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#
# = open3.rb: Popen, but with stderr, too
#
# Author:: Yukihiro Matsumoto
# Documentation:: Konrad Meyer
#
# Open3 gives you access to stdin, stdout, and stderr when running other
# programs.
#
#
# Open3 grants you access to stdin, stdout, stderr and a thread to wait the
# child process when running another program.
#
# Example:
#
# require "open3"
# include Open3
#
# stdin, stdout, stderr, wait_thr = popen3('nroff -man')
#
# Open3.popen3 can also take a block which will receive stdin, stdout,
# stderr and wait_thr as parameters.
# This ensures stdin, stdout and stderr are closed and
# the process is terminated once the block exits.
#
# Example:
#
# require "open3"
#
# Open3.popen3('nroff -man') { |stdin, stdout, stderr, wait_thr| ... }
#
module Open3
# Open stdin, stdout, and stderr streams and start external executable.
# In addition, a thread for waiting the started process is noticed.
# The thread has a pid method and thread variable :pid which is the pid of
# the started process.
#
# Block form:
#
# Open3.popen3(cmd... [, opts]) {|stdin, stdout, stderr, wait_thr|
# pid = wait_thr.pid # pid of the started process.
# ...
# exit_status = wait_thr.value # Process::Status object returned.
# }
#
# Non-block form:
#
# stdin, stdout, stderr, wait_thr = Open3.popen3(cmd... [, opts])
# pid = wait_thr[:pid] # pid of the started process.
# ...
# stdin.close # stdin, stdout and stderr should be closed in this form.
# stdout.close
# stderr.close
# exit_status = wait_thr.value # Process::Status object returned.
#
# The parameters +cmd...+ is passed to Kernel#spawn.
# So a commandline string and list of argument strings can be accepted as follows.
#
# Open3.popen3("echo a") {|i, o, e, t| ... }
# Open3.popen3("echo", "a") {|i, o, e, t| ... }
#
# If the last parameter, opts, is a Hash, it is recognized as an option for Kernel#spawn.
#
# Open3.popen3("pwd", :chdir=>"/") {|i,o,e,t|
# p o.read.chomp #=> "/"
# }
#
# opts[STDIN], opts[STDOUT] and opts[STDERR] in the option are set for redirection.
#
# If some of the three elements in opts are specified,
# pipes for them are not created.
# In that case, block arugments for the block form and
# return values for the non-block form are decreased.
#
# # No pipe "e" for stderr
# Open3.popen3("echo a", STDERR=>nil) {|i,o,t| ... }
# i,o,t = Open3.popen3("echo a", STDERR=>nil)
#
# If the value is nil as above, the elements of opts are removed.
# So standard input/output/error of current process are inherited.
#
# If the value is not nil, it is passed as is to Kernel#spawn.
# So pipeline of commands can be constracted as follows.
#
# Open3.popen3("yes", STDIN=>nil, STDERR=>nil) {|o1,t1|
# Open3.popen3("head -10", STDIN=>o1, STDERR=>nil) {|o2,t2|
# o1.close
# p o2.read #=> "y\ny\ny\ny\ny\ny\ny\ny\ny\ny\n"
# p t1.value #=> #<Process::Status: pid 13508 SIGPIPE (signal 13)>
# p t2.value #=> #<Process::Status: pid 13510 exit 0>
# }
# }
#
# wait_thr.value waits the termination of the process.
# The block form also waits the process when it returns.
#
# Closing stdin, stdout and stderr does not wait the process.
#
def popen3(*cmd)
if Hash === cmd.last
opts = cmd.pop.dup
else
opts = {}
end
child_io = []
parent_io = []
if !opts.include?(STDIN)
pw = IO.pipe # pipe[0] for read, pipe[1] for write
opts[STDIN] = pw[0]
pw[1].sync = true
child_io << pw[0]
parent_io << pw[1]
elsif opts[STDIN] == nil
opts.delete(STDIN)
end
if !opts.include?(STDOUT)
pr = IO.pipe
opts[STDOUT] = pr[1]
child_io << pr[1]
parent_io << pr[0]
elsif opts[STDOUT] == nil
opts.delete(STDOUT)
end
if !opts.include?(STDERR)
pe = IO.pipe
opts[STDERR] = pe[1]
child_io << pe[1]
parent_io << pe[0]
elsif opts[STDERR] == nil
opts.delete(STDERR)
end
pid = spawn(*cmd, opts)
wait_thr = Process.detach(pid)
child_io.each {|io| io.close }
result = [*parent_io, wait_thr]
if defined? yield
begin
return yield(*result)
ensure
parent_io.each{|io| io.close unless io.closed?}
wait_thr.join
end
end
result
end
module_function :popen3
end
if $0 == __FILE__
a = Open3.popen3("nroff -man")
Thread.start do
while line = gets
a[0].print line
end
a[0].close
end
while line = a[1].gets
print ":", line
end
end
|
