/* Memory mapping support. */

#if defined(HAVE_MMAP_ANON) || defined(HAVE_MMAP_DEVZERO) || defined(HAVE_MACH_VM) || defined(HAVE_WIN32_VM)

/* -------------------------- Specification ---------------------------- */

/* This adds support for mapping private memory pages at given addresses.
 If HAVE_MMAP is defined, it also supports private mappings of files
 at given addresses.

 The size of a single page. (This may be a multiple of the actual physical
 page size.) Always a power of two. Initialized by mmap_init_pagesize(). */
local uintP mmap_pagesize;
local void mmap_init_pagesize (void);

/* Initialize the mmap system.
 mmap_init()
 < returns 0 upon success, -1 upon failure */
local int mmap_init (void);

/* Reserves an address range for use with mmap_zeromap().
 It tries to reserve the range [*map_addr,*map_endaddr). If this is not
 possible and shrinkp is true, *map_addr is increased and *map_endaddr is
 reduced as necessary. */
local int mmap_prepare (uintP* map_addr, uintP* map_endaddr, bool shrinkp);

/* Fill a memory range [map_addr,map_addr+map_len-1] with empty pages.
 mmap_zeromap(map_addr,map_len)
 map_addr and map_len must be multiples of mmap_pagesize. */
local int mmap_zeromap (void* map_addr, uintM map_len);

#ifdef HAVE_MMAP
/* Fill a memory range [map_addr,map_addr+map_len-1] with pages mapped in from
 file fd starting at position offset.
 map_addr and map_len must be multiples of mmap_pagesize. */
local void* mmap_filemap (void* map_addr, uintM map_len, int fd, off_t offset);
#endif

/* Unmaps a memory range. */
#if defined(HAVE_MACH_VM) || defined(HAVE_WIN32_VM)
global int munmap (void* addr, size_t len);
#endif

/* Changes the access protection for a memory range. */
#if defined(HAVE_MACH_VM) || defined(HAVE_WIN32_VM)
global int mprotect (void* addr, size_t len, int prot);
#endif

/* -------------------------- Implementation --------------------------- */

#if defined(HAVE_MACH_VM)

local void mmap_init_pagesize (void)
{ mmap_pagesize = vm_page_size; }

#define mmap_init()  0

#define mmap_prepare(map_addr,map_endaddr,shrinkp)  0

local int mmap_zeromap (void* map_addr, uintM map_len)
{
  if (vm_allocate(task_self(), (vm_address_t*) &map_addr, map_len, false)
      != KERN_SUCCESS) {
    fprintf(stderr,GETTEXTL("Cannot map memory to address 0x%lx ."),map_addr);
    errno_out();
    return -1;                  /* error */
  }
  return 0;
}

local void* mmap_filemap (void* map_addr, uintM map_len, int fd, off_t offset)
{
  switch (vm_allocate(task_self(), (vm_address_t*) &map_addr, map_len, false)) {
    case KERN_SUCCESS:
      break;
    default:
      errno = EINVAL; return (void*)(-1);
  }
  switch (map_fd(fd, offset, (vm_address_t*) &map_addr, 0, map_len)) {
    case KERN_SUCCESS:
      return map_addr;
    case KERN_INVALID_ADDRESS:
    case KERN_INVALID_ARGUMENT:
    default:
      errno = EINVAL; return (void*)(-1);
  }
}

/* We need to implement munmap() ourselves. */
global int munmap (void* addr, size_t len)
{
  switch (vm_deallocate(task_self(),addr,len)) {
    case KERN_SUCCESS:
      return 0;
    case KERN_INVALID_ADDRESS:
    default:
      errno = EINVAL; return -1;
  }
}

/* We need to implement mprotect() ourselves. */
global int mprotect (void* addr, size_t len, int prot)
{
  switch (vm_protect(task_self(),addr,len,0,prot)) {
    case KERN_SUCCESS:
      return 0;
    case KERN_PROTECTION_FAILURE:
      errno = EACCES; return -1;
    case KERN_INVALID_ADDRESS:
    default:
      errno = EINVAL; return -1;
  }
}

#endif

#if defined(HAVE_WIN32_VM)

local void mmap_init_pagesize (void)
{ mmap_pagesize = getpagesize(); }

#define mmap_init()  0

/* With Win32 VM, you cannot simply map a page of memory anywhere you want.
 You first have to reserve address space before you can do that.
 It's more programming, but it has the advantage that you cannot accidentally
 overwrite some of the shared libraries or malloc regions. (If you try that,
 VirtualAlloc(..,MEM_RESERVE,..) will return an error.)
 This function reserves an address range for use with mmap_zeromap().
 It tries to reserve the range [*map_addr,*map_endaddr). If this is not
 possible and shrinkp is true, *map_addr is increased and *map_endaddr is
 reduced as necessary. */
local int mmap_prepare (aint* map_addr, aint* map_endaddr, bool shrinkp)
{
  var uintM map_len = *map_endaddr - *map_addr;
  var aint start_addr = round_down(*map_addr,0x10000);
  var aint end_addr = round_up(*map_addr+map_len,0x10000);
  if (shrinkp) {
    /* Try to find the largest free address range subinterval of
       [start_addr,end_addr). */
    var MEMORY_BASIC_INFORMATION info;
    var aint largest_start_addr = start_addr;
    var uintM largest_len = 0;
    var aint addr = start_addr;
    while (VirtualQuery((void*)addr,&info,sizeof(info)) == sizeof(info)) {
      /* Always info.BaseAddress = addr. */
      addr = (aint)info.BaseAddress;
      var uintM len = (info.RegionSize >= end_addr-addr ? end_addr-addr : info.RegionSize);
      if ((info.State == MEM_FREE) && (len > largest_len)) {
        largest_start_addr = addr; largest_len = len;
      }
      if (info.RegionSize >= end_addr-addr)
        break;
      addr += info.RegionSize;
    }
    if (largest_len < 0x10000) {
      fprintf(stderr,GETTEXTL("Cannot reserve address range at 0x%lx ."),
              *map_addr);
      /* DumpProcessMemoryMap(); */
      return -1;
    }
    *map_addr = start_addr = round_up(largest_start_addr,0x10000);
    *map_endaddr = end_addr = largest_start_addr + largest_len;
  }
  if (!VirtualAlloc((void*)start_addr,end_addr-start_addr,MEM_RESERVE,PAGE_NOACCESS/*dummy*/)) {
    var DWORD errcode = GetLastError();
    fprintf(stderr,GETTEXTL("Cannot reserve address range 0x%lx-0x%lx ."),
            start_addr,end_addr-1);
    errno_out(errcode);
    /* DumpProcessMemoryMap(); */
    return -1;
  }
 #ifdef DEBUG_SPVW
  fprintf(stderr,"Reserved address range 0x%lx-0x%lx .\n",
          start_addr,end_addr-1);
 #endif
  return 0;
}

local int mmap_zeromap (void* map_addr, uintM map_len)
{
  if (!VirtualAlloc(map_addr,map_len,MEM_COMMIT,PAGE_READWRITE)) {
    var DWORD errcode = GetLastError();
    fprintf(stderr,GETTEXTL("Cannot map memory to address 0x%lx ."),
            map_addr);
    errno_out(errcode);
    return -1;                  /* error */
  }
  return 0;
}

#if 0
/* This implementation, on top of MapViewOfFileEx(), has three severe flaws:
 - It forces `map_addr' and `offset' to be aligned to 64 KB (not to the
   pagesize, 4KB, as indicated in the documentation), thus the mem files for
   SINGLEMAP_MEMORY get big.
 - On an address range prepared with mmap_prepare(), MapViewOfFileEx()
   returns the error code ERROR_INVALID_ADDRESS. We would have to map the
   first part of each heap to the file and mmap_prepare() only the remainder
   of the heap. This would give problems once a heap shrinks too much:
   munmap() below wouldn't work.
 - It doesn't work on Win95: MapViewOfFileEx() on Win95 cannot guarantee
   that it will be able to map at the desired address. */
local void* mmap_filemap (void* map_addr, uintM map_len, Handle fd,
                          off_t offset) {
  if (map_len==0)
    return map_addr;
  var HANDLE maphandle = CreateFileMapping(fd,NULL,PAGE_WRITECOPY,0,0,NULL);
  if (maphandle == NULL) {
    var DWORD errcode = GetLastError();
    fprintf(stderr,GETTEXTL("CreateFileMapping() failed."));
    errno_out(errcode);
    return (void*)(-1);
  }
  var void* resultaddr = MapViewOfFileEx(maphandle,FILE_MAP_COPY,0,
                                         (DWORD)offset,map_len,map_addr);
  if (resultaddr == NULL) {
    var DWORD errcode = GetLastError();
    fprintf(stderr,GETTEXTL("MapViewOfFileEx(addr=0x%x,off=0x%x) failed."),
            map_addr,offset);
    errno_out(errcode);
    return (void*)(-1);
  }
  if (resultaddr != map_addr) {
    fprintf(stderr,GETTEXTL("MapViewOfFileEx() returned 0x%x instead of 0x%x."),
            resultaddr,map_addr);
    fputc('\n',stderr);
    UnmapViewOfFile(resultaddr);
    return (void*)(-1);
  }
    return map_addr;
}
#endif

/* We need to implement munmap() ourselves. */
global int munmap (void* addr, size_t len)
{
  if (!VirtualFree(addr,len,MEM_DECOMMIT)) {
    var DWORD errcode = GetLastError();
    fprintf(stderr,GETTEXTL("VirtualFree() failed."));
    errno_out(errcode);
    return -1;
  }
  return 0;
}

#ifndef HAVE_MPROTECT
/* We need to implement mprotect() ourselves. */
global int mprotect (void* addr, size_t len, int prot)
{
  var DWORD oldprot;
  if (!VirtualProtect(addr,len,prot,&oldprot)) {
    var DWORD errcode = GetLastError();
    fprintf(stderr,GETTEXTL("VirtualProtect() failed."));
    errno_out(errcode);
    return -1;
  }
  return 0;
}
#endif

#endif

#if defined(HAVE_MMAP_ANON) || defined(HAVE_MMAP_DEVZERO)

/* We don't need both mmap() methods. One is sufficient. */
#ifdef HAVE_MMAP_ANON
  #undef HAVE_MMAP_DEVZERO
#endif

#ifdef HAVE_MMAP_DEVZERO
local int mmap_zero_fd;       /* open handle for /dev/zero */
  /* How to access /dev/zero: Sometimes /dev/zero has permissions 0644.
   Therefore we can OPEN() it only with O_RDONLY instead of O_RDWR.
   Therefore, in the mmap() call, we use MAP_PRIVATE instead of MAP_SHARED. */
  #ifdef MAP_FILE
    #define map_flags  MAP_FILE | MAP_PRIVATE
  #else
    #define map_flags  MAP_PRIVATE
  #endif
#endif
#ifdef HAVE_MMAP_ANON
  #define mmap_zero_fd  -1      /* any invalid handles works! */
  #define map_flags  MAP_ANON | MAP_PRIVATE
#endif

local void mmap_init_pagesize (void)
{
  mmap_pagesize =
   #if (defined(UNIX_SUNOS5) || defined(UNIX_LINUX)) && defined(SPARC)
    /* Normal SPARCs have PAGESIZE=4096, UltraSPARCs have PAGESIZE=8192.
       For compatibility of the .mem files between the architectures,
       choose the same value for both here. */
    8192
   #elif defined(UNIX_IRIX) && defined(MIPS)
    /* Normal MIPSs have pagesize=4096, the Onyx platform has it =16384.
       For compatibility of the .mem files between the architectures,
       choose the same value for both here. */
    16384
   #elif defined(UNIX_LINUX) && defined(IA64)
    /* The pagesize can be 4, 8, 16 or 64 KB.
       For compatibility of the .mem files, choose always the same value. */
    65536
   #elif defined(HAVE_GETPAGESIZE)
    getpagesize()
   #elif defined(UNIX_SUNOS5)
    /* UNIX_SUNOS5 (Solaris < 2.5) has mmap(), but no getpagesize() ! */
    PAGESIZE                    /* see <sys/param.h> */
   #elif defined(UNIX_SINIX) && defined(MIPS)
    16384
   #elif defined(HAVE_SHM)
    SHMLBA                      /* just a wild guess */
   #else
    4096                        /* just another wild guess */
   #endif
    ;
}

local int mmap_init (void)
{
 #ifdef HAVE_MMAP_DEVZERO
  {
    var int fd = OPEN("/dev/zero",O_RDONLY,my_open_mask);
    if (fd<0) {
      fprintf(stderr,GETTEXTL("Cannot open <%s>."),"/dev/zero");
      errno_out(errno);
      return -1; /* error */
    }
    mmap_zero_fd = fd;
  }
 #endif
  return 0;
}

#define mmap_prepare(map_addr,map_endaddr,shrinkp)  0

local int mmap_zeromap (void* map_addr, uintM map_len)
{
  if ( (void*) mmap((void*)map_addr, /* desired address */
                    map_len, /* length */
                    PROT_READ_WRITE, /* access rights */
                    map_flags | MAP_FIXED, /* exactly at this address! */
                    mmap_zero_fd, 0) /* put empty pages */
       == (void*)(-1)) {
    fprintf(stderr,GETTEXTL("Cannot map memory to address 0x%lx ."),
            map_addr);
    errno_out(errno);
    return -1; /* error */
  }
  return 0;
}

#ifdef HAVE_MMAP
local void* mmap_filemap (void* map_addr, uintM map_len, int fd, off_t offset)
{
  return (void*) mmap((void*)map_addr,
                      map_len,
                      PROT_READ_WRITE,
                      MAP_FIXED | MAP_PRIVATE,
                      fd, offset);
}
#endif

#endif

/* --------------------------------------------------------------------- */

#endif
