ref: 42bdc44ec9bbdd4054fb242a9f3c204652cadc73
dir: /mod/init.lua/
local p9 = {}
local raw = require "p9.raw"
p9.raw = raw
-- Defaults &c
p9.iosize = 8192
-- Utility / debugging
local function fwrite(fmt, ...)
io.write(string.format(fmt, ...))
end
-- typecheck(values... : any, types : string) -> string...
-- typecheck matches the types of values against a string
-- of space-separated type names.
-- If a value without a matching type is found an error
-- describing the type mismatch is thrown.
-- Otherwise the function returns a type of each value.
local function typecheck(...)
local values = table.pack(...)
local t = table.remove(values)
local accept = {}
for w in t:gmatch("%w+") do
accept[w] = true
end
local types = {}
for _, v in ipairs(values) do
local tv = type(v)
types[#types + 1] = tv
if not accept[tv] then
error(("expected type(s) [%s], got %s"):format(t, tv), 2)
end
end
return table.unpack(types)
end
-- Namespace
local mntmap <const> = {
["a"] = raw.MAFTER,
["b"] = raw.MBEFORE,
["c"] = raw.MCREATE,
["C"] = raw.MCACHE,
}
local function parsemntflags(s)
local f = raw.MREPL
for c in s:gmatch("%w") do
f = f | (mntmap[c] | 0)
end
return f
end
--- bind(string, string, [string]) -> int
function p9.bind(name, over, flags)
return raw.bind(name, over, parsemntflags(flags or ""))
end
--- mount(int | string, int, string, [string, [string]]) -> int
function p9.mount(fd, afd, over, flags, tree)
if type(fd) == string then
fd = p9.open(fd, "rw")
end
flags = parsemntflags(flags or "")
return raw.mount(fd, afd or -1, over, flags, tree or "")
end
--- unmount(string, [string]) -> int
function p9.unmount(name, over)
if over == nil then
return raw.unmount(nil, name)
end
return raw.unmount(name, over)
end
-- Processes
local rforkmap <const> = {
-- these are the same as in rc(1)
["n"] = raw.RFNAMEG,
["N"] = raw.RFCNAMEG,
["e"] = raw.RFENVG,
["E"] = raw.RFCENVG,
["s"] = raw.RFNOTEG,
["f"] = raw.RFFDG,
["F"] = raw.RFCFDG,
["m"] = raw.RFNOMNT,
-- these are new
["p"] = raw.RFPROC,
["&"] = raw.RFNOWAIT,
-- this is likely useless
["r"] = raw.RFREND,
-- this is gonna panic
["M"] = raw.RFMEM,
}
--- rfork(string) -> int
function p9.rfork(flags)
local f = 0
for c in flags:gmatch("%w") do
f = f | (rforkmap[c] or 0)
end
return raw.rfork(f)
end
-- File I/O
-- These are built on top of the raw API written in C and
-- where applicable they provide a more polished interface
-- with reasonable defaults.
local modemap <const> = {
["r"] = raw.OREAD,
["w"] = raw.OWRITE,
["x"] = raw.OEXEC,
["T"] = raw.OTRUNC,
["C"] = raw.OCEXEC,
["R"] = raw.ORCLOSE,
["E"] = raw.OEXCL,
}
local function parsemode(s)
local m, o, c
m = 0;
o = {r = false, w = false, x = false}
for c in s:gmatch("%w") do
if o[c] ~= nil then
o[c] = true
else
m = m | (modemap[c] or 0)
end
end
if o.r and o.w then
m = m | raw.ORDWR
elseif o.r then
m = m | raw.OREAD
elseif o.w then
m = m | raw.OWRITE
elseif o.x then
m = m | raw.OEXEC
end
return m
end
local permmap <const> = {
["d"] = raw.DMDIR,
["a"] = raw.DMAPPEND,
["e"] = raw.DMEXCL,
["t"] = raw.DMTMP,
}
local function parseperm(s)
local perm, m, p, c
m, p = s:match("([daet]*)([0-7]*)")
perm = tonumber(p, 8) or 0644
for c in m:gmatch("%w") do
perm = perm | (permmap[c] or 0)
end
return perm
end
--- open(string, string) -> int
function p9.open(file, ...)
local mode = ...
mode = parsemode(mode or "r")
return raw.open(file, mode)
end
--- create(string, [string, [string]]) -> int
function p9.create(file, mode, perm)
if not mode or #mode == 0 then mode = "rw" end
if not perm or #perm == 0 then perm = "644" end
mode = parsemode(mode)
perm = parseperm(perm)
if perm & raw.DMDIR then
mode = mode & ~(raw.OWRITE)
end
return raw.create(file, mode, perm)
end
--- read(int, [int, [int]]) -> string
function p9.read(fd, n, off)
return raw.read(fd, n or p9.iosize, off or -1)
end
--- slurp(int, [int]) -> string
function p9.slurp(fd, max)
max = max or math.huge
local tot, n = 0, 0
local buf = {}
while true do
n = math.min(max - tot, p9.iosize)
local r = p9.read(fd, n)
if #r == 0 then
break
end
buf[#buf + 1] = r
tot = tot + #r
if tot == max then
break
end
end
return table.concat(buf)
end
--- write(int, string, [int, [int]]) -> int
function p9.write(fd, buf, n, off)
return raw.write(fd, buf, n or #buf, off or -1)
end
local whencemap <const> = {
["set"] = 0,
["cur"] = 1,
["end"] = 2
}
--- seek(int, int, [string]) -> int
function p9.seek(fd, n, whence)
whence = whence or "set"
if whencemap[whence] == nil then
error("whence must be one of [cur, set, end]")
end
return raw.seek(fd, n, whencemap[whence])
end
--- close(int) -> int
function p9.close(fd)
return raw.close(fd)
end
--- remove(string) -> int
function p9.remove(file)
return raw.remove(file)
end
--- fd2path(int) -> string
function p9.fd2path(fd)
return raw.fd2path(fd)
end
--- pipe() -> int, int
function p9.pipe()
end
-- The File object
-- A file descriptor wrapper.
-- p9.file(fd) takes an open file descriptor and returns a
-- File object f which provides a convenient method interface
-- to the usual file operations.
-- p9.openfile and p9.createfile take a file name and open
-- or create a file. They accept the same arguments as
-- regular open and close.
-- The file descriptor stored in f.fd is garbage collected,
-- that is, it will be automatically closed once the File
-- object becomes unreachable. Note how this means that f.fd
-- should be used sparringly and with much care. In particular
-- you shouldn't store it outside of f, since the actual file
-- descriptor number might become invalid (closed) or refer
-- to a completely different file after f is collected.
-- The f.keep field can be set to true to prevent the finalizer
-- from closing the file.
local fileproto = {
fd = -1,
name = nil,
path = nil,
read = function(self, ...) return p9.read(self.fd, ...) end,
write = function(self, ...) return p9.write(self.fd, ...) end,
slurp = function(self, ...) return p9.slurp(self.fd, ...) end,
seek = function(self, ...) return p9.seek(self.fd, ...) end,
close = function(self)
if self.fd == -1 then
return
end
p9.close(self.fd)
self.fd = -1
end,
__close = function(f, _)
f:close()
end
}
--- file(int, [string]) -> file{}
function p9.file(fd, name)
local f = {}
for k, v in pairs(fileproto) do
f[k] = v
end
f.fd = fd
f.name = name
f.path = p9.fd2path(fd)
return setmetatable(f, f)
end
-- openfile(string, ...) -> file{}
function p9.openfile(file, ...)
return p9.file(p9.open(file, ...), file)
end
-- createfile(string, ...) -> file{}
function p9.createfile(file, ...)
return p9.file(p9.create(file, ...), file)
end
-- Environment variables
--
-- p9.env object provides a map between the /env device and Lua,
-- with its dynamic fields representing the environment variables.
-- Assigning a value to the field writes to the environment:
--
-- p9.env.var = "value"
--
-- while reading a value reads from the environment:
--
-- assert(p9.env.var == "value")
--
-- A value can be a string or a list.
-- A list is encoded (decoded) to (from) the environment as a
-- list of strings according to the encoding used by the rc(1)
-- shell (0-byte separated fields).
--
-- lua> p9.env.list = {"a", "b", "c"}
-- rc> echo $#list -- $list
-- 3 -- a b c
--
-- p9.getenv(name) and p9.setenv(name, val) provide the more
-- usual API.
--- getenv(string) -> string | list
function p9.getenv(key)
typecheck(key, "string")
local f, err = io.open("/env/" .. key)
if err then
return nil, err
end
local buf = f:read("a")
f:close()
-- a value
if #buf == 0 or buf:sub(-1) ~= "\0" then
return buf
end
-- a list (as encoded by rc(1) shell)
local t, p = {}, 1
while p <= #buf do
t[#t + 1], p = string.unpack("z", buf, p)
end
return t
end
--- setenv(string, string | list)
function p9.setenv(key, val)
local tk = typecheck(key, "string")
local tv = typecheck(val, "nil string table")
if val == nil then
pcall(p9.remove, "/env/" .. key)
return
end
local buf
if tv == "string" then
buf = val
elseif tv == "table" then
local t = {}
for i = 1, #val do
t[#t + 1] = string.pack("z", val[i])
end
buf = table.concat(t)
end
local f = assert(io.open("/env/" .. key, "w"))
if not f:write(buf) then
error("can't write environment")
end
f:close()
end
p9.env = setmetatable({}, {
__index = function(_, key)
return p9.getenv(key)
end,
__newindex = function(_, key, val)
p9.setenv(key, val)
end,
})
-- Lethal API
-- p9.lethal() returns a proxy table that is just like the
-- regular p9 module table, except that each function field
-- is wrapped such that any error raised during a call
-- results in program termination. An error is printed to
-- fd 2 and the same error is used for the program's exit status.
-- Note that this only mechanism only works for the fields
-- of the p9 module, like the p9.open and friends.
-- In particular, it doesn't apply to methods of File objects
-- nor to the p9.env object.
-- This limitation should be removed in the future.
local lethalproxy = setmetatable({}, {
__index = function(_, key)
if type(p9[key]) ~= "function" then
return p9[key]
end
return function(...)
local res = table.pack(pcall(p9[key], ...))
if not res[1] then
p9.write(2, string.format("%s: %s\n", arg[0] or "lua", res[2]))
os.exit(res[2])
end
table.remove(res, 1)
return table.unpack(res)
end
end
})
--- lethal() -> p9{}
function p9.lethal()
return lethalproxy
end
return p9