#include "malunal/config.h"

#if MALUNAL_PLATFORM_LINUX
#include <stdlib.h>
#include <unistd.h>
#include <sys/mman.h>
#include "malunal/allocator.h"


static
malunal_size_t
g_platform_page_size = 0;

malunal_size_t
platform_page_size() {
  return g_platform_page_size == 0
    ? g_platform_page_size = sysconf(_SC_PAGE_SIZE)
    : g_platform_page_size;
}

static
error_t
linux_allocator_acquire(
  allocator_mptr_t allocator,
  malunal_size_t   size,
  malunal_mptr_t*  out
) {
  MALUNAL_UNUSED(allocator);

  const malunal_int32_t memops  = PROT_READ | PROT_WRITE;
  const malunal_int32_t memprms = MAP_PRIVATE | MAP_ANONYMOUS;

  malunal_mptr_t ptr = mmap(0, size, memops, memprms, -1, 0);
  if (ptr == MAP_FAILED || ptr == null)
    return (error_t) {
      .domain = &ERROR_DOMAIN_ALLOCATOR_T,
      .code   = ALLOCATOR_ERROR_OUT_OF_MEMORY
    };

  *out = ptr;
  return NO_ERROR;
}

static
error_t
linux_allocator_dispose(
  allocator_mptr_t allocator,
  malunal_mptr_t   address,
  malunal_size_t   size
) {
  MALUNAL_UNUSED(allocator);
  munmap(address, size);
  return NO_ERROR;
}


static const
allocator_vtable_t linux_allocator_vtable = {
  .acquire = (allocator_acquire_pfn_t)&linux_allocator_acquire,
  .dispose = (allocator_dispose_pfn_t)&linux_allocator_dispose
};

static const
allocator_t linux_allocator_instance = {
  .vtable = &linux_allocator_vtable
};

allocator_mptr_t
linux_allocator() {
  return &linux_allocator_instance;
}
#endif /* MALUNAL_PLATFORM_LINUX */