Adding upstream version 4.22.0.upstream/4.22.0

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 349 insertions, 0 deletions

diff --git a/upstream/mageia-cauldron/man3/sd_event_add_child.3 b/upstream/mageia-cauldron/man3/sd_event_add_child.3
new file mode 100644
index 00000000..736efa60
--- /dev/null
+++ b/upstream/mageia-cauldron/man3/sd_event_add_child.3
@@ -0,0 +1,349 @@
+'\" t
+.TH "SD_EVENT_ADD_CHILD" "3" "" "systemd 255" "sd_event_add_child"
+.\" -----------------------------------------------------------------
+.\" * Define some portability stuff
+.\" -----------------------------------------------------------------
+.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.\" http://bugs.debian.org/507673
+.\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html
+.\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+.ie \n(.g .ds Aq \(aq
+.el       .ds Aq '
+.\" -----------------------------------------------------------------
+.\" * set default formatting
+.\" -----------------------------------------------------------------
+.\" disable hyphenation
+.nh
+.\" disable justification (adjust text to left margin only)
+.ad l
+.\" -----------------------------------------------------------------
+.\" * MAIN CONTENT STARTS HERE *
+.\" -----------------------------------------------------------------
+.SH "NAME"
+sd_event_add_child, sd_event_add_child_pidfd, sd_event_source_get_child_pid, sd_event_source_get_child_pidfd, sd_event_source_get_child_pidfd_own, sd_event_source_set_child_pidfd_own, sd_event_source_get_child_process_own, sd_event_source_set_child_process_own, sd_event_source_send_child_signal, sd_event_child_handler_t \- Add a child process state change event source to an event loop
+.SH "SYNOPSIS"
+.sp
+.ft B
+.nf
+#include <systemd/sd\-event\&.h>
+.fi
+.ft
+.sp
+.ft B
+.nf
+typedef struct sd_event_source sd_event_source;
+.fi
+.ft
+.HP \w'typedef\ int\ (*sd_event_child_handler_t)('u
+.BI "typedef int (*sd_event_child_handler_t)(sd_event_source\ *" "s" ", const\ siginfo_t\ *" "si" ", void\ *" "userdata" ");"
+.HP \w'int\ sd_event_add_child('u
+.BI "int sd_event_add_child(sd_event\ *" "event" ", sd_event_source\ **" "source" ", pid_t\ " "pid" ", int\ " "options" ", sd_event_child_handler_t\ " "handler" ", void\ *" "userdata" ");"
+.HP \w'int\ sd_event_add_child_pidfd('u
+.BI "int sd_event_add_child_pidfd(sd_event\ *" "event" ", sd_event_source\ **" "source" ", int\ " "pidfd" ", int\ " "options" ", sd_event_child_handler_t\ " "handler" ", void\ *" "userdata" ");"
+.HP \w'int\ sd_event_source_get_child_pid('u
+.BI "int sd_event_source_get_child_pid(sd_event_source\ *" "source" ", pid_t\ *" "pid" ");"
+.HP \w'int\ sd_event_source_get_child_pidfd('u
+.BI "int sd_event_source_get_child_pidfd(sd_event_source\ *" "source" ");"
+.HP \w'int\ sd_event_source_get_child_pidfd_own('u
+.BI "int sd_event_source_get_child_pidfd_own(sd_event_source\ *" "source" ");"
+.HP \w'int\ sd_event_source_set_child_pidfd_own('u
+.BI "int sd_event_source_set_child_pidfd_own(sd_event_source\ *" "source" ", int\ " "own" ");"
+.HP \w'int\ sd_event_source_get_child_process_own('u
+.BI "int sd_event_source_get_child_process_own(sd_event_source\ *" "source" ");"
+.HP \w'int\ sd_event_source_set_child_process_own('u
+.BI "int sd_event_source_set_child_process_own(sd_event_source\ *" "source" ", int\ " "own" ");"
+.HP \w'int\ sd_event_source_send_child_signal('u
+.BI "int sd_event_source_send_child_signal(sd_event_source\ *" "source" ", int\ " "sig" ", const\ siginfo_t\ *" "info" ", unsigned\ " "flags" ");"
+.SH "DESCRIPTION"
+.PP
+\fBsd_event_add_child()\fR
+adds a new child process state change event source to an event loop\&. The event loop object is specified in the
+\fIevent\fR
+parameter, the event source object is returned in the
+\fIsource\fR
+parameter\&. The
+\fIpid\fR
+parameter specifies the PID of the process to watch, which must be a direct child process of the invoking process\&. The
+\fIoptions\fR
+parameter determines which state changes will be watched for\&. It must contain an OR\-ed mask of
+\fBWEXITED\fR
+(watch for the child process terminating),
+\fBWSTOPPED\fR
+(watch for the child process being stopped by a signal), and
+\fBWCONTINUED\fR
+(watch for the child process being resumed by a signal)\&. See
+\fBwaitid\fR(2)
+for further information\&.
+.PP
+The
+\fIhandler\fR
+must be a function to call when the process changes state or
+\fBNULL\fR\&. The handler function will be passed the
+\fIuserdata\fR
+pointer, which may be chosen freely by the caller\&. The handler also receives a pointer to a
+siginfo_t
+structure containing information about the child process event\&. The handler may return negative to signal an error (see below), other return values are ignored\&. If
+\fIhandler\fR
+is
+\fBNULL\fR, a default handler that calls
+\fBsd_event_exit\fR(3)
+will be used\&.
+.PP
+Only a single handler may be installed for a specific child process\&. The handler is enabled for a single event (\fBSD_EVENT_ONESHOT\fR), but this may be changed with
+\fBsd_event_source_set_enabled\fR(3)\&. If the handler function returns a negative error code, it will either be disabled after the invocation, even if the
+\fBSD_EVENT_ON\fR
+mode was requested before, or it will cause the loop to terminate, see
+\fBsd_event_source_set_exit_on_failure\fR(3)\&.
+.PP
+To destroy an event source object use
+\fBsd_event_source_unref\fR(3), but note that the event source is only removed from the event loop when all references to the event source are dropped\&. To make sure an event source does not fire anymore, even when there\*(Aqs still a reference to it kept, consider setting the event source to
+\fBSD_EVENT_OFF\fR
+with
+\fBsd_event_source_set_enabled\fR(3)\&.
+.PP
+The
+\fBSIGCHLD\fR
+signal must be blocked in all threads before this function is called (using
+\fBsigprocmask\fR(2)
+or
+\fBpthread_sigmask\fR(3))\&.
+.PP
+If the second parameter of
+\fBsd_event_add_child()\fR
+is passed as
+\fBNULL\fR
+no reference to the event source object is returned\&. In this case the event source is considered "floating", and will be destroyed implicitly when the event loop itself is destroyed\&.
+.PP
+Note that the
+\fIhandler\fR
+function is invoked at a time where the child process is not reaped yet (and thus still is exposed as a zombie process by the kernel)\&. However, the child will be reaped automatically after the function returns\&. Child processes for which no child process state change event sources are installed will not be reaped by the event loop implementation\&.
+.PP
+If the
+\fIhandler\fR
+parameter to
+\fBsd_event_add_child()\fR
+is
+\fBNULL\fR, and the event source fires, this will be considered a request to exit the event loop\&. In this case, the
+\fIuserdata\fR
+parameter, cast to an integer, is passed as the exit code parameter to
+\fBsd_event_exit\fR(3)\&.
+.PP
+If both a child process state change event source and a
+\fBSIGCHLD\fR
+signal event source is installed in the same event loop, the configured event source priorities decide which event source is dispatched first\&. If the signal handler is processed first, it should leave the child processes for which child process state change event sources are installed unreaped\&.
+.PP
+\fBsd_event_add_child_pidfd()\fR
+is similar to
+\fBsd_event_add_child()\fR
+but takes a file descriptor referencing the process ("pidfd") instead of the numeric PID\&. A suitable file descriptor may be acquired via
+\fBpidfd_open\fR(2)
+and related calls\&. The passed file descriptor is not closed when the event source is freed again, unless
+\fBsd_event_source_set_child_pidfd_own()\fR
+is used to turn this behaviour on\&. Note that regardless which of
+\fBsd_event_add_child()\fR
+and
+\fBsd_event_add_child_pidfd()\fR
+is used for allocating an event source, the watched process has to be a direct child process of the invoking process\&. Also in both cases
+\fBSIGCHLD\fR
+has to be blocked in the invoking process\&.
+.PP
+\fBsd_event_source_get_child_pid()\fR
+retrieves the configured PID of a child process state change event source created previously with
+\fBsd_event_add_child()\fR\&. It takes the event source object as the
+\fIsource\fR
+parameter and a pointer to a
+\fBpid_t\fR
+variable to return the process ID in\&.
+.PP
+\fBsd_event_source_get_child_pidfd()\fR
+retrieves the file descriptor referencing the watched process ("pidfd") if this functionality is available\&. On kernels that support the concept the event loop will make use of pidfds to watch child processes, regardless if the individual event sources are allocated via
+\fBsd_event_add_child()\fR
+or
+\fBsd_event_add_child_pidfd()\fR\&. If the latter call was used to allocate the event source, this function returns the file descriptor used for allocation\&. On kernels that do not support the pidfd concept this function will fail with
+\fBEOPNOTSUPP\fR\&. This call takes the event source object as the
+\fIsource\fR
+parameter and returns the numeric file descriptor\&.
+.PP
+\fBsd_event_source_get_child_pidfd_own()\fR
+may be used to query whether the pidfd the event source encapsulates shall be closed when the event source is freed\&. This function returns zero if the pidfd shall be left open, and positive if it shall be closed automatically\&. By default this setting defaults to on if the event source was allocated via
+\fBsd_event_add_child()\fR
+and off if it was allocated via
+\fBsd_event_add_child_pidfd()\fR\&. The
+\fBsd_event_source_set_child_pidfd_own()\fR
+function may be used to change the setting and takes a boolean parameter with the new setting\&.
+.PP
+\fBsd_event_source_get_child_process_own()\fR
+may be used to query whether the process the event source watches shall be killed (with
+\fBSIGKILL\fR) and reaped when the event source is freed\&. This function returns zero if the process shell be left running, and positive if it shall be killed and reaped automatically\&. By default this setting defaults to off\&. The
+\fBsd_event_source_set_child_process_own()\fR
+function may be used to change the setting and takes a boolean parameter with the new setting\&. Note that currently if the calling process is terminated abnormally the watched process might survive even thought the event source ceases to exist\&. This behaviour might change eventually\&.
+.PP
+\fBsd_event_source_send_child_signal()\fR
+may be used to send a UNIX signal to the watched process\&. If the pidfd concept is supported in the kernel, this is implemented via
+\fBpidfd_send_signal\fR(2)
+and otherwise via
+\fBrt_sigqueueinfo\fR(2)
+(or via
+\fBkill\fR(2)
+in case
+\fIinfo\fR
+is
+\fBNULL\fR)\&. The specified parameters match those of these underlying system calls, except that the
+\fIinfo\fR
+is never modified (and is thus declared constant)\&. Like for the underlying system calls, the
+\fIflags\fR
+parameter currently must be zero\&.
+.SH "RETURN VALUE"
+.PP
+On success, these functions return 0 or a positive integer\&. On failure, they return a negative errno\-style error code\&.
+.SS "Errors"
+.PP
+Returned errors may indicate the following problems:
+.PP
+\fB\-ENOMEM\fR
+.RS 4
+Not enough memory to allocate an object\&.
+.RE
+.PP
+\fB\-EINVAL\fR
+.RS 4
+An invalid argument has been passed\&. This includes specifying an empty mask in
+\fIoptions\fR
+or a mask which contains values different than a combination of
+\fBWEXITED\fR,
+\fBWSTOPPED\fR, and
+\fBWCONTINUED\fR\&.
+.RE
+.PP
+\fB\-EBUSY\fR
+.RS 4
+A handler is already installed for this child process, or
+\fBSIGCHLD\fR
+is not blocked\&.
+.RE
+.PP
+\fB\-ESTALE\fR
+.RS 4
+The event loop is already terminated\&.
+.RE
+.PP
+\fB\-ECHILD\fR
+.RS 4
+The event loop has been created in a different process, library or module instance\&.
+.RE
+.PP
+\fB\-EDOM\fR
+.RS 4
+The passed event source is not a child process event source\&.
+.RE
+.PP
+\fB\-EOPNOTSUPP\fR
+.RS 4
+A pidfd was requested but the kernel does not support this concept\&.
+.sp
+Added in version 245\&.
+.RE
+.SH "NOTES"
+.PP
+Functions described here are available as a shared library, which can be compiled against and linked to with the
+\fBlibsystemd\fR\ \&\fBpkg-config\fR(1)
+file\&.
+.PP
+The code described here uses
+\fBgetenv\fR(3), which is declared to be not multi\-thread\-safe\&. This means that the code calling the functions described here must not call
+\fBsetenv\fR(3)
+from a parallel thread\&. It is recommended to only do calls to
+\fBsetenv()\fR
+from an early phase of the program when no other threads have been started\&.
+.SH "EXAMPLE"
+.PP
+\fBExample\ \&1.\ \&Exit loop when the child terminates\fR
+.sp
+.if n \{\
+.RS 4
+.\}
+.nf
+/* SPDX\-License\-Identifier: MIT\-0 */
+
+#include <assert\&.h>
+#include <stdio\&.h>
+#include <unistd\&.h>
+#include <sd\-event\&.h>
+
+int main(int argc, char **argv) {
+  pid_t pid = fork();
+  assert(pid >= 0);
+
+  /* SIGCHLD signal must be blocked for sd_event_add_child to work */
+  sigset_t ss;
+  sigemptyset(&ss);
+  sigaddset(&ss, SIGCHLD);
+  sigprocmask(SIG_BLOCK, &ss, NULL);
+
+  if (pid == 0)  /* child */
+    sleep(1);
+
+  else {         /* parent */
+    sd_event *e = NULL;
+    int r;
+
+    /* Create the default event loop */
+    sd_event_default(&e);
+    assert(e);
+
+    /* We create a floating child event source (attached to \*(Aqe\*(Aq)\&.
+     * The default handler will be called with 666 as userdata, which
+     * will become the exit value of the loop\&. */
+    r = sd_event_add_child(e, NULL, pid, WEXITED, NULL, (void*) 666);
+    assert(r >= 0);
+
+    r = sd_event_loop(e);
+    assert(r == 666);
+
+    sd_event_unref(e);
+  }
+
+  return 0;
+}
+.fi
+.if n \{\
+.RE
+.\}
+.SH "HISTORY"
+.PP
+\fBsd_event_add_child()\fR,
+\fBsd_event_child_handler_t()\fR, and
+\fBsd_event_source_get_child_pid()\fR
+were added in version 217\&.
+.PP
+\fBsd_event_add_child_pidfd()\fR,
+\fBsd_event_source_get_child_pidfd()\fR,
+\fBsd_event_source_get_child_pidfd_own()\fR,
+\fBsd_event_source_set_child_pidfd_own()\fR,
+\fBsd_event_source_get_child_process_own()\fR,
+\fBsd_event_source_set_child_process_own()\fR, and
+\fBsd_event_source_send_child_signal()\fR
+were added in version 245\&.
+.SH "SEE ALSO"
+.PP
+\fBsystemd\fR(1),
+\fBsd-event\fR(3),
+\fBsd_event_new\fR(3),
+\fBsd_event_now\fR(3),
+\fBsd_event_add_io\fR(3),
+\fBsd_event_add_time\fR(3),
+\fBsd_event_add_signal\fR(3),
+\fBsd_event_add_inotify\fR(3),
+\fBsd_event_add_defer\fR(3),
+\fBsd_event_source_set_enabled\fR(3),
+\fBsd_event_source_set_priority\fR(3),
+\fBsd_event_source_set_userdata\fR(3),
+\fBsd_event_source_set_description\fR(3),
+\fBsd_event_source_set_floating\fR(3),
+\fBwaitid\fR(2),
+\fBsigprocmask\fR(2),
+\fBpthread_sigmask\fR(3),
+\fBpidfd_open\fR(2),
+\fBpidfd_send_signal\fR(2),
+\fBrt_sigqueueinfo\fR(2),
+\fBkill\fR(2)