libxl: define a per-domain logger.

libxl doesn't provide a way to write one log for each domain. Thus
we need to demux the messages. If our logger doesn't know to which
domain to attribute a message, then it will write it to the default
log file.

Starting with Xen 4.9 (commit f9858025 and following), libxl will
write the domain ID in an easy to grab manner. The logger introduced
by this commit will use it to demux the libxl log messages.

Thanks to the default log file, this logger will also work with older
versions of Xen.

src/Makefile.am

@@ -851,6 +851,7 @@ LIBXL_DRIVER_SOURCES =							\
 		libxl/libxl_capabilities.c libxl/libxl_capabilities.h	\
 		libxl/libxl_domain.c libxl/libxl_domain.h       	\
 		libxl/libxl_driver.c libxl/libxl_driver.h       	\
+		libxl/libxl_logger.c libxl/libxl_logger.h           \
 		libxl/libxl_migration.c libxl/libxl_migration.h
 
 UML_DRIVER_SOURCES =						\

src/libxl/libxl_conf.c

@@ -76,9 +76,7 @@ libxlDriverConfigDispose(void *obj)
 
     virObjectUnref(cfg->caps);
     libxl_ctx_free(cfg->ctx);
-    xtl_logger_destroy(cfg->logger);
+    libxlLoggerFree(cfg->logger);
-    if (cfg->logger_file)
-        VIR_FORCE_FCLOSE(cfg->logger_file);
 
     VIR_FREE(cfg->configDir);
     VIR_FREE(cfg->autostartDir);
@@ -1356,8 +1354,6 @@ libxlDriverConfigPtr
 libxlDriverConfigNew(void)
 {
     libxlDriverConfigPtr cfg;
-    char *log_file = NULL;
-    xentoollog_level log_level = XTL_DEBUG;
     char ebuf[1024];
     unsigned int free_mem;
 
@@ -1386,9 +1382,6 @@ libxlDriverConfigNew(void)
     if (VIR_STRDUP(cfg->channelDir, LIBXL_CHANNEL_DIR) < 0)
         goto error;
 
-    if (virAsprintf(&log_file, "%s/libxl-driver.log", cfg->logDir) < 0)
-        goto error;
-
     if (virFileMakePath(cfg->logDir) < 0) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
                        _("failed to create log dir '%s': %s"),
@@ -1397,37 +1390,13 @@ libxlDriverConfigNew(void)
         goto error;
     }
 
-    if ((cfg->logger_file = fopen(log_file, "a")) == NULL)  {
+    cfg->logger = libxlLoggerNew(cfg->logDir, virLogGetDefaultPriority());
-        VIR_ERROR(_("Failed to create log file '%s': %s"),
-                  log_file, virStrerror(errno, ebuf, sizeof(ebuf)));
-        goto error;
-    }
-    VIR_FREE(log_file);
-
-    switch (virLogGetDefaultPriority()) {
-    case VIR_LOG_DEBUG:
-        log_level = XTL_DEBUG;
-        break;
-    case VIR_LOG_INFO:
-        log_level = XTL_INFO;
-        break;
-    case VIR_LOG_WARN:
-        log_level = XTL_WARN;
-        break;
-    case VIR_LOG_ERROR:
-        log_level = XTL_ERROR;
-        break;
-    }
-
-    cfg->logger =
-        (xentoollog_logger *)xtl_createlogger_stdiostream(cfg->logger_file,
-                                      log_level, XTL_STDIOSTREAM_SHOW_DATE);
     if (!cfg->logger) {
         VIR_ERROR(_("cannot create logger for libxenlight, disabling driver"));
         goto error;
     }
 
-    if (libxl_ctx_alloc(&cfg->ctx, LIBXL_VERSION, 0, cfg->logger)) {
+    if (libxl_ctx_alloc(&cfg->ctx, LIBXL_VERSION, 0, (xentoollog_logger *)cfg->logger)) {
         VIR_ERROR(_("cannot initialize libxenlight context, probably not "
                     "running in a Xen Dom0, disabling driver"));
         goto error;
@@ -1478,7 +1447,6 @@ libxlDriverConfigNew(void)
     return cfg;
 
  error:
-    VIR_FREE(log_file);
     virObjectUnref(cfg);
     return NULL;
 }

src/libxl/libxl_conf.h

@@ -41,6 +41,7 @@
 # include "locking/lock_manager.h"
 # include "virfirmware.h"
 # include "libxl_capabilities.h"
+# include "libxl_logger.h"
 
 # define LIBXL_DRIVER_NAME "xenlight"
 # define LIBXL_VNC_PORT_MIN  5900
@@ -74,8 +75,7 @@ struct _libxlDriverConfig {
     unsigned int version;
 
     /* log stream for driver-wide libxl ctx */
-    FILE *logger_file;
+    libxlLoggerPtr logger;
-    xentoollog_logger *logger;
     /* libxl ctx for driver wide ops; getVersion, getNodeInfo, ... */
     libxl_ctx *ctx;
 

src/libxl/libxl_domain.c

@@ -809,6 +809,8 @@ libxlDomainCleanup(libxlDriverPrivatePtr driver,
         VIR_FREE(xml);
     }
 
+    libxlLoggerCloseFile(cfg->logger, vm->def->id);
+
     virDomainObjRemoveTransientDef(vm);
     virObjectUnref(cfg);
 }
@@ -1127,6 +1129,7 @@ libxlDomainStart(libxlDriverPrivatePtr driver,
     libxl_asyncprogress_how aop_console_how;
     libxl_domain_restore_params params;
     unsigned int hostdev_flags = VIR_HOSTDEV_SP_PCI;
+    char *config_json = NULL;
 
 #ifdef LIBXL_HAVE_PVUSB
     hostdev_flags |= VIR_HOSTDEV_SP_USB;
@@ -1290,6 +1293,9 @@ libxlDomainStart(libxlDriverPrivatePtr driver,
      * be cleaned up if there are any subsequent failures.
      */
     vm->def->id = domid;
+    config_json = libxl_domain_config_to_json(cfg->ctx, &d_config);
+
+    libxlLoggerOpenFile(cfg->logger, domid, vm->def->name, config_json);
 
     /* Always enable domain death events */
     if (libxl_evenable_domain_death(cfg->ctx, vm->def->id, 0, &priv->deathW))
@@ -1366,6 +1372,7 @@ libxlDomainStart(libxlDriverPrivatePtr driver,
 
  cleanup:
     libxl_domain_config_dispose(&d_config);
+    VIR_FREE(config_json);
     VIR_FREE(dom_xml);
     VIR_FREE(managed_save_path);
     virDomainDefFree(def);

src/libxl/libxl_driver.c

@@ -406,6 +406,8 @@ libxlReconnectDomain(virDomainObjPtr vm,
     /* Update domid in case it changed (e.g. reboot) while we were gone? */
     vm->def->id = d_info.domid;
 
+    libxlLoggerOpenFile(cfg->logger, vm->def->id, vm->def->name, NULL);
+
     /* Update hostdev state */
     if (virHostdevUpdateActiveDomainDevices(hostdev_mgr, LIBXL_DRIVER_NAME,
                                             vm->def, hostdev_flags) < 0)

src/libxl/libxl_logger.c

@@ -0,0 +1,235 @@
+/*
+ * libxl_logger.c: libxl logger implementation
+ *
+ * Copyright (c) 2016 SUSE LINUX Products GmbH, Nuernberg, Germany.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *     Cédric Bosdonnat <cbosdonnat@suse.com>
+ */
+#include <config.h>
+
+#include <string.h>
+#include <libxl.h>
+
+#include "internal.h"
+#include "libxl_logger.h"
+#include "util/viralloc.h"
+#include "util/virerror.h"
+#include "util/virfile.h"
+#include "util/virhash.h"
+#include "util/virstring.h"
+#include "util/virtime.h"
+
+#define VIR_FROM_THIS VIR_FROM_LIBXL
+
+VIR_LOG_INIT("libxl.libxl_logger");
+
+typedef struct xentoollog_logger_libvirt xentoollog_logger_libvirt;
+
+struct xentoollog_logger_libvirt {
+    xentoollog_logger vtable;
+    xentoollog_level minLevel;
+    const char *logDir;
+
+    /* map storing the opened fds: "domid" -> FILE* */
+    virHashTablePtr files;
+    FILE *defaultLogFile;
+};
+
+static void
+libxlLoggerFileFree(void *payload, const void *key ATTRIBUTE_UNUSED)
+{
+    FILE *file = payload;
+    VIR_FORCE_FCLOSE(file);
+    file = NULL;
+}
+
+ATTRIBUTE_FMT_PRINTF(5, 0) static void
+libvirt_vmessage(xentoollog_logger *logger_in,
+                 xentoollog_level level,
+                 int errnoval,
+                 const char *context,
+                 const char *format,
+                 va_list args)
+{
+    xentoollog_logger_libvirt *lg = (xentoollog_logger_libvirt *)logger_in;
+    FILE *logFile = lg->defaultLogFile;
+    char timestamp[VIR_TIME_STRING_BUFLEN];
+    char *message = NULL;
+    char *start, *end;
+    char ebuf[1024];
+
+    VIR_DEBUG("libvirt_vmessage: context='%s' format='%s'", context, format);
+
+    if (level < lg->minLevel)
+        return;
+
+    if (virVasprintf(&message, format, args) < 0)
+        return;
+
+    /* Should we print to a domain-specific log file? */
+    if ((start = strstr(message, ": Domain ")) &&
+        (end = strstr(start + 9, ":"))) {
+        FILE *domainLogFile;
+
+        VIR_DEBUG("Found domain log message");
+
+        start = start + 9;
+        *end = '\0';
+
+        domainLogFile = virHashLookup(lg->files, start);
+        if (domainLogFile)
+            logFile = domainLogFile;
+
+        *end = ':';
+    }
+
+    /* Do the actual print to the log file */
+    if (virTimeStringNowRaw(timestamp) < 0)
+        timestamp[0] = '\0';
+
+    fprintf(logFile, "%s: ", timestamp);
+    if (context)
+        fprintf(logFile, "%s: ", context);
+
+    fprintf(logFile, "%s", message);
+
+    if (errnoval >= 0)
+        fprintf(logFile, ": %s", virStrerror(errnoval, ebuf, sizeof(ebuf)));
+
+    fputc('\n', logFile);
+    fflush(logFile);
+
+    VIR_FREE(message);
+}
+
+static void
+libvirt_progress(xentoollog_logger *logger_in ATTRIBUTE_UNUSED,
+                 const char *context ATTRIBUTE_UNUSED,
+                 const char *doingwhat ATTRIBUTE_UNUSED,
+                 int percent ATTRIBUTE_UNUSED,
+                 unsigned long done ATTRIBUTE_UNUSED,
+                 unsigned long total ATTRIBUTE_UNUSED)
+{
+    /* This function purposedly does nothing: it's no logging info */
+}
+
+static void
+libvirt_destroy(xentoollog_logger *logger_in)
+{
+    xentoollog_logger_libvirt *lg = (xentoollog_logger_libvirt*)logger_in;
+    VIR_FREE(lg);
+}
+
+
+libxlLoggerPtr
+libxlLoggerNew(const char *logDir, virLogPriority minLevel)
+{
+    xentoollog_logger_libvirt logger;
+    libxlLoggerPtr logger_out = NULL;
+    char *path = NULL;
+
+    switch (minLevel) {
+    case VIR_LOG_DEBUG:
+        logger.minLevel = XTL_DEBUG;
+        break;
+    case VIR_LOG_INFO:
+        logger.minLevel = XTL_INFO;
+        break;
+    case VIR_LOG_WARN:
+        logger.minLevel = XTL_WARN;
+        break;
+    case VIR_LOG_ERROR:
+        logger.minLevel = XTL_ERROR;
+        break;
+    }
+    logger.logDir = logDir;
+
+    if ((logger.files = virHashCreate(3, libxlLoggerFileFree)) == NULL)
+        return NULL;
+
+    if (virAsprintf(&path, "%s/libxl-driver.log", logDir) < 0)
+        goto error;
+
+    if ((logger.defaultLogFile = fopen(path, "a")) == NULL)
+        goto error;
+
+    logger_out = XTL_NEW_LOGGER(libvirt, logger);
+
+ cleanup:
+    VIR_FREE(path);
+    return logger_out;
+
+ error:
+    virHashFree(logger.files);
+    goto cleanup;
+}
+
+void
+libxlLoggerFree(libxlLoggerPtr logger)
+{
+    xentoollog_logger *xtl_logger = (xentoollog_logger*)logger;
+    if (logger->defaultLogFile)
+        VIR_FORCE_FCLOSE(logger->defaultLogFile);
+    virHashFree(logger->files);
+    xtl_logger_destroy(xtl_logger);
+}
+
+void
+libxlLoggerOpenFile(libxlLoggerPtr logger,
+                    int id,
+                    const char *name,
+                    const char *domain_config)
+{
+    char *path = NULL;
+    FILE *logFile = NULL;
+    char *domidstr = NULL;
+    char ebuf[1024];
+
+    if (virAsprintf(&path, "%s/%s.log", logger->logDir, name) < 0 ||
+        virAsprintf(&domidstr, "%d", id) < 0)
+        goto cleanup;
+
+    if (!(logFile = fopen(path, "a"))) {
+        VIR_WARN("Failed to open log file %s: %s",
+                 path, virStrerror(errno, ebuf, sizeof(ebuf)));
+        goto cleanup;
+    }
+    ignore_value(virHashAddEntry(logger->files, domidstr, logFile));
+
+    /* domain_config is non NULL only when starting a new domain */
+    if (domain_config) {
+        fprintf(logFile, "Domain start: %s\n", domain_config);
+        fflush(logFile);
+    }
+
+ cleanup:
+    VIR_FREE(path);
+    VIR_FREE(domidstr);
+}
+
+void
+libxlLoggerCloseFile(libxlLoggerPtr logger, int id)
+{
+    char *domidstr = NULL;
+    if (virAsprintf(&domidstr, "%d", id) < 0)
+        return;
+
+    ignore_value(virHashRemoveEntry(logger->files, domidstr));
+
+    VIR_FREE(domidstr);
+}

src/libxl/libxl_logger.h

@@ -0,0 +1,40 @@
+/*
+ * libxl_logger.h: libxl logger implementation
+ *
+ * Copyright (c) 2016 SUSE LINUX Products GmbH, Nuernberg, Germany.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library.  If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * Authors:
+ *     Cédric Bosdonnat <cbosdonnat@suse.com>
+ */
+
+#ifndef __LIBXL_LOGGER_H
+# define __LIBXL_LOGGER_H
+
+# include "util/virlog.h"
+
+typedef struct xentoollog_logger_libvirt libxlLogger;
+typedef libxlLogger *libxlLoggerPtr;
+
+libxlLoggerPtr libxlLoggerNew(const char *logDir,
+                              virLogPriority minLevel);
+void libxlLoggerFree(libxlLoggerPtr logger);
+
+void libxlLoggerOpenFile(libxlLoggerPtr logger, int id, const char *name,
+                         const char *domain_config);
+void libxlLoggerCloseFile(libxlLoggerPtr logger, int id);
+
+#endif /* __LIBXL_LOGGER_H */