Introduce LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION #1124
Conversation
This changeset introduces new compile time switch macro LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION which removes the following functions when it's defined. ``` // lz4.c LZ4_createStream LZ4_freeStream LZ4_createStreamDecode LZ4_freeStreamDecode LZ4_create // legacy // lz4hc.c LZ4_createStreamHC(void) LZ4_freeStreamHC LZ4_createHC // legacy LZ4_freeHC // legacy ``` These functions uses dynamic memory allocation functions such as malloc() and free(). It'll be useful for freestanding environment which doesn't have these allocation functions. Since this change breaks API, this macro is only valid with lz4 as a static linked object.
lib/lz4.c
Outdated
| # undef LZ4_ALLOC | ||
| # undef LZ4_ALLOC_AND_ZERO | ||
| # undef LZ4_FREEMEM | ||
| # define LZ4_ALLOC(x) lz4_error_memory_allocation_is_disabled |
There was a problem hiding this comment.
If I understand properly, these macros LZ4_ALLOC(x) and next are designed to fail at compile time, as a way to detect if they are employed anywhere.
However, these macros are also not used anywhere.
Did you mean to replace ALLOC(s) ?
There was a problem hiding this comment.
oops. You're right. They must be ALLOC(s), ALLOC_AND_ZERO(s) and FREEMEM(p).
| @@ -188,7 +188,11 @@ | |||
| /*-************************************ | |||
| * Memory routines | |||
| **************************************/ | |||
| #ifdef LZ4_USER_MEMORY_FUNCTIONS | |||
| #if defined(LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION) | |||
There was a problem hiding this comment.
How will users be made aware of this new capability ?
Maybe it should be documented ?
There was a problem hiding this comment.
Yes! It needs document. Draft version:
/*!
* LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION :
* Disable relatively high-level LZ4/HC functions which uses dynamic memory
* allocation (malloc(), calloc(), free()).
*
* Note that this is a compile-time switch. And since it disables public/stable
* LZ4 v1 API functions, we don't recommend to use this symbol to generate
* library for distribution.
*
* The following functions are removed when this symbol is defined.
*
* // lz4.c
* LZ4_createStream
* LZ4_freeStream
* LZ4_createStreamDecode
* LZ4_freeStreamDecode
* LZ4_create // legacy
*
* // lz4hc.c
* LZ4_createStreamHC(void)
* LZ4_freeStreamHC
* LZ4_createHC // legacy
* LZ4_freeHC // legacy
*/I also realize I should add #ifndef to declaration of these functions in header.
There was a problem hiding this comment.
Do you expect to provide this documentation as part of this PR ?
Or do you want to make it a separate PR ?
There was a problem hiding this comment.
I'd like to send it as a separate PR. Sorry!
Part of #1071.
This changeset introduces new compile time switch macro
LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATIONwhich removes the following functions when it's defined.
These functions uses dynamic memory allocation functions such as malloc() and free().
It'll be useful for freestanding environment which doesn't have these allocation functions.
Since this change breaks API, this macro is only valid with lz4 as a static linked object.