	ruby_xfree (void *ptr)
	Deallocates a storage instance. More...

Detailed Description

Declares ruby_xmalloc().

Author

Ruby developers ruby-.nosp@m.core.nosp@m.@ruby.nosp@m.-lan.nosp@m.g.org

Copyright

This file is a part of the programming language Ruby. Permission is hereby granted, to either redistribute and/or modify this file, provided that the conditions mentioned in the file COPYING are met. Consult the file for details.

Warning

Symbols prefixed with either RBIMPL or rbimpl are implementation details. Don't take them as canon. They could rapidly appear then vanish. The name (path) of this header file is also an implementation detail. Do not expect it to persist at the place it is now. Developers are free to move it anywhere anytime at will.

Note

To ruby-core: remember that this header can be possibly recursively included from extension libraries written in C++. Do not expect for instance __VA_ARGS__ is always available. We assume C99 for ruby itself but we don't assume languages of extension libraries. They could be written in C++98.

Definition in file xmalloc.h.

Macro Definition Documentation

USE_GC_MALLOC_OBJ_INFO_DETAILS

#define USE_GC_MALLOC_OBJ_INFO_DETAILS   0

Warning

Do not touch this macro.

It is an implementation detail.

It was a failure at the first place to let you know about it.

The value of this macro must match for ruby itself and all extension libraries, otherwise serious memory corruption shall occur.

Definition at line 50 of file xmalloc.h.

Function Documentation

ruby_xcalloc()

void* ruby_xcalloc	(	size_t	nelems,
		size_t	elemsiz
	)

Identical to ruby_xmalloc2(), except it returns a zero-filled storage instance.

It can also be seen as a routine identical to ruby_xmalloc(), except it calls calloc() instead of malloc().

Parameters

[in]	nelems	Number of elements.
[in]	elemsiz	Size of an element.

Exceptions

rb_eNoMemError	No space left for allocation.
rb_eArgError	nelems * elemsiz would overflow.

Returns

A valid pointer to an allocated storage instance; which has at least nelems * elemsiz bytes width, with appropriate alignment detected by the underlying calloc() routine.

Postcondition

The returned storage instance is filled with zeros.

Note

It doesn't return NULL.

Unlike some calloc() implementations, it allocates something and returns a meaningful value even when nelems or elemsiz or both are zero.

Warning

The return value shall be invalidated exactly once by either ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a failure to pass it to system free(), because the system and Ruby might or might not share the same malloc() implementation.

Definition at line 4239 of file gc.c.

ruby_xfree()

void ruby_xfree

(

void *

ptr

)

Deallocates a storage instance.

Parameters

[out]

ptr

Either NULL, or a valid pointer previously returned from one of: ruby_xmalloc(), ruby_xmalloc2(), ruby_xcalloc(), ruby_xrealloc(), or ruby_xrealloc2().

Precondition

The passed pointer must point to a valid live storage instance. It is a failure to pass an already freed pointer.

Postcondition

The storage instance pointed by the passed pointer gets invalidated; it is no longer addressable.

Warning

Every single storage instance that was previously allocated by either ruby_xmalloc(), ruby_xmalloc2(), ruby_xcalloc(), ruby_xrealloc(), or ruby_xrealloc2() shall be invalidated exactly once by either passing it to ruby_xfree(), or passing it to either ruby_xrealloc(), ruby_xrealloc2() then check the return value for invalidation.

Do not pass anything other than pointers described above. For instance pointers returned from malloc() or mmap() shall not be passed to this function, because the underlying memory management mechanism could differ.

Do not pass any invalid pointers to this function e.g. by calling it twice with a same argument.

Definition at line 4299 of file gc.c.

Referenced by rb_str_resize().

ruby_xmalloc()

void* ruby_xmalloc

(

size_t

size

)

Allocates a storage instance.

It is largely the same as system malloc(), except:

• It raises Ruby exceptions instead of returning NULL, and
• In case of ENOMEM it tries to GC to make some room.

Parameters

[in]

size

Requested amount of memory.

Exceptions

rb_eNoMemError

No space left for size bytes allocation.

Returns

A valid pointer to an allocated storage instance; which has at least size bytes width, with appropriate alignment detected by the underlying malloc() routine.

Note

It doesn't return NULL.

Unlike some malloc() implementations, it allocates something and returns a meaningful value even when size is equal to zero.

Warning

The return value shall be invalidated exactly once by either ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a failure to pass it to system free(), because the system and Ruby might or might not share the same malloc() implementation.

Definition at line 4215 of file gc.c.

ruby_xmalloc2()

void* ruby_xmalloc2	(	size_t	nelems,
		size_t	elemsiz
	)

Identical to ruby_xmalloc(), except it allocates nelems * elemsiz bytes.

This is needed because the multiplication could integer overflow. On such situations Ruby does not try to allocate at all but raises Ruby level exceptions instead. If there is no integer overflow the behaviour is exactly the same as ruby_xmalloc(nelems*elemsiz).

Parameters

[in]	nelems	Number of elements.
[in]	elemsiz	Size of an element.

Exceptions

rb_eNoMemError	No space left for allocation.
rb_eArgError	nelems * elemsiz would overflow.

Returns

A valid pointer to an allocated storage instance; which has at least nelems * elemsiz bytes width, with appropriate alignment detected by the underlying malloc() routine.

Note

It doesn't return NULL.

Unlike some malloc() implementations, it allocates something and returns a meaningful value even when nelems or elemsiz or both are zero.

Warning

The return value shall be invalidated exactly once by either ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a failure to pass it to system free(), because the system and Ruby might or might not share the same malloc() implementation.

Definition at line 4233 of file gc.c.

ruby_xrealloc()

void* ruby_xrealloc	(	void *	ptr,
		size_t	newsiz
	)

Resize the storage instance.

Parameters

[in]	ptr	A valid pointer to a storage instance that was previously returned from either: ruby_xmalloc(), ruby_xmalloc2(), ruby_xcalloc(), ruby_xrealloc(), or ruby_xrealloc2().
[in]	newsiz	Requested new amount of memory.

Exceptions

rb_eNoMemError

No space left for newsiz bytes allocation.

Returns

A valid pointer to a (possibly newly allocated) storage instance; which has at least newsiz bytes width, with appropriate alignment detected by the underlying realloc() routine.

Precondition

The passed pointer must point to a valid live storage instance. It is a failure to pass an already freed pointer.

Postcondition

In case the function returns the passed pointer as-is, the storage instance that the pointer holds is either grown or shrunken to have at least newsiz bytes. Otherwise a valid pointer to a newly allocated storage instance is returned. In this case ptr is invalidated as if it was passed to ruby_xfree().

Note

It doesn't return NULL.

Warning

Unlike some realloc() implementations, passing zero to newsiz is not the same as calling ruby_xfree(), because this function never returns NULL. Something meaningful still returns then.

It is a failure not to check the return value. Do not assume anything on it. It could be either identical to, or distinct form the passed argument.

Do not assume anything on the alignment of the return value. There is no guarantee that it inherits the passed argument's one.

The return value shall be invalidated exactly once by either ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a failure to pass it to system free(), because the system and Ruby might or might not share the same malloc() implementation.

Definition at line 4258 of file gc.c.

ruby_xrealloc2()

void* ruby_xrealloc2	(	void *	ptr,
		size_t	newelems,
		size_t	newsiz
	)

Identical to ruby_xrealloc(), except it resizes the given storage instance to newelems * newsiz bytes.

This is needed because the multiplication could integer overflow. On such situations Ruby does not try to touch the contents of argument pointer at all but raises Ruby level exceptions instead. If there is no integer overflow the behaviour is exactly the same as ruby_xrealloc(ptr,nelems*elemsiz).

This is roughly the same as reallocarray() function that OpenBSD etc. provides, but also interacts with our GC.

Parameters

[in]	ptr	A valid pointer to a storage instance that was previously returned from either: ruby_xmalloc(), ruby_xmalloc2(), ruby_xcalloc(), ruby_xrealloc(), or ruby_xrealloc2().
[in]	newelems	Requested new number of elements.
[in]	newsiz	Requested new size of each element.

Exceptions

rb_eNoMemError	No space left for allocation.
rb_eArgError	newelems * newsiz would overflow.

Returns

A valid pointer to a (possibly newly allocated) storage instance; which has at least newelems * newsiz bytes width, with appropriate alignment detected by the underlying realloc() routine.

Precondition

The passed pointer must point to a valid live storage instance. It is a failure to pass an already freed pointer.

Postcondition

In case the function returns the passed pointer as-is, the storage instance that the pointer holds is either grown or shrunken to have at least newelems * newsiz bytes. Otherwise a valid pointer to a newly allocated storage instance is returned. In this case ptr is invalidated as if it was passed to ruby_xfree().

Note

It doesn't return NULL.

Warning

Unlike some realloc() implementations, passing zero to either newelems or elemsiz are not the same as calling ruby_xfree(), because this function never returns NULL. Something meaningful still returns then.

It is a failure not to check the return value. Do not assume anything on it. It could be either identical to, or distinct form the passed argument.

Do not assume anything on the alignment of the return value. There is no guarantee that it inherits the passed argument's one.

The return value shall be invalidated exactly once by either ruby_xfree(), ruby_xrealloc(), or ruby_xrealloc2(). It is a failure to pass it to system free(), because the system and Ruby might or might not share the same malloc() implementation.

Definition at line 4274 of file gc.c.