dpkg: better and shorter code to compare versions

 (taken from "official" dpkg).
 By Eugene T. Bordenkircher (eugebo AT gmail.com)

function                                             old     new   delta
order                                                  -      48     +48
test_version                                         273     276      +3
version_compare_part                                 396     187    -209
------------------------------------------------------------------------------
(add/remove: 1/0 grow/shrink: 1/1 up/down: 51/-209)          Total: -158 bytes

diff --git a/archival/dpkg.c b/archival/dpkg.c
index 1bc8d27..577b77f 100644 (file)
--- a/archival/dpkg.c
+++ b/archival/dpkg.c
@@ -6,6 +6,10 @@
  *  written by glenn mcgrath with the help of others
  *  copyright (c) 2001 by glenn mcgrath
  *
+ *  parts of the version comparison code is plucked from the real dpkg
+ *  application which is licensed GPLv2 and
+ *  copyright (c) 1995 Ian Jackson <ian@chiark.greenend.org.uk>
+ *
  *  started life as a busybox implementation of udpkg
  *
  * licensed under gplv2 or later, see file license in this tarball for details.
@@ -135,7 +139,7 @@ static void make_hash(const char *key, unsigned *start, unsigned *decrement, con
                /* shifts the ascii based value and adds it to previous value
                 * shift amount is mod 24 because long int is 32 bit and data
                 * to be shifted is 8, don't want to shift data to where it has
-                * no effect*/
+                * no effect */
                hash_num += (key[i] + key[i-1]) << ((key[i] * i) % 24);
        }
        *start = (unsigned) hash_num % hash_prime;
@@ -183,60 +187,52 @@ static unsigned search_status_hashtable(const char *key)
        return probe_address;
 }
 
-/* Need to rethink version comparison, maybe the official dpkg has something i can use ? */
-static int version_compare_part(const char *version1, const char *version2)
+static int order(char x)
 {
-       int upstream_len1 = 0;
-       int upstream_len2 = 0;
-       char *name1_char;
-       char *name2_char;
-       int len1 = 0;
-       int len2 = 0;
-       int tmp_int;
-       int ver_num1;
-       int ver_num2;
-
-       if (version1 == NULL) {
-               version1 = xstrdup("");
-       }
-       if (version2 == NULL) {
-               version2 = xstrdup("");
-       }
-       upstream_len1 = strlen(version1);
-       upstream_len2 = strlen(version2);
-
-       while ((len1 < upstream_len1) || (len2 < upstream_len2)) {
-               /* Compare non-digit section */
-               tmp_int = strcspn(&version1[len1], "0123456789");
-               name1_char = xstrndup(&version1[len1], tmp_int);
-               len1 += tmp_int;
-               tmp_int = strcspn(&version2[len2], "0123456789");
-               name2_char = xstrndup(&version2[len2], tmp_int);
-               len2 += tmp_int;
-               tmp_int = strcmp(name1_char, name2_char);
-               free(name1_char);
-               free(name2_char);
-               if (tmp_int != 0) {
-                       return tmp_int;
+       return (x == '~' ? -1
+               : x == '\0' ? 0
+               : isdigit(x) ? 0
+               : isalpha(x) ? x
+               : (unsigned char)x + 256
+       );
+}
+
+/* This code is taken from dpkg and modified slightly to work with busybox */
+static int version_compare_part(const char *val, const char *ref)
+{
+       if (!val) val = "";
+       if (!ref) ref = "";
+
+       while (*val || *ref) {
+               int first_diff;
+
+               while ((*val && !isdigit(*val)) || (*ref && !isdigit(*ref))) {
+                       int vc = order(*val);
+                       int rc = order(*ref);
+                       if (vc != rc)
+                               return vc - rc;
+                       val++;
+                       ref++;
                }
 
-               /* Compare digits */
-               tmp_int = strspn(&version1[len1], "0123456789");
-               name1_char = xstrndup(&version1[len1], tmp_int);
-               len1 += tmp_int;
-               tmp_int = strspn(&version2[len2], "0123456789");
-               name2_char = xstrndup(&version2[len2], tmp_int);
-               len2 += tmp_int;
-               ver_num1 = atoi(name1_char);
-               ver_num2 = atoi(name2_char);
-               free(name1_char);
-               free(name2_char);
-               if (ver_num1 < ver_num2) {
-                       return -1;
+               while (*val == '0')
+                       val++;
+               while (*ref == '0')
+                       ref++;
+
+               first_diff = 0;
+               while (isdigit(*val) && isdigit(*ref)) {
+                       if (first_diff == 0)
+                               first_diff = *val - *ref;
+                       val++;
+                       ref++;
                }
-               if (ver_num1 > ver_num2) {
+               if (isdigit(*val))
                        return 1;
-               }
+               if (isdigit(*ref))
+                       return -1;
+               if (first_diff)
+                       return first_diff;
        }
        return 0;
 }
@@ -249,39 +245,34 @@ static int version_compare(const unsigned ver1, const unsigned ver2)
 {
        char *ch_ver1 = name_hashtable[ver1];
        char *ch_ver2 = name_hashtable[ver2];
-
-       char epoch1, epoch2;
+       unsigned long epoch1 = 0, epoch2 = 0;
+       char *colon;
        char *deb_ver1, *deb_ver2;
-       char *ver1_ptr, *ver2_ptr;
        char *upstream_ver1;
        char *upstream_ver2;
        int result;
 
        /* Compare epoch */
-       if (ch_ver1[1] == ':') {
-               epoch1 = ch_ver1[0];
-               ver1_ptr = strchr(ch_ver1, ':') + 1;
-       } else {
-               epoch1 = '0';
-               ver1_ptr = ch_ver1;
+       colon = strchr(ch_ver1, ':');
+       if (colon) {
+               epoch1 = atoi(ch_ver1);
+               ch_ver1 = colon + 1;
        }
-       if (ch_ver2[1] == ':') {
-               epoch2 = ch_ver2[0];
-               ver2_ptr = strchr(ch_ver2, ':') + 1;
-       } else {
-               epoch2 = '0';
-               ver2_ptr = ch_ver2;
+       colon = strchr(ch_ver2, ':');
+       if (colon) {
+               epoch2 = atoi(ch_ver2);
+               ch_ver2 = colon + 1;
        }
        if (epoch1 < epoch2) {
                return -1;
        }
-       else if (epoch1 > epoch2) {
+       if (epoch1 > epoch2) {
                return 1;
        }
 
        /* Compare upstream version */
-       upstream_ver1 = xstrdup(ver1_ptr);
-       upstream_ver2 = xstrdup(ver2_ptr);
+       upstream_ver1 = xstrdup(ch_ver1);
+       upstream_ver2 = xstrdup(ch_ver2);
 
        /* Chop off debian version, and store for later use */
        deb_ver1 = strrchr(upstream_ver1, '-');