slirp: Enable multi-instance support for the smb service

Push the smb state, smb_dir, into SlirpState and construct it in a way
that allows multiple smb instances (one per slirp stack). Remove the smb
directory on slirp cleanup instead of qemu termination. As VLAN clients
are also cleaned up on process termination, no feature is lost.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

net.c

@@ -681,6 +681,9 @@ typedef struct SlirpState {
     TAILQ_ENTRY(SlirpState) entry;
     VLANClientState *vc;
     Slirp *slirp;
+#ifndef _WIN32
+    char smb_dir[128];
+#endif
 } SlirpState;
 
 static struct slirp_config_str *slirp_configs;
@@ -699,6 +702,9 @@ static const char *legacy_smb_export;
 
 static void slirp_smb(SlirpState *s, Monitor *mon, const char *exported_dir,
                       struct in_addr vserver_addr);
+static void slirp_smb_cleanup(SlirpState *s);
+#else
+static inline void slirp_smb_cleanup(SlirpState *s) { }
 #endif
 
 int slirp_can_output(void *opaque)
@@ -736,6 +742,7 @@ static void net_slirp_cleanup(VLANClientState *vc)
     SlirpState *s = vc->opaque;
 
     slirp_cleanup(s->slirp);
+    slirp_smb_cleanup(s);
     TAILQ_REMOVE(&slirp_stacks, s, entry);
     qemu_free(s);
 }
@@ -1012,35 +1019,38 @@ void net_slirp_redir(const char *redir_str)
 
 #ifndef _WIN32
 
-static char smb_dir[1024];
-
 /* automatic user mode samba server configuration */
-static void smb_exit(void)
+static void slirp_smb_cleanup(SlirpState *s)
 {
-    char cmd[1024];
+    char cmd[128];
 
-    snprintf(cmd, sizeof(cmd), "rm -rf %s", smb_dir);
-    system(cmd);
+    if (s->smb_dir[0] != '\0') {
+        snprintf(cmd, sizeof(cmd), "rm -rf %s", s->smb_dir);
+        system(cmd);
+        s->smb_dir[0] = '\0';
+    }
 }
 
 static void slirp_smb(SlirpState* s, Monitor *mon, const char *exported_dir,
                       struct in_addr vserver_addr)
 {
-    char smb_conf[1024];
-    char smb_cmdline[1024];
+    static int instance;
+    char smb_conf[128];
+    char smb_cmdline[128];
     FILE *f;
 
-    /* XXX: better tmp dir construction */
-    snprintf(smb_dir, sizeof(smb_dir), "/tmp/qemu-smb.%ld", (long)getpid());
-    if (mkdir(smb_dir, 0700) < 0) {
-        config_error(mon, "could not create samba server dir '%s'\n", smb_dir);
+    snprintf(s->smb_dir, sizeof(s->smb_dir), "/tmp/qemu-smb.%ld-%d",
+             (long)getpid(), instance++);
+    if (mkdir(s->smb_dir, 0700) < 0) {
+        config_error(mon, "could not create samba server dir '%s'\n",
+                     s->smb_dir);
         return;
     }
-    snprintf(smb_conf, sizeof(smb_conf), "%s/%s", smb_dir, "smb.conf");
+    snprintf(smb_conf, sizeof(smb_conf), "%s/%s", s->smb_dir, "smb.conf");
 
     f = fopen(smb_conf, "w");
     if (!f) {
-        smb_exit();
+        slirp_smb_cleanup(s);
         config_error(mon, "could not create samba server "
                      "configuration file '%s'\n", smb_conf);
         return;
@@ -1059,20 +1069,20 @@ static void slirp_smb(SlirpState* s, Monitor *mon, const char *exported_dir,
             "path=%s\n"
             "read only=no\n"
             "guest ok=yes\n",
-            smb_dir,
-            smb_dir,
-            smb_dir,
-            smb_dir,
-            smb_dir,
+            s->smb_dir,
+            s->smb_dir,
+            s->smb_dir,
+            s->smb_dir,
+            s->smb_dir,
             exported_dir
             );
     fclose(f);
-    atexit(smb_exit);
 
     snprintf(smb_cmdline, sizeof(smb_cmdline), "%s -s %s",
              SMBD_COMMAND, smb_conf);
 
     if (slirp_add_exec(s->slirp, 0, smb_cmdline, vserver_addr, 139) < 0) {
+        slirp_smb_cleanup(s);
         config_error(mon, "conflicting/invalid smbserver address\n");
     }
 }