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-- Copyright (c) 2024 Florian Fischer. All rights reserved.
--
-- vis-lockfiles is free software: you can redistribute it and/or modify it under
-- the terms of the GNU General Public License as published by the Free Software
-- Foundation, either version 3 of the License, or (at your option) any later
-- version.
--
-- vis-lockfiles is distributed in the hope that it will be useful, but WITHOUT
-- ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
-- FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
--
-- You should have received a copy of the GNU General Public License along with
-- vis-lockfiles found in the LICENSE file.
-- If not, see <https://www.gnu.org/licenses/>.
local M = {}
M.directory = '${XDG_CACHE_HOME:-${HOME}/.local/share}/vis/locks'
-- Helper to execute a command and capture its output
local function capture_cmd(cmd)
local p = assert(io.popen(cmd, 'r'))
local s = assert(p:read('*a'))
local success, _, status = p:close()
if not success then
local err = cmd .. ' failed with exit code: ' .. status
vis:info('vis-lockfiles: ' .. err)
end
return s
end
local function lock_file_path(path)
local filename = path:gsub('/', '%%')
assert(os.execute('mkdir -p "' .. M.directory .. '"'))
local lfile_path = capture_cmd('echo "' .. M.directory .. '/' .. filename .. '.lock"')
return lfile_path:sub(1, #lfile_path - 1) -- trim newline from path
end
-- determine vis' pid
local vis_pid
do
local vis_proc_file = io.open('/proc/self/stat', 'r')
if vis_proc_file then
vis_pid = vis_proc_file:read('*n')
vis_proc_file:close()
else -- fallback if /proc/self/stat is not available
local out = capture_cmd('sh -c "echo $PPID"')
vis_pid = tonumber(out)
end
end
assert(vis_pid)
-- get a user confirmation
-- return true if user selected yes, false otherwise
local function confirm(path)
local choices = 'no\nyes'
local prompt = path .. ' exists. Edit anyway:'
local cmd = 'printf "' .. choices .. '" | vis-menu -b -p \'' .. prompt .. '\''
local choice = nil
-- local status, output = vis:pipe(nil, {start = 0, finish = 0}, cmd)
local menu = assert(io.popen(cmd))
local output = menu:read('*a')
local _, _, status = menu:close()
if status == 0 then
-- trim newline from selection
if output:sub(-1) == '\n' then
choice = output:sub(1, -2)
else
choice = output
end
end
vis:redraw()
return choice == 'yes'
end
local created_locks = {}
local function create_lock_file(lfile_path)
local already_locked = os.execute('test -e ' .. '"' .. lfile_path .. '"')
if already_locked then
return false
end
-- create the lock file with our pid
local cmd = 'echo ' .. vis_pid .. ' > "' .. lfile_path .. '"'
assert(os.execute(cmd))
-- detect a possible race
local lock_file = io.open(lfile_path)
assert(lock_file)
local lock_pid = lock_file:read('*n')
lock_file:close()
local locked = tonumber(lock_pid) == vis_pid
-- remember we created the lock file
if locked then
created_locks[lfile_path] = true
end
return locked
end
local function delete_lock_file(lfile_path)
os.execute('rm ' .. '"' .. lfile_path .. '"')
created_locks[lfile_path] = nil
end
vis.events.subscribe(vis.events.FILE_OPEN, function(file)
local lfile_path = lock_file_path(file.path)
if not create_lock_file(lfile_path) and not confirm(lfile_path) then
os.exit(1)
end
end)
vis.events.subscribe(vis.events.FILE_CLOSE, function(file)
local lfile_path = lock_file_path(file.path)
if created_locks[lfile_path] then
delete_lock_file(lfile_path)
end
end)
return M
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