--- a/packages/language/c/libc/stdio/current/ChangeLog
+++ b/packages/language/c/libc/stdio/current/ChangeLog
@@ -1,3 +1,12 @@
+2009-08-20  Uwe Kindler  <uwe_kindler@web.de>
+
+	* cdl/stdio.cdl Added option CYGIMP_LIBC_STDIO_C99_SNPRINTF
+	for activation of C99 compliant snprintf() return value.
+	* src/output/vfnprintf.cxx: Added optional C99 compliant return
+	value calculation.
+	* tests/snprintf.c: New test for snprintf including C99
+	implementation.
+
 2009-08-07  Jonathan Larmour  <jifl@eCosCentric.com>
 
 	* src/common/vsnprintf.cxx (class Cyg_VsnprintfStream):

--- a/packages/language/c/libc/stdio/current/cdl/stdio.cdl
+++ b/packages/language/c/libc/stdio/current/cdl/stdio.cdl
@@ -8,7 +8,7 @@
 ## ####ECOSGPLCOPYRIGHTBEGIN####                                            
 ## -------------------------------------------                              
 ## This file is part of eCos, the Embedded Configurable Operating System.   
-## Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
+## Copyright (C) 1998, 1999, 2000, 2001, 2002, 2009 Free Software Foundation, Inc.
 ##
 ## eCos is free software; you can redistribute it and/or modify it under    
 ## the terms of the GNU General Public License as published by the Free     
@@ -378,6 +378,19 @@ cdl_package CYGPKG_LIBC_STDIO {
             the streams to be locked when accessed by
             multiple threads simultaneously."
     }
+	
+    cdl_option CYGIMP_LIBC_STDIO_C99_SNPRINTF {
+        display       "C99 compliant snprintf() family"
+        default_value 0
+        description   "
+                This option allows C99 compliant implementation of 
+                snprintf() family (i.e. snprintf(), vsnprintf()) 
+                of functions. C99 compliant snprintf() functions
+                return the number of characters that would have been written 
+                to a sufficiently sized buffer (excluding the '\\0'). 
+                If this option is disabled, the functions simply return 
+                the number of bytes that have been written to the buffer."
+    }
     
 
 # ====================================================================
@@ -435,7 +448,7 @@ cdl_package CYGPKG_LIBC_STDIO {
             flavor  data
             no_define
             calculated { 
-                "tests/sprintf1 tests/sprintf2 tests/sscanf tests/stdiooutput " 
+                "tests/sprintf1 tests/sprintf2 tests/snprintf tests/sscanf tests/stdiooutput " 
                 . ((CYGPKG_IO_FILEIO && CYGPKG_FS_RAM) ? "tests/fileio " : "")
             }
             description   "

--- a/packages/language/c/libc/stdio/current/src/output/vfnprintf.cxx
+++ b/packages/language/c/libc/stdio/current/src/output/vfnprintf.cxx
@@ -8,7 +8,7 @@
 // ####ECOSGPLCOPYRIGHTBEGIN####                                            
 // -------------------------------------------                              
 // This file is part of eCos, the Embedded Configurable Operating System.   
-// Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc.
+// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2009 Free Software Foundation, Inc.
 //
 // eCos is free software; you can redistribute it and/or modify it under    
 // the terms of the GNU General Public License as published by the Free     
@@ -206,6 +206,17 @@ vfnprintf ( FILE *stream, size_t n, cons
         /*
          * BEWARE, these `goto error' on error, and PAD uses `n'.
          */
+#ifdef CYGIMP_LIBC_STDIO_C99_SNPRINTF
+#define PRINT(ptr, len)                                                      \
+CYG_MACRO_START                                                              \
+    if ((size_t)(ret + 1) < n) {                                             \
+        cyg_ucount32 length = MIN( (cyg_ucount32) len, n - ret - 1);         \
+        if (((Cyg_OutputStream *)stream)->write( (const cyg_uint8 *)ptr,     \
+                                            length, &length ))               \
+            goto error;                                                      \
+    }                                                                        \
+CYG_MACRO_END
+#else
 #define PRINT(ptr, len)                                                      \
 CYG_MACRO_START                                                              \
     cyg_ucount32 length = MIN( (cyg_ucount32) len, n - ret - 1);             \
@@ -217,7 +228,7 @@ CYG_MACRO_START                         
         goto done;                                                           \
     }                                                                        \
 CYG_MACRO_END
-
+#endif // CYGIMP_LIBC_STDIO_C99_SNPRINTF
 
 #define PAD(howmany, with)                                                   \
 CYG_MACRO_START                                                              \
@@ -276,7 +287,11 @@ CYG_MACRO_END
                         PRINT(cp, y);
                         ret += y;
                 }
+#ifdef CYGIMP_LIBC_STDIO_C99_SNPRINTF
+                if (x <= 0)
+#else
                 if ((x <= 0) || (ret >= (int)n))  // @@@ this check with n isn't good enough
+#endif
                         goto done;
                 fmt++;          /* skip over '%' */
 

new file mode 100644
--- /dev/null
+++ b/packages/language/c/libc/stdio/current/tests/snprintf.c
@@ -0,0 +1,131 @@
+//=================================================================
+//
+//        snprintf.c
+//
+//        Testcase for C library snprintf() implementation
+//
+//=================================================================
+// ####ECOSGPLCOPYRIGHTBEGIN####
+// -------------------------------------------
+// This file is part of eCos, the Embedded Configurable Operating System.
+// Copyright (C) 1998, 1999, 2000, 2001, 2002, 2009 Free Software Foundation, Inc.
+//
+// eCos is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License as published by the Free
+// Software Foundation; either version 2 or (at your option) any later
+// version.
+//
+// eCos is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+// for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with eCos; if not, write to the Free Software Foundation, Inc.,
+// 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+//
+// As a special exception, if other files instantiate templates or use
+// macros or inline functions from this file, or you compile this file
+// and link it with other works to produce a work based on this file,
+// this file does not by itself cause the resulting work to be covered by
+// the GNU General Public License. However the source code for this file
+// must still be made available in accordance with section (3) of the GNU
+// General Public License v2.
+//
+// This exception does not invalidate any other reasons why a work based
+// on this file might be covered by the GNU General Public License.
+// -------------------------------------------
+// ####ECOSGPLCOPYRIGHTEND####
+//=================================================================
+//#####DESCRIPTIONBEGIN####
+//
+// Author(s):       Uwe Kindler
+// Contributors:
+// Date:            2009-08-05
+// Description:     Contains testcode for C library snprintf() function
+//
+//
+//####DESCRIPTIONEND####
+
+// CONFIGURATION
+
+#include <pkgconf/libc_stdio.h>   // Configuration header
+
+// INCLUDES
+
+#include <stdio.h>
+#include <cyg/infra/testcase.h>
+
+static int my_strnlen(const char *s, size_t maxlen)
+{
+    const char *ptr;
+    const char *endptr;
+
+    ptr = s;
+    endptr = s + maxlen;
+    while ((*ptr != '\0') && (ptr != endptr))
+    {
+        ptr++;
+    }
+
+    return (int)(ptr-s);
+} // my_strlen()
+
+static void
+test( CYG_ADDRWORD data )
+{
+    static char x[32];
+    static char y[4];
+    int xret;
+    int yret;
+    int xstrlen;
+    int ystrlen;
+
+    // fill buffer to ensure that there are no zeros in the buffers
+    memset(x, 0xFF, sizeof(x));
+    memset(y, 0xFF, sizeof(y));
+    
+    // print into a buffer with sufficient size 
+    xret = snprintf(x, sizeof(x), "%d:%d:%d:%d", 1, 2, 3, 4);
+    xstrlen = my_strnlen(x, sizeof(x));
+    
+    // print into a buffer that is too small
+    yret = snprintf(y, sizeof(y), "%d:%d:%d:%d", 1, 2, 3, 4);
+    ystrlen = my_strnlen(y, sizeof(y));
+    
+    CYG_TEST_PASS_FAIL(xret == xstrlen, "[buffer > strlen] return code");
+    
+#ifdef CYGIMP_LIBC_STDIO_C99_SNPRINTF
+    // C99 compliant implementation returns the number of characters that 
+    // would have been written had size been sufficiently large, 
+    // not counting the terminating nul character
+    CYG_TEST_PASS_FAIL(xret == yret, "[buffer < strlen] return code");
+    CYG_TEST_INFO("C99 compliant implementation of snprintf()");
+#else
+    // default eCos implementation returns number of bytes written into
+    // the buffer without terminating nul character
+    CYG_TEST_PASS_FAIL(yret == ystrlen, "[buffer < strlen] return code");
+    CYG_TEST_INFO("Default implementation of snprintf() (no C99 compliance)");
+#endif
+
+
+    CYG_TEST_FINISH("Finished tests from testcase " __FILE__
+                    " for C library snprintf() function return values");
+
+} // test()
+
+int
+main(int argc, char *argv[])
+{
+    CYG_TEST_INIT();
+
+    CYG_TEST_INFO("Starting tests from testcase " __FILE__ " for C "
+                  "library snprintf() function return values");
+    CYG_TEST_INFO("These test return values of snprinf() family of functions");
+
+    test(0);
+
+    return 0;
+} // main()
+
+// EOF snprintf.c