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https://github.com/koreader/koreader
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ff3ca5d98d
I was reminded by @KenMaltby that this is disabled on Android. https://www.mobileread.com/forums/showthread.php?p=3586162#post3586162
97 lines
3.4 KiB
Lua
97 lines
3.4 KiB
Lua
local ffi = require("ffi")
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local C = ffi.C
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-- Utilities functions needed by this plugin, but that may be added to
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-- existing base/ffi/ files
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local xutil = {}
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-- Sub-process management (may be put into base/ffi/util.lua)
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function xutil.runInSubProcess(func)
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local pid = C.fork()
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if pid == 0 then -- child process
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-- Just run the provided lua code object in this new process,
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-- and exit immediatly (so we do not release drivers and
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-- resources still used by parent process)
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func()
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os.exit(0)
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end
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-- parent/main process, return pid of child
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if pid == -1 then -- On failure, -1 is returned in the parent
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return false
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end
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return pid
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end
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function xutil.isSubProcessDone(pid)
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local status = ffi.new('int[1]')
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local ret = C.waitpid(pid, status, 1) -- 1 = WNOHANG : don't wait, just tell
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-- status = tonumber(status[0])
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-- local logger = require("logger")
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-- logger.dbg("waitpid for", pid, ":", ret, "/", status)
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-- still running: ret = 0 , status = 0
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-- exited: ret = pid , status = 0 or 9 if killed
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-- no more running: ret = -1 , status = 0
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if ret == pid or ret == -1 then
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return true
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end
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end
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function xutil.terminateSubProcess(pid)
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local done = xutil.isSubProcessDone(pid)
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if not done then
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-- local logger = require("logger")
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-- logger.dbg("killing subprocess", pid)
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-- we kill with signal 9/SIGKILL, which may be violent, but ensures
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-- that it is terminated (a process may catch or ignore SIGTERM)
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C.kill(pid, 9)
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-- process will still have to be collected with calls to util.isSubProcessDone(),
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-- which may still return false for some small amount of time after our kill()
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end
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end
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-- Data compression/decompression of strings thru zlib (may be put in a new base/ffi/zlib.lua)
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-- from http://luajit.org/ext_ffi_tutorial.html
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ffi.cdef[[
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unsigned long compressBound(unsigned long sourceLen);
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int compress2(uint8_t *dest, unsigned long *destLen,
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const uint8_t *source, unsigned long sourceLen, int level);
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int uncompress(uint8_t *dest, unsigned long *destLen,
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const uint8_t *source, unsigned long sourceLen);
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]]
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local zlib = ffi.load(ffi.os == "Windows" and "zlib1" or "z")
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function xutil.zlib_compress(data)
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local n = zlib.compressBound(#data)
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local buf = ffi.new("uint8_t[?]", n)
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local buflen = ffi.new("unsigned long[1]", n)
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local res = zlib.compress2(buf, buflen, data, #data, 9)
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assert(res == 0)
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return ffi.string(buf, buflen[0])
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end
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function xutil.zlib_uncompress(zdata, datalen)
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local buf = ffi.new("uint8_t[?]", datalen)
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local buflen = ffi.new("unsigned long[1]", datalen)
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local res = zlib.uncompress(buf, buflen, zdata, #zdata)
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assert(res == 0)
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return ffi.string(buf, buflen[0])
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end
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-- Not provided by base/thirdparty/lua-ljsqlite3/init.lua
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-- Add a timeout to a lua-ljsqlite3 connection
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-- We need that if we have multiple processes accessing the same
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-- SQLite db for reading or writting (read lock and write lock can't be
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-- obtained at the same time, so waiting & retry is needed)
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-- SQLite will retry getting a lock every 1ms to 100ms for
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-- the timeout_ms given here
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local sql = ffi.load("sqlite3")
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function xutil.sqlite_set_timeout(conn, timeout_ms)
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sql.sqlite3_busy_timeout(conn._ptr, timeout_ms)
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end
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-- For reference, SQ3 doc at: http://scilua.org/ljsqlite3.html
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return xutil
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