NAME
dfork.h - Contains an API for doing a daemonizing fork().
SYNOPSIS
#include <sys/types.h>
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.
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.
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.
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.
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.
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.
Author
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