Process.ffi.lua

local ffi = require 'ffi'
local fs = require 'fs'

local Process = {}
Process.__index = Process

if ffi.abi('win') then
    local psapi = ffi.load('psapi')

    ffi.cdef [[
    
    void* OpenProcess(unsigned long access, int inherit, unsigned long pid);
    unsigned long GetProcessImageFileNameA(void* process, char* image_file_name, unsigned long size);
    int CloseHandle(void* handle);
    
    ]]

    local PROCESS_QUERY_INFORMATION = 0x0400

    function Process.new(pid)
        local handle = ffi.C.OpenProcess(PROCESS_QUERY_INFORMATION, false, pid)

        local self = setmetatable({}, Process)
        self.inner = handle

        ffi.gc(self.inner, Process.destroy)

        return self
    end

    function Process:destroy()
        ffi.C.CloseHandle(self.inner)
    end

    function Process:getName()
        local name_buffer = ffi.new('char[?]', 260);

        local len = psapi.GetProcessImageFileNameA(self.inner, name_buffer, 260)

        local full_path = ffi.string(name_buffer, len);
        local process_name = full_path:match('\\([^\\]+)$', 1) or full_path

        return process_name
    end
elseif ffi.os == 'Linux' then
    function Process.new(pid)
        local self = setmetatable({}, Process)
        self.inner = pid

        return self
    end

    function Process:destroy()
    end

    function Process:getName()
        local cmdline = fs.readFileSync('/proc/' .. self.inner .. '/cmdline')
        local first_sep = cmdline:find('\0', 1, true)

        return cmdline:sub(1, first_sep - 1)
    end
else
    -- untested
    ffi.cdef [[
    
    int sysctl(const int *name, unsigned int namelen, void *oldp, size_t *oldlenp, const void *newp, size_t newlen);
    int sysctlnametomib(const char *name, int *mib, size_t *miblen);

    ]]

    function Process.new(pid)
        local self = setmetatable({}, Process)
        self.inner = pid

        -- ffi.gc(self.inner, Process.destroy)

        return self
    end

    function Process:destroy()
    end

    function Process:getName()
        local mib = ffi.new('int[?]', 4)
        local miblen = ffi.new('size_t[1]', 4)

        local name_buffer = ffi.new('char[?]', 256)
        local name_buffer_len = ffi.new('size_t[1]', 256)

        ffi.C.sysctlnametomib("kern.proc.args", mib, miblen)
        mib[3] = self.inner

        -- should we allocate the whole args buffer?
        ffi.C.sysctl(mib, 4, name_buffer, name_buffer_len, nil, 0)

        return ffi.string(name_buffer, name_buffer_len[0])
    end
end

return Process