Fix eventual segmentation violation in imap4d

The coredump occurred if a recently started child received a
termination signal before initializing iostream.

* imap4d/bye.c (imap4d_bye0): Rename to imap4d_bye_command.
All uses changed.
* imap4d/io.c (io_untagged_response): Check if iostream is
initialized.

4 files changed, 21 insertions, 12 deletions

diff --git a/imap4d/bye.c b/imap4d/bye.c
index 47a95976b..6765e9edb 100644
--- a/imap4d/bye.c
+++ b/imap4d/bye.c
@@ -20,7 +20,7 @@
 int
 imap4d_bye (int reason)
 {
-  return imap4d_bye0 (reason, NULL);
+  return imap4d_bye_command (reason, NULL);
 }
 
 static jmp_buf pipejmp;
@@ -32,7 +32,7 @@ sigpipe (int sig)
 }
 
 int
-imap4d_bye0 (int reason, struct imap4d_command *command)
+imap4d_bye_command (int reason, struct imap4d_command *command)
 {
   int status = EX_SOFTWARE;
 
diff --git a/imap4d/imap4d.h b/imap4d/imap4d.h
index 5d5287b5a..7a0cdafc1 100644
--- a/imap4d/imap4d.h
+++ b/imap4d/imap4d.h
@@ -252,7 +252,8 @@ void io_getline (char **pbuf, size_t *psize, size_t *pnbytes);
 void io_setio (int, int, struct mu_tls_config *);
 void io_flush (void);
 int io_wait_input (int);
-  
+void io_enable_crlf (int);
+
 imap4d_tokbuf_t imap4d_tokbuf_init (void);
 void imap4d_tokbuf_destroy (imap4d_tokbuf_t *tok);
 int imap4d_tokbuf_argc (imap4d_tokbuf_t tok);
@@ -392,7 +393,7 @@ extern void imap4d_set_observer (mu_mailbox_t mbox);
 extern RETSIGTYPE imap4d_master_signal (int);
 extern RETSIGTYPE imap4d_child_signal (int);
 extern int imap4d_bye (int);
-extern int imap4d_bye0 (int reason, struct imap4d_command *command);
+extern int imap4d_bye_command (int, struct imap4d_command *);
 void imap4d_enter_critical (void);
 void imap4d_leave_critical (void);
 
@@ -462,7 +463,6 @@ int util_attribute_matches_flag (mu_attribute_t attr, const char *item);
 int util_uidvalidity (mu_mailbox_t smbox, unsigned long *uidvp);
 
   
-int util_is_master (void);
 void util_bye (void);  
 void util_chdir (const char *homedir);
 int is_atom (const char *s);
diff --git a/imap4d/io.c b/imap4d/io.c
index aafbe44c7..a66e6b79a 100644
--- a/imap4d/io.c
+++ b/imap4d/io.c
@@ -289,6 +289,21 @@ io_untagged_response (int rc, const char *format, ...)
   int status;
   va_list ap;
 
+  if (iostream == NULL)
+    {
+      if (rc == RESP_BYE)
+	/* RESP_BYE can be emitted when iostream has not been initialized,
+	   e.g. when a recently started child receives termination signal
+	   during initialization. */
+	return 0;
+      mu_diag_output (MU_DIAG_ERROR,
+		      /* TANSLATORS: %s is replaced with the untagged response
+			 name, followed by a space character. */
+		      _("iostream is NULL while trying to send the %suntagged response"),
+		      sc2string (rc));
+      exit (EX_SOFTWARE);
+    }
+  
   mu_stream_printf (iostream, "* %s", sc2string (rc));
   va_start (ap, format);
   status = mu_stream_vprintf (iostream, format, ap);
@@ -388,12 +403,6 @@ io_flush ()
   mu_stream_flush (iostream);
 }
 
-int
-util_is_master ()
-{
-  return iostream == NULL;
-}
-
 void
 io_getline (char **pbuf, size_t *psize, size_t *pnbytes)
 {
diff --git a/imap4d/logout.c b/imap4d/logout.c
index 9ffdc8f28..69e5224f2 100644
--- a/imap4d/logout.c
+++ b/imap4d/logout.c
@@ -34,6 +34,6 @@ imap4d_logout (struct imap4d_session *session,
 {
   if (imap4d_tokbuf_argc (tok) != 2)
     return io_completion_response (command, RESP_BAD, "Invalid arguments");
-  imap4d_bye0 (OK, command);
+  imap4d_bye_command (OK, command);
   return 0;
 }