Merge remote-tracking branch 'origin/master' into llvm8

8 files changed, 782 insertions, 0 deletions

diff --git a/libc/musl/src/malloc/DESIGN b/libc/musl/src/malloc/DESIGN
new file mode 100644
index 0000000000..58b0523ffd
--- /dev/null
+++ b/libc/musl/src/malloc/DESIGN
@@ -0,0 +1,22 @@
+
+
+In principle, this memory allocator is roughly equivalent to Doug
+Lea's dlmalloc with fine-grained locking.
+
+
+
+malloc:
+
+Uses a freelist binned by chunk size, with a bitmap to optimize
+searching for the smallest non-empty bin which can satisfy an
+allocation. If no free chunks are available, it creates a new chunk of
+the requested size and attempts to merge it with any existing free
+chunk immediately below the newly created chunk.
+
+Whether the chunk was obtained from a bin or newly created, it's
+likely to be larger than the requested allocation. malloc always
+finishes its work by passing the new chunk to realloc, which will
+split it into two chunks and free the tail portion.
+
+
+
diff --git a/libc/musl/src/malloc/aligned_alloc.c b/libc/musl/src/malloc/aligned_alloc.c
new file mode 100644
index 0000000000..b6143f303f
--- /dev/null
+++ b/libc/musl/src/malloc/aligned_alloc.c
@@ -0,0 +1,7 @@
+#include <stdlib.h>
+#include "malloc_impl.h"
+
+void *aligned_alloc(size_t align, size_t len)
+{
+	return __memalign(align, len);
+}
diff --git a/libc/musl/src/malloc/expand_heap.c b/libc/musl/src/malloc/expand_heap.c
new file mode 100644
index 0000000000..e6a3d7a000
--- /dev/null
+++ b/libc/musl/src/malloc/expand_heap.c
@@ -0,0 +1,71 @@
+#include <limits.h>
+#include <stdint.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include "libc.h"
+#include "syscall.h"
+#include "malloc_impl.h"
+
+/* This function returns true if the interval [old,new]
+ * intersects the 'len'-sized interval below &libc.auxv
+ * (interpreted as the main-thread stack) or below &b
+ * (the current stack). It is used to defend against
+ * buggy brk implementations that can cross the stack. */
+
+static int traverses_stack_p(uintptr_t old, uintptr_t new)
+{
+	const uintptr_t len = 8<<20;
+	uintptr_t a, b;
+
+	b = (uintptr_t)libc.auxv;
+	a = b > len ? b-len : 0;
+	if (new>a && old<b) return 1;
+
+	b = (uintptr_t)&b;
+	a = b > len ? b-len : 0;
+	if (new>a && old<b) return 1;
+
+	return 0;
+}
+
+/* Expand the heap in-place if brk can be used, or otherwise via mmap,
+ * using an exponential lower bound on growth by mmap to make
+ * fragmentation asymptotically irrelevant. The size argument is both
+ * an input and an output, since the caller needs to know the size
+ * allocated, which will be larger than requested due to page alignment
+ * and mmap minimum size rules. The caller is responsible for locking
+ * to prevent concurrent calls. */
+
+void *__expand_heap(size_t *pn)
+{
+	static uintptr_t brk;
+	static unsigned mmap_step;
+	size_t n = *pn;
+
+	if (n > SIZE_MAX/2 - PAGE_SIZE) {
+		errno = ENOMEM;
+		return 0;
+	}
+	n += -n & PAGE_SIZE-1;
+
+	if (!brk) {
+		brk = __syscall(SYS_brk, 0);
+		brk += -brk & PAGE_SIZE-1;
+	}
+
+	if (n < SIZE_MAX-brk && !traverses_stack_p(brk, brk+n)
+	    && __syscall(SYS_brk, brk+n)==brk+n) {
+		*pn = n;
+		brk += n;
+		return (void *)(brk-n);
+	}
+
+	size_t min = (size_t)PAGE_SIZE << mmap_step/2;
+	if (n < min) n = min;
+	void *area = __mmap(0, n, PROT_READ|PROT_WRITE,
+		MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+	if (area == MAP_FAILED) return 0;
+	*pn = n;
+	mmap_step++;
+	return area;
+}
diff --git a/libc/musl/src/malloc/lite_malloc.c b/libc/musl/src/malloc/lite_malloc.c
new file mode 100644
index 0000000000..050d84f648
--- /dev/null
+++ b/libc/musl/src/malloc/lite_malloc.c
@@ -0,0 +1,59 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <limits.h>
+#include <errno.h>
+#include "lock.h"
+#include "malloc_impl.h"
+
+#define ALIGN 16
+
+static void *__simple_malloc(size_t n)
+{
+	static char *cur, *end;
+	static volatile int lock[1];
+	size_t align=1, pad;
+	void *p;
+
+	if (!n) n++;
+	while (align<n && align<ALIGN)
+		align += align;
+
+	LOCK(lock);
+
+	pad = -(uintptr_t)cur & align-1;
+
+	if (n <= SIZE_MAX/2 + ALIGN) n += pad;
+
+	if (n > end-cur) {
+		size_t m = n;
+		char *new = __expand_heap(&m);
+		if (!new) {
+			UNLOCK(lock);
+			return 0;
+		}
+		if (new != end) {
+			cur = new;
+			n -= pad;
+			pad = 0;
+		}
+		end = new + m;
+	}
+
+	p = cur + pad;
+	cur += n;
+	UNLOCK(lock);
+	return p;
+}
+
+weak_alias(__simple_malloc, malloc);
+
+static void *__simple_calloc(size_t m, size_t n)
+{
+	if (n && m > (size_t)-1/n) {
+		errno = ENOMEM;
+		return 0;
+	}
+	return __simple_malloc(n * m);
+}
+
+weak_alias(__simple_calloc, calloc);
diff --git a/libc/musl/src/malloc/malloc.c b/libc/musl/src/malloc/malloc.c
new file mode 100644
index 0000000000..96982596b9
--- /dev/null
+++ b/libc/musl/src/malloc/malloc.c
@@ -0,0 +1,548 @@
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+#include <stdint.h>
+#include <errno.h>
+#include <sys/mman.h>
+#include "libc.h"
+#include "atomic.h"
+#include "pthread_impl.h"
+#include "malloc_impl.h"
+
+#if defined(__GNUC__) && defined(__PIC__)
+#define inline inline __attribute__((always_inline))
+#endif
+
+static struct {
+	volatile uint64_t binmap;
+	struct bin bins[64];
+	volatile int free_lock[2];
+} mal;
+
+int __malloc_replaced;
+
+/* Synchronization tools */
+
+static inline void lock(volatile int *lk)
+{
+	if (libc.threads_minus_1)
+		while(a_swap(lk, 1)) __wait(lk, lk+1, 1, 1);
+}
+
+static inline void unlock(volatile int *lk)
+{
+	if (lk[0]) {
+		a_store(lk, 0);
+		if (lk[1]) __wake(lk, 1, 1);
+	}
+}
+
+static inline void lock_bin(int i)
+{
+	lock(mal.bins[i].lock);
+	if (!mal.bins[i].head)
+		mal.bins[i].head = mal.bins[i].tail = BIN_TO_CHUNK(i);
+}
+
+static inline void unlock_bin(int i)
+{
+	unlock(mal.bins[i].lock);
+}
+
+static int first_set(uint64_t x)
+{
+#if 1
+	return a_ctz_64(x);
+#else
+	static const char debruijn64[64] = {
+		0, 1, 2, 53, 3, 7, 54, 27, 4, 38, 41, 8, 34, 55, 48, 28,
+		62, 5, 39, 46, 44, 42, 22, 9, 24, 35, 59, 56, 49, 18, 29, 11,
+		63, 52, 6, 26, 37, 40, 33, 47, 61, 45, 43, 21, 23, 58, 17, 10,
+		51, 25, 36, 32, 60, 20, 57, 16, 50, 31, 19, 15, 30, 14, 13, 12
+	};
+	static const char debruijn32[32] = {
+		0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13,
+		31, 22, 28, 18, 26, 10, 7, 12, 21, 17, 9, 6, 16, 5, 15, 14
+	};
+	if (sizeof(long) < 8) {
+		uint32_t y = x;
+		if (!y) {
+			y = x>>32;
+			return 32 + debruijn32[(y&-y)*0x076be629 >> 27];
+		}
+		return debruijn32[(y&-y)*0x076be629 >> 27];
+	}
+	return debruijn64[(x&-x)*0x022fdd63cc95386dull >> 58];
+#endif
+}
+
+static const unsigned char bin_tab[60] = {
+	            32,33,34,35,36,36,37,37,38,38,39,39,
+	40,40,40,40,41,41,41,41,42,42,42,42,43,43,43,43,
+	44,44,44,44,44,44,44,44,45,45,45,45,45,45,45,45,
+	46,46,46,46,46,46,46,46,47,47,47,47,47,47,47,47,
+};
+
+static int bin_index(size_t x)
+{
+	x = x / SIZE_ALIGN - 1;
+	if (x <= 32) return x;
+	if (x < 512) return bin_tab[x/8-4];
+	if (x > 0x1c00) return 63;
+	return bin_tab[x/128-4] + 16;
+}
+
+static int bin_index_up(size_t x)
+{
+	x = x / SIZE_ALIGN - 1;
+	if (x <= 32) return x;
+	x--;
+	if (x < 512) return bin_tab[x/8-4] + 1;
+	return bin_tab[x/128-4] + 17;
+}
+
+#if 0
+void __dump_heap(int x)
+{
+	struct chunk *c;
+	int i;
+	for (c = (void *)mal.heap; CHUNK_SIZE(c); c = NEXT_CHUNK(c))
+		fprintf(stderr, "base %p size %zu (%d) flags %d/%d\n",
+			c, CHUNK_SIZE(c), bin_index(CHUNK_SIZE(c)),
+			c->csize & 15,
+			NEXT_CHUNK(c)->psize & 15);
+	for (i=0; i<64; i++) {
+		if (mal.bins[i].head != BIN_TO_CHUNK(i) && mal.bins[i].head) {
+			fprintf(stderr, "bin %d: %p\n", i, mal.bins[i].head);
+			if (!(mal.binmap & 1ULL<<i))
+				fprintf(stderr, "missing from binmap!\n");
+		} else if (mal.binmap & 1ULL<<i)
+			fprintf(stderr, "binmap wrongly contains %d!\n", i);
+	}
+}
+#endif
+
+static struct chunk *expand_heap(size_t n)
+{
+	static int heap_lock[2];
+	static void *end;
+	void *p;
+	struct chunk *w;
+
+	/* The argument n already accounts for the caller's chunk
+	 * overhead needs, but if the heap can't be extended in-place,
+	 * we need room for an extra zero-sized sentinel chunk. */
+	n += SIZE_ALIGN;
+
+	lock(heap_lock);
+
+	p = __expand_heap(&n);
+	if (!p) {
+		unlock(heap_lock);
+		return 0;
+	}
+
+	/* If not just expanding existing space, we need to make a
+	 * new sentinel chunk below the allocated space. */
+	if (p != end) {
+		/* Valid/safe because of the prologue increment. */
+		n -= SIZE_ALIGN;
+		p = (char *)p + SIZE_ALIGN;
+		w = MEM_TO_CHUNK(p);
+		w->psize = 0 | C_INUSE;
+	}
+
+	/* Record new heap end and fill in footer. */
+	end = (char *)p + n;
+	w = MEM_TO_CHUNK(end);
+	w->psize = n | C_INUSE;
+	w->csize = 0 | C_INUSE;
+
+	/* Fill in header, which may be new or may be replacing a
+	 * zero-size sentinel header at the old end-of-heap. */
+	w = MEM_TO_CHUNK(p);
+	w->csize = n | C_INUSE;
+
+	unlock(heap_lock);
+
+	return w;
+}
+
+static int adjust_size(size_t *n)
+{
+	/* Result of pointer difference must fit in ptrdiff_t. */
+	if (*n-1 > PTRDIFF_MAX - SIZE_ALIGN - PAGE_SIZE) {
+		if (*n) {
+			errno = ENOMEM;
+			return -1;
+		} else {
+			*n = SIZE_ALIGN;
+			return 0;
+		}
+	}
+	*n = (*n + OVERHEAD + SIZE_ALIGN - 1) & SIZE_MASK;
+	return 0;
+}
+
+static void unbin(struct chunk *c, int i)
+{
+	if (c->prev == c->next)
+		a_and_64(&mal.binmap, ~(1ULL<<i));
+	c->prev->next = c->next;
+	c->next->prev = c->prev;
+	c->csize |= C_INUSE;
+	NEXT_CHUNK(c)->psize |= C_INUSE;
+}
+
+static int alloc_fwd(struct chunk *c)
+{
+	int i;
+	size_t k;
+	while (!((k=c->csize) & C_INUSE)) {
+		i = bin_index(k);
+		lock_bin(i);
+		if (c->csize == k) {
+			unbin(c, i);
+			unlock_bin(i);
+			return 1;
+		}
+		unlock_bin(i);
+	}
+	return 0;
+}
+
+static int alloc_rev(struct chunk *c)
+{
+	int i;
+	size_t k;
+	while (!((k=c->psize) & C_INUSE)) {
+		i = bin_index(k);
+		lock_bin(i);
+		if (c->psize == k) {
+			unbin(PREV_CHUNK(c), i);
+			unlock_bin(i);
+			return 1;
+		}
+		unlock_bin(i);
+	}
+	return 0;
+}
+
+
+/* pretrim - trims a chunk _prior_ to removing it from its bin.
+ * Must be called with i as the ideal bin for size n, j the bin
+ * for the _free_ chunk self, and bin j locked. */
+static int pretrim(struct chunk *self, size_t n, int i, int j)
+{
+	size_t n1;
+	struct chunk *next, *split;
+
+	/* We cannot pretrim if it would require re-binning. */
+	if (j < 40) return 0;
+	if (j < i+3) {
+		if (j != 63) return 0;
+		n1 = CHUNK_SIZE(self);
+		if (n1-n <= MMAP_THRESHOLD) return 0;
+	} else {
+		n1 = CHUNK_SIZE(self);
+	}
+	if (bin_index(n1-n) != j) return 0;
+
+	next = NEXT_CHUNK(self);
+	split = (void *)((char *)self + n);
+
+	split->prev = self->prev;
+	split->next = self->next;
+	split->prev->next = split;
+	split->next->prev = split;
+	split->psize = n | C_INUSE;
+	split->csize = n1-n;
+	next->psize = n1-n;
+	self->csize = n | C_INUSE;
+	return 1;
+}
+
+static void trim(struct chunk *self, size_t n)
+{
+	size_t n1 = CHUNK_SIZE(self);
+	struct chunk *next, *split;
+
+	if (n >= n1 - DONTCARE) return;
+
+	next = NEXT_CHUNK(self);
+	split = (void *)((char *)self + n);
+
+	split->psize = n | C_INUSE;
+	split->csize = n1-n | C_INUSE;
+	next->psize = n1-n | C_INUSE;
+	self->csize = n | C_INUSE;
+
+	__bin_chunk(split);
+}
+
+void *malloc(size_t n)
+{
+	struct chunk *c;
+	int i, j;
+
+	if (adjust_size(&n) < 0) return 0;
+
+	if (n > MMAP_THRESHOLD) {
+		size_t len = n + OVERHEAD + PAGE_SIZE - 1 & -PAGE_SIZE;
+		char *base = __mmap(0, len, PROT_READ|PROT_WRITE,
+			MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
+		if (base == (void *)-1) return 0;
+		c = (void *)(base + SIZE_ALIGN - OVERHEAD);
+		c->csize = len - (SIZE_ALIGN - OVERHEAD);
+		c->psize = SIZE_ALIGN - OVERHEAD;
+		return CHUNK_TO_MEM(c);
+	}
+
+	i = bin_index_up(n);
+	for (;;) {
+		uint64_t mask = mal.binmap & -(1ULL<<i);
+		if (!mask) {
+			c = expand_heap(n);
+			if (!c) return 0;
+			if (alloc_rev(c)) {
+				struct chunk *x = c;
+				c = PREV_CHUNK(c);
+				NEXT_CHUNK(x)->psize = c->csize =
+					x->csize + CHUNK_SIZE(c);
+			}
+			break;
+		}
+		j = first_set(mask);
+		lock_bin(j);
+		c = mal.bins[j].head;
+		if (c != BIN_TO_CHUNK(j)) {
+			if (!pretrim(c, n, i, j)) unbin(c, j);
+			unlock_bin(j);
+			break;
+		}
+		unlock_bin(j);
+	}
+
+	/* Now patch up in case we over-allocated */
+	trim(c, n);
+
+	return CHUNK_TO_MEM(c);
+}
+
+static size_t mal0_clear(char *p, size_t pagesz, size_t n)
+{
+#ifdef __GNUC__
+	typedef uint64_t __attribute__((__may_alias__)) T;
+#else
+	typedef unsigned char T;
+#endif
+	char *pp = p + n;
+	size_t i = (uintptr_t)pp & (pagesz - 1);
+	for (;;) {
+		pp = memset(pp - i, 0, i);
+		if (pp - p < pagesz) return pp - p;
+		for (i = pagesz; i; i -= 2*sizeof(T), pp -= 2*sizeof(T))
+		        if (((T *)pp)[-1] | ((T *)pp)[-2])
+				break;
+	}
+}
+
+void *calloc(size_t m, size_t n)
+{
+	if (n && m > (size_t)-1/n) {
+		errno = ENOMEM;
+		return 0;
+	}
+	n *= m;
+	void *p = malloc(n);
+	if (!p) return p;
+	if (!__malloc_replaced) {
+		if (IS_MMAPPED(MEM_TO_CHUNK(p)))
+			return p;
+		if (n >= PAGE_SIZE)
+			n = mal0_clear(p, PAGE_SIZE, n);
+	}
+	return memset(p, 0, n);
+}
+
+void *realloc(void *p, size_t n)
+{
+	struct chunk *self, *next;
+	size_t n0, n1;
+	void *new;
+
+	if (!p) return malloc(n);
+
+	if (adjust_size(&n) < 0) return 0;
+
+	self = MEM_TO_CHUNK(p);
+	n1 = n0 = CHUNK_SIZE(self);
+
+	if (IS_MMAPPED(self)) {
+		size_t extra = self->psize;
+		char *base = (char *)self - extra;
+		size_t oldlen = n0 + extra;
+		size_t newlen = n + extra;
+		/* Crash on realloc of freed chunk */
+		if (extra & 1) a_crash();
+		if (newlen < PAGE_SIZE && (new = malloc(n-OVERHEAD))) {
+			n0 = n;
+			goto copy_free_ret;
+		}
+		newlen = (newlen + PAGE_SIZE-1) & -PAGE_SIZE;
+		if (oldlen == newlen) return p;
+		base = __mremap(base, oldlen, newlen, MREMAP_MAYMOVE);
+		if (base == (void *)-1)
+			goto copy_realloc;
+		self = (void *)(base + extra);
+		self->csize = newlen - extra;
+		return CHUNK_TO_MEM(self);
+	}
+
+	next = NEXT_CHUNK(self);
+
+	/* Crash on corrupted footer (likely from buffer overflow) */
+	if (next->psize != self->csize) a_crash();
+
+	/* Merge adjacent chunks if we need more space. This is not
+	 * a waste of time even if we fail to get enough space, because our
+	 * subsequent call to free would otherwise have to do the merge. */
+	if (n > n1 && alloc_fwd(next)) {
+		n1 += CHUNK_SIZE(next);
+		next = NEXT_CHUNK(next);
+	}
+	/* FIXME: find what's wrong here and reenable it..? */
+	if (0 && n > n1 && alloc_rev(self)) {
+		self = PREV_CHUNK(self);
+		n1 += CHUNK_SIZE(self);
+	}
+	self->csize = n1 | C_INUSE;
+	next->psize = n1 | C_INUSE;
+
+	/* If we got enough space, split off the excess and return */
+	if (n <= n1) {
+		//memmove(CHUNK_TO_MEM(self), p, n0-OVERHEAD);
+		trim(self, n);
+		return CHUNK_TO_MEM(self);
+	}
+
+copy_realloc:
+	/* As a last resort, allocate a new chunk and copy to it. */
+	new = malloc(n-OVERHEAD);
+	if (!new) return 0;
+copy_free_ret:
+	memcpy(new, p, n0-OVERHEAD);
+	free(CHUNK_TO_MEM(self));
+	return new;
+}
+
+void __bin_chunk(struct chunk *self)
+{
+	struct chunk *next = NEXT_CHUNK(self);
+	size_t final_size, new_size, size;
+	int reclaim=0;
+	int i;
+
+	final_size = new_size = CHUNK_SIZE(self);
+
+	/* Crash on corrupted footer (likely from buffer overflow) */
+	if (next->psize != self->csize) a_crash();
+
+	for (;;) {
+		if (self->psize & next->csize & C_INUSE) {
+			self->csize = final_size | C_INUSE;
+			next->psize = final_size | C_INUSE;
+			i = bin_index(final_size);
+			lock_bin(i);
+			lock(mal.free_lock);
+			if (self->psize & next->csize & C_INUSE)
+				break;
+			unlock(mal.free_lock);
+			unlock_bin(i);
+		}
+
+		if (alloc_rev(self)) {
+			self = PREV_CHUNK(self);
+			size = CHUNK_SIZE(self);
+			final_size += size;
+			if (new_size+size > RECLAIM && (new_size+size^size) > size)
+				reclaim = 1;
+		}
+
+		if (alloc_fwd(next)) {
+			size = CHUNK_SIZE(next);
+			final_size += size;
+			if (new_size+size > RECLAIM && (new_size+size^size) > size)
+				reclaim = 1;
+			next = NEXT_CHUNK(next);
+		}
+	}
+
+	if (!(mal.binmap & 1ULL<<i))
+		a_or_64(&mal.binmap, 1ULL<<i);
+
+	self->csize = final_size;
+	next->psize = final_size;
+	unlock(mal.free_lock);
+
+	self->next = BIN_TO_CHUNK(i);
+	self->prev = mal.bins[i].tail;
+	self->next->prev = self;
+	self->prev->next = self;
+
+	/* Replace middle of large chunks with fresh zero pages */
+	if (reclaim) {
+		uintptr_t a = (uintptr_t)self + SIZE_ALIGN+PAGE_SIZE-1 & -PAGE_SIZE;
+		uintptr_t b = (uintptr_t)next - SIZE_ALIGN & -PAGE_SIZE;
+#if 1
+		__madvise((void *)a, b-a, MADV_DONTNEED);
+#else
+		__mmap((void *)a, b-a, PROT_READ|PROT_WRITE,
+			MAP_PRIVATE|MAP_ANONYMOUS|MAP_FIXED, -1, 0);
+#endif
+	}
+
+	unlock_bin(i);
+}
+
+static void unmap_chunk(struct chunk *self)
+{
+	size_t extra = self->psize;
+	char *base = (char *)self - extra;
+	size_t len = CHUNK_SIZE(self) + extra;
+	/* Crash on double free */
+	if (extra & 1) a_crash();
+	__munmap(base, len);
+}
+
+void free(void *p)
+{
+	if (!p) return;
+
+	struct chunk *self = MEM_TO_CHUNK(p);
+
+	if (IS_MMAPPED(self))
+		unmap_chunk(self);
+	else
+		__bin_chunk(self);
+}
+
+void __malloc_donate(char *start, char *end)
+{
+	size_t align_start_up = (SIZE_ALIGN-1) & (-(uintptr_t)start - OVERHEAD);
+	size_t align_end_down = (SIZE_ALIGN-1) & (uintptr_t)end;
+
+	/* Getting past this condition ensures that the padding for alignment
+	 * and header overhead will not overflow and will leave a nonzero
+	 * multiple of SIZE_ALIGN bytes between start and end. */
+	if (end - start <= OVERHEAD + align_start_up + align_end_down)
+		return;
+	start += align_start_up + OVERHEAD;
+	end   -= align_end_down;
+
+	struct chunk *c = MEM_TO_CHUNK(start), *n = MEM_TO_CHUNK(end);
+	c->psize = n->csize = C_INUSE;
+	c->csize = n->psize = C_INUSE | (end-start);
+	__bin_chunk(c);
+}
diff --git a/libc/musl/src/malloc/malloc_usable_size.c b/libc/musl/src/malloc/malloc_usable_size.c
new file mode 100644
index 0000000000..672b518ad0
--- /dev/null
+++ b/libc/musl/src/malloc/malloc_usable_size.c
@@ -0,0 +1,9 @@
+#include <malloc.h>
+#include "malloc_impl.h"
+ 
+hidden void *(*const __realloc_dep)(void *, size_t) = realloc;
+
+size_t malloc_usable_size(void *p)
+{
+	return p ? CHUNK_SIZE(MEM_TO_CHUNK(p)) - OVERHEAD : 0;
+}
diff --git a/libc/musl/src/malloc/memalign.c b/libc/musl/src/malloc/memalign.c
new file mode 100644
index 0000000000..cf9dfbda66
--- /dev/null
+++ b/libc/musl/src/malloc/memalign.c
@@ -0,0 +1,54 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <errno.h>
+#include "malloc_impl.h"
+
+void *__memalign(size_t align, size_t len)
+{
+	unsigned char *mem, *new;
+
+	if ((align & -align) != align) {
+		errno = EINVAL;
+		return 0;
+	}
+
+	if (len > SIZE_MAX - align || __malloc_replaced) {
+		errno = ENOMEM;
+		return 0;
+	}
+
+	if (align <= SIZE_ALIGN)
+		return malloc(len);
+
+	if (!(mem = malloc(len + align-1)))
+		return 0;
+
+	new = (void *)((uintptr_t)mem + align-1 & -align);
+	if (new == mem) return mem;
+
+	struct chunk *c = MEM_TO_CHUNK(mem);
+	struct chunk *n = MEM_TO_CHUNK(new);
+
+	if (IS_MMAPPED(c)) {
+		/* Apply difference between aligned and original
+		 * address to the "extra" field of mmapped chunk. */
+		n->psize = c->psize + (new-mem);
+		n->csize = c->csize - (new-mem);
+		return new;
+	}
+
+	struct chunk *t = NEXT_CHUNK(c);
+
+	/* Split the allocated chunk into two chunks. The aligned part
+	 * that will be used has the size in its footer reduced by the
+	 * difference between the aligned and original addresses, and
+	 * the resulting size copied to its header. A new header and
+	 * footer are written for the split-off part to be freed. */
+	n->psize = c->csize = C_INUSE | (new-mem);
+	n->csize = t->psize -= new-mem;
+
+	__bin_chunk(c);
+	return new;
+}
+
+weak_alias(__memalign, memalign);
diff --git a/libc/musl/src/malloc/posix_memalign.c b/libc/musl/src/malloc/posix_memalign.c
new file mode 100644
index 0000000000..2ea8bd8a43
--- /dev/null
+++ b/libc/musl/src/malloc/posix_memalign.c
@@ -0,0 +1,12 @@
+#include <stdlib.h>
+#include <errno.h>
+#include "malloc_impl.h"
+
+int posix_memalign(void **res, size_t align, size_t len)
+{
+	if (align < sizeof(void *)) return EINVAL;
+	void *mem = __memalign(align, len);
+	if (!mem) return errno;
+	*res = mem;
+	return 0;
+}