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4eb8d2e6bb47164f2696228e629b3e9d2126c223
[etc/awesome.git] / asyncshell.lua
1
2 --[[
3                                                   
4      Licensed under GNU General Public License v2 
5       * (c) 2013, Alexander Yakushev              
6                                                   
7 --]]
8
9 -- Asynchronous io.popen for Awesome WM.
10 -- How to use...
11 -- ...asynchronously:
12 -- asyncshell.request('wscript -Kiev', function(f) wwidget.text = f:read("*l") end)
13 -- ...synchronously
14 -- wwidget.text = asyncshell.demand('wscript -Kiev', 5):read("*l") or "Error"
15
16 local spawn = require('awful.util').spawn
17
18 asyncshell               = {}
19 asyncshell.request_table = {}
20 asyncshell.id_counter    = 0
21 asyncshell.folder        = "/tmp/asyncshell"
22 asyncshell.file_template = asyncshell.folder .. '/req'
23
24 -- Create a directory for asynchell response files
25 os.execute("mkdir -p " .. asyncshell.folder)
26
27 -- Returns next tag - unique identifier of the request
28 local function next_id()
29    asyncshell.id_counter = (asyncshell.id_counter + 1) % 100000
30    return asyncshell.id_counter
31 end
32
33 -- Sends an asynchronous request for an output of the shell command.
34 -- @param command Command to be executed and taken output from
35 -- @param callback Function to be called when the command finishes
36 -- @return Request ID
37 function asyncshell.request(command, callback)
38    local id = next_id()
39    local tmpfname = asyncshell.file_template .. id
40    asyncshell.request_table[id] = {callback = callback}
41    local req =
42       string.format("sh -c '%s > %s; " ..
43                     'echo "asyncshell.deliver(%s)" | ' ..
44                     "awesome-client' 2> /dev/null",
45                     string.gsub(command, "'", "'\\''"), tmpfname,
46                     id, tmpfname)
47    spawn(req, false)
48    return id
49 end
50
51 -- Calls the remembered callback function on the output of the shell
52 -- command.
53 -- @param id Request ID
54 -- @param output The output file of the shell command to be delievered
55 function asyncshell.deliver(id)
56    if asyncshell.request_table[id] and
57       asyncshell.request_table[id].callback then
58       local output = io.open(asyncshell.file_template .. id, 'r')
59       asyncshell.request_table[id].callback(output)
60    end
61 end
62
63 -- Sends a synchronous request for an output of the command. Waits for
64 -- the output, but if the given timeout expires returns nil.
65 -- @param command Command to be executed and taken output from
66 -- @param timeout Maximum amount of time to wait for the result
67 -- @return File handler on success, nil otherwise
68 function asyncshell.demand(command, timeout)
69    local id = next_id()
70    local tmpfname = asyncshell.file_template .. id
71    local f = io.popen(string.format("(%s > %s; echo asyncshell_done) & " ..
72                                     "(sleep %s; echo asynchell_timeout)",
73                                     command, tmpfname, timeout))
74    local result = f:read("*line")
75    if result == "asyncshell_done" then
76       return io.open(tmpfname)
77    end
78 end
79
80 return asyncshell