[Libguestfs] [libnbd PATCH v3 02/19] socket activation: clean up responsibilities of prep.sock.act.env.()

[Laszlo Ersek]

prepare_socket_activation_environment() is a construction function that is
supposed to fill in a string_vector object from the ground up. Right now
it has its responsibilities mixed up in two ways:

- it expects the caller to pass in a previously re-set string_vector,

- if it fails, it calls set_error() internally (with a blanket reference
  to "malloc").

Fix the first wart:

- pass in an *uninitialized* (only allocated) string vector from the
  caller, and initialize it in prepare_socket_activation_environment().

Document the second wart:

- in the caller, add a comment about the set_error() call that's
  internal to the callee.

Signed-off-by: Laszlo Ersek <lersek at redhat.com>
Reviewed-by: Eric Blake <eblake at redhat.com>
Acked-by: Richard W.M. Jones <rjones at redhat.com>
---

Notes:
    v4:
    
    - Pick up Eric's R-b.
    
    - Pick up Rich's A-b for initializing the string vector (via struct
      assignment) internally to prepare_socket_activation_environment().
    
    - Keep the set_error() call internal to
      prepare_socket_activation_environment(), just add a comment about it
      near the prepare_socket_activation_environment() call site [Rich].
      (Unfortunately, this creates a long series of rebase conflicts.)
    
    - Update the commit message.

 generator/states-connect-socket-activation.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/generator/states-connect-socket-activation.c b/generator/states-connect-socket-activation.c
index ddbccff8240d..61d3d1900f45 100644
--- a/generator/states-connect-socket-activation.c
+++ b/generator/states-connect-socket-activation.c
@@ -51,7 +51,7 @@ prepare_socket_activation_environment (string_vector *env)
   char *p;
   size_t i;
 
-  assert (env->len == 0);
+  *env = (string_vector)empty_vector;
 
   /* Reserve slots env[0] and env[1]. */
   p = strdup ("LISTEN_PID=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx");
@@ -99,7 +99,7 @@ STATE_MACHINE {
  CONNECT_SA.START:
   int s;
   struct sockaddr_un addr;
-  string_vector env = empty_vector;
+  string_vector env;
   pid_t pid;
 
   assert (!h->sock);
@@ -156,6 +156,7 @@  CONNECT_SA.START:
 
   if (prepare_socket_activation_environment (&env) == -1) {
     SET_NEXT_STATE (%.DEAD);
+    /* prepare_socket_activation_environment() calls set_error() internally */
     close (s);
     return 0;
   }