syscall for node.js

Execute POSIX/Linux syscall command from Node.js.

Usage, see syscall reference:

var syscall = require('libsys').syscall;

// Print `Hello world` in console using kernel's `syscall` command.
var buf = new Buffer('Hello world\n');
syscall(1, 1, buf, buf.length);

// Where, on x86_64 Linux:
// 1 - `sys_write` system call
// 1 - STDOUT file descriptor
// buf - pointer to data in memory
// buf.length - size of the memory block to print

See libjs for POSIX command implementation.

Part of jskernel project.

Reference

syscall and syscall64

type TArg = number|string|Buffer;
function syscall(command: number, ...args: TArg[]): number;
function syscall64(command: number, ...args: TArg[]): [number, number];

syscall accepts up to 6 command arguments args, which are treated as follows depending on their type:

• number is put directly in the appropriate CPU register as is.
• string gets converted to C's char * string and that pointer is put in CPU register.
• Buffer pointer to the raw data in-memory is put in CPU register.

syscall returns a number which is the result returned by the kernel, negative numbers usually represent an error. If sytem call returns -1, the C errno variable will be returned, which usually has more information about the error.

malloc

Returns a Buffer object of size size that is mapped to memory location specified in addr argument.

function malloc(addr: number, size: number): Buffer;

addr and addr64

Return memory address of Buffer's data contents.

function addr(buffer: Buffer): number;
function addr64(buffer: Buffer): [number, number];

addr64 returns a tuple which represents 64-bit number, where first element contains the lower 32 bits and second element has the high 32 bits.

asm [NOT IMPLEMENTED]

Execute assembly code, buffer contains raw op-codes to run.

function asm(buffer: Buffer);

errno

Returns errno variable.

function errno(): number;

Installation

npm i libsys

Compiles on Ubuntu 14.04 x86_64 running under Docker with Node.js 4.4.3, has not been tested on other machines.

Building addon:

node-gyp configure
node-gyp rebuild