lib/libalpm/version.c

   1 /*
   2  *  Copyright (c) 2006-2011 Pacman Development Team <pacman-dev@archlinux.org>
   3  *
   4  *  This program is free software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License as published by
   6  *  the Free Software Foundation; either version 2 of the License, or
   7  *  (at your option) any later version.
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *  You should have received a copy of the GNU General Public License
  15  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 #include "config.h"
  19
  20 #include <string.h>
  21 #include <ctype.h>
  22
  23 /* libalpm */
  24 #include "util.h"
  25
  26 /**
  27  * Some functions in this file have been adopted from the rpm source, notably
  28  * 'rpmvercmp' located at lib/rpmvercmp.c and 'parseEVR' located at
  29  * lib/rpmds.c. It was most recently updated against rpm version 4.8.1. Small
  30  * modifications have been made to make it more consistent with the libalpm
  31  * coding style.
  32  */
  33
  34 /**
  35  * Split EVR into epoch, version, and release components.
  36  * @param evr           [epoch:]version[-release] string
  37  * @retval *ep          pointer to epoch
  38  * @retval *vp          pointer to version
  39  * @retval *rp          pointer to release
  40  */
  41 static void parseEVR(char *evr, const char **ep, const char **vp,
  42                 const char **rp)
  43 {
  44         const char *epoch;
  45         const char *version;
  46         const char *release;
  47         char *s, *se;
  48
  49         s = evr;
  50         /* s points to epoch terminator */
  51         while (*s && isdigit(*s)) s++;
  52         /* se points to version terminator */
  53         se = strrchr(s, '-');
  54
  55         if(*s == ':') {
  56                 epoch = evr;
  57                 *s++ = '\0';
  58                 version = s;
  59                 if(*epoch == '\0') {
  60                         epoch = "0";
  61                 }
  62         } else {
  63                 /* different from RPM- always assume 0 epoch */
  64                 epoch = "0";
  65                 version = evr;
  66         }
  67         if(se) {
  68                 *se++ = '\0';
  69                 release = se;
  70         } else {
  71                 release = NULL;
  72         }
  73
  74         if(ep) *ep = epoch;
  75         if(vp) *vp = version;
  76         if(rp) *rp = release;
  77 }
  78
  79 /**
  80  * Compare alpha and numeric segments of two versions.
  81  * return 1: a is newer than b
  82  *        0: a and b are the same version
  83  *       -1: b is newer than a
  84  */
  85 static int rpmvercmp(const char *a, const char *b)
  86 {
  87         char oldch1, oldch2;
  88         char *str1, *str2;
  89         char *ptr1, *ptr2;
  90         char *one, *two;
  91         int rc;
  92         int isnum;
  93         int ret = 0;
  94
  95         /* easy comparison to see if versions are identical */
  96         if(strcmp(a, b) == 0) return 0;
  97
  98         str1 = strdup(a);
  99         str2 = strdup(b);
 100
 101         one = str1;
 102         two = str2;
 103
 104         /* loop through each version segment of str1 and str2 and compare them */
 105         while(*one && *two) {
 106                 while(*one && !isalnum((int)*one)) one++;
 107                 while(*two && !isalnum((int)*two)) two++;
 108
 109                 /* If we ran to the end of either, we are finished with the loop */
 110                 if(!(*one && *two)) break;
 111
 112                 ptr1 = one;
 113                 ptr2 = two;
 114
 115                 /* grab first completely alpha or completely numeric segment */
 116                 /* leave one and two pointing to the start of the alpha or numeric */
 117                 /* segment and walk ptr1 and ptr2 to end of segment */
 118                 if(isdigit((int)*ptr1)) {
 119                         while(*ptr1 && isdigit((int)*ptr1)) ptr1++;
 120                         while(*ptr2 && isdigit((int)*ptr2)) ptr2++;
 121                         isnum = 1;
 122                 } else {
 123                         while(*ptr1 && isalpha((int)*ptr1)) ptr1++;
 124                         while(*ptr2 && isalpha((int)*ptr2)) ptr2++;
 125                         isnum = 0;
 126                 }
 127
 128                 /* save character at the end of the alpha or numeric segment */
 129                 /* so that they can be restored after the comparison */
 130                 oldch1 = *ptr1;
 131                 *ptr1 = '\0';
 132                 oldch2 = *ptr2;
 133                 *ptr2 = '\0';
 134
 135                 /* this cannot happen, as we previously tested to make sure that */
 136                 /* the first string has a non-null segment */
 137                 if (one == ptr1) {
 138                         ret = -1;       /* arbitrary */
 139                         goto cleanup;
 140                 }
 141
 142                 /* take care of the case where the two version segments are */
 143                 /* different types: one numeric, the other alpha (i.e. empty) */
 144                 /* numeric segments are always newer than alpha segments */
 145                 /* XXX See patch #60884 (and details) from bugzilla #50977. */
 146                 if (two == ptr2) {
 147                         ret = isnum ? 1 : -1;
 148                         goto cleanup;
 149                 }
 150
 151                 if (isnum) {
 152                         /* this used to be done by converting the digit segments */
 153                         /* to ints using atoi() - it's changed because long  */
 154                         /* digit segments can overflow an int - this should fix that. */
 155
 156                         /* throw away any leading zeros - it's a number, right? */
 157                         while (*one == '0') one++;
 158                         while (*two == '0') two++;
 159
 160                         /* whichever number has more digits wins */
 161                         if (strlen(one) > strlen(two)) {
 162                                 ret = 1;
 163                                 goto cleanup;
 164                         }
 165                         if (strlen(two) > strlen(one)) {
 166                                 ret = -1;
 167                                 goto cleanup;
 168                         }
 169                 }
 170
 171                 /* strcmp will return which one is greater - even if the two */
 172                 /* segments are alpha or if they are numeric.  don't return  */
 173                 /* if they are equal because there might be more segments to */
 174                 /* compare */
 175                 rc = strcmp(one, two);
 176                 if (rc) {
 177                         ret = rc < 1 ? -1 : 1;
 178                         goto cleanup;
 179                 }
 180
 181                 /* restore character that was replaced by null above */
 182                 *ptr1 = oldch1;
 183                 one = ptr1;
 184                 *ptr2 = oldch2;
 185                 two = ptr2;
 186         }
 187
 188         /* this catches the case where all numeric and alpha segments have */
 189         /* compared identically but the segment separating characters were */
 190         /* different */
 191         if ((!*one) && (!*two)) {
 192                 ret = 0;
 193                 goto cleanup;
 194         }
 195
 196         /* the final showdown. we never want a remaining alpha string to
 197          * beat an empty string. the logic is a bit weird, but:
 198          * - if one is empty and two is not an alpha, two is newer.
 199          * - if one is an alpha, two is newer.
 200          * - otherwise one is newer.
 201          * */
 202         if ( (!*one && !isalpha((int)*two))
 203                         || isalpha((int)*one) ) {
 204                 ret = -1;
 205         } else {
 206                 ret = 1;
 207         }
 208
 209 cleanup:
 210         free(str1);
 211         free(str2);
 212         return ret;
 213 }
 214
 215 /** Compare two version strings and determine which one is 'newer'.
 216  * Returns a value comparable to the way strcmp works. Returns 1
 217  * if a is newer than b, 0 if a and b are the same version, or -1
 218  * if b is newer than a.
 219  *
 220  * Different epoch values for version strings will override any further
 221  * comparison. If no epoch is provided, 0 is assumed.
 222  *
 223  * Keep in mind that the pkgrel is only compared if it is available
 224  * on both versions handed to this function. For example, comparing
 225  * 1.5-1 and 1.5 will yield 0; comparing 1.5-1 and 1.5-2 will yield
 226  * -1 as expected. This is mainly for supporting versioned dependencies
 227  * that do not include the pkgrel.
 228  */
 229 int SYMEXPORT alpm_pkg_vercmp(const char *a, const char *b)
 230 {
 231         char *full1, *full2;
 232         const char *epoch1, *ver1, *rel1;
 233         const char *epoch2, *ver2, *rel2;
 234         int ret;
 235
 236         /* ensure our strings are not null */
 237         if(!a && !b) {
 238                 return 0;
 239         } else if(!a) {
 240                 return -1;
 241         } else if(!b) {
 242                 return 1;
 243         }
 244         /* another quick shortcut- if full version specs are equal */
 245         if(strcmp(a, b) == 0) {
 246                 return 0;
 247         }
 248
 249         /* Parse both versions into [epoch:]version[-release] triplets. We probably
 250          * don't need epoch and release to support all the same magic, but it is
 251          * easier to just run it all through the same code. */
 252         full1 = strdup(a);
 253         full2 = strdup(b);
 254
 255         /* parseEVR modifies passed in version, so have to dupe it first */
 256         parseEVR(full1, &epoch1, &ver1, &rel1);
 257         parseEVR(full2, &epoch2, &ver2, &rel2);
 258
 259         ret = rpmvercmp(epoch1, epoch2);
 260         if(ret == 0) {
 261                 ret = rpmvercmp(ver1, ver2);
 262                 if(ret == 0 && rel1 && rel2) {
 263                         ret = rpmvercmp(rel1, rel2);
 264                 }
 265         }
 266
 267         free(full1);
 268         free(full2);
 269         return ret;
 270 }
 271
 272 /* vim: set ts=2 sw=2 noet: */