3 files changed, 86 insertions, 0 deletions
diff --git a/common/ChangeLog b/common/ChangeLog
index a42b07b4d..4688d2765 100644
--- a/common/ChangeLog
+++ b/common/ChangeLog
@@ -1,3 +1,8 @@
+2005-04-17  Werner Koch  <[email protected]>
+
+	* sexputil.c (cmp_simple_canon_sexp): New.
+	(make_simple_sexp_from_hexstr): New.
+
 2005-04-07  Werner Koch  <[email protected]>
 
 	* sexputil.c: New.
diff --git a/common/sexputil.c b/common/sexputil.c
index 853d7e58a..802916b44 100644
--- a/common/sexputil.c
+++ b/common/sexputil.c
@@ -61,3 +61,81 @@ keygrip_from_canon_sexp (const unsigned char *key, size_t keylen,
   return err;
 }
 
+
+/* Compare two simple S-expressions like "(3:foo)".  Returns 0 if they
+   are identical or !0 if they are not.  Not that this function can't
+   be used for sorting. */
+int
+cmp_simple_canon_sexp (const unsigned char *a, const unsigned char *b)
+{
+  unsigned long n1, n2;
+  char *endp;
+
+  if (!a && !b)
+    return 0; /* Both are NULL, they are identical. */
+  if (!a || !b)
+    return 1; /* One is NULL, they are not identical. */
+  if (*a != '(' || *b != '(')
+    log_bug ("invalid S-exp in cmp_simple_canon_sexp\n");
+
+  a++;
+  n1 = strtoul (a, &endp, 10);
+  a = endp;
+  b++;
+  n2 = strtoul (b, &endp, 10);
+  b = endp;
+
+  if (*a != ':' || *b != ':' )
+    log_bug ("invalid S-exp in cmp_simple_canon_sexp\n");
+  if (n1 != n2)
+    return 1; /* Not the same. */
+
+  for (a++, b++; n1; n1--, a++, b++)
+    if (*a != *b)
+      return 1; /* Not the same. */
+  return 0;
+}
+
+
+/* Create a simple S-expression from the hex string at LIBNE.  Returns
+   a newly allocated buffer with that canonical encoded S-expression
+   or NULL in case of an error.  On return the number of characters
+   scanned in LINE will be stored at NSCANNED.  This fucntions stops
+   converting at the first character not representing a hexdigit. Odd
+   numbers of hex digits are allowed; a leading zero is then
+   assumed. If no characters have been found, NULL is returned.*/
+unsigned char *
+make_simple_sexp_from_hexstr (const char *line, size_t *nscanned)
+{
+  size_t n, len;
+  const char *s;
+  unsigned char *buf;
+  unsigned char *p;
+  char numbuf[50];
+
+  for (n=0, s=line; hexdigitp (s); s++, n++)
+    ;
+  if (nscanned)
+    *nscanned = n;
+  if (!n)
+    return NULL;
+  len = ((n+1) & ~0x01)/2; 
+  sprintf (numbuf, "(%u:", (unsigned int)len);
+  buf = xtrymalloc (strlen (numbuf) + len + 1 + 1);
+  if (!buf)
+    return NULL;
+  p = stpcpy (buf, numbuf);
+  s = line;
+  if ((n&1))
+    {
+      *p++ = xtoi_1 (s);
+      s++;
+      n--;
+    }
+  for (; n > 1; n -=2, s += 2)
+    *p++ = xtoi_2 (s);
+  *p++ = ')';
+  *p = 0; /* (Not really neaded.) */
+
+  return buf;
+}
diff --git a/common/util.h b/common/util.h
index 14180bec4..6a9b54ef5 100644
--- a/common/util.h
+++ b/common/util.h
@@ -123,6 +123,9 @@ gpg_error_t b64enc_finish (struct b64state *state);
 /*-- sexputil.c */
 gpg_error_t keygrip_from_canon_sexp (const unsigned char *key, size_t keylen,
                                      unsigned char *grip);
+int cmp_simple_canon_sexp (const unsigned char *a, const unsigned char *b);
+unsigned char *make_simple_sexp_from_hexstr (const char *line,
+                                             size_t *nscanned);
 
 /*-- homedir. c --*/
 const char *default_homedir (void);