Commit 4d54ec78 authored by Paolo Bonzini's avatar Paolo Bonzini Committed by Anthony Liguori
Browse files

add a service to reap zombies, use it in SLIRP 



SLIRP -smb support wants to fork a process and forget about reaping it.
To please it, add a generic service to register a process id and let
QEMU reap it.  In the future it could be enhanced to pass a status,
but this would be unused.

With this in place, the SIGCHLD signal handler would not stomp on pclose
anymore.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Signed-off-by: default avatarAnthony Liguori <aliguori@us.ibm.com>
parent 02981419

iohandler.c

+64 −0
Original line number Diff line number Diff line
@@ -27,6 +27,10 @@ 
#include "qemu-char.h"

#include "qemu-queue.h"



#ifndef _WIN32

#include <sys/wait.h>

#endif



typedef struct IOHandlerRecord {

    int fd;

    IOCanReadHandler *fd_read_poll;
@@ -127,3 +131,63 @@ void qemu_iohandler_poll(fd_set *readfds, fd_set *writefds, fd_set *xfds, int re 
        }

    }

}



/* reaping of zombies.  right now we're not passing the status to

   anyone, but it would be possible to add a callback.  */

#ifndef _WIN32

typedef struct ChildProcessRecord {

    int pid;

    QLIST_ENTRY(ChildProcessRecord) next;

} ChildProcessRecord;



static QLIST_HEAD(, ChildProcessRecord) child_watches =

    QLIST_HEAD_INITIALIZER(child_watches);



static QEMUBH *sigchld_bh;



static void sigchld_handler(int signal)

{

    qemu_bh_schedule(sigchld_bh);

}



static void sigchld_bh_handler(void *opaque)

{

    ChildProcessRecord *rec, *next;



    QLIST_FOREACH_SAFE(rec, &child_watches, next, next) {

        if (waitpid(rec->pid, NULL, WNOHANG) == rec->pid) {

            QLIST_REMOVE(rec, next);

            qemu_free(rec);

        }

    }

}



static void qemu_init_child_watch(void)

{

    struct sigaction act;

    sigchld_bh = qemu_bh_new(sigchld_bh_handler, NULL);



    act.sa_handler = sigchld_handler;

    act.sa_flags = SA_NOCLDSTOP;

    sigaction(SIGCHLD, &act, NULL);

}



int qemu_add_child_watch(pid_t pid)

{

    ChildProcessRecord *rec;



    if (!sigchld_bh) {

        qemu_init_child_watch();

    }



    QLIST_FOREACH(rec, &child_watches, next) {

        if (rec->pid == pid) {

            return 1;

        }

    }

    rec = qemu_mallocz(sizeof(ChildProcessRecord));

    rec->pid = pid;

    QLIST_INSERT_HEAD(&child_watches, rec, next);

    return 0;

}

#endif

os-posix.c

+0 −9
Original line number Diff line number Diff line
@@ -67,11 +67,6 @@ static void termsig_handler(int signal, siginfo_t *info, void *c) 
    qemu_system_killed(info->si_signo, info->si_pid);

}



static void sigchld_handler(int signal)

{

    waitpid(-1, NULL, WNOHANG);

}



void os_setup_signal_handling(void)

{

    struct sigaction act;
@@ -82,10 +77,6 @@ void os_setup_signal_handling(void) 
    sigaction(SIGINT,  &act, NULL);

    sigaction(SIGHUP,  &act, NULL);

    sigaction(SIGTERM, &act, NULL);



    act.sa_handler = sigchld_handler;

    act.sa_flags = SA_NOCLDSTOP;

    sigaction(SIGCHLD, &act, NULL);

}



/* Find a likely location for support files using the location of the binary.

qemu-common.h

+1 −0
Original line number Diff line number Diff line
@@ -214,6 +214,7 @@ ssize_t qemu_write_full(int fd, const void *buf, size_t count) 
void qemu_set_cloexec(int fd);



#ifndef _WIN32

int qemu_add_child_watch(pid_t pid);

int qemu_eventfd(int pipefd[2]);

int qemu_pipe(int pipefd[2]);

#endif

slirp/misc.c

+4 −1
Original line number Diff line number Diff line
@@ -119,6 +119,7 @@ fork_exec(struct socket *so, const char *ex, int do_pty) 
	char *bptr;

	const char *curarg;

	int c, i, ret;

	pid_t pid;



	DEBUG_CALL("fork_exec");

	DEBUG_ARG("so = %lx", (long)so);
@@ -142,7 +143,8 @@ fork_exec(struct socket *so, const char *ex, int do_pty) 
		}

	}



	switch(fork()) {

	pid = fork();

	switch(pid) {

	 case -1:

		lprint("Error: fork failed: %s\n", strerror(errno));

		close(s);
@@ -206,6 +208,7 @@ fork_exec(struct socket *so, const char *ex, int do_pty) 
		exit(1);



	 default:

		qemu_add_child_watch(pid);

		if (do_pty == 2) {

			close(s);

			so->s = master;