Add support for a exec callback in virExecWithHook

ChangeLog

@@ -1,3 +1,9 @@
+Thu Feb 26 16:01:04 GMT 2009 Daniel P. Berrange <berrange@redhat.com>
+
+	* src/libvirt_private.syms, src/util.c, src/util.h: Add new
+	virExecWithHook function to allow passing of a callback to run
+	between fork() & exec()
+
 Thu Feb 26 17:13:09 CET 2009 Daniel Veillard <veillard@redhat.com>
 
 	* Makefile.am configure.in examples/hellolibvirt/Makefile.am

src/libvirt_private.syms

@@ -294,6 +294,7 @@ virEnumToString;
 virEventAddHandle;
 virEventRemoveHandle;
 virExec;
+virExecWithHook;
 virSetCloseExec;
 virSetNonBlock;
 virFormatMacAddr;

src/util.c

@@ -202,7 +202,10 @@ __virExec(virConnectPtr conn,
           const fd_set *keepfd,
           pid_t *retpid,
           int infd, int *outfd, int *errfd,
-          int flags) {
+          int flags,
+          virExecHook hook,
+          void *data)
+{
     pid_t pid;
     int null, i, openmax;
     int pipeout[2] = {-1,-1};
@@ -416,6 +419,9 @@ __virExec(virConnectPtr conn,
         childerr != childout)
         close(childerr);
 
+    if (hook)
+        (hook)(data);
+
     if (envp)
         execve(argv[0], (char **) argv, (char**)envp);
     else
@@ -450,13 +456,16 @@ __virExec(virConnectPtr conn,
 }
 
 int
-virExec(virConnectPtr conn,
-        const char *const*argv,
-        const char *const*envp,
-        const fd_set *keepfd,
-        pid_t *retpid,
-        int infd, int *outfd, int *errfd,
-        int flags) {
+virExecWithHook(virConnectPtr conn,
+                const char *const*argv,
+                const char *const*envp,
+                const fd_set *keepfd,
+                pid_t *retpid,
+                int infd, int *outfd, int *errfd,
+                int flags,
+                virExecHook hook,
+                void *data)
+{
     char *argv_str;
 
     if ((argv_str = virArgvToString(argv)) == NULL) {
@@ -467,7 +476,21 @@ virExec(virConnectPtr conn,
     VIR_FREE(argv_str);
 
     return __virExec(conn, argv, envp, keepfd, retpid, infd, outfd, errfd,
-                     flags);
+                     flags, hook, data);
+}
+
+int
+virExec(virConnectPtr conn,
+        const char *const*argv,
+        const char *const*envp,
+        const fd_set *keepfd,
+        pid_t *retpid,
+        int infd, int *outfd, int *errfd,
+        int flags)
+{
+    return virExecWithHook(conn, argv, envp, keepfd, retpid,
+                           infd, outfd, errfd,
+                           flags, NULL, NULL);
 }
 
 static int
@@ -585,7 +608,7 @@ virRun(virConnectPtr conn,
 
     if ((execret = __virExec(conn, argv, NULL, NULL,
                              &childpid, -1, &outfd, &errfd,
-                             VIR_EXEC_NONE)) < 0) {
+                             VIR_EXEC_NONE, NULL, NULL)) < 0) {
         ret = execret;
         goto error;
     }

src/util.h

@@ -41,6 +41,21 @@ enum {
 int virSetNonBlock(int fd);
 int virSetCloseExec(int fd);
 
+/* This will execute in the context of the first child
+ * after fork() but before execve() */
+typedef int (*virExecHook)(void *data);
+
+int virExecWithHook(virConnectPtr conn,
+                    const char *const*argv,
+                    const char *const*envp,
+                    const fd_set *keepfd,
+                    int *retpid,
+                    int infd,
+                    int *outfd,
+                    int *errfd,
+                    int flags,
+                    virExecHook hook,
+                    void *data);
 int virExec(virConnectPtr conn,
             const char *const*argv,
             const char *const*envp,