-#elif darwin_TARGET_OS
- ret = mmap(addr, size, PROT_READ | PROT_WRITE,
- MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0);
+#elif darwin_HOST_OS
+ // Without MAP_FIXED, Apple's mmap ignores addr.
+ // With MAP_FIXED, it overwrites already mapped regions, whic
+ // mmap(0, ... MAP_FIXED ...) is worst of all: It unmaps the program text
+ // and replaces it with zeroes, causing instant death.
+ // This behaviour seems to be conformant with IEEE Std 1003.1-2001.
+ // Let's just use the underlying Mach Microkernel calls directly,
+ // they're much nicer.
+
+ kern_return_t err;
+ ret = addr;
+ if(addr) // try to allocate at adress
+ err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, FALSE);
+ if(!addr || err) // try to allocate anywhere
+ err = vm_allocate(mach_task_self(),(vm_address_t*) &ret, size, TRUE);
+
+ if(err) // don't know what the error codes mean exactly
+ barf("memory allocation failed (requested %lu bytes)", size);
+ else
+ vm_protect(mach_task_self(),ret,size,FALSE,VM_PROT_READ|VM_PROT_WRITE);