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open_nonblock(3) Arcan Lua API open_nonblock(3) NAME open_nonblock - Open a file in read or write mode for non-blocking I/O. SYNOPSIS blocktbl open_nonblock( vid:res ) open_nonblock( vid:res, bool:write ) open_nonblock( vid:res, bool:write, string:identifier=stream ) open_nonblock( vid:res, bool:write, string:identifier=stream, user- data:nbioud ) open_nonblock( vid:res, table:opts, string:identifier=stream ) open_nonblock( vid:res, table:opts, string:identifier=stream, user- data:nbioud ) open_nonblock( string:res ) open_nonblock( string:res, bool:write ) DESCRIPTION Create or open the resource indicated by res in (default) read-mode or (if mode is provided, write mode) If res is a vid connected to a frameserver, either a streaming fifo session will be set up over the connection along with the corresponding _BCHUNK events or an pre-existing nonblock-io stream, nbioud , will be redirected to said client and the backing descriptor closed locally. The identifier argument can then be used to specify some client an- nounced type identifier, or one of the reserved "stdin", "stdout", "stderr". If res is a string, the initial character determines if it creates a FIFO (<) or a SOCKET (=). Unless a namespace is explicitly set and the namespace is marked as valid for IPC , FIFO s and SOCKET s will be created in the RESOURCE_APPL_TEMP namespace. For sockets, the write argument determines if the connection should be outbound (=true) or listening (=false). If the identifier starts with a valid namespace identifier and separa- tor (alphanum:/) the identifier will first be matched to a user de- fined namespace (see list_namespaces ). If the res is connected to a frameserver, the namespace identifier is fixed and only defined for connections coming from net_open . The de- fault is to target the private store of the authenticated client. To let the server side controller script decide, prefix the identifier with appl:/ If successful, FIFO s and normal resources return a table wih a close operation (which is activated on garbage collection unless called in beforehand) and a read or write function depending on the mode that the resource was opened in. The socket table is special in that it allows multiple connections. the initial table for a socket only has a close and an accept function. The accept function takes no arguments and returns a table in both read and write mode when there is a client waiting. The opts table argument form is used to tune transfer parameters. NOTES 1 Do note that input processing has soft realtime constraints, and care should be taken to avoid processing large chunks of data in one go as it may affect application responsiveness. 2 FIFO s and sockets that were created will be unlinked when the close method is called or when the table reference is garbage collected. 3 When a nonblocking userdata is handed over to a frameserver, the write argument will be ignored and the corresponding BCHUNK event will match the userdata. This was a bug in a previous ver- sion where the write argument was respected and the argument had to be kept to avoid breaking compatibility. EXAMPLE function open_nonblock0() a = open_nonblock("test.txt") if (a == nil) then return shutdown("couldn't open test.txt"); end end function main_clock_pulse() local line = a:read(); if (line ~= nil) then print(line); end end EXAMPLE function open_nonblock1() a = open_nonblock("=test", false) b = open_nonblock("=test", true) -- our reader, note the scoping and the closure here local counter = 20 local dh dh = function() local res, alive = a:read() if res then print("read:", res) counter = counter - 1 if alive and counter > 0 then a:data_handler(dh) return end end a:close() -- will close on error or if counter reaches 0 end a:data_handler(dh) end function main_clock_pulse() if CLOCK % 100 == 0 then local _, alive = b:write("sent at " .. tostring(CLOCK)) if not alive then return shutdown() end end end SEE ALSO: resource March 2026 open_nonblock(3)
NAME | SYNOPSIS | DESCRIPTION | NOTES | EXAMPLE | EXAMPLE | SEE ALSO:
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