New. Taken from gnupg 1.9.

util/ChangeLog

@@ -1,3 +1,7 @@
+2004-10-15  Werner Koch  <wk@g10code.com>
+
+	* vasprintf.c: New.  Taken from gnupg 1.9.
+
 2004-10-14  Werner Koch  <wk@g10code.com>
 
 	* iobuf.c (iobuf_get_fd): Removed double check on directfp and

util/vasprintf.c

@@ -0,0 +1,169 @@
+/* Like vsprintf but provides a pointer to malloc'd storage, which must
+   be freed by the caller.
+   Copyright (C) 1994, 2002 Free Software Foundation, Inc.
+
+This file is part of the libiberty library.
+Libiberty is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public
+License as published by the Free Software Foundation; either
+version 2 of the License, or (at your option) any later version.
+
+Libiberty 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with libiberty; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA.  */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+
+#ifdef TEST
+int global_total_width;
+#endif
+
+int
+vasprintf (char **result, const char *format, va_list args)
+{
+  const char *p = format;
+  /* Add one to make sure that it is never zero, which might cause malloc
+     to return NULL.  */
+  int total_width = strlen (format) + 1;
+  va_list ap;
+
+#ifdef va_copy
+  va_copy (ap, args);
+#else
+#ifdef __va_copy
+  __va_copy (ap, args);
+#else
+  memcpy (&ap, args, sizeof (va_list));
+#endif /* __va_copy */
+#endif /* va_copy */
+
+  while (*p != '\0')
+    {
+      if (*p++ == '%')
+	{
+	  while (strchr ("-+ #0", *p))
+	    ++p;
+	  if (*p == '*')
+	    {
+	      ++p;
+	      total_width += abs (va_arg (ap, int));
+	    }
+	  else
+	    total_width += strtoul (p, (char**)&p, 10);
+	  if (*p == '.')
+	    {
+	      ++p;
+	      if (*p == '*')
+		{
+		  ++p;
+		  total_width += abs (va_arg (ap, int));
+		}
+	      else
+	      total_width += strtoul (p, (char**)&p, 10);
+	    }
+	  while (strchr ("hlL", *p))
+	    ++p;
+	  /* Should be big enough for any format specifier except %s
+             and floats.  */
+	  total_width += 30;
+	  switch (*p)
+	    {
+	    case 'd':
+	    case 'i':
+	    case 'o':
+	    case 'u':
+	    case 'x':
+	    case 'X':
+	    case 'c':
+	      (void) va_arg (ap, int);
+	      break;
+	    case 'f':
+	    case 'e':
+	    case 'E':
+	    case 'g':
+	    case 'G':
+	      (void) va_arg (ap, double);
+	      /* Since an ieee double can have an exponent of 307, we'll
+		 make the buffer wide enough to cover the gross case. */
+	      total_width += 307;
+	      break;
+	    case 's':
+              {
+                char *tmp = va_arg (ap, char *);
+                if (tmp)
+                  total_width += strlen (tmp);
+                else /* in case the vsprintf does prints a text */
+                  total_width += 25; /* e.g. "(null pointer reference)" */
+              }
+	      break;
+	    case 'p':
+	    case 'n':
+	      (void) va_arg (ap, char *);
+	      break;
+	    }
+	}
+    }
+#ifdef TEST
+  global_total_width = total_width;
+#endif
+  *result = malloc (total_width);
+  if (*result != NULL)
+    return vsprintf (*result, format, args);
+  else
+    return 0;
+}
+
+
+int
+asprintf (char **buf, const char *fmt, ...)
+{
+  int status;
+  va_list ap;
+
+  va_start (ap, fmt);
+  status = vasprintf (buf, fmt, ap);
+  va_end (ap);
+  return status;
+}
+
+
+#ifdef TEST
+void
+checkit (const char* format, ...)
+{
+  va_list args;
+  char *result;
+
+  va_start (args, format);
+  vasprintf (&result, format, args);
+  if (strlen (result) < global_total_width)
+    printf ("PASS: ");
+  else
+    printf ("FAIL: ");
+  printf ("%d %s\n", global_total_width, result);
+}
+
+int
+main (void)
+{
+  checkit ("%d", 0x12345678);
+  checkit ("%200d", 5);
+  checkit ("%.300d", 6);
+  checkit ("%100.150d", 7);
+  checkit ("%s", "jjjjjjjjjiiiiiiiiiiiiiiioooooooooooooooooppppppppppppaa\n\
+777777777777777777333333333333366666666666622222222222777777777777733333");
+  checkit ("%f%s%d%s", 1.0, "foo", 77, "asdjffffffffffffffiiiiiiiiiiixxxxx");
+}
+#endif /* TEST */