Get LIBC_MEM and LIBC_STDIO building with aarch64

libc/mem/realloc.c

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+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/mem/hook.internal.h"
+#include "libc/mem/mem.h"
+#include "third_party/dlmalloc/dlmalloc.h"
+
+void *(*hook_realloc)(void *, size_t) = dlrealloc;
+
+/**
+ * Allocates / resizes / frees memory, e.g.
+ *
+ * Returns a pointer to a chunk of size n that contains the same data as
+ * does chunk p up to the minimum of (n, p's size) bytes, or null if no
+ * space is available.
+ *
+ * If p is NULL, realloc is equivalent to malloc.
+ * If p is not NULL and n is 0, realloc is equivalent to free.
+ *
+ * The returned pointer may or may not be the same as p. The algorithm
+ * prefers extending p in most cases when possible, otherwise it employs
+ * the equivalent of a malloc-copy-free sequence.
+ *
+ * Please note that p is NOT free()'d should realloc() fail, thus:
+ *
+ *     if ((p2 = realloc(p, n2))) {
+ *       p = p2;
+ *       ...
+ *     } else {
+ *       ...
+ *     }
+ *
+ * if n is for fewer bytes than already held by p, the newly unused
+ * space is lopped off and freed if possible.
+ *
+ * The old unix realloc convention of allowing the last-free'd chunk to
+ * be used as an argument to realloc is not supported.
+ *
+ * @param p is address of current allocation or NULL
+ * @param n is number of bytes needed
+ * @return rax is result, or NULL w/ errno w/o free(p)
+ * @note realloc(p=0, n=0) → malloc(32)
+ * @note realloc(p≠0, n=0) → free(p)
+ * @see dlrealloc()
+ * @threadsafe
+ */
+void *realloc(void *p, size_t n) {
+  return hook_realloc(p, n);
+}