[Qemu-devel] [PATCH v2] tap: Add optional parameters to up/down script

[Sasha Levin <levinsasha928@gmail.com>]

This allows the user to add custom parameters to the up or down
scripts.

Extra parameters are useful in more complex networking scenarios
where we would like to configure network devices when starting
or stopping the guest.

Cc: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
---
 net.c     |    8 ++++++++
 net/tap.c |   45 ++++++++++++++++++++++++++++++++++++---------
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/net.c b/net.c
index d05930c..bb27598 100644
--- a/net.c
+++ b/net.c
@@ -952,10 +952,18 @@ static const struct {
                 .type = QEMU_OPT_STRING,
                 .help = "script to initialize the interface",
             }, {
+                .name = "scriptparams",
+                .type = QEMU_OPT_STRING,
+                .help = "parameters for the initialization script",
+            }, {
                 .name = "downscript",
                 .type = QEMU_OPT_STRING,
                 .help = "script to shut down the interface",
             }, {
+                .name = "downscriptparams",
+                .type = QEMU_OPT_STRING,
+                .help = "parameters for the deinitialization script",
+            }, {
                 .name = "sndbuf",
                 .type = QEMU_OPT_SIZE,
                 .help = "send buffer limit"
diff --git a/net/tap.c b/net/tap.c
index 1f26dc9..f2f1fe5 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -53,6 +53,7 @@ typedef struct TAPState {
     int fd;
     char down_script[1024];
     char down_script_arg[128];
+    char down_script_params[1024];
     uint8_t buf[TAP_BUFSIZE];
     unsigned int read_poll : 1;
     unsigned int write_poll : 1;
@@ -62,7 +63,8 @@ typedef struct TAPState {
     unsigned host_vnet_hdr_len;
 } TAPState;
 
-static int launch_script(const char *setup_script, const char *ifname, int fd);
+static int launch_script(const char *setup_script, const char *ifname,
+                         const char *params, int fd);
 
 static int tap_can_send(void *opaque);
 static void tap_send(void *opaque);
@@ -287,7 +289,8 @@ static void tap_cleanup(VLANClientState *nc)
     qemu_purge_queued_packets(nc);
 
     if (s->down_script[0])
-        launch_script(s->down_script, s->down_script_arg, s->fd);
+        launch_script(s->down_script, s->down_script_arg,
+                      s->down_script_params, s->fd);
 
     tap_read_poll(s, 0);
     tap_write_poll(s, 0);
@@ -344,11 +347,12 @@ static TAPState *net_tap_fd_init(VLANState *vlan,
     return s;
 }
 
-static int launch_script(const char *setup_script, const char *ifname, int fd)
+static int launch_script(const char *setup_script, const char *ifname,
+                         const char *params, int fd)
 {
     sigset_t oldmask, mask;
     int pid, status;
-    char *args[3];
+    char *args[4];
     char **parg;
 
     sigemptyset(&mask);
@@ -371,6 +375,7 @@ static int launch_script(const char *setup_script, const char *ifname, int fd)
         parg = args;
         *parg++ = (char *)setup_script;
         *parg++ = (char *)ifname;
+        *parg++ = (char *)params;
         *parg = NULL;
         execv(setup_script, args);
         _exit(1);
@@ -392,7 +397,7 @@ static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
 {
     int fd, vnet_hdr_required;
     char ifname[128] = {0,};
-    const char *setup_script;
+    const char *setup_script, *setup_script_params;
 
     if (qemu_opt_get(opts, "ifname")) {
         pstrcpy(ifname, sizeof(ifname), qemu_opt_get(opts, "ifname"));
@@ -411,10 +416,15 @@ static int net_tap_init(QemuOpts *opts, int *vnet_hdr)
     }
 
     setup_script = qemu_opt_get(opts, "script");
+    setup_script_params = qemu_opt_get(opts, "scriptparams");
+    if (setup_script_params == NULL) {
+        setup_script_params = "";
+    }
+
     if (setup_script &&
         setup_script[0] != '\0' &&
         strcmp(setup_script, "no") != 0 &&
-        launch_script(setup_script, ifname, fd)) {
+        launch_script(setup_script, ifname, setup_script_params, fd)) {
         close(fd);
         return -1;
     }
@@ -432,9 +442,12 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan
     if (qemu_opt_get(opts, "fd")) {
         if (qemu_opt_get(opts, "ifname") ||
             qemu_opt_get(opts, "script") ||
+            qemu_opt_get(opts, "scriptparams") ||
             qemu_opt_get(opts, "downscript") ||
+            qemu_opt_get(opts, "downscriptparams") ||
             qemu_opt_get(opts, "vnet_hdr")) {
-            error_report("ifname=, script=, downscript= and vnet_hdr= is invalid with fd=");
+            error_report("ifname=, script=, downscript=, scriptparams=, "
+                         "downscriptparams= and vnet_hdr= is invalid with fd=");
             return -1;
         }
 
@@ -455,6 +468,14 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan
             qemu_opt_set(opts, "downscript", DEFAULT_NETWORK_DOWN_SCRIPT);
         }
 
+        if (!qemu_opt_get(opts, "scriptparams")) {
+            qemu_opt_set(opts, "scriptparams", "");
+        }
+
+        if (!qemu_opt_get(opts, "downscriptparams")) {
+            qemu_opt_set(opts, "downscriptparams", "");
+        }
+
         fd = net_tap_init(opts, &vnet_hdr);
         if (fd == -1) {
             return -1;
@@ -475,18 +496,24 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan
         snprintf(s->nc.info_str, sizeof(s->nc.info_str), "fd=%d", fd);
     } else {
         const char *ifname, *script, *downscript;
+        const char *scriptparams, *downscriptparams;
 
         ifname     = qemu_opt_get(opts, "ifname");
         script     = qemu_opt_get(opts, "script");
         downscript = qemu_opt_get(opts, "downscript");
+        scriptparams = qemu_opt_get(opts, "scriptparams");
+        downscriptparams = qemu_opt_get(opts, "downscriptparams");
 
         snprintf(s->nc.info_str, sizeof(s->nc.info_str),
-                 "ifname=%s,script=%s,downscript=%s",
-                 ifname, script, downscript);
+                 "ifname=%s,script=%s,scriptparams=%s,downscript=%s,"
+                 "downscriptparams=%s", ifname, script, scriptparams,
+                 downscript, downscriptparams);
 
         if (strcmp(downscript, "no") != 0) {
             snprintf(s->down_script, sizeof(s->down_script), "%s", downscript);
             snprintf(s->down_script_arg, sizeof(s->down_script_arg), "%s", ifname);
+            snprintf(s->down_script_params, sizeof(s->down_script_params), "%s",
+                     downscriptparams);
         }
     }
 
-- 
1.7.6.1