logging: change log protocol to be more reusable

The current virtlogd RPC protocol provides the ability to
handle log files associated with QEMU stdout/err. The log
protocol messages take the virt driver, domain name and
use that to form a log file path. This is quite restrictive
as it prevents us re-using the same RPC protocol messages
for logging to char device backends where the filename
can be arbitrarily user specified. It is also bad because
it means we have 2 separate locations which have to decide
on logfile name.

This change alters the RPC protocol so that we pass the
desired log file path along when opening the log file
initially. Now the virt driver is exclusively in charge
of deciding the log filename
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/logging/log_daemon_dispatch.c

@@ -55,6 +55,7 @@ virLogManagerProtocolDispatchDomainOpenLogFile(virNetServerPtr server ATTRIBUTE_
                                              args->driver,
                                              (unsigned char *)args->dom.uuid,
                                              args->dom.name,
+                                             args->path,
                                              &inode, &offset)) < 0)
         goto cleanup;
 
@@ -87,9 +88,7 @@ virLogManagerProtocolDispatchDomainGetLogFilePosition(virNetServerPtr server ATT
     ino_t inode;
 
     if (virLogHandlerDomainGetLogFilePosition(virLogDaemonGetHandler(logDaemon),
-                                              args->driver,
-                                              (unsigned char *)args->dom.uuid,
-                                              args->dom.name,
+                                              args->path,
                                               &inode, &offset) < 0)
         goto cleanup;
 
@@ -125,9 +124,7 @@ virLogManagerProtocolDispatchDomainReadLogFile(virNetServerPtr server ATTRIBUTE_
     }
 
     if ((data = virLogHandlerDomainReadLogFile(virLogDaemonGetHandler(logDaemon),
-                                               args->driver,
-                                               (unsigned char *)args->dom.uuid,
-                                               args->dom.name,
+                                               args->path,
                                                args->pos.inode,
                                                args->pos.offset,
                                                args->maxlen)) == NULL)

src/logging/log_handler.c

@@ -351,59 +351,23 @@ virLogHandlerDispose(void *obj)
 }
 
 
-static char *
-virLogHandlerGetLogFilePathForDomain(virLogHandlerPtr handler,
-                                     const char *driver,
-                                     const unsigned char *domuuid ATTRIBUTE_UNUSED,
-                                     const char *domname)
-{
-    char *path;
-    if (handler->privileged) {
-        if (virAsprintf(&path,
-                        LOCALSTATEDIR "/log/libvirt/%s/%s.log",
-                        driver, domname) < 0)
-            return NULL;
-    } else {
-        char *cachedir;
-
-        cachedir = virGetUserCacheDirectory();
-        if (!cachedir)
-            return NULL;
-
-        if (virAsprintf(&path,
-                        "%s/%s/log/%s.log", cachedir, driver, domname) < 0) {
-            VIR_FREE(cachedir);
-            return NULL;
-        }
-
-    }
-    return path;
-}
-
-
 int
 virLogHandlerDomainOpenLogFile(virLogHandlerPtr handler,
                                const char *driver,
                                const unsigned char *domuuid,
                                const char *domname,
+                               const char *path,
                                ino_t *inode,
                                off_t *offset)
 {
     size_t i;
     virLogHandlerLogFilePtr file = NULL;
     int pipefd[2] = { -1, -1 };
-    char *path;
 
     virObjectLock(handler);
 
     handler->inhibitor(true, handler->opaque);
 
-    if (!(path = virLogHandlerGetLogFilePathForDomain(handler,
-                                                      driver,
-                                                      domuuid,
-                                                      domname)))
-        goto error;
-
     for (i = 0; i < handler->nfiles; i++) {
         if (STREQ(virRotatingFileWriterGetPath(handler->files[i]->file),
                   path)) {
@@ -449,8 +413,6 @@ virLogHandlerDomainOpenLogFile(virLogHandlerPtr handler,
         goto error;
     }
 
-    VIR_FREE(path);
-
     *inode = virRotatingFileWriterGetINode(file->file);
     *offset = virRotatingFileWriterGetOffset(file->file);
 
@@ -458,7 +420,6 @@ virLogHandlerDomainOpenLogFile(virLogHandlerPtr handler,
     return pipefd[1];
 
  error:
-    VIR_FREE(path);
     VIR_FORCE_CLOSE(pipefd[0]);
     VIR_FORCE_CLOSE(pipefd[1]);
     handler->inhibitor(false, handler->opaque);
@@ -470,25 +431,16 @@ virLogHandlerDomainOpenLogFile(virLogHandlerPtr handler,
 
 int
 virLogHandlerDomainGetLogFilePosition(virLogHandlerPtr handler,
-                                      const char *driver,
-                                      const unsigned char *domuuid,
-                                      const char *domname,
+                                      const char *path,
                                       ino_t *inode,
                                       off_t *offset)
 {
-    char *path;
     virLogHandlerLogFilePtr file = NULL;
     int ret = -1;
     size_t i;
 
     virObjectLock(handler);
 
-    if (!(path = virLogHandlerGetLogFilePathForDomain(handler,
-                                                      driver,
-                                                      domuuid,
-                                                      domname)))
-        goto cleanup;
-
     for (i = 0; i < handler->nfiles; i++) {
         if (STREQ(virRotatingFileWriterGetPath(handler->files[i]->file),
                   path)) {
@@ -499,8 +451,8 @@ virLogHandlerDomainGetLogFilePosition(virLogHandlerPtr handler,
 
     if (!file) {
         virReportError(VIR_ERR_INTERNAL_ERROR,
-                       _("No open log file for domain %s"),
-                       domname);
+                       _("No open log file %s"),
+                       path);
         goto cleanup;
     }
 
@@ -510,7 +462,6 @@ virLogHandlerDomainGetLogFilePosition(virLogHandlerPtr handler,
     ret = 0;
 
  cleanup:
-    VIR_FREE(path);
     virObjectUnlock(handler);
     return ret;
 }
@@ -518,26 +469,17 @@ virLogHandlerDomainGetLogFilePosition(virLogHandlerPtr handler,
 
 char *
 virLogHandlerDomainReadLogFile(virLogHandlerPtr handler,
-                               const char *driver,
-                               const unsigned char *domuuid,
-                               const char *domname,
+                               const char *path,
                                ino_t inode,
                                off_t offset,
                                size_t maxlen)
 {
-    char *path;
     virRotatingFileReaderPtr file = NULL;
     char *data = NULL;
     ssize_t got;
 
     virObjectLock(handler);
 
-    if (!(path = virLogHandlerGetLogFilePathForDomain(handler,
-                                                      driver,
-                                                      domuuid,
-                                                      domname)))
-        goto error;
-
     if (!(file = virRotatingFileReaderNew(path, DEFAULT_MAX_BACKUP)))
         goto error;
 
@@ -554,11 +496,9 @@ virLogHandlerDomainReadLogFile(virLogHandlerPtr handler,
 
     virRotatingFileReaderFree(file);
     virObjectUnlock(handler);
-    VIR_FREE(path);
     return data;
 
  error:
-    VIR_FREE(path);
     VIR_FREE(data);
     virRotatingFileReaderFree(file);
     virObjectUnlock(handler);

src/logging/log_handler.h

@@ -47,20 +47,17 @@ int virLogHandlerDomainOpenLogFile(virLogHandlerPtr handler,
                                    const char *driver,
                                    const unsigned char *domuuid,
                                    const char *domname,
+                                   const char *path,
                                    ino_t *inode,
                                    off_t *offset);
 
 int virLogHandlerDomainGetLogFilePosition(virLogHandlerPtr handler,
-                                          const char *driver,
-                                          const unsigned char *domuuid,
-                                          const char *domname,
+                                          const char *path,
                                           ino_t *inode,
                                           off_t *offset);
 
 char *virLogHandlerDomainReadLogFile(virLogHandlerPtr handler,
-                                     const char *driver,
-                                     const unsigned char *domuuid,
-                                     const char *domname,
+                                     const char *path,
                                      ino_t inode,
                                      off_t offset,
                                      size_t maxlen);

src/logging/log_manager.c

@@ -156,6 +156,7 @@ virLogManagerDomainOpenLogFile(virLogManagerPtr mgr,
                                const char *driver,
                                const unsigned char *domuuid,
                                const char *domname,
+                               const char *path,
                                unsigned int flags,
                                ino_t *inode,
                                off_t *offset)
@@ -172,6 +173,7 @@ virLogManagerDomainOpenLogFile(virLogManagerPtr mgr,
     args.driver = (char *)driver;
     memcpy(args.dom.uuid, domuuid, VIR_UUID_BUFLEN);
     args.dom.name = (char *)domname;
+    args.path = (char *)path;
     args.flags = flags;
 
     if (virNetClientProgramCall(mgr->program,
@@ -211,9 +213,7 @@ virLogManagerDomainOpenLogFile(virLogManagerPtr mgr,
 
 int
 virLogManagerDomainGetLogFilePosition(virLogManagerPtr mgr,
-                                      const char *driver,
-                                      const unsigned char *domuuid,
-                                      const char *domname,
+                                      const char *path,
                                       unsigned int flags,
                                       ino_t *inode,
                                       off_t *offset)
@@ -225,9 +225,7 @@ virLogManagerDomainGetLogFilePosition(virLogManagerPtr mgr,
     memset(&args, 0, sizeof(args));
     memset(&ret, 0, sizeof(ret));
 
-    args.driver = (char *)driver;
-    memcpy(args.dom.uuid, domuuid, VIR_UUID_BUFLEN);
-    args.dom.name = (char *)domname;
+    args.path = (char *)path;
     args.flags = flags;
 
     if (virNetClientProgramCall(mgr->program,
@@ -250,9 +248,7 @@ virLogManagerDomainGetLogFilePosition(virLogManagerPtr mgr,
 
 char *
 virLogManagerDomainReadLogFile(virLogManagerPtr mgr,
-                               const char *driver,
-                               const unsigned char *domuuid,
-                               const char *domname,
+                               const char *path,
                                ino_t inode,
                                off_t offset,
                                size_t maxlen,
@@ -267,9 +263,7 @@ virLogManagerDomainReadLogFile(virLogManagerPtr mgr,
     memset(&args, 0, sizeof(args));
     memset(&ret, 0, sizeof(ret));
 
-    args.driver = (char *)driver;
-    memcpy(args.dom.uuid, domuuid, VIR_UUID_BUFLEN);
-    args.dom.name = (char *)domname;
+    args.path = (char *)path;
     args.flags = flags;
     args.pos.inode = inode;
     args.pos.offset = offset;

src/logging/log_manager.h

@@ -37,22 +37,19 @@ int virLogManagerDomainOpenLogFile(virLogManagerPtr mgr,
                                    const char *driver,
                                    const unsigned char *domuuid,
                                    const char *domname,
+                                   const char *path,
                                    unsigned int flags,
                                    ino_t *inode,
                                    off_t *offset);
 
 int virLogManagerDomainGetLogFilePosition(virLogManagerPtr mgr,
-                                          const char *driver,
-                                          const unsigned char *domuuid,
-                                          const char *domname,
+                                          const char *path,
                                           unsigned int flags,
                                           ino_t *inode,
                                           off_t *offset);
 
 char *virLogManagerDomainReadLogFile(virLogManagerPtr mgr,
-                                     const char *driver,
-                                     const unsigned char *domuuid,
-                                     const char *domname,
+                                     const char *path,
                                      ino_t inode,
                                      off_t offset,
                                      size_t maxlen,

src/logging/log_protocol.x

@@ -35,6 +35,7 @@ typedef struct virLogManagerProtocolLogFilePosition virLogManagerProtocolLogFile
 struct virLogManagerProtocolDomainOpenLogFileArgs {
     virLogManagerProtocolNonNullString driver;
     virLogManagerProtocolDomain dom;
+    virLogManagerProtocolNonNullString path;
     unsigned int flags;
 };
 
@@ -43,8 +44,7 @@ struct virLogManagerProtocolDomainOpenLogFileRet {
 };
 
 struct virLogManagerProtocolDomainGetLogFilePositionArgs {
-    virLogManagerProtocolNonNullString driver;
-    virLogManagerProtocolDomain dom;
+    virLogManagerProtocolNonNullString path;
     unsigned int flags;
 };
 
@@ -53,8 +53,7 @@ struct virLogManagerProtocolDomainGetLogFilePositionRet {
 };
 
 struct virLogManagerProtocolDomainReadLogFileArgs {
-    virLogManagerProtocolNonNullString driver;
-    virLogManagerProtocolDomain dom;
+    virLogManagerProtocolNonNullString path;
     virLogManagerProtocolLogFilePosition pos;
     unsigned hyper maxlen;
     unsigned int flags;

src/qemu/qemu_domain.c

@@ -85,8 +85,7 @@ struct _qemuDomainLogContext {
     int readfd; /* Only used if manager == NULL */
     off_t pos;
     ino_t inode; /* Only used if manager != NULL */
-    unsigned char uuid[VIR_UUID_BUFLEN]; /* Only used if manager != NULL */
-    char *name; /* Only used if manager != NULL */
+    char *path;
     virLogManagerPtr manager;
 };
 
@@ -2285,7 +2284,6 @@ qemuDomainLogContextPtr qemuDomainLogContextNew(virQEMUDriverPtr driver,
 {
     virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
     qemuDomainLogContextPtr ctxt = NULL;
-    char *logfile = NULL;
 
     if (VIR_ALLOC(ctxt) < 0)
         goto error;
@@ -2295,37 +2293,33 @@ qemuDomainLogContextPtr qemuDomainLogContextNew(virQEMUDriverPtr driver,
     ctxt->readfd = -1;
     virAtomicIntSet(&ctxt->refs, 1);
 
+    if (virAsprintf(&ctxt->path, "%s/%s.log", cfg->logDir, vm->def->name) < 0)
+        goto error;
+
     if (cfg->stdioLogD) {
         ctxt->manager = virLogManagerNew(virQEMUDriverIsPrivileged(driver));
         if (!ctxt->manager)
             goto error;
 
-        if (VIR_STRDUP(ctxt->name, vm->def->name) < 0)
-            goto error;
-
-        memcpy(ctxt->uuid, vm->def->uuid, VIR_UUID_BUFLEN);
-
         ctxt->writefd = virLogManagerDomainOpenLogFile(ctxt->manager,
                                                        "qemu",
                                                        vm->def->uuid,
                                                        vm->def->name,
+                                                       ctxt->path,
                                                        0,
                                                        &ctxt->inode,
                                                        &ctxt->pos);
         if (ctxt->writefd < 0)
             goto error;
     } else {
-        if (virAsprintf(&logfile, "%s/%s.log", cfg->logDir, vm->def->name) < 0)
-            goto error;
-
-        if ((ctxt->writefd = open(logfile, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)) < 0) {
+        if ((ctxt->writefd = open(ctxt->path, O_WRONLY | O_CREAT | O_APPEND, S_IRUSR | S_IWUSR)) < 0) {
             virReportSystemError(errno, _("failed to create logfile %s"),
-                                 logfile);
+                                 ctxt->path);
             goto error;
         }
         if (virSetCloseExec(ctxt->writefd) < 0) {
             virReportSystemError(errno, _("failed to set close-on-exec flag on %s"),
-                                 logfile);
+                                 ctxt->path);
             goto error;
         }
 
@@ -2336,33 +2330,32 @@ qemuDomainLogContextPtr qemuDomainLogContextNew(virQEMUDriverPtr driver,
             !virQEMUDriverIsPrivileged(driver) &&
             ftruncate(ctxt->writefd, 0) < 0) {
             virReportSystemError(errno, _("failed to truncate %s"),
-                                 logfile);
+                                 ctxt->path);
             goto error;
         }
 
         if (mode == QEMU_DOMAIN_LOG_CONTEXT_MODE_START) {
-            if ((ctxt->readfd = open(logfile, O_RDONLY, S_IRUSR | S_IWUSR)) < 0) {
+            if ((ctxt->readfd = open(ctxt->path, O_RDONLY, S_IRUSR | S_IWUSR)) < 0) {
                 virReportSystemError(errno, _("failed to open logfile %s"),
-                                     logfile);
+                                     ctxt->path);
                 goto error;
             }
             if (virSetCloseExec(ctxt->readfd) < 0) {
                 virReportSystemError(errno, _("failed to set close-on-exec flag on %s"),
-                                     logfile);
+                                     ctxt->path);
                 goto error;
             }
         }
 
         if ((ctxt->pos = lseek(ctxt->writefd, 0, SEEK_END)) < 0) {
             virReportSystemError(errno, _("failed to seek in log file %s"),
-                                 logfile);
+                                 ctxt->path);
             goto error;
         }
     }
 
  cleanup:
     virObjectUnref(cfg);
-    VIR_FREE(logfile);
     return ctxt;
 
  error:
@@ -2415,9 +2408,7 @@ ssize_t qemuDomainLogContextRead(qemuDomainLogContextPtr ctxt,
     size_t buflen;
     if (ctxt->manager) {
         buf = virLogManagerDomainReadLogFile(ctxt->manager,
-                                             "qemu",
-                                             ctxt->uuid,
-                                             ctxt->name,
+                                             ctxt->path,
                                              ctxt->inode,
                                              ctxt->pos,
                                              1024 * 128,
@@ -2466,9 +2457,7 @@ void qemuDomainLogContextMarkPosition(qemuDomainLogContextPtr ctxt)
 {
     if (ctxt->manager)
         virLogManagerDomainGetLogFilePosition(ctxt->manager,
-                                              "qemu",
-                                              ctxt->uuid,
-                                              ctxt->name,
+                                              ctxt->path,
                                               0,
                                               &ctxt->inode,
                                               &ctxt->pos);
@@ -2497,7 +2486,7 @@ void qemuDomainLogContextFree(qemuDomainLogContextPtr ctxt)
         return;
 
     virLogManagerFree(ctxt->manager);
-    VIR_FREE(ctxt->name);
+    VIR_FREE(ctxt->path);
     VIR_FORCE_CLOSE(ctxt->writefd);
     VIR_FORCE_CLOSE(ctxt->readfd);
     VIR_FREE(ctxt);