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rpc: pass listen FD to the daemon being started

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This eliminates the need for active waiting.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=927369

Signed-off-by: Martin Kletzander <mkletzan@redhat.com>
This commit is contained in:
Martin Kletzander 2014-07-16 08:00:19 +02:00
parent 62f263a73e
commit 1b807f92db
1 changed files with 66 additions and 19 deletions
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85
src/rpc/virnetsocket.c
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@ -1,7 +1,7 @@
/*
* virnetsocket.c: generic network socket handling
*
* Copyright (C) 2006-2013 Red Hat, Inc.
* Copyright (C) 2006-2014 Red Hat, Inc.
* Copyright (C) 2006 Daniel P. Berrange
*
* This library is free software; you can redistribute it and/or
@ -121,7 +121,7 @@ VIR_ONCE_GLOBAL_INIT(virNetSocket)
#ifndef WIN32
static int virNetSocketForkDaemon(const char *binary)
static int virNetSocketForkDaemon(const char *binary, int passfd)
{
int ret;
virCommandPtr cmd = virCommandNewArgList(binary,
@ -134,6 +134,10 @@ static int virNetSocketForkDaemon(const char *binary)
virCommandAddEnvPassBlockSUID(cmd, "XDG_RUNTIME_DIR", NULL);
virCommandClearCaps(cmd);
virCommandDaemonize(cmd);
if (passfd) {
virCommandPassFD(cmd, passfd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
virCommandPassListenFDs(cmd);
}
ret = virCommandRun(cmd, NULL);
virCommandFree(cmd);
return ret;
@ -540,10 +544,10 @@ int virNetSocketNewConnectUNIX(const char *path,
const char *binary,
virNetSocketPtr *retsock)
{
char *buf = NULL;
int fd, passfd;
virSocketAddr localAddr;
virSocketAddr remoteAddr;
int fd;
int retries = 0;
memset(&localAddr, 0, sizeof(localAddr));
memset(&remoteAddr, 0, sizeof(remoteAddr));
@ -570,25 +574,65 @@ int virNetSocketNewConnectUNIX(const char *path,
remoteAddr.data.un.sun_path[0] = '\0';
retry:
if (connect(fd, &remoteAddr.data.sa, remoteAddr.len) < 0) {
if ((errno == ECONNREFUSED ||
errno == ENOENT) &&
spawnDaemon && retries < 20) {
VIR_DEBUG("Connection refused for %s, trying to spawn %s",
path, binary);
if (retries == 0 &&
virNetSocketForkDaemon(binary) < 0)
goto error;
if (connect(fd, &remoteAddr.data.sa, remoteAddr.len) < 0 && !spawnDaemon) {
virReportSystemError(errno, _("Failed to connect socket to '%s'"),
path);
goto error;
} else if (spawnDaemon) {
int status = 0;
pid_t pid = 0;
retries++;
usleep(1000 * 100 * retries);
if ((passfd = socket(PF_UNIX, SOCK_STREAM, 0)) < 0) {
virReportSystemError(errno, "%s", _("Failed to create socket"));
goto error;
}
/*
* We have to fork() here, because umask() is set
* per-process, chmod() is racy and fchmod() has undefined
* behaviour on sockets according to POSIX, so it doesn't
* work outside Linux.
*/
if ((pid = virFork()) < 0)
goto error;
if (pid == 0) {
umask(0077);
if (bind(passfd, &remoteAddr.data.sa, remoteAddr.len) < 0)
_exit(EXIT_FAILURE);
_exit(EXIT_SUCCESS);
}
if (virProcessWait(pid, &status, false) < 0)
goto error;
if (status != EXIT_SUCCESS) {
/*
* OK, so the subprocces failed to bind() the socket. This may mean
* that another daemon was starting at the same time and succeeded
* with its bind(). So we'll try connecting again, but this time
* without spawning the daemon.
*/
spawnDaemon = false;
goto retry;
}
virReportSystemError(errno,
_("Failed to connect socket to '%s'"),
path);
goto error;
if (listen(passfd, 0) < 0) {
virReportSystemError(errno, "%s",
_("Failed to listen on socket that's about "
"to be passed to the daemon"));
goto error;
}
if (connect(fd, &remoteAddr.data.sa, remoteAddr.len) < 0) {
virReportSystemError(errno, _("Failed to connect socket to '%s'"),
path);
goto error;
}
if (virNetSocketForkDaemon(binary, passfd) < 0)
goto error;
}
localAddr.len = sizeof(localAddr.data);
@ -603,7 +647,10 @@ int virNetSocketNewConnectUNIX(const char *path,
return 0;
error:
VIR_FREE(buf);
VIR_FORCE_CLOSE(fd);
if (spawnDaemon)
unlink(path);
return -1;
}
#else