servutil: Implement version number comparison.

[tripe] / server / servutil.c

diff --git a/server/servutil.c b/server/servutil.c
index 92a5f775f03b456a0068317508db70294bedcb77..77cfd2c6c7fceba19c55c14ef60b380985be9409 100644 (file)
--- a/server/servutil.c
+++ b/server/servutil.c
@@ -140,4 +140,157 @@ int seq_check(seqwin *s, uint32 q, const char *service)
   return (0);
 }
 
+/* --- @versioncmp@ --- *
+ *
+ * Arguments:  @const char *va, *vb@ = two version strings
+ *
+ * Returns:    Less than, equal to, or greater than zero, according to
+ *             whether @va@ is less than, equal to, or greater than @vb@.
+ *
+ * Use:                Compares version number strings.
+ *
+ *             The algorithm is an extension of the Debian version
+ *             comparison algorithm.  A version number consists of three
+ *             components:
+ *
+ *               [EPOCH :] MAIN [- SUB]
+ *
+ *             The MAIN part may contain colons or hyphens if there is an
+ *             EPOCH or SUB, respectively.  Version strings are compared
+ *             componentwise: first epochs, then main parts, and finally
+ *             subparts.
+ *
+ *             The component comparison is done as follows.  First, the
+ *             initial subsequence of nondigit characters is extracted from
+ *             each string, and these are compared lexicographically, using
+ *             ASCII ordering, except that letters precede non-letters.  If
+ *             both are the same, an initial sequence of digits is extracted
+ *             from the remaining parts of the version strings, and these
+ *             are compared numerically (an empty sequence being considered
+ *             to have the value zero).  This process is repeated until we
+ *             have a winner or until both strings are exhausted.
+ */
+
+struct vinfo {
+  const char *e, *el;
+  const char *m, *ml;
+  const char *s, *sl;
+};
+
+static int vint(const char **vv, const char *vl)
+{
+  int n = 0;
+  const char *v = *vv;
+  int ch;
+
+  while (v < vl) {
+    ch = *v;
+    if (!isdigit((unsigned char)ch))
+      break;
+    v++;
+    n = n * 10 + (ch - '0');
+  }
+  *vv = v;
+  return (n);
+}
+
+static const char *vchr(const char **vv, const char *vl)
+{
+  const char *v = *vv;
+  const char *b = v;
+  int ch;
+
+  while (v < vl) {
+    ch = *v;
+    if (isdigit((unsigned char)ch))
+      break;
+    v++;
+  }
+  *vv = v;
+  return (b);
+}
+
+#define CMP(x, y) ((x) < (y) ? -1 : +1)
+
+static int vcmp(const char *va, const char *val,
+               const char *vb, const char *vbl)
+{
+  const char *pa, *pb;
+  int ia, ib;
+
+  for (;;) {
+
+    /* --- See if we're done --- */
+
+    if (va == val && vb == vbl)
+      return (0);
+
+    /* --- Compare nondigit portions --- */
+
+    pa = vchr(&va, val); pb = vchr(&vb, vbl);
+    for (;;) {
+      if (pa == va && pb == vb)
+       break;
+      else if (pa == va)
+       return (-1);
+      else if (pb == vb)
+       return (+1);
+      else if (*pa == *pb) {
+       pa++; pb++;
+       continue;
+      } else if (isalpha((unsigned char)*pa) == isalpha((unsigned char)*pb))
+       return (CMP(*pa, *pb));
+      else if (isalpha((unsigned char)*pa))
+       return (-1);
+      else
+       return (+1);
+    }
+
+    /* --- Compare digit portions --- */
+
+    ia = vint(&va, val); ib = vint(&vb, vbl);
+    if (ia != ib)
+      return (CMP(ia, ib));
+  }
+}
+
+static void vsplit(const char *v, struct vinfo *vi)
+{
+  const char *p;
+  size_t n;
+
+  if ((p = strchr(v, ':')) == 0)
+    vi->e = vi->el = 0;
+  else {
+    vi->e = v;
+    vi->el = p;
+    v = p + 1;
+  }
+
+  n = strlen(v);
+  if ((p = strrchr(v, '-')) == 0)
+    vi->s = vi->sl = 0;
+  else {    
+    vi->s = p + 1;
+    vi->sl = v + n;
+    n = p - v;
+  }
+
+  vi->m = v;
+  vi->ml = v + n;
+}
+
+int versioncmp(const char *va, const char *vb)
+{
+  struct vinfo via, vib;
+  int rc;
+
+  vsplit(va, &via); vsplit(vb, &vib);
+  if ((rc = vcmp(via.e, via.el, vib.e, vib.el)) != 0 ||
+      (rc = vcmp(via.m, via.ml, vib.m, vib.ml)) != 0 ||
+      (rc = vcmp(via.s, via.sl, vib.s, vib.sl)) != 0)
+    return (rc);
+  return (0);
+}
+
 /*----- That's all, folks -------------------------------------------------*/