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syscalls.lua
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syscalls.lua
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-- This is the actual system calls for Linux
local require, error, assert, tonumber, tostring,
setmetatable, pairs, ipairs, unpack, rawget, rawset,
pcall, type, table, string =
require, error, assert, tonumber, tostring,
setmetatable, pairs, ipairs, unpack, rawget, rawset,
pcall, type, table, string
local abi = require "syscall.abi"
return function(S, hh, c, C, types)
local ret64, retnum, retfd, retbool, retptr, retiter = hh.ret64, hh.retnum, hh.retfd, hh.retbool, hh.retptr, hh.retiter
local ffi = require "ffi"
local errno = ffi.errno
local bit = require "syscall.bit"
local t, pt, s = types.t, types.pt, types.s
local h = require "syscall.helpers"
local istype, mktype, getfd = h.istype, h.mktype, h.getfd
if abi.abi32 then
-- override open call with largefile -- TODO move this hack to c.lua instead
function S.open(pathname, flags, mode)
flags = c.O(flags, "LARGEFILE")
return retfd(C.open(pathname, flags, c.MODE[mode]))
end
function S.openat(dirfd, pathname, flags, mode)
flags = c.O(flags, "LARGEFILE")
return retfd(C.openat(c.AT_FDCWD[dirfd], pathname, flags, c.MODE[mode]))
end
-- creat has no largefile flag so cannot be used
function S.creat(pathname, mode) return S.open(pathname, "CREAT,WRONLY,TRUNC", mode) end
end
function S.pause() return retbool(C.pause()) end
function S.acct(filename) return retbool(C.acct(filename)) end
function S.getpriority(which, who)
local ret, err = C.getpriority(c.PRIO[which], who or 0)
if ret == -1 then return nil, t.error(err or errno()) end
return 20 - ret -- adjust for kernel returned values as this is syscall not libc
end
-- we could allocate ptid, ctid, tls if required in flags instead. TODO add signal into flag parsing directly
function S.clone(flags, signal, stack, ptid, tls, ctid)
flags = c.CLONE[flags] + c.SIG[signal or 0]
return retnum(C.clone(flags, stack, ptid, tls, ctid))
end
if C.unshare then -- quite new, also not defined in rump yet
function S.unshare(flags) return retbool(C.unshare(c.CLONE[flags])) end
end
if C.setns then
function S.setns(fd, nstype) return retbool(C.setns(getfd(fd), c.CLONE[nstype])) end
end
function S.reboot(cmd)
return retbool(C.reboot(c.LINUX_REBOOT.MAGIC1, c.LINUX_REBOOT.MAGIC2, c.LINUX_REBOOT_CMD[cmd]))
end
-- note waitid also provides rusage that Posix does not have, override default
function S.waitid(idtype, id, options, infop, rusage) -- note order of args, as usually dont supply infop, rusage
if not infop then infop = t.siginfo() end
if not rusage and rusage ~= false then rusage = t.rusage() end
local ret, err = C.waitid(c.P[idtype], id or 0, infop, c.W[options], rusage)
if ret == -1 then return nil, t.error(err or errno()) end
return infop, nil, rusage
end
function S.exit(status) C.exit_group(c.EXIT[status or 0]) end
function S.sync_file_range(fd, offset, count, flags)
return retbool(C.sync_file_range(getfd(fd), offset, count, c.SYNC_FILE_RANGE[flags]))
end
function S.getcwd(buf, size)
size = size or c.PATH_MAX
buf = buf or t.buffer(size)
local ret, err = C.getcwd(buf, size)
if ret == -1 then return nil, t.error(err or errno()) end
return ffi.string(buf)
end
function S.statfs(path)
local st = t.statfs()
local ret, err = C.statfs(path, st)
if ret == -1 then return nil, t.error(err or errno()) end
return st
end
function S.fstatfs(fd)
local st = t.statfs()
local ret, err = C.fstatfs(getfd(fd), st)
if ret == -1 then return nil, t.error(err or errno()) end
return st
end
function S.mremap(old_address, old_size, new_size, flags, new_address)
return retptr(C.mremap(old_address, old_size, new_size, c.MREMAP[flags], new_address))
end
function S.remap_file_pages(addr, size, prot, pgoff, flags)
return retbool(C.remap_file_pages(addr, size, c.PROT[prot], pgoff, c.MAP[flags]))
end
function S.fadvise(fd, advice, offset, len) -- note argument order TODO change back?
return retbool(C.fadvise64(getfd(fd), offset or 0, len or 0, c.POSIX_FADV[advice]))
end
function S.fallocate(fd, mode, offset, len)
return retbool(C.fallocate(getfd(fd), c.FALLOC_FL[mode], offset or 0, len))
end
function S.posix_fallocate(fd, offset, len) return S.fallocate(fd, 0, offset, len) end
function S.readahead(fd, offset, count) return retbool(C.readahead(getfd(fd), offset, count)) end
-- TODO change to type?
function S.uname()
local u = t.utsname()
local ret, err = C.uname(u)
if ret == -1 then return nil, t.error(err or errno()) end
return {sysname = ffi.string(u.sysname), nodename = ffi.string(u.nodename), release = ffi.string(u.release),
version = ffi.string(u.version), machine = ffi.string(u.machine), domainname = ffi.string(u.domainname)}
end
function S.sethostname(s, len) return retbool(C.sethostname(s, len or #s)) end
function S.setdomainname(s, len) return retbool(C.setdomainname(s, len or #s)) end
if C.time then
function S.time(time) return retnum(C.time(time)) end
end
function S.sysinfo(info)
info = info or t.sysinfo()
local ret, err = C.sysinfo(info)
if ret == -1 then return nil, t.error(err or errno()) end
return info
end
function S.signalfd(set, flags, fd) -- note different order of args, as fd usually empty. See also signalfd_read()
set = mktype(t.sigset, set)
if fd then fd = getfd(fd) else fd = -1 end
-- note includes (hidden) size argument
return retfd(C.signalfd(fd, set, s.sigset, c.SFD[flags]))
end
-- note that syscall does return timeout remaining but libc does not, due to standard prototype TODO use syscall
-- note this is the only difference with NetBSD pollts, so could merge them
function S.ppoll(fds, timeout, set)
if timeout then timeout = mktype(t.timespec, timeout) end
if set then set = mktype(t.sigset, set) end
return retnum(C.ppoll(fds.pfd, #fds, timeout, set))
end
if not S.poll then
function S.poll(fd, timeout)
if timeout then timeout = mktype(t.timespec, timeout / 1000) end
return S.ppoll(fd, timeout)
end
end
function S.mount(source, target, fstype, mountflags, data)
return retbool(C.mount(source or "none", target, fstype, c.MS[mountflags], data))
end
function S.umount(target, flags)
return retbool(C.umount2(target, c.UMOUNT[flags]))
end
function S.prlimit(pid, resource, new_limit, old_limit)
if new_limit then new_limit = mktype(t.rlimit, new_limit) end
old_limit = old_limit or t.rlimit()
local ret, err = C.prlimit64(pid or 0, c.RLIMIT[resource], new_limit, old_limit)
if ret == -1 then return nil, t.error(err or errno()) end
return old_limit
end
function S.epoll_create(flags)
return retfd(C.epoll_create1(c.EPOLLCREATE[flags]))
end
function S.epoll_ctl(epfd, op, fd, event)
if type(event) == "string" or type(event) == "number" then event = {events = event, fd = getfd(fd)} end
event = mktype(t.epoll_event, event)
return retbool(C.epoll_ctl(getfd(epfd), c.EPOLL_CTL[op], getfd(fd), event))
end
if C.epoll_wait then
function S.epoll_wait(epfd, events, timeout)
local ret, err = C.epoll_wait(getfd(epfd), events.ep, #events, timeout or -1)
return retiter(ret, err, events.ep)
end
else
function S.epoll_wait(epfd, events, timeout)
local ret, err = C.epoll_pwait(getfd(epfd), events.ep, #events, timeout or -1, nil)
return retiter(ret, err, events.ep)
end
end
function S.epoll_pwait(epfd, events, timeout, sigmask)
if sigmask then sigmask = mktype(t.sigset, sigmask) end
local ret, err = C.epoll_pwait(getfd(epfd), events.ep, #events, timeout or -1, sigmask)
return retiter(ret, err, events.ep)
end
function S.splice(fd_in, off_in, fd_out, off_out, len, flags)
local offin, offout = off_in, off_out
if off_in and not ffi.istype(t.off1, off_in) then
offin = t.off1()
offin[0] = off_in
end
if off_out and not ffi.istype(t.off1, off_out) then
offout = t.off1()
offout[0] = off_out
end
return retnum(C.splice(getfd(fd_in), offin, getfd(fd_out), offout, len, c.SPLICE_F[flags]))
end
function S.vmsplice(fd, iov, flags)
iov = mktype(t.iovecs, iov)
return retnum(C.vmsplice(getfd(fd), iov.iov, #iov, c.SPLICE_F[flags]))
end
function S.tee(fd_in, fd_out, len, flags)
return retnum(C.tee(getfd(fd_in), getfd(fd_out), len, c.SPLICE_F[flags]))
end
function S.inotify_init(flags) return retfd(C.inotify_init1(c.IN_INIT[flags])) end
function S.inotify_add_watch(fd, pathname, mask) return retnum(C.inotify_add_watch(getfd(fd), pathname, c.IN[mask])) end
function S.inotify_rm_watch(fd, wd) return retbool(C.inotify_rm_watch(getfd(fd), wd)) end
function S.sendfile(out_fd, in_fd, offset, count)
if type(offset) == "number" then
offset = t.off1(offset)
end
return retnum(C.sendfile(getfd(out_fd), getfd(in_fd), offset, count))
end
function S.eventfd(initval, flags) return retfd(C.eventfd(initval or 0, c.EFD[flags])) end
function S.timerfd_create(clockid, flags)
return retfd(C.timerfd_create(c.CLOCK[clockid], c.TFD[flags]))
end
function S.timerfd_settime(fd, flags, it, oldtime)
oldtime = oldtime or t.itimerspec()
local ret, err = C.timerfd_settime(getfd(fd), c.TFD_TIMER[flags or 0], mktype(t.itimerspec, it), oldtime)
if ret == -1 then return nil, t.error(err or errno()) end
return oldtime
end
function S.timerfd_gettime(fd, curr_value)
curr_value = curr_value or t.itimerspec()
local ret, err = C.timerfd_gettime(getfd(fd), curr_value)
if ret == -1 then return nil, t.error(err or errno()) end
return curr_value
end
function S.pivot_root(new_root, put_old) return retbool(C.pivot_root(new_root, put_old)) end
-- aio functions
function S.io_setup(nr_events)
local ctx = t.aio_context1()
local ret, err = C.io_setup(nr_events, ctx)
if ret == -1 then return nil, t.error(err or errno()) end
return ctx[0]
end
function S.io_destroy(ctx) return retbool(C.io_destroy(ctx)) end
function S.io_cancel(ctx, iocb, result)
result = result or t.io_event()
local ret, err = C.io_cancel(ctx, iocb, result)
if ret == -1 then return nil, t.error(err or errno()) end
return result
end
function S.io_getevents(ctx, min, events, timeout)
if timeout then timeout = mktype(t.timespec, timeout) end
local ret, err = C.io_getevents(ctx, min or events.count, events.count, events.ev, timeout)
return retiter(ret, err, events.ev)
end
-- iocb must persist until retrieved (as we get pointer), so cannot be passed as table must take t.iocb_array
function S.io_submit(ctx, iocb)
return retnum(C.io_submit(ctx, iocb.ptrs, iocb.nr))
end
-- TODO prctl should be in a seperate file like ioctl fnctl (this is a Linux only interface)
-- map for valid options for arg2
local prctlmap = {
[c.PR.CAPBSET_READ] = c.CAP,
[c.PR.CAPBSET_DROP] = c.CAP,
[c.PR.SET_ENDIAN] = c.PR_ENDIAN,
[c.PR.SET_FPEMU] = c.PR_FPEMU,
[c.PR.SET_FPEXC] = c.PR_FP_EXC,
[c.PR.SET_PDEATHSIG] = c.SIG,
--[c.PR.SET_SECUREBITS] = c.SECBIT, -- TODO not defined yet
[c.PR.SET_TIMING] = c.PR_TIMING,
[c.PR.SET_TSC] = c.PR_TSC,
[c.PR.SET_UNALIGN] = c.PR_UNALIGN,
[c.PR.MCE_KILL] = c.PR_MCE_KILL,
[c.PR.SET_SECCOMP] = c.SECCOMP_MODE,
[c.PR.SET_NO_NEW_PRIVS] = h.booltoc,
}
local prctlrint = { -- returns an integer directly TODO add metatables to set names
[c.PR.GET_DUMPABLE] = true,
[c.PR.GET_KEEPCAPS] = true,
[c.PR.CAPBSET_READ] = true,
[c.PR.GET_TIMING] = true,
[c.PR.GET_SECUREBITS] = true,
[c.PR.MCE_KILL_GET] = true,
[c.PR.GET_SECCOMP] = true,
[c.PR.GET_NO_NEW_PRIVS] = true,
}
local prctlpint = { -- returns result in a location pointed to by arg2
[c.PR.GET_ENDIAN] = true,
[c.PR.GET_FPEMU] = true,
[c.PR.GET_FPEXC] = true,
[c.PR.GET_PDEATHSIG] = true,
[c.PR.GET_UNALIGN] = true,
}
-- this is messy, TODO clean up, its own file see above
function S.prctl(option, arg2, arg3, arg4, arg5)
local i, name
option = c.PR[option]
local m = prctlmap[option]
if m then arg2 = m[arg2] end
if option == c.PR.MCE_KILL and arg2 == c.PR_MCE_KILL.SET then
arg3 = c.PR_MCE_KILL_OPT[arg3]
elseif prctlpint[option] then
i = t.int1()
arg2 = ffi.cast(t.ulong, i)
elseif option == c.PR.GET_NAME then
name = t.buffer(16)
arg2 = ffi.cast(t.ulong, name)
elseif option == c.PR.SET_NAME then
if type(arg2) == "string" then arg2 = ffi.cast(t.ulong, arg2) end
elseif option == c.PR.SET_SECCOMP then
arg3 = t.intptr(arg3 or 0)
end
local ret = C.prctl(option, arg2 or 0, arg3 or 0, arg4 or 0, arg5 or 0)
if ret == -1 then return nil, t.error() end
if prctlrint[option] then return ret end
if prctlpint[option] then return i[0] end
if option == c.PR.GET_NAME then
if name[15] ~= 0 then return ffi.string(name, 16) end -- actually, 15 bytes seems to be longest, aways 0 terminated
return ffi.string(name)
end
return true
end
function S.syslog(tp, buf, len)
if not buf and (tp == 2 or tp == 3 or tp == 4) then
if not len then
-- this is the glibc name for the syslog syscall
len = C.klogctl(10, nil, 0) -- get size so we can allocate buffer
if len == -1 then return nil, t.error() end
end
buf = t.buffer(len)
end
local ret, err = C.klogctl(tp, buf or nil, len or 0)
if ret == -1 then return nil, t.error(err or errno()) end
if tp == 9 or tp == 10 then return tonumber(ret) end
if tp == 2 or tp == 3 or tp == 4 then return ffi.string(buf, ret) end
return true
end
function S.adjtimex(a)
a = mktype(t.timex, a)
local ret, err = C.adjtimex(a)
if ret == -1 then return nil, t.error(err or errno()) end
return t.adjtimex(ret, a)
end
if C.alarm then
function S.alarm(s) return C.alarm(s) end
end
function S.setreuid(ruid, euid) return retbool(C.setreuid(ruid, euid)) end
function S.setregid(rgid, egid) return retbool(C.setregid(rgid, egid)) end
function S.getresuid(ruid, euid, suid)
ruid, euid, suid = ruid or t.uid1(), euid or t.uid1(), suid or t.uid1()
local ret, err = C.getresuid(ruid, euid, suid)
if ret == -1 then return nil, t.error(err or errno()) end
return true, nil, ruid[0], euid[0], suid[0]
end
function S.getresgid(rgid, egid, sgid)
rgid, egid, sgid = rgid or t.gid1(), egid or t.gid1(), sgid or t.gid1()
local ret, err = C.getresgid(rgid, egid, sgid)
if ret == -1 then return nil, t.error(err or errno()) end
return true, nil, rgid[0], egid[0], sgid[0]
end
function S.setresuid(ruid, euid, suid) return retbool(C.setresuid(ruid, euid, suid)) end
function S.setresgid(rgid, egid, sgid) return retbool(C.setresgid(rgid, egid, sgid)) end
function S.vhangup() return retbool(C.vhangup()) end
function S.swapon(path, swapflags) return retbool(C.swapon(path, c.SWAP_FLAG[swapflags])) end
function S.swapoff(path) return retbool(C.swapoff(path)) end
if C.getrandom then
function S.getrandom(buf, count, flags)
return retnum(C.getrandom(buf, count or #buf or 64, c.GRND[flags]))
end
end
if C.memfd_create then
function S.memfd_create(name, flags) return retfd(C.memfd_create(name, c.MFD[flags])) end
end
-- capabilities. Somewhat complex kernel interface due to versioning, Posix requiring malloc in API.
-- only support version 3, should be ok for recent kernels, or pass your own hdr, data in
-- to detect capability API version, pass in hdr with empty version, version will be set
function S.capget(hdr, data) -- normally just leave as nil for get, can pass pid in
hdr = istype(t.user_cap_header, hdr) or t.user_cap_header(c.LINUX_CAPABILITY_VERSION[3], hdr or 0)
if not data and hdr.version ~= 0 then data = t.user_cap_data2() end
local ret, err = C.capget(hdr, data)
if ret == -1 then return nil, t.error(err or errno()) end
if not data then return hdr end
return t.capabilities(hdr, data)
end
function S.capset(hdr, data)
if ffi.istype(t.capabilities, hdr) then hdr, data = hdr:hdrdata() end
return retbool(C.capset(hdr, data))
end
function S.getcpu(cpu, node)
cpu = cpu or t.uint1()
node = node or t.uint1()
local ret, err = C.getcpu(cpu, node)
if ret == -1 then return nil, t.error(err or errno()) end
return {cpu = cpu[0], node = node[0]}
end
function S.sched_getscheduler(pid) return retnum(C.sched_getscheduler(pid or 0)) end
function S.sched_setscheduler(pid, policy, param)
param = mktype(t.sched_param, param or 0)
return retbool(C.sched_setscheduler(pid or 0, c.SCHED[policy], param))
end
function S.sched_yield() return retbool(C.sched_yield()) end
function S.sched_getaffinity(pid, mask, len) -- note len last as rarely used. All parameters optional
mask = mktype(t.cpu_set, mask)
local ret, err = C.sched_getaffinity(pid or 0, len or s.cpu_set, mask)
if ret == -1 then return nil, t.error(err or errno()) end
return mask
end
function S.sched_setaffinity(pid, mask, len) -- note len last as rarely used
return retbool(C.sched_setaffinity(pid or 0, len or s.cpu_set, mktype(t.cpu_set, mask)))
end
local function get_maxnumnodes()
local function readfile (filename)
local ret = {}
local bufsz = 1024
local buf = ffi.new("uint8_t[?]", bufsz)
local fd, errno = S.open(filename, 0)
if not fd then error(errno) end
while true do
local len = S.read(fd, buf, bufsz)
table.insert(ret, ffi.string(buf, len))
if len ~= bufsz then break end
end
fd:close()
return table.concat(ret)
end
local content = readfile("/proc/self/status")
for line in content:gmatch("[^\n]+") do
if line:match("^Mems_allowed:") then
line = line:gsub("^Mems_allowed:%s+", "")
-- In Mems_allowed each 9 characters (8 digit plus comma) represents
-- a 32-bit mask. Total number of maxnumnodes is the total sum of
-- the masks multiplied by 32. Line length is increased by one since
-- there's no comma at the end of line.
return math.floor(((#line+1)/9)*32)
end
end
end
function S.get_mempolicy(mode, mask, addr, flags)
mode = mode or t.int1()
local size
if ffi.istype(t.bitmask, mask) then
-- if mask was provided by the caller, then use its size
-- and let the syscall error if it's too small
size = ffi.cast("uint64_t", tonumber(mask.size))
else
local mask_for_size = t.bitmask(mask)
-- Size should be at least equals to maxnumnodes.
size = ffi.cast("uint64_t", math.max(tonumber(mask_for_size.size), get_maxnumnodes()))
mask = t.bitmask(mask, tonumber(size))
end
local ret, err = C.get_mempolicy(mode, mask.mask, size, addr or 0, c.MPOL_FLAG[flags])
if ret == -1 then return nil, t.error(err or errno()) end
return { mode=mode[0], mask=mask }
end
function S.set_mempolicy(mode, mask)
mask = mktype(t.bitmask, mask)
return retbool(C.set_mempolicy(c.MPOL_MODE[mode], mask.mask, mask.size))
end
function S.migrate_pages(pid, from, to)
from = mktype(t.bitmask, from)
to = mktype(t.bitmask, to)
assert(from.size == to.size, "incompatible nodemask sizes")
return retbool(C.migrate_pages(pid or 0, from.size, from.mask, to.mask))
end
function S.sched_get_priority_max(policy) return retnum(C.sched_get_priority_max(c.SCHED[policy])) end
function S.sched_get_priority_min(policy) return retnum(C.sched_get_priority_min(c.SCHED[policy])) end
function S.sched_setparam(pid, param)
return retbool(C.sched_setparam(pid or 0, mktype(t.sched_param, param or 0)))
end
function S.sched_getparam(pid, param)
param = mktype(t.sched_param, param or 0)
local ret, err = C.sched_getparam(pid or 0, param)
if ret == -1 then return nil, t.error(err or errno()) end
return param.sched_priority -- only one useful parameter
end
function S.sched_rr_get_interval(pid, ts)
ts = mktype(t.timespec, ts)
local ret, err = C.sched_rr_get_interval(pid or 0, ts)
if ret == -1 then return nil, t.error(err or errno()) end
return ts
end
-- this is recommended way to size buffers for xattr
local function growattrbuf(f, a, b)
local len = 512
local buffer = t.buffer(len)
local ret, err
repeat
if b then
ret, err = f(a, b, buffer, len)
else
ret, err = f(a, buffer, len)
end
ret = tonumber(ret)
if ret == -1 and (err or errno()) ~= c.E.RANGE then return nil, t.error(err or errno()) end
if ret == -1 then
len = len * 2
buffer = t.buffer(len)
end
until ret >= 0
return ffi.string(buffer, ret)
end
local function lattrbuf(f, a)
local s, err = growattrbuf(f, a)
if not s then return nil, err end
local tab = h.split('\0', s)
tab[#tab] = nil -- there is a trailing \0 so one extra
return tab
end
-- TODO Note these should be in NetBSD too, but no useful filesystem (ex nfs) has xattr support, so never tested
if C.listxattr then
function S.listxattr(path) return lattrbuf(C.listxattr, path) end
function S.llistxattr(path) return lattrbuf(C.llistxattr, path) end
function S.flistxattr(fd) return lattrbuf(C.flistxattr, getfd(fd)) end
end
if C.setxattr then
function S.setxattr(path, name, value, flags) return retbool(C.setxattr(path, name, value, #value, c.XATTR[flags])) end
function S.lsetxattr(path, name, value, flags) return retbool(C.lsetxattr(path, name, value, #value, c.XATTR[flags])) end
function S.fsetxattr(fd, name, value, flags) return retbool(C.fsetxattr(getfd(fd), name, value, #value, c.XATTR[flags])) end
end
if C.getxattr then
function S.getxattr(path, name) return growattrbuf(C.getxattr, path, name) end
function S.lgetxattr(path, name) return growattrbuf(C.lgetxattr, path, name) end
function S.fgetxattr(fd, name) return growattrbuf(C.fgetxattr, getfd(fd), name) end
end
if C.removexattr then
function S.removexattr(path, name) return retbool(C.removexattr(path, name)) end
function S.lremovexattr(path, name) return retbool(C.lremovexattr(path, name)) end
function S.fremovexattr(fd, name) return retbool(C.fremovexattr(getfd(fd), name)) end
end
-- helper function to set and return attributes in tables
-- TODO this would make more sense as types?
-- TODO listxattr should return an iterator not a table?
local function xattr(list, get, set, remove, path, t)
local l, err = list(path)
if not l then return nil, err end
if not t then -- no table, so read
local r = {}
for _, name in ipairs(l) do
r[name] = get(path, name) -- ignore errors
end
return r
end
-- write
for _, name in ipairs(l) do
if t[name] then
set(path, name, t[name]) -- ignore errors, replace
t[name] = nil
else
remove(path, name)
end
end
for name, value in pairs(t) do
set(path, name, value) -- ignore errors, create
end
return true
end
if S.listxattr and S.getxattr then
function S.xattr(path, t) return xattr(S.listxattr, S.getxattr, S.setxattr, S.removexattr, path, t) end
function S.lxattr(path, t) return xattr(S.llistxattr, S.lgetxattr, S.lsetxattr, S.lremovexattr, path, t) end
function S.fxattr(fd, t) return xattr(S.flistxattr, S.fgetxattr, S.fsetxattr, S.fremovexattr, fd, t) end
end
-- POSIX message queues. Note there is no mq_close as it is just close in Linux
function S.mq_open(name, flags, mode, attr)
local ret, err = C.mq_open(name, c.O[flags], c.MODE[mode], mktype(t.mq_attr, attr))
if ret == -1 then return nil, t.error(err or errno()) end
return t.mqd(ret)
end
function S.mq_unlink(name)
return retbool(C.mq_unlink(name))
end
function S.mq_getsetattr(mqd, new, old) -- provided for completeness, but use getattr, setattr which are methods
return retbool(C.mq_getsetattr(getfd(mqd), new, old))
end
function S.mq_timedsend(mqd, msg_ptr, msg_len, msg_prio, abs_timeout)
if abs_timeout then abs_timeout = mktype(t.timespec, abs_timeout) end
return retbool(C.mq_timedsend(getfd(mqd), msg_ptr, msg_len or #msg_ptr, msg_prio or 0, abs_timeout))
end
-- like read, return string if buffer not provided. Length required. TODO should we return prio?
function S.mq_timedreceive(mqd, msg_ptr, msg_len, msg_prio, abs_timeout)
if abs_timeout then abs_timeout = mktype(t.timespec, abs_timeout) end
if msg_ptr then return retbool(C.mq_timedreceive(getfd(mqd), msg_ptr, msg_len or #msg_ptr, msg_prio, abs_timeout)) end
msg_ptr = t.buffer(msg_len)
local ret, err = C.mq_timedreceive(getfd(mqd), msg_ptr, msg_len or #msg_ptr, msg_prio, abs_timeout)
if ret == -1 then return nil, t.error(err or errno()) end
return ffi.string(msg_ptr,ret)
end
-- pty functions where not in common code TODO move to linux/libc?
function S.grantpt(fd) return true end -- Linux does not need to do anything here (Musl does not)
function S.unlockpt(fd) return S.ioctl(fd, "TIOCSPTLCK", 0) end
function S.ptsname(fd)
local pts, err = S.ioctl(fd, "TIOCGPTN")
if not pts then return nil, err end
return "/dev/pts/" .. tostring(pts)
end
function S.tcgetattr(fd) return S.ioctl(fd, "TCGETS") end
local tcsets = {
[c.TCSA.NOW] = "TCSETS",
[c.TCSA.DRAIN] = "TCSETSW",
[c.TCSA.FLUSH] = "TCSETSF",
}
function S.tcsetattr(fd, optional_actions, tio)
local inc = c.TCSA[optional_actions]
return S.ioctl(fd, tcsets[inc], tio)
end
function S.tcsendbreak(fd, duration)
return S.ioctl(fd, "TCSBRK", pt.void(0)) -- Linux ignores duration
end
function S.tcdrain(fd)
return S.ioctl(fd, "TCSBRK", pt.void(1)) -- note use of literal 1 cast to pointer
end
function S.tcflush(fd, queue_selector)
return S.ioctl(fd, "TCFLSH", pt.void(c.TCFLUSH[queue_selector]))
end
function S.tcflow(fd, action)
return S.ioctl(fd, "TCXONC", pt.void(c.TCFLOW[action]))
end
-- compat code for stuff that is not actually a syscall under Linux
-- old rlimit functions in Linux are 32 bit only so now defined using prlimit
function S.getrlimit(resource)
return S.prlimit(0, resource)
end
function S.setrlimit(resource, rlim)
local ret, err = S.prlimit(0, resource, rlim)
if not ret then return nil, err end
return true
end
function S.gethostname()
local u, err = S.uname()
if not u then return nil, err end
return u.nodename
end
function S.getdomainname()
local u, err = S.uname()
if not u then return nil, err end
return u.domainname
end
function S.killpg(pgrp, sig) return S.kill(-pgrp, sig) end
-- helper function to read inotify structs as table from inotify fd, TODO could be in util
function S.inotify_read(fd, buffer, len)
len = len or 1024
buffer = buffer or t.buffer(len)
local ret, err = S.read(fd, buffer, len)
if not ret then return nil, err end
return t.inotify_events(buffer, ret)
end
-- in Linux mkfifo is not a syscall, emulate
function S.mkfifo(path, mode) return S.mknod(path, bit.bor(c.MODE[mode], c.S_I.FIFO)) end
function S.mkfifoat(fd, path, mode) return S.mknodat(fd, path, bit.bor(c.MODE[mode], c.S_I.FIFO), 0) end
-- in Linux getpagesize is not a syscall for most architectures.
-- It is pretty obscure how you get the page size for architectures that have variable page size, I think it is coded into libc
-- that matches kernel. Which is not much use for us.
-- fortunately Linux (unlike BSD) checks correct offsets on mapping /dev/zero
local pagesize -- store so we do not repeat this
if not S.getpagesize then
function S.getpagesize()
if pagesize then return pagesize end
local sz = 4096
local fd, err = S.open("/dev/zero", "rdwr")
if not fd then return nil, err end
while sz < 4096 * 1024 + 1024 do
local mm, err = S.mmap(nil, sz, "read", "shared", fd, sz)
if mm then
S.munmap(mm, sz)
pagesize = sz
return sz
end
sz = sz * 2
end
end
end
-- in Linux shm_open and shm_unlink are not syscalls
local shm = "/dev/shm"
function S.shm_open(pathname, flags, mode)
if pathname:sub(1, 1) ~= "/" then pathname = "/" .. pathname end
pathname = shm .. pathname
return S.open(pathname, c.O(flags, "nofollow", "cloexec", "nonblock"), mode)
end
function S.shm_unlink(pathname)
if pathname:sub(1, 1) ~= "/" then pathname = "/" .. pathname end
pathname = shm .. pathname
return S.unlink(pathname)
end
-- TODO setpgrp and similar - see the man page
-- in Linux pathconf can just return constants
-- TODO these could go into constants, although maybe better to get from here
local PAGE_SIZE = S.getpagesize
local NAME_MAX = 255
local PATH_MAX = 4096 -- TODO this is in constants, inconsistently
local PIPE_BUF = 4096
local FILESIZEBITS = 64
local SYMLINK_MAX = 255
local _POSIX_LINK_MAX = 8
local _POSIX_MAX_CANON = 255
local _POSIX_MAX_INPUT = 255
local pathconf_values = {
[c.PC.LINK_MAX] = _POSIX_LINK_MAX,
[c.PC.MAX_CANON] = _POSIX_MAX_CANON,
[c.PC.MAX_INPUT] = _POSIX_MAX_INPUT,
[c.PC.NAME_MAX] = NAME_MAX,
[c.PC.PATH_MAX] = PATH_MAX,
[c.PC.PIPE_BUF] = PIPE_BUF,
[c.PC.CHOWN_RESTRICTED] = 1,
[c.PC.NO_TRUNC] = 1,
[c.PC.VDISABLE] = 0,
[c.PC.SYNC_IO] = 1,
[c.PC.ASYNC_IO] = -1,
[c.PC.PRIO_IO] = -1,
[c.PC.SOCK_MAXBUF] = -1,
[c.PC.FILESIZEBITS] = FILESIZEBITS,
[c.PC.REC_INCR_XFER_SIZE] = PAGE_SIZE,
[c.PC.REC_MAX_XFER_SIZE] = PAGE_SIZE,
[c.PC.REC_MIN_XFER_SIZE] = PAGE_SIZE,
[c.PC.REC_XFER_ALIGN] = PAGE_SIZE,
[c.PC.ALLOC_SIZE_MIN] = PAGE_SIZE,
[c.PC.SYMLINK_MAX] = SYMLINK_MAX,
[c.PC["2_SYMLINKS"]] = 1,
}
function S.pathconf(_, name)
local pc = pathconf_values[c.PC[name]]
if type(pc) == "function" then pc = pc() end
return pc
end
S.fpathconf = S.pathconf
-- setegid and set euid are not syscalls
function S.seteuid(euid) return S.setresuid(-1, euid, -1) end
function S.setegid(egid) return S.setresgid(-1, egid, -1) end
-- in Linux sysctl is not a sycall any more (well it is but legacy)
-- note currently all returned as strings, may want to list which should be numbers
function S.sysctl(name, new)
name = "/proc/sys/" .. name:gsub("%.", "/")
local flag = c.O.RDONLY
if new then flag = c.O.RDWR end
local fd, err = S.open(name, flag)
if not fd then return nil, err end
local len = 1024
local old, err = S.read(fd, nil, len)
if not old then return nil, err end
old = old:sub(1, #old - 1) -- remove trailing newline
if not new then return old end
local ok, err = S.write(fd, new)
if not ok then return nil, err end
return old
end
-- BPF syscall has a complex semantics with one union serving for all purposes
-- The interface exports both raw syscall and helper functions based on libbpf
if C.bpf then
local function ptr_to_u64(p) return ffi.cast('uint64_t', ffi.cast('void *', p)) end
function S.bpf(cmd, attr)
return C.bpf(c.BPF_CMD[cmd], attr)
end
function S.bpf_prog_load(type, insns, len, license, version, log_level)
if not license then license = "GPL" end -- Must stay alive during the syscall
local bpf_log_buf = ffi.new('char [?]', 64*1024) -- Must stay alive during the syscall
if not version then
-- We have no better way to extract current kernel hex-string other
-- than parsing headers, compiling a helper function or reading /proc
local ver_str, count = S.sysctl('kernel.osrelease'):match('%d+.%d+.%d+'), 2
version = 0
for i in ver_str:gmatch('%d+') do -- Convert 'X.Y.Z' to 0xXXYYZZ
version = bit.bor(version, bit.lshift(tonumber(i), 8*count))
count = count - 1
end
end
local attr = t.bpf_attr1()
attr[0].prog_type = c.BPF_PROG[type]
attr[0].insns = ptr_to_u64(insns)
attr[0].insn_cnt = len
attr[0].license = ptr_to_u64(license)
attr[0].log_buf = ptr_to_u64(bpf_log_buf)
attr[0].log_size = ffi.sizeof(bpf_log_buf)
attr[0].log_level = log_level or 1
attr[0].kern_version = version -- MUST match current kernel version
local fd = S.bpf(c.BPF_CMD.PROG_LOAD, attr)
if fd < 0 then
return nil, t.error(errno()), ffi.string(bpf_log_buf)
end
return retfd(fd), ffi.string(bpf_log_buf)
end
function S.bpf_map_create(type, key_size, value_size, max_entries)
local attr = t.bpf_attr1()
attr[0].map_type = c.BPF_MAP[type]
attr[0].key_size = key_size
attr[0].value_size = value_size
attr[0].max_entries = max_entries
local fd = S.bpf(c.BPF_CMD.MAP_CREATE, attr)
if fd < 0 then
return nil, t.error(errno())
end
return retfd(fd)
end
function S.bpf_map_op(op, fd, key, val_or_next, flags)
local attr = t.bpf_attr1()
attr[0].map_fd = getfd(fd)
attr[0].key = ptr_to_u64(key)
attr[0].value = ptr_to_u64(val_or_next)
attr[0].flags = flags or 0
local ret = S.bpf(op, attr)
if ret ~= 0 then
return nil, t.error(errno())
end
return ret
end
end
-- Linux performance monitoring
if C.perf_event_open then
-- Open perf event fd
-- @note see man 2 perf_event_open
-- @return fd, err
function S.perf_event_open(attr, pid, cpu, group_fd, flags)
if attr[0].size == 0 then attr[0].size = ffi.sizeof(attr[0]) end
local fd = C.perf_event_open(attr, pid or 0, cpu or -1, group_fd or -1, c.PERF_FLAG[flags or 0])
if fd < 0 then
return nil, t.error(errno())
end
return retfd(fd)
end
-- Read the tracepoint configuration (see "/sys/kernel/debug/tracing/available_events")
-- @param event_path path to tracepoint (e.g. "/sys/kernel/debug/tracing/events/syscalls/sys_enter_write")
-- @return tp, err (e.g. 538, nil)
function S.perf_tracepoint(event_path)
local config = nil
event_path = event_path.."/id"
local fd, err = S.open(event_path, c.O.RDONLY)
if fd then
local ret, err = fd:read(nil, 256)
if ret then
config = tonumber(ret)
end
fd:close()
end
return config, err
end
-- Attach or detach a probe, same semantics as Lua tables.
-- See https://www.kernel.org/doc/Documentation/trace/kprobetrace.txt
-- (When the definition is not nil, it will be created, otherwise it will be detached)
-- @param probe_type either "kprobe" or "uprobe", no other probe types are supported
-- @param name chosen probe name (e.g. "myprobe")
-- @param definition (set to nil to disable probe) (e.g. "do_sys_open $retval")
-- @param retval true/false if this should be entrypoint probe or return probe
-- @return tp, err (e.g. 1099, nil)
function S.perf_probe(probe_type, name, definition, retval)
local event_path = string.format('/sys/kernel/debug/tracing/%s_events', probe_type)
local probe_path = string.format('/sys/kernel/debug/tracing/events/%ss/%s', probe_type, name)
-- Check if probe already exists
if definition and S.statfs(probe_path) then return nil, t.error(c.E.EEXIST) end
local fd, err = S.open(event_path, "wronly, append")
if not fd then return nil, err end
-- Format a probe definition
if not definition then
definition = "-:"..name -- Detach
else
definition = string.format("%s:%s %s", retval and "r" or "p", name, definition)
end
local ok, err = fd:write(definition)
fd:close()
-- Return tracepoint or success
if ok and definition then
return S.perf_tracepoint(probe_path)
end
return ok, err
end
-- Attach perf event reader to tracepoint (see "/sys/kernel/debug/tracing/available_events")
-- @param tp tracepoint identifier (e.g.: 538, use `S.perf_tracepoint()`)
-- @param type perf_attr.sample_type (default: "raw")
-- @param attrs table of attributes (e.g. {sample_type="raw, callchain"}, see `struct perf_event_attr`)
-- @return reader, err
function S.perf_attach_tracepoint(tp, pid, cpu, group_fd, attrs)
local pe = t.perf_event_attr1()
pe[0].type = "tracepoint"
pe[0].config = tp
pe[0].sample_type = "raw"
pe[0].sample_period = 1
pe[0].wakeup_events = 1
if attrs then
for k,v in pairs(attrs) do pe[0][k] = v end
end
-- Open perf event reader with given parameters
local fd, err = S.perf_event_open(pe, pid, cpu, group_fd, "fd_cloexec")
if not fd then return nil, err end
return t.perf_reader(fd)
end
end
return S
end