Infrastructure: Split the files into subdirectories.

[mLib] / utils / versioncmp.c

diff --git a/utils/versioncmp.c b/utils/versioncmp.c
new file mode 100644 (file)
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--- /dev/null
+++ b/utils/versioncmp.c
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+/* -*-c-*-
+ *
+ * Compare version numbers using the Debian algorithm
+ *
+ * (c) 2007 Straylight/Edgeware
+ */
+
+/*----- Licensing notice --------------------------------------------------*
+ *
+ * This file is part of the mLib utilities library.
+ *
+ * mLib 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.
+ *
+ * mLib 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 mLib; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+ * MA 02111-1307, USA.
+ */
+
+/*----- Header files ------------------------------------------------------*/
+
+#include <ctype.h>
+#include <string.h>
+
+#include "versioncmp.h"
+
+/*----- Main code ---------------------------------------------------------*/
+
+/* --- @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) ia = 1;
+      else if (isalpha((unsigned char)*pa)) ia = 2;
+      else if (*pa == '~') ia = 0;
+      else ia = 3;
+
+      if (pb == vb) ib = 1;
+      else if (isalpha((unsigned char)*pb)) ib = 2;
+      else if (*pb == '~') ib = 0;
+      else ib = 3;
+
+      if (ia != ib) return (CMP(ia, ib));
+      else if (pa == va && pb == vb) break;
+      else if (*pa != *pb) return (CMP(*pa, *pb));
+      pa++; pb++;
+    }
+
+    /* --- 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 -------------------------------------------------*/