gecko-dev/xpcom/glue/nsVersionComparator.cpp

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Mozilla XPCOM.
 *
 * The Initial Developer of the Original Code is
 * Benjamin Smedberg <benjamin@smedbergs.us>.
 *
 * Portions created by the Initial Developer are Copyright (C) 2005
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

#include "nsVersionComparator.h"

#include <stdlib.h>
#include <string.h>

struct VersionPart {
  PRInt32     numA;

  const char *strB;    // NOT null-terminated, can be a null pointer
  PRUint32    strBlen;

  PRInt32     numC;

  char       *extraD;  // null-terminated
};

/**
 * Parse a version part into a number and "extra text".
 *
 * @returns A pointer to the next versionpart, or null if none.
 */
static char*
ParseVP(char *part, VersionPart &result)
{
  char *dot;

  result.numA = 0;
  result.strB = nsnull;
  result.strBlen = 0;
  result.numC = 0;
  result.extraD = nsnull;

  if (!part)
    return part;

  dot = strchr(part, '.');
  if (dot)
    *dot = '\0';

  if (part[0] == '*' && part[1] == '\0') {
    result.numA = PR_INT32_MAX;
    result.strB = "";
  }
  else {
    result.numA = strtol(part, const_cast<char**>(&result.strB), 10);
  }

  if (!*result.strB) {
    result.strB = nsnull;
    result.strBlen = 0;
  }
  else {
    if (result.strB[0] == '+') {
      static const char kPre[] = "pre";

      ++result.numA;
      result.strB = kPre;
      result.strBlen = sizeof(kPre) - 1;
    }
    else {
      const char *numstart = strpbrk(result.strB, "0123456789+-");
      if (!numstart) {
	result.strBlen = strlen(result.strB);
      }
      else {
	result.strBlen = numstart - result.strB;

	result.numC = strtol(numstart, &result.extraD, 10);
	if (!*result.extraD)
	  result.extraD = nsnull;
      }
    }
  }

  if (dot) {
    ++dot;

    if (!*dot)
      dot = nsnull;
  }

  return dot;
}

// compare two null-terminated strings, which may be null pointers
static PRInt32
ns_strcmp(const char *str1, const char *str2)
{
  // any string is *before* no string
  if (!str1)
    return str2 != 0;

  if (!str2)
    return -1;

  return strcmp(str1, str2);
}

// compare two length-specified string, which may be null pointers
static PRInt32
ns_strnncmp(const char *str1, PRUint32 len1, const char *str2, PRUint32 len2)
{
  // any string is *before* no string
  if (!str1)
    return str2 != 0;

  if (!str2)
    return -1;

  for (; len1 && len2; --len1, --len2, ++str1, ++str2) {
    if (*str1 < *str2)
      return -1;

    if (*str1 > *str2)
      return 1;
  }

  if (len1 == 0)
    return len2 == 0 ? 0 : -1;

  return 1;
}

// compare two PRInt32
static PRInt32
ns_cmp(PRInt32 n1, PRInt32 n2)
{
  if (n1 < n2)
    return -1;

  return n1 != n2;
}

/**
 * Compares two VersionParts
 */
static PRInt32
CompareVP(VersionPart &v1, VersionPart &v2)
{
  PRInt32 r = ns_cmp(v1.numA, v2.numA);
  if (r)
    return r;

  r = ns_strnncmp(v1.strB, v1.strBlen, v2.strB, v2.strBlen);
  if (r)
    return r;

  r = ns_cmp(v1.numC, v2.numC);
  if (r)
    return r;

  return ns_strcmp(v1.extraD, v2.extraD);
}

PRInt32
NS_CompareVersions(const char *A, const char *B)
{
  char *A2 = strdup(A);
  if (!A2)
    return 1;

  char *B2 = strdup(B);
  if (!B2) {
    free(A2);
    return 1;
  }

  PRInt32 result;
  char *a = A2, *b = B2;

  do {
    VersionPart va, vb;

    a = ParseVP(a, va);
    b = ParseVP(b, vb);

    result = CompareVP(va, vb);
    if (result)
      break;

  } while (a || b);

  free(A2);
  free(B2);

  return result;
}