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qemu: Make QMP probing process reusable

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The code that runs a new QEMU process to be used for probing
capabilities is separated into four reusable functions so that any code
that wants to probe a QEMU process may just follow a few simple steps:

    cmd = virQEMUCapsInitQMPCommandNew(...);
    virQEMUCapsInitQMPCommandRun(cmd);

    /* talk to the running QEMU process using its QMP monitor */

    if (reprobeIsRequired) {
        virQEMUCapsInitQMPCommandAbort(cmd, ...);
        virQEMUCapsInitQMPCommandRun(cmd);

        /* talk to the running QEMU process again */
    }

    virQEMUCapsInitQMPCommandFree(cmd);

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
This commit is contained in:
Jiri Denemark 2013-07-22 19:38:37 +02:00
parent 745263589f
commit 4c5d05ea8a
1 changed files with 180 additions and 86 deletions
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266
src/qemu/qemu_capabilities.c
View File

@ -4024,32 +4024,101 @@ virQEMUCapsInitQMPMonitor(virQEMUCapsPtr qemuCaps,
return ret;
}
static int
virQEMUCapsInitQMP(virQEMUCapsPtr qemuCaps,
const char *libDir,
uid_t runUid,
gid_t runGid,
char **qmperr)
{
int ret = -1;
virCommandPtr cmd = NULL;
qemuMonitorPtr mon = NULL;
int status = 0;
typedef struct _virQEMUCapsInitQMPCommand virQEMUCapsInitQMPCommand;
typedef virQEMUCapsInitQMPCommand *virQEMUCapsInitQMPCommandPtr;
struct _virQEMUCapsInitQMPCommand {
char *binary;
uid_t runUid;
gid_t runGid;
char **qmperr;
char *monarg;
char *monpath;
char *pidfile;
virCommandPtr cmd;
qemuMonitorPtr mon;
virDomainChrSourceDef config;
char *monarg = NULL;
char *monpath = NULL;
char *pidfile = NULL;
pid_t pid = 0;
virDomainObjPtr vm = NULL;
virDomainXMLOptionPtr xmlopt = NULL;
pid_t pid;
virDomainObjPtr vm;
};
static void
virQEMUCapsInitQMPCommandAbort(virQEMUCapsInitQMPCommandPtr cmd)
{
if (cmd->mon)
virObjectUnlock(cmd->mon);
qemuMonitorClose(cmd->mon);
cmd->mon = NULL;
virCommandAbort(cmd->cmd);
virCommandFree(cmd->cmd);
cmd->cmd = NULL;
if (cmd->monpath)
ignore_value(unlink(cmd->monpath));
virDomainObjEndAPI(&cmd->vm);
if (cmd->pid != 0) {
char ebuf[1024];
VIR_DEBUG("Killing QMP caps process %lld", (long long) cmd->pid);
if (virProcessKill(cmd->pid, SIGKILL) < 0 && errno != ESRCH)
VIR_ERROR(_("Failed to kill process %lld: %s"),
(long long) cmd->pid,
virStrerror(errno, ebuf, sizeof(ebuf)));
VIR_FREE(*cmd->qmperr);
}
if (cmd->pidfile)
unlink(cmd->pidfile);
cmd->pid = 0;
}
static void
virQEMUCapsInitQMPCommandFree(virQEMUCapsInitQMPCommandPtr cmd)
{
if (!cmd)
return;
virQEMUCapsInitQMPCommandAbort(cmd);
VIR_FREE(cmd->binary);
VIR_FREE(cmd->monpath);
VIR_FREE(cmd->monarg);
VIR_FREE(cmd->pidfile);
VIR_FREE(cmd);
}
static virQEMUCapsInitQMPCommandPtr
virQEMUCapsInitQMPCommandNew(char *binary,
const char *libDir,
uid_t runUid,
gid_t runGid,
char **qmperr)
{
virQEMUCapsInitQMPCommandPtr cmd = NULL;
if (VIR_ALLOC(cmd) < 0)
goto error;
if (VIR_STRDUP(cmd->binary, binary) < 0)
goto error;
cmd->runUid = runUid;
cmd->runGid = runGid;
cmd->qmperr = qmperr;
/* the ".sock" sufix is important to avoid a possible clash with a qemu
* domain called "capabilities"
*/
if (virAsprintf(&monpath, "%s/%s", libDir, "capabilities.monitor.sock") < 0)
goto cleanup;
if (virAsprintf(&monarg, "unix:%s,server,nowait", monpath) < 0)
goto cleanup;
if (virAsprintf(&cmd->monpath, "%s/%s", libDir,
"capabilities.monitor.sock") < 0)
goto error;
if (virAsprintf(&cmd->monarg, "unix:%s,server,nowait", cmd->monpath) < 0)
goto error;
/* ".pidfile" suffix is used rather than ".pid" to avoid a possible clash
* with a qemu domain called "capabilities"
@ -4057,17 +4126,35 @@ virQEMUCapsInitQMP(virQEMUCapsPtr qemuCaps,
* -daemonize we need QEMU to be allowed to create them, rather
* than libvirtd. So we're using libDir which QEMU can write to
*/
if (virAsprintf(&pidfile, "%s/%s", libDir, "capabilities.pidfile") < 0)
goto cleanup;
if (virAsprintf(&cmd->pidfile, "%s/%s", libDir, "capabilities.pidfile") < 0)
goto error;
memset(&config, 0, sizeof(config));
config.type = VIR_DOMAIN_CHR_TYPE_UNIX;
config.data.nix.path = monpath;
config.data.nix.listen = false;
virPidFileForceCleanupPath(cmd->pidfile);
virPidFileForceCleanupPath(pidfile);
cmd->config.type = VIR_DOMAIN_CHR_TYPE_UNIX;
cmd->config.data.nix.path = cmd->monpath;
cmd->config.data.nix.listen = false;
VIR_DEBUG("Try to get caps via QMP qemuCaps=%p", qemuCaps);
return cmd;
error:
virQEMUCapsInitQMPCommandFree(cmd);
return NULL;
}
/* Returns -1 on fatal error,
* 0 on success,
* 1 when probing QEMU failed
*/
static int
virQEMUCapsInitQMPCommandRun(virQEMUCapsInitQMPCommandPtr cmd)
{
virDomainXMLOptionPtr xmlopt = NULL;
int status = 0;
int ret = -1;
VIR_DEBUG("Try to probe capabilities of '%s' via QMP", cmd->binary);
/*
* We explicitly need to use -daemonize here, rather than
@ -4076,86 +4163,93 @@ virQEMUCapsInitQMP(virQEMUCapsPtr qemuCaps,
* daemonize guarantees control won't return to libvirt
* until the socket is present.
*/
cmd = virCommandNewArgList(qemuCaps->binary,
"-S",
"-no-user-config",
"-nodefaults",
"-nographic",
"-M", "none",
"-qmp", monarg,
"-pidfile", pidfile,
"-daemonize",
NULL);
virCommandAddEnvPassCommon(cmd);
virCommandClearCaps(cmd);
virCommandSetGID(cmd, runGid);
virCommandSetUID(cmd, runUid);
cmd->cmd = virCommandNewArgList(cmd->binary,
"-S",
"-no-user-config",
"-nodefaults",
"-nographic",
"-M", "none",
"-qmp", cmd->monarg,
"-pidfile", cmd->pidfile,
"-daemonize",
NULL);
virCommandAddEnvPassCommon(cmd->cmd);
virCommandClearCaps(cmd->cmd);
virCommandSetGID(cmd->cmd, cmd->runGid);
virCommandSetUID(cmd->cmd, cmd->runUid);
virCommandSetErrorBuffer(cmd, qmperr);
virCommandSetErrorBuffer(cmd->cmd, cmd->qmperr);
/* Log, but otherwise ignore, non-zero status. */
if (virCommandRun(cmd, &status) < 0)
if (virCommandRun(cmd->cmd, &status) < 0)
goto cleanup;
if (status != 0) {
ret = 0;
VIR_DEBUG("QEMU %s exited with status %d: %s",
qemuCaps->binary, status, *qmperr);
goto cleanup;
cmd->binary, status, *cmd->qmperr);
goto ignore;
}
if (virPidFileReadPath(pidfile, &pid) < 0) {
VIR_DEBUG("Failed to read pidfile %s", pidfile);
ret = 0;
goto cleanup;
if (virPidFileReadPath(cmd->pidfile, &cmd->pid) < 0) {
VIR_DEBUG("Failed to read pidfile %s", cmd->pidfile);
goto ignore;
}
if (!(xmlopt = virDomainXMLOptionNew(NULL, NULL, NULL)) ||
!(vm = virDomainObjNew(xmlopt)))
!(cmd->vm = virDomainObjNew(xmlopt)))
goto cleanup;
vm->pid = pid;
cmd->vm->pid = cmd->pid;
if (!(mon = qemuMonitorOpen(vm, &config, true, &callbacks, NULL))) {
ret = 0;
if (!(cmd->mon = qemuMonitorOpen(cmd->vm, &cmd->config, true,
&callbacks, NULL)))
goto ignore;
virObjectLock(cmd->mon);
ret = 0;
cleanup:
if (!cmd->mon)
virQEMUCapsInitQMPCommandAbort(cmd);
virObjectUnref(xmlopt);
return ret;
ignore:
ret = 1;
goto cleanup;
}
static int
virQEMUCapsInitQMP(virQEMUCapsPtr qemuCaps,
const char *libDir,
uid_t runUid,
gid_t runGid,
char **qmperr)
{
virQEMUCapsInitQMPCommandPtr cmd = NULL;
int ret = -1;
int rc;
if (!(cmd = virQEMUCapsInitQMPCommandNew(qemuCaps->binary, libDir,
runUid, runGid, qmperr)))
goto cleanup;
if ((rc = virQEMUCapsInitQMPCommandRun(cmd)) != 0) {
if (rc == 1)
ret = 0;
goto cleanup;
}
virObjectLock(mon);
if (virQEMUCapsInitQMPMonitor(qemuCaps, mon) < 0)
if (virQEMUCapsInitQMPMonitor(qemuCaps, cmd->mon) < 0)
goto cleanup;
ret = 0;
cleanup:
if (mon)
virObjectUnlock(mon);
qemuMonitorClose(mon);
virCommandAbort(cmd);
virCommandFree(cmd);
VIR_FREE(monarg);
if (monpath)
ignore_value(unlink(monpath));
VIR_FREE(monpath);
virDomainObjEndAPI(&vm);
virObjectUnref(xmlopt);
if (pid != 0) {
char ebuf[1024];
VIR_DEBUG("Killing QMP caps process %lld", (long long) pid);
if (virProcessKill(pid, SIGKILL) < 0 && errno != ESRCH)
VIR_ERROR(_("Failed to kill process %lld: %s"),
(long long) pid,
virStrerror(errno, ebuf, sizeof(ebuf)));
VIR_FREE(*qmperr);
}
if (pidfile) {
unlink(pidfile);
VIR_FREE(pidfile);
}
virQEMUCapsInitQMPCommandFree(cmd);
return ret;
}