#
# = 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, and stderr when running another
# program. Example:
#
# require "open3"
# include Open3
#
# stdin, stdout, stderr = popen3('nroff -man')
#
# Open3.popen3 can also take a block which will receive stdin, stdout and
# stderr as parameters. This ensures stdin, stdout and stderr are closed
# once the block exits. Example:
#
# require "open3"
#
# Open3.popen3('nroff -man') { |stdin, stdout, stderr| ... }
#
module Open3
#
# Open stdin, stdout, and stderr streams and start external executable.
# Non-block form:
#
# require 'open3'
#
# stdin, stdout, stderr = Open3.popen3(cmd)
#
# Block form:
#
# require 'open3'
#
# Open3.popen3(cmd) { |stdin, stdout, stderr| ... }
#
# The parameter +cmd+ is passed directly to Kernel#exec.
#
# _popen3_ is like _system_ in that you can pass extra parameters, and the
# strings won't be mangled by shell expansion.
#
# stdin, stdout, stderr = Open3.popen3('identify', '/weird path/with spaces/and "strange" characters.jpg')
# result = stdout.read
#
def popen3(*cmd)
pw = IO::pipe # pipe[0] for read, pipe[1] for write
pr = IO::pipe
pe = IO::pipe
pid = fork{
# child
fork{
# grandchild
pw[1].close
STDIN.reopen(pw[0])
pw[0].close
pr[0].close
STDOUT.reopen(pr[1])
pr[1].close
pe[0].close
STDERR.reopen(pe[1])
pe[1].close
exec(*cmd)
}
exit!(0)
}
pw[0].close
pr[1].close
pe[1].close
Process.waitpid(pid)
pi = [pw[1], pr[0], pe[0]]
pw[1].sync = true
if defined? yield
begin
return yield(*pi)
ensure
pi.each{|p| p.close unless p.closed?}
end
end
pi
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
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