Scroll to navigation

dfork.h(3) libdaemon dfork.h(3)

NAME

dfork.h - Contains an API for doing a daemonizing fork().

SYNOPSIS

#include <sys/types.h>

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.
Mon Dec 21 2020 Version 0.14