DNA

Dart Native Access lets you deal with native libraries from Dart with zero lines of C/C++ code. Just pure Dart.

How to

For instance, you want to call getppid function from libc library on Linux.

  1. Find method signature in documentation:

pid_t getpid(void);

  1. Map arguments types and return type to C date types:

FIXME: Platform specific step

typedef int pid_t;

  1. Map C types to Dart types and DNA type constants:

FIXME: Decribe pointers and in/out arguments

| C | Dart | DNA | |-----|------|-----| |void|void|ARG_VOID| |char|int|ARG_CHAR| |short|int|ARG_SHORT| |int|int|ARG_INT| |long|int|ARG_LONG| |longlong|int|ARG_LONGLONG| |bool|boool|ARG_BOOL| |float|double|ARG_FLOAT| |double|double|ARG_DOUBLE| |type *|Ref|ARG_POINTER|

  1. Define class Libc with annotation @Lib:
@Lib('libc.so.6')
class Libc {
  
}

libc.so.6 is library name

FIXME: Symlinks aren't supported yet

  1. Define method getppid. Annotate arguments with @Arg and method with @Ret with corresponding type constants:
class Libc {
 
  @Ret(ARG_INT)
  int getpid() { ... }
}
  1. Finish with boilerplate code:

FIXME: This is temporary step for early versions

class Libc {
  dynamic lib = new DynamicLibrary<Libc>();  
  
  int getpid() { return lib.getpid(); }
}

  1. Use it
Libc libc = new Libc();
var processId = libc.getpid();

Examples

Linux

libc library

@Lib('libc.so.6')
class Libc {
  dynamic lib = new DynamicLibrary<Libc>();

  int getpid() { return lib.getpid(); }
  int getuid() { return lib.getuid(); }
      
  int rand() { return lib.rand(); }
  int rand_r(@Arg(ARG_POINTER) seedp) { return lib.rand_r(seedp); }
}

void main(){
  Libc libc = new Libc();
  var processId = libc.getpid();
  print('pid $processId = ${io.pid}');

  var userId = libc.getuid();
  print('userId ${userId}');

  libc.srand(0xDEADBEEF);
  var rand = libc.rand();
  print('rand $rand');

  var seed = new Ref<int>(0xDEADBEEF);
  var srand = libc.rand_r(seed);
  print('rand with seed $srand');

}

Windows

kenel32 library

@Lib('Kernel32.dll')
class Kernel32 {
  dynamic lib = new DynamicLibrary<Kernel32>();

  int GetCurrentProcess() { return lib.GetCurrentProcess(); }
  int GetProcessId(@Arg(ARG_INT) int process) { return lib.GetProcessId(process); }
  int GetModuleFileNameA(@Arg(ARG_INT) int process, @Arg(ARG_STRING) Ref<String> imageFileName, @Arg(ARG_INT) int size)  { return lib.GetModuleFileNameA(process, imageFileName, size); }
  bool GetProcessWorkingSetSize(@Arg(ARG_INT) int process, @Arg(ARG_POINTER) Ref<int> minimumWorkingSetSize, @Arg(ARG_POINTER) Ref<int> maximumWorkingSetSize) { return lib.GetProcessWorkingSetSize(process, minimumWorkingSetSize, maximumWorkingSetSize); }

  int GetLastError() { return lib.GetLastError(); }
}

void main(){
  Kernel32 kernel32 = new Kernel32();
  var process = kernel32.GetCurrentProcess();
  var processId = kernel32.GetProcessId(process);
  print('pid $processId = ${io.pid}');

  var min = new Ref<int>(0);
  var max = new Ref<int>(0);
  var result = kernel32.GetProcessWorkingSetSize(process, min, max);
  print('working set min ${min.value} max ${max.value}');

  var name = new Ref<String>(Strings.fill(' ', 64));
  result = kernel32.GetModuleFileNameA(0, name, name.value.length);
  print('module name ${name.value}');

}

Requirements

  • Linux 64-bit
  • Windows 32-bit and 64-bit

Trade off

  • Performance?
  • A lot of things aren't supported yet

Libraries

dartgl_dna

dna

Dart Native Access