mirror of
https://github.com/moparisthebest/socat
synced 2024-08-13 16:43:48 -04:00
318 lines
8.8 KiB
C
318 lines
8.8 KiB
C
/* source: xiosigchld.c */
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/* Copyright Gerhard Rieger 2001-2008 */
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/* Published under the GNU General Public License V.2, see file COPYING */
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/* this is the source of the extended child signal handler */
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#include "xiosysincludes.h"
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#include "xioopen.h"
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#include "xiosigchld.h"
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/*****************************************************************************/
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/* we maintain a table of all known child processes */
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/* for now, we use a very primitive data structure - just an unsorted, size
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limited array */
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#define XIO_MAXCHILDPIDS 16
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struct _xiosigchld_child {
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pid_t pid;
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void (*sigaction)(int, siginfo_t *, void *);
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void *context;
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} ;
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static struct _xiosigchld_child * _xiosigchld_find(pid_t pid);
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static struct _xiosigchld_child xio_childpids[XIO_MAXCHILDPIDS];
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#if 1 /*!!!*/
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/*!! with socat, at most 4 managed children exist */
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pid_t diedunknown1; /* child died before it is registered */
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pid_t diedunknown2;
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pid_t diedunknown3;
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pid_t diedunknown4;
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#endif
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/* register for a xio filedescriptor a callback (handler).
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when a SIGCHLD occurs, the signal handler will ??? */
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int xiosetsigchild(xiofile_t *xfd, int (*callback)(struct single *)) {
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if (xfd->tag != XIO_TAG_DUAL) {
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xfd->stream.child.sigchild = callback;
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} else {
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xfd->dual.stream[0]->child.sigchild = callback;
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xfd->dual.stream[1]->child.sigchild = callback;
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}
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return 0;
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}
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/* exec'd child has died, perform appropriate changes to descriptor */
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static int sigchld_stream(struct single *file) {
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/*!! call back to application */
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file->child.pid = 0;
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if (file->child.sigchild) {
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return (*file->child.sigchild)(file);
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}
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return 0;
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}
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/* return 0 if socket is not responsible for deadchild */
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static int xio_checkchild(xiofile_t *socket, int socknum, pid_t deadchild) {
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int retval;
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if (socket != NULL) {
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if (socket->tag != XIO_TAG_DUAL) {
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if (socket->stream.child.pid == deadchild) {
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Info2("exec'd process %d on socket %d terminated",
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socket->stream.child.pid, socknum);
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sigchld_stream(&socket->stream);
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return 1;
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}
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} else {
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if (retval = xio_checkchild((xiofile_t *)socket->dual.stream[0], socknum, deadchild))
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return retval;
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else
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return xio_checkchild((xiofile_t *)socket->dual.stream[1], socknum, deadchild);
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}
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}
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return 0;
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}
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/* this is the "physical" signal handler for SIGCHLD */
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/* the current socat/xio implementation knows two kinds of children:
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exec/system addresses perform a fork: their children are registered and
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their death's influence the parents' flow;
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listen-socket with fork children: these children are "anonymous" and their
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death does not affect the parent process (now; maybe we have a child
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process counter later) */
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void childdied(int signum
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#if HAVE_SIGACTION
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, siginfo_t *siginfo, void *context
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#endif /* HAVE_SIGACTION */
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) {
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pid_t pid;
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int _errno;
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int status = 0;
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bool wassig = false;
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int i;
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struct _xiosigchld_child *entry;
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_errno = errno; /* save current value; e.g., select() on Cygwin seems
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to set it to EINTR _before_ handling the signal, and
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then passes the value left by the signal handler to
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the caller of select(), accept() etc. */
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/* is not thread/signal save, but confused messages in rare cases are better
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than no messages at all */
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Info1("childdied(signum=%d)", signum);
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do {
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pid = Waitpid(-1, &status, WNOHANG);
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if (pid == 0) {
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Msg(wassig?E_INFO:E_WARN,
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"waitpid(-1, {}, WNOHANG): no child has exited");
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Info("childdied() finished");
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errno = _errno;
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return;
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} else if (pid < 0 && errno == ECHILD) {
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Msg1(wassig?E_INFO:E_WARN,
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"waitpid(-1, {}, WNOHANG): %s", strerror(errno));
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Info("childdied() finished");
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errno = _errno;
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return;
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}
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wassig = true;
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if (pid < 0) {
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Warn2("waitpid(-1, {%d}, WNOHANG): %s", status, strerror(errno));
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Info("childdied() finished");
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errno = _errno;
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return;
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}
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#if 0
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/*! indent */
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/* check if it was a registered child process */
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i = 0;
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while (i < XIO_MAXSOCK) {
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if (xio_checkchild(sock[i], i, pid)) break;
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++i;
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}
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if (i == XIO_MAXSOCK) {
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Info2("childdied(%d): cannot identify child %d", signum, pid);
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if (diedunknown1 == 0) {
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diedunknown1 = pid;
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Debug("saving pid in diedunknown1");
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} else if (diedunknown2 == 0) {
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diedunknown2 = pid;
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Debug("saving pid in diedunknown2");
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} else if (diedunknown3 == 0) {
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diedunknown3 = pid;
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Debug("saving pid in diedunknown3");
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} else {
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diedunknown4 = pid;
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Debug("saving pid in diedunknown4");
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}
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}
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#else
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entry = _xiosigchld_find(pid);
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if (entry == NULL) {
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Info("dead child "F_pid" died unknown");
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} else {
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(*entry->sigaction)(signum, siginfo, entry->context);
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xiosigchld_unregister(pid);
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}
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#endif
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if (WIFEXITED(status)) {
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if (WEXITSTATUS(status) == 0) {
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Info2("waitpid(): child %d exited with status %d",
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pid, WEXITSTATUS(status));
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} else {
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Warn2("waitpid(): child %d exited with status %d",
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pid, WEXITSTATUS(status));
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}
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} else if (WIFSIGNALED(status)) {
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Info2("waitpid(): child %d exited on signal %d",
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pid, WTERMSIG(status));
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} else if (WIFSTOPPED(status)) {
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Info2("waitpid(): child %d stopped on signal %d",
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pid, WSTOPSIG(status));
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} else {
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Warn1("waitpid(): cannot determine status of child %d", pid);
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}
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#if !HAVE_SIGACTION
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/* we might need to re-register our handler */
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if (Signal(SIGCHLD, childdied) == SIG_ERR) {
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Warn2("signal(SIGCHLD, %p): %s", childdied, strerror(errno));
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}
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#endif /* !HAVE_SIGACTION */
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} while (1);
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Info("childdied() finished");
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errno = _errno;
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}
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/* search for given pid in child process table. returns matching entry on
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success, or NULL if not found. Can be used with pid==0 to look for an empty
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entry. */
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static struct _xiosigchld_child *
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_xiosigchld_find(pid_t pid) {
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int i;
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/* is it already registered? */
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for (i = 0; i < XIO_MAXCHILDPIDS; ++i) {
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if (pid == xio_childpids[i].pid) {
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return &xio_childpids[i];
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}
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}
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return NULL;
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}
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/* add a child process to the table
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returns 0 on success (registered or reregistered child)
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returns -1 on table overflow
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*/
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int xiosigchld_register(pid_t pid,
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void (*sigaction)(int, siginfo_t *, void *),
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void *context) {
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struct _xiosigchld_child *entry;
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/* is it already registered? */
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if (entry = _xiosigchld_find(pid)) {
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/* was already registered, override */
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entry->sigaction = sigaction;
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entry->context = context;
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return 0;
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}
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/* try to register it */
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if (entry = _xiosigchld_find(0)) {
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entry->pid = pid;
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entry->sigaction = sigaction;
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entry->context = context;
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return 0;
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}
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Warn("xiosigchld_register(): table overflow");
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return -1;
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}
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/* remove a child process to the table
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returns 0 on success
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returns 1 if pid was not found in table
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*/
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int xiosigchld_unregister(pid_t pid) {
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struct _xiosigchld_child *entry;
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/* is it already registered? */
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if (entry = _xiosigchld_find(pid)) {
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/* found, remove it from table */
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entry->pid = 0;
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return 0;
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}
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return 1;
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}
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/* clear the child process table */
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/* especially interesting after fork() in child process
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returns 0
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*/
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int xiosigchld_clearall(void) {
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int i;
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for (i = 0; i < XIO_MAXCHILDPIDS; ++i) {
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xio_childpids[i].pid = 0;
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}
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return 0;
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}
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void xiosigaction_subaddr_ok(int signum, siginfo_t *siginfo, void *ucontext) {
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pid_t subpid = siginfo->si_pid;
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struct _xiosigchld_child *entry;
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xiosingle_t *xfd;
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entry = _xiosigchld_find(subpid);
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if (entry == NULL) {
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Warn1("SIGUSR1 from unregistered process "F_pid, subpid);
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return;
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}
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xfd = entry->context;
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xfd->subaddrstat = 1;
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}
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void xiosigaction_child(int signum, siginfo_t *siginfo, void *ucontext) {
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pid_t subpid = siginfo->si_pid;
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xiosingle_t *xfd = ucontext;
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/* the sub process that is connected to this xio address has terminated */
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Notice2("sub process "F_pid" died, setting in xfd %p", subpid, xfd);
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xfd->subaddrstat = -1;
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xfd->subaddrexit = siginfo->si_status;
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if (xfd->child.sigchild) {
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(*xfd->child.sigchild)(xfd);
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}
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}
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int xiosetchilddied(void) {
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#if HAVE_SIGACTION
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struct sigaction act;
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memset(&act, 0, sizeof(struct sigaction));
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act.sa_flags = SA_NOCLDSTOP|SA_RESTART|SA_SIGINFO
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#ifdef SA_NOMASK
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|SA_NOMASK
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#endif
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;
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act.sa_sigaction = childdied;
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if (Sigaction(SIGCHLD, &act, NULL) < 0) {
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/*! man does not say that errno is defined */
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Warn2("sigaction(SIGCHLD, %p, NULL): %s", childdied, strerror(errno));
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}
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#else /* HAVE_SIGACTION */
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if (Signal(SIGCHLD, childdied) == SIG_ERR) {
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Warn2("signal(SIGCHLD, %p): %s", childdied, strerror(errno));
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}
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#endif /* !HAVE_SIGACTION */
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return 0;
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}
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