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

syscall(command: number, ...args: Targ[]): number;
syscall64(command: number, ...args: TArg[]): [number, number];

syscall accepts up to 6 command arguments args. See discussion on Arguments below to see how JavaScript objects are converted to 64-bit integers.

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

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

malloc(addr: Targ, 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.

addressTypedArray and addressTypedArray64

Returns Uint8Array address.

call

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

Up to ten arguments in arguments array supported.

call(addr: Targ, offset: number = 0, args?: number[]);

Arguments

type Targ = number|[number, number]|[number, number, number]|string|ArrayBuffer|TypedArray|Buffer;

Different JavaScript objects can be used as C arguments. Here is how they are converted to 64-bit integers:

• number is treated as 32-bit integer and gets extended to 64-bit integer;
• [number, number] treated as a [lo, hi] tuple of two 32-bit integers, which are combined to 64-bit integer;
• [number, number, number] treated as a [lo, hi, offset] tuple, same as above with the difference that offset is added to the resulting 64-bit integer;
• string gets converted to C null-terminated string and 64-bit pointer created to the beginning of that string;
• ArrayBuffer, TypedArray, Buffer 64-bit pointer to the beginning of data contents of those objects is created;

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