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-- cqueue filesystem with luaposix
-- TODO: closing files
-- TODO: error handling. right now it *always* returns errno instead of
-- throwing it, which may be what we want. code depends on this
local unistd = require("posix.unistd")
local cqueues = require("cqueues")
local file = {}
function file.new(fd, mode)
if not mode then mode = "r" end
local f = setmetatable({}, { __index = file })
f.pollfd = fd
f.mode = mode
if string.match(mode, "r") then
f.rbuf = {}
end
if string.match(mode, "w") then
f.wbuf = {}
end
return f
end
function file.events(f)
return f.mode
end
-- input/output buffers
--
-- buffers are arrays of objects containing "data" (a string) and "index" (their position)
-- indexing allows us to avoid recreating string objects
local function buffer_length(buf)
local total = 0
for _, entry in ipairs(buf) do
total = total + #entry.data - entry.index + 1
end
return total
end
-- returns nil on empty length
local function buffer_get(buf, length)
local out = {}
if not length then length = buffer_length(buf) end
while length > 0 do
assert(#buf > 0)
local x = string.sub(buf[1].data, buf[1].index, buf[1].index + length - 1)
table.insert(out, x)
if #buf[1].data - buf[1].index + 1 <= length then
table.remove(buf, 1)
else
buf[1].index = buf[1].index + length
end
length = length - #x
end
if out[1] then return table.concat(out) else return nil end
end
local function buffer_char_index(buf, char)
local num = 1
for _, entry in ipairs(buf) do
if string.find(entry.data, char, entry.index, true) then
return num + string.find(entry.data, char, entry.index, true) - entry.index
else
num = num + #entry.data - entry.index + 1
end
end
return nil
end
do
local test_buf = { { data = "abcde", index = 2 }, { data = "\na", index = 1 } }
assert(buffer_length(test_buf) == 6)
assert(buffer_char_index(test_buf, "\n") == 5)
assert(buffer_get(test_buf, 5) == "bcde\n")
assert(buffer_length(test_buf) == 1)
end
local function try_read(buffer, fd, max)
cqueues.poll({ pollfd = fd, events = function () return "r" end })
local data, _, errno = unistd.read(fd, max)
if not data then return nil, errno end
if #data == 0 then return nil end
table.insert(buffer, { data = data, index = 1 })
return #data
end
function file.read(f, what)
assert(f.rbuf)
if (type(what) == "number" and what > 0) then
while buffer_length(f.rbuf) < what do
if not try_read(f.rbuf, f.pollfd, what - buffer_length(f.rbuf)) then
break
end
end
return buffer_get(f.rbuf, math.min(what, buffer_length(f.rbuf)))
elseif (type(what) == "number" and what < 0) then
while buffer_length(f.rbuf) == 0 do
if not try_read(f.rbuf, f.pollfd, 0 - what) then return nil end
end
return buffer_get(f.rbuf, math.min(0 - what, buffer_length(f.rbuf)))
elseif what == "*l" or what == "*L" then
while not buffer_char_index(f.rbuf, "\n") do
-- TODO: constantize this
local x = try_read(f.rbuf, f.pollfd, 1024)
if not x then
break
end
end
local line = buffer_get(f.rbuf, buffer_char_index(f.rbuf, "\n"))
if not line then
return nil
end
local ret = string.gsub(
line,
"\n",
(what == "*l" and "" or "\n")
)
return ret
else
-- TODO
end
end
function file.lines(f, what)
return function () return file.read(f, what or "*l") end
end
function file.write(f, data)
local index = 1
while index <= #data do
cqueues.poll({ pollfd = f.pollfd, events = function () return "w" end })
local nb, _, errno = unistd.write(f.pollfd, string.sub(data, index))
if nb then
index = index + nb
else
return nil, errno -- TODO?
end
end
return f
end
function file.close(f)
cqueues.cancel(f.pollfd)
end
return file
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