1 files changed, 58 insertions, 26 deletions

diff --git a/util/log.c b/util/log.c
index c2198badf2..7837ff9917 100644
--- a/util/log.c
+++ b/util/log.c
@@ -45,7 +45,6 @@ static __thread FILE *thread_file;
 static __thread Notifier qemu_log_thread_cleanup_notifier;
 
 int qemu_loglevel;
-static bool log_append;
 static bool log_per_thread;
 static GArray *debug_regions;
 
@@ -80,13 +79,15 @@ static int log_thread_id(void)
 
 static void qemu_log_thread_cleanup(Notifier *n, void *unused)
 {
-    fclose(thread_file);
-    thread_file = NULL;
+    if (thread_file != stderr) {
+        fclose(thread_file);
+        thread_file = NULL;
+    }
 }
 
 /* Lock/unlock output. */
 
-FILE *qemu_log_trylock(void)
+static FILE *qemu_log_trylock_with_err(Error **errp)
 {
     FILE *logfile;
 
@@ -97,6 +98,9 @@ FILE *qemu_log_trylock(void)
                 = g_strdup_printf(global_filename, log_thread_id());
             logfile = fopen(filename, "w");
             if (!logfile) {
+                error_setg_errno(errp, errno,
+                                 "Error opening logfile %s for thread %d",
+                                 filename, log_thread_id());
                 return NULL;
             }
             thread_file = logfile;
@@ -123,6 +127,11 @@ FILE *qemu_log_trylock(void)
     return logfile;
 }
 
+FILE *qemu_log_trylock(void)
+{
+    return qemu_log_trylock_with_err(NULL);
+}
+
 void qemu_log_unlock(FILE *logfile)
 {
     if (logfile) {
@@ -266,40 +275,61 @@ static bool qemu_set_log_internal(const char *filename, bool changed_name,
 #endif
     qemu_loglevel = log_flags;
 
-    /*
-     * In all cases we only log if qemu_loglevel is set.
-     * Also:
-     *   If per-thread, open the file for each thread in qemu_log_lock.
-     *   If not daemonized we will always log either to stderr
-     *     or to a file (if there is a filename).
-     *   If we are daemonized, we will only log if there is a filename.
-     */
     daemonized = is_daemonized();
-    need_to_open_file = log_flags && !per_thread && (!daemonized || filename);
+    need_to_open_file = false;
+    if (!daemonized) {
+        /*
+         * If not daemonized we only log if qemu_loglevel is set, either to
+         * stderr or to a file (if there is a filename).
+         * If per-thread, open the file for each thread in qemu_log_trylock().
+         */
+        need_to_open_file = qemu_loglevel && !log_per_thread;
+    } else {
+        /*
+         * If we are daemonized, we will only log if there is a filename.
+         */
+        need_to_open_file = filename != NULL;
+    }
 
-    if (logfile && (!need_to_open_file || changed_name)) {
-        qatomic_rcu_set(&global_file, NULL);
-        if (logfile != stderr) {
+    if (logfile) {
+        fflush(logfile);
+        if (changed_name && logfile != stderr) {
             RCUCloseFILE *r = g_new0(RCUCloseFILE, 1);
             r->fd = logfile;
+            qatomic_rcu_set(&global_file, NULL);
             call_rcu(r, rcu_close_file, rcu);
+            logfile = NULL;
         }
-        logfile = NULL;
+    }
+
+    if (log_per_thread && daemonized) {
+        logfile = thread_file;
     }
 
     if (!logfile && need_to_open_file) {
         if (filename) {
-            logfile = fopen(filename, log_append ? "a" : "w");
-            if (!logfile) {
-                error_setg_errno(errp, errno, "Error opening logfile %s",
-                                 filename);
-                return false;
+            if (log_per_thread) {
+                logfile = qemu_log_trylock_with_err(errp);
+                if (!logfile) {
+                    return false;
+                }
+                qemu_log_unlock(logfile);
+            } else {
+                logfile = fopen(filename, "w");
+                if (!logfile) {
+                    error_setg_errno(errp, errno, "Error opening logfile %s",
+                                     filename);
+                    return false;
+                }
             }
             /* In case we are a daemon redirect stderr to logfile */
             if (daemonized) {
                 dup2(fileno(logfile), STDERR_FILENO);
                 fclose(logfile);
-                /* This will skip closing logfile in rcu_close_file. */
+                /*
+                 * This will skip closing logfile in rcu_close_file()
+                 * or qemu_log_thread_cleanup().
+                 */
                 logfile = stderr;
             }
         } else {
@@ -308,9 +338,11 @@ static bool qemu_set_log_internal(const char *filename, bool changed_name,
             logfile = stderr;
         }
 
-        log_append = 1;
-
-        qatomic_rcu_set(&global_file, logfile);
+        if (log_per_thread && daemonized) {
+            thread_file = logfile;
+        } else {
+            qatomic_rcu_set(&global_file, logfile);
+        }
     }
     return true;
 }