New file, implementing an sexp canonical syntax

formatter.

Rev: src/nettle/sexp_format.c:1.1

sexp_format.c

+/* sexp-output.c
+ *
+ * Writing s-expressions.
+ */
+
+/* nettle, low-level cryptographics library
+ *
+ * Copyright (C) 2002 Niels Mller
+ *  
+ * The nettle library is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or (at your
+ * option) any later version.
+ * 
+ * The nettle library 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 Lesser General Public
+ * License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with the nettle library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+#if HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include "sexp.h"
+#include "buffer.h"
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if HAVE_LIBGMP
+# include "bignum.h"
+#endif
+
+static int
+format_prefix(struct nettle_buffer *output,
+	      unsigned length)
+{
+  unsigned prefix_length;
+  char prefix[10];
+
+  /* NOTE: Using the return value of sprintf is not entirely
+   * portable. */
+  prefix_length = snprintf(prefix, sizeof(prefix), "%u:", length);
+  if (prefix_length >= sizeof(prefix))
+    return 0;
+
+  return nettle_buffer_write(buffer, prefix_length, prefix);
+}
+
+static int
+format_length_string(struct nettle_buffer *buffer,
+		     unsigned length, const char *s)
+{
+  return format_prefix(buffer, length)
+    && nettle_buffer_write(buffer, length, s);
+}
+
+static uint8_t *
+format_space(struct nettle_buffer *buffer,
+	     unsigned length)
+{
+  return format_prefix(output, length)
+    ? nettle_buffer_space(output, length) : NULL;
+}
+
+static int
+format_string(struct nettle_buffer *buffer,
+	      const char *s)
+{
+  return format_length_string(buffer, strlen(s), s);
+}
+
+int
+sexp_format(struct nettle_buffer *buffer, const char *format, ...)
+{
+  va_list args;
+  va_start(args, format);
+
+  unsigned nesting = 0;
+  
+  for (;;)
+    switch (*format++)
+      {
+      case '\0':
+	if (nesting)
+	  {
+	  fail:
+	    va_end(args);
+	    return 0;
+	  }
+	else
+	  {
+	    va_end(args);
+	    return 1;
+	  }
+      case '(':
+	if (!NETTLE_BUFFER_PUTC(buffer, '('))
+	  goto fail;
+
+	nesting++;
+	break;
+
+      case ')':
+	if (!nesting)
+	  abort();
+	if (!NETTLE_BUFFER_PUTC(buffer, ')'))
+	  goto fail;
+	
+	nesting--;
+	break;
+
+      case '%':
+	switch (*format++)
+	  {
+	  case 's':
+	    {
+	      const char *s = va_arg(args, const char *);
+	      format_string(buffer, s);
+	      break;
+	    }
+	  case 'b':
+	    {
+#if HAVE_LIBGMP
+	      const MP_INT *n = va_arg(args, const MP_INT *);
+	      uint8_t *space;
+	      unsigned length;
+	      
+	      if (mpz_sgn(n) < 0)
+		goto fail;
+
+	      length = nettle_mpz_sizeinbase_256(n);
+
+	      space = format_space(buffer, length);
+	      if (!space)
+		goto fail;
+	      nettle_mpz_get_str_256(length, space, n);
+#else /* ! HAVE_LIBGMP */
+	      abort();
+#endif /* ! HAVE_LIBGMP */
+	      break;
+	    }
+	  default:
+	    abort();
+	  }
+      }
+}