lib/rpmvercmp.c

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00001 
00005 #include "system.h"
00006 
00007 #include <rpmlib.h>
00008 
00009 #include "debug.h"
00010 
00011 /* compare alpha and numeric segments of two versions */
00012 /* return 1: a is newer than b */
00013 /*        0: a and b are the same version */
00014 /*       -1: b is newer than a */
00015 int rpmvercmp(const char * a, const char * b)
00016 {
00017     char oldch1, oldch2;
00018     char * str1, * str2;
00019     char * one, * two;
00020     int rc;
00021     int isnum;
00022 
00023     /* easy comparison to see if versions are identical */
00024     if (!strcmp(a, b)) return 0;
00025 
00026     str1 = alloca(strlen(a) + 1);
00027     str2 = alloca(strlen(b) + 1);
00028 
00029     strcpy(str1, a);
00030     strcpy(str2, b);
00031 
00032     one = str1;
00033     two = str2;
00034 
00035     /* loop through each version segment of str1 and str2 and compare them */
00036     while (*one && *two) {
00037         while (*one && !xisalnum(*one)) one++;
00038         while (*two && !xisalnum(*two)) two++;
00039 
00040         str1 = one;
00041         str2 = two;
00042 
00043         /* grab first completely alpha or completely numeric segment */
00044         /* leave one and two pointing to the start of the alpha or numeric */
00045         /* segment and walk str1 and str2 to end of segment */
00046         if (xisdigit(*str1)) {
00047             while (*str1 && xisdigit(*str1)) str1++;
00048             while (*str2 && xisdigit(*str2)) str2++;
00049             isnum = 1;
00050         } else {
00051             while (*str1 && xisalpha(*str1)) str1++;
00052             while (*str2 && xisalpha(*str2)) str2++;
00053             isnum = 0;
00054         }
00055 
00056         /* save character at the end of the alpha or numeric segment */
00057         /* so that they can be restored after the comparison */
00058         oldch1 = *str1;
00059         *str1 = '\0';
00060         oldch2 = *str2;
00061         *str2 = '\0';
00062 
00063         /* take care of the case where the two version segments are */
00064         /* different types: one numeric, the other alpha (i.e. empty) */
00065         if (one == str1) return -1;     /* arbitrary */
00066         if (two == str2) return -1;
00067 
00068         if (isnum) {
00069             /* this used to be done by converting the digit segments */
00070             /* to ints using atoi() - it's changed because long  */
00071             /* digit segments can overflow an int - this should fix that. */
00072 
00073             /* throw away any leading zeros - it's a number, right? */
00074             while (*one == '0') one++;
00075             while (*two == '0') two++;
00076 
00077             /* whichever number has more digits wins */
00078             if (strlen(one) > strlen(two)) return 1;
00079             if (strlen(two) > strlen(one)) return -1;
00080         }
00081 
00082         /* strcmp will return which one is greater - even if the two */
00083         /* segments are alpha or if they are numeric.  don't return  */
00084         /* if they are equal because there might be more segments to */
00085         /* compare */
00086         rc = strcmp(one, two);
00087         if (rc) return rc;
00088 
00089         /* restore character that was replaced by null above */
00090         *str1 = oldch1;
00091         one = str1;
00092         *str2 = oldch2;
00093         two = str2;
00094     }
00095 
00096     /* this catches the case where all numeric and alpha segments have */
00097     /* compared identically but the segment sepparating characters were */
00098     /* different */
00099     if ((!*one) && (!*two)) return 0;
00100 
00101     /* whichever version still has characters left over wins */
00102     if (!*one) return -1; else return 1;
00103 }

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