--- name: "dfork.h" section: "3" platform: "linux" package: "libdaemon-doc" version: "0.14-7.1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/dfork.h" --- # dfork.h(3) Contains an API for doing a daemonizing fork(). ## NAME dfork.h - Contains an API for doing a daemonizing fork(). ## SYNOPSIS `#include `\ ### Macros \#define **DAEMON\_CLOSE\_ALL\_AVAILABLE** 1\ This variable is defined to 1 iff **daemon\_close\_all()** and **daemon\_close\_allv()** are supported. #define **DAEMON\_UNBLOCK\_SIGS\_AVAILABLE** 1\ This variable is defined to 1 iff **daemon\_unblock\_sigs()** and **daemon\_unblock\_sigsv()** are supported. #define **DAEMON\_RESET\_SIGS\_AVAILABLE** 1\ This variable is defined to 1 iff **daemon\_reset\_sigs()** and **daemon\_reset\_sigsv()** are supported. ### Functions pid\_t **daemon\_fork** (void)\ Does a daemonizing fork(). int **daemon\_retval\_init** (void)\ Allocate and initialize resources required by the daemon\_retval\_xxx() functions. void **daemon\_retval\_done** (void)\ Frees the resources allocated by **daemon\_retval\_init()**. int **daemon\_retval\_wait** (int timeout)\ Return the value sent by the child via the **daemon\_retval\_send()** function, but wait only the specified number of seconds before timing out and returning a negative number. int **daemon\_retval\_send** (int s)\ Send the specified integer to the parent process. int **daemon\_close\_all** (int except\_fd,...)\ Close all file descriptors except those passed. int **daemon\_close\_allv** (const int except\_fds\[\])\ Same as daemon\_close\_all but takes an array of fds, terminated by -1. int **daemon\_unblock\_sigs** (int except,...)\ Unblock all signals except those passed. int **daemon\_unblock\_sigsv** (const int except\[\])\ Same as **daemon\_unblock\_sigs()** but takes an array of signals, terminated by -1. int **daemon\_reset\_sigs** (int except,...)\ Reset all signal handlers except those passed. int **daemon\_reset\_sigsv** (const int except\[\])\ Same as **daemon\_reset\_sigs()** but takes an array of signals, terminated by -1. ## Detailed Description Contains an API for doing a daemonizing fork(). You may daemonize by calling **daemon\_fork()**, a function similar to the plain fork(). If you want to return a return value of the initialization procedure of the child from the parent, you may use the daemon\_retval\_xxx() functions. Definition in file **dfork.h**. ## Macro Definition Documentation ### #define DAEMON\_CLOSE\_ALL\_AVAILABLE 1 This variable is defined to 1 iff **daemon\_close\_all()** and **daemon\_close\_allv()** are supported. **Since** 0\.11 **See also** **daemon\_close\_all()**, **daemon\_close\_allv()** Definition at line 106 of file dfork.h. ### #define DAEMON\_RESET\_SIGS\_AVAILABLE 1 This variable is defined to 1 iff **daemon\_reset\_sigs()** and **daemon\_reset\_sigsv()** are supported. **Since** 0\.13 **See also** **daemon\_reset\_sigs()**, **daemon\_reset\_sigsv()** Definition at line 142 of file dfork.h. ### #define DAEMON\_UNBLOCK\_SIGS\_AVAILABLE 1 This variable is defined to 1 iff **daemon\_unblock\_sigs()** and **daemon\_unblock\_sigsv()** are supported. **Since** 0\.13 **See also** **daemon\_unblock\_sigs()**, **daemon\_unblock\_sigsv()** Definition at line 124 of file dfork.h. ## Function Documentation ### int daemon\_close\_all (int except\_fd, ...) Close all file descriptors except those passed. List needs to be terminated by -1. FDs 0, 1, 2 will be kept open anyway. **Since** 0\.11 **See also** **DAEMON\_CLOSE\_ALL\_AVAILABLE** **Examples** **testd.c**. ### int daemon\_close\_allv (const int except\_fds\[\]) Same as daemon\_close\_all but takes an array of fds, terminated by -1. **Since** 0\.11 **See also** **DAEMON\_CLOSE\_ALL\_AVAILABLE** ### pid\_t daemon\_fork (void) Does a daemonizing fork(). For the new daemon process STDIN, STDOUT, STDERR are connected to /dev/null, the process is a session leader, the current directory is changed to /, the umask is set to 777. **Returns** On success, the PID of the child process is returned in the parent's thread of execution, and a 0 is returned in the child's thread of execution. On failure, -1 will be returned in the parent's context, no child process will be created, and errno will be set appropriately. **Examples** **testd.c**. ### int daemon\_reset\_sigs (int except, ...) Reset all signal handlers except those passed. List needs to be terminated by -1. **Since** 0\.13 **See also** **DAEMON\_RESET\_SIGS\_AVAILABLE** **Examples** **testd.c**. ### int daemon\_reset\_sigsv (const int except\[\]) Same as **daemon\_reset\_sigs()** but takes an array of signals, terminated by -1. **Since** 0\.13 **See also** **DAEMON\_RESET\_SIGS\_AVAILABLE** ### void daemon\_retval\_done (void) Frees the resources allocated by **daemon\_retval\_init()**. This should be called if neither **daemon\_retval\_wait()** nor **daemon\_retval\_send()** is called in the current process. The resources allocated by **daemon\_retval\_init()** should be freed in both parent and daemon process. This may be achieved by using **daemon\_retval\_wait()** resp. **daemon\_retval\_send()**, or by using **daemon\_retval\_done()**. **Examples** **testd.c**. ### int daemon\_retval\_init (void) Allocate and initialize resources required by the daemon\_retval\_xxx() functions. These functions allow the child to send a value to the parent after completing its initialisation. Call this in the parent before forking. **Returns** zero on success, nonzero on failure. **Examples** **testd.c**. ### int daemon\_retval\_send (int s) Send the specified integer to the parent process. Do not send -1 because this signifies a library error. Should be called just once from the daemon process only. A subsequent call to **daemon\_retval\_done()** in the daemon is ignored. **Parameters** *s* The integer to pass to **daemon\_retval\_wait()** in the parent process **Returns** Zero on success, nonzero on failure. **Examples** **testd.c**. ### int daemon\_retval\_wait (int timeout) Return the value sent by the child via the **daemon\_retval\_send()** function, but wait only the specified number of seconds before timing out and returning a negative number. Should be called just once from the parent process only. A subsequent call to **daemon\_retval\_done()** in the parent is ignored. **Parameters** *timeout* Thetimeout in seconds **Returns** The integer passed **daemon\_retval\_send()** in the daemon process, or -1 on failure. **Examples** **testd.c**. ### int daemon\_unblock\_sigs (int except, ...) Unblock all signals except those passed. List needs to be terminated by -1. **Since** 0\.13 **See also** **DAEMON\_UNBLOCK\_SIGS\_AVAILABLE** **Examples** **testd.c**. ### int daemon\_unblock\_sigsv (const int except\[\]) Same as **daemon\_unblock\_sigs()** but takes an array of signals, terminated by -1. **Since** 0\.13 **See also** **DAEMON\_UNBLOCK\_SIGS\_AVAILABLE** ## Author Generated automatically by Doxygen for libdaemon from the source code.