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|ArrayBuffer|Uint8Array|Buffer;
syscall(command: number, ...args: TArg[]): number;
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 used as an argument.
• for ArrayBuffer, Uint8Array, and Buffer pointer to the raw data in-memory is used as argument.

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.

errno

Returns errno variable.

function errno(): number;

malloc as malloc64

malloc returns an ArrayBuffer object of size size that is mapped to memory location specified in addr argument.

malloc64 is the same but memory address is split in two 32-bit numbers lo and hi.

malloc(addr: number, size: number): ArrayBuffer;
malloc64(lo: number, hi: number, size: number): ArrayBuffer;

addressBuffer and addressBuffer64

Return memory address of Buffer's data contents.

addressBuffer(buffer: Buffer): number;
addressBuffer64(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.

addressArrayBuffer and addressArrayBuffer64

Returns ArrayBuffer address.

addressUint8Array and addressUint8Array64

Returns Uint8Array address.

call as call64

Execute machine code at specified memory address. The memory address is converted to function pointer and called using your architecture calling conventions.

call(addr: number);
call64(addr_lo: number, addr_hi: 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