Support non-standard vsnprintf() return code

[ngircd-alex.git] / src / ngircd / conn.c

diff --git a/src/ngircd/conn.c b/src/ngircd/conn.c
index 3f447c61ec367916f528f13a9da0852ac83eb0f4..fef568e4a17094b2513b9fbc9a722ed18a83f3d2 100644 (file)
--- a/src/ngircd/conn.c
+++ b/src/ngircd/conn.c
@@ -1,6 +1,6 @@
 /*
  * ngIRCd -- The Next Generation IRC Daemon
- * Copyright (c)2001-2013 Alexander Barton (alex@barton.de) and Contributors.
+ * Copyright (c)2001-2014 Alexander Barton (alex@barton.de) and Contributors.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -984,6 +984,7 @@ va_dcl
        size_t len;
        bool ok;
        va_list ap;
+       int r;
 
        assert( Idx > NONE );
        assert( Format != NULL );
@@ -993,7 +994,8 @@ va_dcl
 #else
        va_start( ap );
 #endif
-       if (vsnprintf( buffer, COMMAND_LEN - 2, Format, ap ) >= COMMAND_LEN - 2 ) {
+       r = vsnprintf(buffer, COMMAND_LEN - 2, Format, ap);
+       if (r >= COMMAND_LEN - 2 || r == -1) {
                /*
                 * The string that should be written to the socket is longer
                 * than the allowed size of COMMAND_LEN bytes (including both
@@ -1014,6 +1016,13 @@ va_dcl
                 * an other server only routing the message!), so the only
                 * option left is to shorten the string and to hope that the
                 * result is still somewhat useful ...
+                *
+                * Note:
+                * C99 states that vsnprintf() "returns the number of characters
+                * that would have been printed if the n were unlimited"; but
+                * according to the Linux manual page "glibc until 2.0.6 would
+                * return -1 when the output was truncated" -- so we have to
+                * handle both cases ...
                 *                                                   -alex-
                 */