4 * This file is part of LyX, the document processor.
5 * Licence details can be found in the file COPYING.
7 * \author Asger Alstrup
9 * Interface cleaned up by
10 * \author Angus Leeming
12 * Full author contact details are available in file CREDITS.
14 * An instance of Class Forkedcall represents a single child process.
16 * Class Forkedcall uses fork() and execvp() to lauch the child process.
18 * Once launched, control is returned immediately to the parent process
19 * but a Signal can be emitted upon completion of the child.
21 * The child process is not killed when the Forkedcall instance goes out of
22 * scope, but it can be killed by an explicit invocation of the kill() member
31 #include <boost/shared_ptr.hpp>
32 #include <boost/signals/signal2.hpp>
33 #include <boost/function/function0.hpp>
35 #include <sys/types.h>
53 virtual ~ForkedProcess() {}
55 virtual ForkedProcess * clone() const = 0;
57 /** A SignalType signal is can be emitted once the forked process
58 * has finished. It passes:
59 * the PID of the child and;
60 * the return value from the child.
62 * We use a signal rather than simply a callback function so that
63 * we can return easily to C++ methods, rather than just globally
64 * accessible functions.
66 typedef boost::signal2<void, pid_t, int> SignalType;
68 /** The signal is connected in the calling routine to the desired
69 * slot. We pass a shared_ptr rather than a reference to the signal
70 * because it is eminently possible for the instance of the calling
71 * class (and hence the signal) to be destructed before the forked
74 * It doesn't matter if the slot disappears, SigC takes care of that.
76 typedef boost::shared_ptr<SignalType> SignalTypePtr;
78 /** Invoking the following methods makes sense only if the command
79 * is running asynchronously!
82 /** gets the PID of the child process.
85 pid_t pid() const { return pid_; }
92 /** Set the return value of the child process.
95 void setRetValue(int r) { retval_ = r; }
97 /// Returns the identifying command (for display in the GUI perhaps).
98 string const & command() const { return command_; }
100 /// is the process running ?
101 bool running() const;
103 /** Kill child prematurely.
104 * First, a SIGHUP is sent to the child.
105 * If that does not end the child process within "tolerance"
106 * seconds, the SIGKILL signal is sent to the child.
107 * When the child is dead, the callback is called.
109 void kill(int tolerance = 5);
112 /** Wait for child process to finish.
113 * Returns returncode from child.
116 /** Do not wait for child process to finish.
117 * Returns returncode from child.
119 int runNonBlocking();
121 /// Callback function
122 SignalTypePtr signal_;
124 /// identifying command (for display in the GUI perhaps).
127 /// Process ID of child
130 /// Return value from child
133 /// generate child in background
134 virtual int generateChild() = 0;
136 /// Wait for child process to finish. Updates returncode from child.
141 class Forkedcall : public ForkedProcess {
144 virtual ForkedProcess * clone() const {
145 return new Forkedcall(*this);
148 /** Start the child process.
150 * The command "what" is passed to execvp() for execution.
152 * There are two startscript commands available. They differ in that
153 * the second receives a signal that is executed on completion of
154 * the command. This makes sense only for a command executed
155 * in the background, ie DontWait.
157 * The other startscript command can be executed either blocking
158 * or non-blocking, but no signal will be emitted on finishing.
160 int startscript(Starttype, string const & what);
163 int startscript(string const & what, SignalTypePtr);
167 virtual int generateChild();
170 } // namespace support
173 #endif // FORKEDCALL_H