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-rw-r--r--src/malloc/posix_memalign.c47
1 files changed, 47 insertions, 0 deletions
diff --git a/src/malloc/posix_memalign.c b/src/malloc/posix_memalign.c
new file mode 100644
index 00000000..ef86260d
--- /dev/null
+++ b/src/malloc/posix_memalign.c
@@ -0,0 +1,47 @@
+#include <stdlib.h>
+#include <stdint.h>
+#include <errno.h>
+
+/* This function should work with most dlmalloc-like chunk bookkeeping
+ * systems, but it's only guaranteed to work with the native implementation
+ * used in this library. */
+
+int posix_memalign(void **res, size_t align, size_t len)
+{
+ unsigned char *mem, *new, *end;
+ size_t header, footer;
+
+ if ((align & -align) != align) return EINVAL;
+ if (len > SIZE_MAX - align) return ENOMEM;
+
+ if (align <= 4*sizeof(size_t)) {
+ if (!(mem = malloc(len)))
+ return errno;
+ *res = mem;
+ return 0;
+ }
+
+ if (!(mem = malloc(len + align-1)))
+ return errno;
+
+ header = ((size_t *)mem)[-1];
+ end = mem + (header & -8);
+ footer = ((size_t *)end)[-2];
+ new = (void *)((uintptr_t)mem + align-1 & -align);
+
+ if (!(header & 7)) {
+ ((size_t *)new)[-2] = ((size_t *)mem)[-2] + (new-mem);
+ ((size_t *)new)[-1] = ((size_t *)mem)[-1] - (new-mem);
+ *res = new;
+ return 0;
+ }
+
+ ((size_t *)mem)[-1] = header&7 | new-mem;
+ ((size_t *)new)[-2] = footer&7 | new-mem;
+ ((size_t *)new)[-1] = header&7 | end-new;
+ ((size_t *)end)[-2] = footer&7 | end-new;
+
+ if (new != mem) free(mem);
+ *res = new;
+ return 0;
+}