lib/libalpm/delta.c

   1 /*
   2  *  delta.c
   3  *
   4  *  Copyright (c) 2006-2011 Pacman Development Team <pacman-dev@archlinux.org>
   5  *  Copyright (c) 2007-2006 by Judd Vinet <jvinet@zeroflux.org>
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License as published by
   9  *  the Free Software Foundation; either version 2 of the License, or
  10  *  (at your option) any later version.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  19  */
  20
  21 #include "config.h"
  22
  23 #include <stdlib.h>
  24 #include <string.h>
  25 #include <stdint.h> /* intmax_t */
  26 #include <limits.h>
  27 #include <sys/types.h>
  28 #include <regex.h>
  29
  30 /* libalpm */
  31 #include "delta.h"
  32 #include "alpm_list.h"
  33 #include "util.h"
  34 #include "log.h"
  35 #include "graph.h"
  36
  37 static alpm_list_t *graph_init(alpm_list_t *deltas, int reverse)
  38 {
  39         alpm_list_t *i, *j;
  40         alpm_list_t *vertices = NULL;
  41         /* create the vertices */
  42         for(i = deltas; i; i = i->next) {
  43                 pmgraph_t *v = _alpm_graph_new();
  44                 if(!v) {
  45                         alpm_list_free(vertices);
  46                         return NULL;
  47                 }
  48                 pmdelta_t *vdelta = i->data;
  49                 vdelta->download_size = vdelta->delta_size;
  50                 v->weight = LONG_MAX;
  51                 v->data = vdelta;
  52                 vertices = alpm_list_add(vertices, v);
  53         }
  54
  55         /* compute the edges */
  56         for(i = vertices; i; i = i->next) {
  57                 pmgraph_t *v_i = i->data;
  58                 pmdelta_t *d_i = v_i->data;
  59                 /* loop a second time so we make all possible comparisons */
  60                 for(j = vertices; j; j = j->next) {
  61                         pmgraph_t *v_j = j->data;
  62                         pmdelta_t *d_j = v_j->data;
  63                         /* We want to create a delta tree like the following:
  64                          *          1_to_2
  65                          *            |
  66                          * 1_to_3   2_to_3
  67                          *   \        /
  68                          *     3_to_4
  69                          * If J 'from' is equal to I 'to', then J is a child of I.
  70                          * */
  71                         if((!reverse && strcmp(d_j->from, d_i->to) == 0) ||
  72                                         (reverse && strcmp(d_j->to, d_i->from) == 0)) {
  73                                 v_i->children = alpm_list_add(v_i->children, v_j);
  74                         }
  75                 }
  76                 v_i->childptr = v_i->children;
  77         }
  78         return vertices;
  79 }
  80
  81 static void graph_init_size(alpm_handle_t *handle, alpm_list_t *vertices)
  82 {
  83         alpm_list_t *i;
  84
  85         for(i = vertices; i; i = i->next) {
  86                 char *fpath, *md5sum;
  87                 pmgraph_t *v = i->data;
  88                 pmdelta_t *vdelta = v->data;
  89
  90                 /* determine whether the delta file already exists */
  91                 fpath = _alpm_filecache_find(handle, vdelta->delta);
  92                 md5sum = alpm_compute_md5sum(fpath);
  93                 if(fpath && md5sum && strcmp(md5sum, vdelta->delta_md5) == 0) {
  94                         vdelta->download_size = 0;
  95                 }
  96                 FREE(fpath);
  97                 FREE(md5sum);
  98
  99                 /* determine whether a base 'from' file exists */
 100                 fpath = _alpm_filecache_find(handle, vdelta->from);
 101                 if(fpath) {
 102                         v->weight = vdelta->download_size;
 103                 }
 104                 FREE(fpath);
 105         }
 106 }
 107
 108
 109 static void dijkstra(alpm_list_t *vertices)
 110 {
 111         alpm_list_t *i;
 112         pmgraph_t *v;
 113         while(1) {
 114                 v = NULL;
 115                 /* find the smallest vertice not visited yet */
 116                 for(i = vertices; i; i = i->next) {
 117                         pmgraph_t *v_i = i->data;
 118
 119                         if(v_i->state == -1) {
 120                                 continue;
 121                         }
 122
 123                         if(v == NULL || v_i->weight < v->weight) {
 124                                 v = v_i;
 125                         }
 126                 }
 127                 if(v == NULL || v->weight == LONG_MAX) {
 128                         break;
 129                 }
 130
 131                 v->state = -1;
 132
 133                 v->childptr = v->children;
 134                 while(v->childptr) {
 135                         pmgraph_t *v_c = v->childptr->data;
 136                         pmdelta_t *d_c = v_c->data;
 137                         if(v_c->weight > v->weight + d_c->download_size) {
 138                                 v_c->weight = v->weight + d_c->download_size;
 139                                 v_c->parent = v;
 140                         }
 141
 142                         v->childptr = (v->childptr)->next;
 143
 144                 }
 145         }
 146 }
 147
 148 static off_t shortest_path(alpm_list_t *vertices, const char *to, alpm_list_t **path)
 149 {
 150         alpm_list_t *i;
 151         pmgraph_t *v = NULL;
 152         off_t bestsize = 0;
 153         alpm_list_t *rpath = NULL;
 154
 155         for(i = vertices; i; i = i->next) {
 156                 pmgraph_t *v_i = i->data;
 157                 pmdelta_t *d_i = v_i->data;
 158
 159                 if(strcmp(d_i->to, to) == 0) {
 160                         if(v == NULL || v_i->weight < v->weight) {
 161                                 v = v_i;
 162                                 bestsize = v->weight;
 163                         }
 164                 }
 165         }
 166
 167         while(v != NULL) {
 168                 pmdelta_t *vdelta = v->data;
 169                 rpath = alpm_list_add(rpath, vdelta);
 170                 v = v->parent;
 171         }
 172         *path = alpm_list_reverse(rpath);
 173         alpm_list_free(rpath);
 174
 175         return bestsize;
 176 }
 177
 178 /** Calculates the shortest path from one version to another.
 179  * The shortest path is defined as the path with the smallest combined
 180  * size, not the length of the path.
 181  * @param handle the context handle
 182  * @param deltas the list of pmdelta_t * objects that a file has
 183  * @param to the file to start the search at
 184  * @param path the pointer to a list location where pmdelta_t * objects that
 185  * have the smallest size are placed. NULL is set if there is no path
 186  * possible with the files available.
 187  * @return the size of the path stored, or LONG_MAX if path is unfindable
 188  */
 189 off_t _alpm_shortest_delta_path(alpm_handle_t *handle, alpm_list_t *deltas,
 190                 const char *to, alpm_list_t **path)
 191 {
 192         alpm_list_t *bestpath = NULL;
 193         alpm_list_t *vertices;
 194         off_t bestsize = LONG_MAX;
 195
 196         if(deltas == NULL) {
 197                 *path = NULL;
 198                 return bestsize;
 199         }
 200
 201         _alpm_log(handle, PM_LOG_DEBUG, "started delta shortest-path search for '%s'\n", to);
 202
 203         vertices = graph_init(deltas, 0);
 204         graph_init_size(handle, vertices);
 205         dijkstra(vertices);
 206         bestsize = shortest_path(vertices, to, &bestpath);
 207
 208         _alpm_log(handle, PM_LOG_DEBUG, "delta shortest-path search complete : '%jd'\n", (intmax_t)bestsize);
 209
 210         alpm_list_free_inner(vertices, _alpm_graph_free);
 211         alpm_list_free(vertices);
 212
 213         *path = bestpath;
 214         return bestsize;
 215 }
 216
 217 static alpm_list_t *find_unused(alpm_list_t *deltas, const char *to, off_t quota)
 218 {
 219         alpm_list_t *unused = NULL;
 220         alpm_list_t *vertices;
 221         alpm_list_t *i;
 222         vertices = graph_init(deltas, 1);
 223
 224         for(i = vertices; i; i = i->next) {
 225                 pmgraph_t *v = i->data;
 226                 pmdelta_t *vdelta = v->data;
 227                 if(strcmp(vdelta->to, to) == 0)
 228                 {
 229                         v->weight = vdelta->download_size;
 230                 }
 231         }
 232         dijkstra(vertices);
 233         for(i = vertices; i; i = i->next) {
 234                 pmgraph_t *v = i->data;
 235                 pmdelta_t *vdelta = v->data;
 236                 if(v->weight > quota) {
 237                         unused = alpm_list_add(unused, vdelta->delta);
 238                 }
 239         }
 240         alpm_list_free_inner(vertices, _alpm_graph_free);
 241         alpm_list_free(vertices);
 242         return unused;
 243 }
 244
 245 /** \addtogroup alpm_deltas Delta Functions
 246  * @brief Functions to manipulate libalpm deltas
 247  * @{
 248  */
 249
 250 alpm_list_t SYMEXPORT *alpm_pkg_unused_deltas(pmpkg_t *pkg)
 251 {
 252         off_t pkgsize = alpm_pkg_get_size(pkg);
 253         alpm_list_t *unused = find_unused(
 254                         alpm_pkg_get_deltas(pkg),
 255                         alpm_pkg_get_filename(pkg),
 256                         pkgsize * MAX_DELTA_RATIO);
 257         return unused;
 258 }
 259
 260 /** @} */
 261
 262 /** Parses the string representation of a pmdelta_t object.
 263  * This function assumes that the string is in the correct format.
 264  * This format is as follows:
 265  * $deltafile $deltamd5 $deltasize $oldfile $newfile
 266  * @param line the string to parse
 267  * @return A pointer to the new pmdelta_t object
 268  */
 269 /* TODO this does not really belong here, but in a parsing lib */
 270 pmdelta_t *_alpm_delta_parse(char *line)
 271 {
 272         pmdelta_t *delta;
 273         char *tmp = line, *tmp2;
 274         regex_t reg;
 275
 276         regcomp(&reg,
 277                         "^[^[:space:]]* [[:xdigit:]]{32} [[:digit:]]*"
 278                         " [^[:space:]]* [^[:space:]]*$",
 279                         REG_EXTENDED | REG_NOSUB | REG_NEWLINE);
 280         if(regexec(&reg, line, 0, 0, 0) != 0) {
 281                 /* delta line is invalid, return NULL */
 282                 regfree(&reg);
 283                 return NULL;
 284         }
 285         regfree(&reg);
 286
 287         CALLOC(delta, 1, sizeof(pmdelta_t), return NULL);
 288
 289         tmp2 = tmp;
 290         tmp = strchr(tmp, ' ');
 291         *(tmp++) = '\0';
 292         STRDUP(delta->delta, tmp2, return NULL);
 293
 294         tmp2 = tmp;
 295         tmp = strchr(tmp, ' ');
 296         *(tmp++) = '\0';
 297         STRDUP(delta->delta_md5, tmp2, return NULL);
 298
 299         tmp2 = tmp;
 300         tmp = strchr(tmp, ' ');
 301         *(tmp++) = '\0';
 302         delta->delta_size = atol(tmp2);
 303
 304         tmp2 = tmp;
 305         tmp = strchr(tmp, ' ');
 306         *(tmp++) = '\0';
 307         STRDUP(delta->from, tmp2, return NULL);
 308
 309         tmp2 = tmp;
 310         STRDUP(delta->to, tmp2, return NULL);
 311
 312         return delta;
 313 }
 314
 315 void _alpm_delta_free(pmdelta_t *delta)
 316 {
 317         FREE(delta->delta);
 318         FREE(delta->delta_md5);
 319         FREE(delta->from);
 320         FREE(delta->to);
 321         FREE(delta);
 322 }
 323
 324 pmdelta_t *_alpm_delta_dup(const pmdelta_t *delta)
 325 {
 326         pmdelta_t *newdelta;
 327         CALLOC(newdelta, 1, sizeof(pmdelta_t), return NULL);
 328         STRDUP(newdelta->delta, delta->delta, return NULL);
 329         STRDUP(newdelta->delta_md5, delta->delta_md5, return NULL);
 330         STRDUP(newdelta->from, delta->from, return NULL);
 331         STRDUP(newdelta->to, delta->to, return NULL);
 332         newdelta->delta_size = delta->delta_size;
 333         newdelta->download_size = delta->download_size;
 334
 335         return newdelta;
 336 }
 337
 338 /* vim: set ts=2 sw=2 noet: */