[Qemu-devel] [PATCH v3 07/26] qio: add qio_channel_command_new_spawn_with_pre_exec()

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

Add a new function to let caller do some tuning thanks to a callback
before exec().

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
 include/io/channel-command.h | 18 ++++++++++++++++++
 io/channel-command.c         | 33 ++++++++++++++++++++++++++-------
 2 files changed, 44 insertions(+), 7 deletions(-)

diff --git a/include/io/channel-command.h b/include/io/channel-command.h
index 336d47fa5c..96c833daab 100644
--- a/include/io/channel-command.h
+++ b/include/io/channel-command.h
@@ -71,6 +71,24 @@ qio_channel_command_new_pid(int writefd,
                             int readfd,
                             pid_t pid);
 
+/**
+ * qio_channel_command_new_spawn_with_pre_exec:
+ * @argv: the NULL terminated list of command arguments
+ * @flags: the I/O mode, one of O_RDONLY, O_WRONLY, O_RDWR
+ * @errp: pointer to a NULL-initialized error object
+ *
+ * Create a channel for performing I/O with the
+ * command to be spawned with arguments @argv.
+ *
+ * Returns: the command channel object, or NULL on error
+ */
+QIOChannelCommand *
+qio_channel_command_new_spawn_with_pre_exec(const char *const argv[],
+                                            int flags,
+                                            void (*pre_exec_cb)(void *),
+                                            void *data,
+                                            Error **errp);
+
 /**
  * qio_channel_command_new_spawn:
  * @argv: the NULL terminated list of command arguments
diff --git a/io/channel-command.c b/io/channel-command.c
index 3e7eb17eff..05903ff194 100644
--- a/io/channel-command.c
+++ b/io/channel-command.c
@@ -46,9 +46,12 @@ qio_channel_command_new_pid(int writefd,
 
 #ifndef WIN32
 QIOChannelCommand *
-qio_channel_command_new_spawn(const char *const argv[],
-                              int flags,
-                              Error **errp)
+qio_channel_command_new_spawn_with_pre_exec(const char *const argv[],
+                                            int flags,
+                                            void (*pre_exec_cb)(void *),
+                                            void *data,
+                                            Error **errp)
+
 {
     pid_t pid = -1;
     int stdinfd[2] = { -1, -1 };
@@ -104,6 +107,10 @@ qio_channel_command_new_spawn(const char *const argv[],
             close(devnull);
         }
 
+        if (pre_exec_cb) {
+            pre_exec_cb(data);
+        }
+
         execv(argv[0], (char * const *)argv);
         _exit(1);
     }
@@ -139,12 +146,13 @@ qio_channel_command_new_spawn(const char *const argv[],
     }
     return NULL;
 }
-
 #else /* WIN32 */
 QIOChannelCommand *
-qio_channel_command_new_spawn(const char *const argv[],
-                              int flags,
-                              Error **errp)
+qio_channel_command_new_spawn_with_pre_exec(const char *const argv[],
+                                            int flags,
+                                            void (*pre_exec_cb)(void *),
+                                            void *data,
+                                            Error **errp)
 {
     error_setg_errno(errp, ENOSYS,
                      "Command spawn not supported on this platform");
@@ -152,6 +160,17 @@ qio_channel_command_new_spawn(const char *const argv[],
 }
 #endif /* WIN32 */
 
+
+QIOChannelCommand *
+qio_channel_command_new_spawn(const char *const argv[],
+                              int flags,
+                              Error **errp)
+{
+    return qio_channel_command_new_spawn_with_pre_exec(argv, flags,
+                                                       NULL, NULL, errp);
+}
+
+
 #ifndef WIN32
 static int qio_channel_command_abort(QIOChannelCommand *ioc,
                                      Error **errp)
-- 
2.18.0.rc1