musl - musl - an implementation of the standard library for Linux-based systems

Age	Commit message (Collapse)	Author	Lines
2020-06-16	only use memcpy realloc to shrink if an exact-sized free chunk exists	Rich Felker	-0/+12
	otherwise, shrink in-place. as explained in the description of commit 3e16313f8fe2ed143ae0267fd79d63014c24779f, the split here is valid without holding split_merge_lock because all chunks involved are in the in-use state.
2020-06-16	fix memset overflow in oldmalloc race fix overhaul	Rich Felker	-1/+1
	commit 3e16313f8fe2ed143ae0267fd79d63014c24779f introduced this bug by making the copy case reachable with n (new size) smaller than n0 (original size). this was left as the only way of shrinking an allocation because it reduces fragmentation if a free chunk of the appropriate size is available. when that's not the case, another approach may be better, but any such improvement would be independent of fixing this bug.
2020-06-10	reintroduce calloc elison of memset for direct-mmapped allocations	Rich Felker	-0/+5
	a new weak predicate function replacable by the malloc implementation, __malloc_allzerop, is introduced. by default it's always false; the default version will be used when static linking if the bump allocator was used (in which case performance doesn't matter) or if malloc was replaced by the application. only if the real internal malloc is linked (always the case with dynamic linking) does the real version get used. if malloc was replaced dynamically, as indicated by __malloc_replaced, the predicate function is ignored and conditional-memset is always performed.
2020-06-10	move __malloc_replaced to a top-level malloc file	Rich Felker	-2/+0
	it's not part of the malloc implementation but glue with musl dynamic linker.
2020-06-10	switch to a common calloc implementation	Rich Felker	-36/+0
	abstractly, calloc is completely malloc-implementation-independent; it's malloc followed by memset, or as we do it, a "conditional memset" that avoids touching fresh zero pages. previously, calloc was kept separate for the bump allocator, which can always skip memset, and the version of calloc provided with the full malloc conditionally skipped the clearing for large direct-mmapped allocations. the latter is a moderately attractive optimization, and can be added back if needed. however, further consideration to make it correct under malloc replacement would be needed. commit b4b1e10364c8737a632be61582e05a8d3acf5690 documented the contract for malloc replacement as allowing omission of calloc, and indeed that worked for dynamic linking, but for static linking it was possible to get the non-clearing definition from the bump allocator; if not for that, it would have been a link error trying to pull in malloc.o. the conditional-clearing code for the new common calloc is taken from mal0_clear in oldmalloc, but drops the need to access actual page size and just uses a fixed value of 4096. this avoids potentially needing access to global data for the sake of an optimization that at best marginally helps archs with offensively-large page sizes.
2020-06-03	move oldmalloc to its own directory under src/malloc	Rich Felker	-0/+550
	this sets the stage for replacement, and makes it practical to keep oldmalloc around as a build option for a while if that ends up being useful. only the files which are actually part of the implementation are moved. memalign and posix_memalign are entirely generic. in theory calloc could be pulled out too, but it's useful to have it tied to the implementation so as to optimize out unnecessary memset when implementation details make it possible to know the memory is already clear.