lib/libalpm/delta.c

   1 /*
   2  *  delta.c
   3  *
   4  *  Copyright (c) 2006-2012 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 <stdlib.h>
  22 #include <string.h>
  23 #include <stdint.h> /* intmax_t */
  24 #include <limits.h>
  25 #include <sys/types.h>
  26 #include <regex.h>
  27
  28 /* libalpm */
  29 #include "delta.h"
  30 #include "alpm_list.h"
  31 #include "util.h"
  32 #include "log.h"
  33 #include "graph.h"
  34
  35 static alpm_list_t *graph_init(alpm_list_t *deltas, int reverse)
  36 {
  37         alpm_list_t *i, *j;
  38         alpm_list_t *vertices = NULL;
  39         /* create the vertices */
  40         for(i = deltas; i; i = i->next) {
  41                 alpm_graph_t *v = _alpm_graph_new();
  42                 if(!v) {
  43                         alpm_list_free(vertices);
  44                         return NULL;
  45                 }
  46                 alpm_delta_t *vdelta = i->data;
  47                 vdelta->download_size = vdelta->delta_size;
  48                 v->weight = LONG_MAX;
  49                 v->data = vdelta;
  50                 vertices = alpm_list_add(vertices, v);
  51         }
  52
  53         /* compute the edges */
  54         for(i = vertices; i; i = i->next) {
  55                 alpm_graph_t *v_i = i->data;
  56                 alpm_delta_t *d_i = v_i->data;
  57                 /* loop a second time so we make all possible comparisons */
  58                 for(j = vertices; j; j = j->next) {
  59                         alpm_graph_t *v_j = j->data;
  60                         alpm_delta_t *d_j = v_j->data;
  61                         /* We want to create a delta tree like the following:
  62                          *          1_to_2
  63                          *            |
  64                          * 1_to_3   2_to_3
  65                          *   \        /
  66                          *     3_to_4
  67                          * If J 'from' is equal to I 'to', then J is a child of I.
  68                          * */
  69                         if((!reverse && strcmp(d_j->from, d_i->to) == 0) ||
  70                                         (reverse && strcmp(d_j->to, d_i->from) == 0)) {
  71                                 v_i->children = alpm_list_add(v_i->children, v_j);
  72                         }
  73                 }
  74                 v_i->childptr = v_i->children;
  75         }
  76         return vertices;
  77 }
  78
  79 static void graph_init_size(alpm_handle_t *handle, alpm_list_t *vertices)
  80 {
  81         alpm_list_t *i;
  82
  83         for(i = vertices; i; i = i->next) {
  84                 char *fpath, *md5sum;
  85                 alpm_graph_t *v = i->data;
  86                 alpm_delta_t *vdelta = v->data;
  87
  88                 /* determine whether the delta file already exists */
  89                 fpath = _alpm_filecache_find(handle, vdelta->delta);
  90                 if(fpath) {
  91                         md5sum = alpm_compute_md5sum(fpath);
  92                         if(md5sum && strcmp(md5sum, vdelta->delta_md5) == 0) {
  93                                 vdelta->download_size = 0;
  94                         }
  95                         FREE(md5sum);
  96                         FREE(fpath);
  97                 } else {
  98                         char *fnamepart;
  99                         CALLOC(fnamepart, strlen(vdelta->delta) + 6, sizeof(char), return);
 100                         sprintf(fnamepart, "%s.part", vdelta->delta);
 101                         fpath = _alpm_filecache_find(handle, fnamepart);
 102                         if(fpath) {
 103                                 struct stat st;
 104                                 if(stat(fpath, &st) == 0) {
 105                                         vdelta->download_size = vdelta->delta_size - st.st_size;
 106                                         vdelta->download_size = vdelta->download_size < 0 ? 0 : vdelta->download_size;
 107                                 }
 108                                 FREE(fpath);
 109                         }
 110                         FREE(fnamepart);
 111                 }
 112
 113                 /* determine whether a base 'from' file exists */
 114                 fpath = _alpm_filecache_find(handle, vdelta->from);
 115                 if(fpath) {
 116                         v->weight = vdelta->download_size;
 117                 }
 118                 FREE(fpath);
 119         }
 120 }
 121
 122
 123 static void dijkstra(alpm_list_t *vertices)
 124 {
 125         alpm_list_t *i;
 126         alpm_graph_t *v;
 127         while(1) {
 128                 v = NULL;
 129                 /* find the smallest vertice not visited yet */
 130                 for(i = vertices; i; i = i->next) {
 131                         alpm_graph_t *v_i = i->data;
 132
 133                         if(v_i->state == -1) {
 134                                 continue;
 135                         }
 136
 137                         if(v == NULL || v_i->weight < v->weight) {
 138                                 v = v_i;
 139                         }
 140                 }
 141                 if(v == NULL || v->weight == LONG_MAX) {
 142                         break;
 143                 }
 144
 145                 v->state = -1;
 146
 147                 v->childptr = v->children;
 148                 while(v->childptr) {
 149                         alpm_graph_t *v_c = v->childptr->data;
 150                         alpm_delta_t *d_c = v_c->data;
 151                         if(v_c->weight > v->weight + d_c->download_size) {
 152                                 v_c->weight = v->weight + d_c->download_size;
 153                                 v_c->parent = v;
 154                         }
 155
 156                         v->childptr = (v->childptr)->next;
 157
 158                 }
 159         }
 160 }
 161
 162 static off_t shortest_path(alpm_list_t *vertices, const char *to, alpm_list_t **path)
 163 {
 164         alpm_list_t *i;
 165         alpm_graph_t *v = NULL;
 166         off_t bestsize = 0;
 167         alpm_list_t *rpath = NULL;
 168
 169         for(i = vertices; i; i = i->next) {
 170                 alpm_graph_t *v_i = i->data;
 171                 alpm_delta_t *d_i = v_i->data;
 172
 173                 if(strcmp(d_i->to, to) == 0) {
 174                         if(v == NULL || v_i->weight < v->weight) {
 175                                 v = v_i;
 176                                 bestsize = v->weight;
 177                         }
 178                 }
 179         }
 180
 181         while(v != NULL) {
 182                 alpm_delta_t *vdelta = v->data;
 183                 rpath = alpm_list_add(rpath, vdelta);
 184                 v = v->parent;
 185         }
 186         *path = alpm_list_reverse(rpath);
 187         alpm_list_free(rpath);
 188
 189         return bestsize;
 190 }
 191
 192 /** Calculates the shortest path from one version to another.
 193  * The shortest path is defined as the path with the smallest combined
 194  * size, not the length of the path.
 195  * @param handle the context handle
 196  * @param deltas the list of alpm_delta_t * objects that a file has
 197  * @param to the file to start the search at
 198  * @param path the pointer to a list location where alpm_delta_t * objects that
 199  * have the smallest size are placed. NULL is set if there is no path
 200  * possible with the files available.
 201  * @return the size of the path stored, or LONG_MAX if path is unfindable
 202  */
 203 off_t _alpm_shortest_delta_path(alpm_handle_t *handle, alpm_list_t *deltas,
 204                 const char *to, alpm_list_t **path)
 205 {
 206         alpm_list_t *bestpath = NULL;
 207         alpm_list_t *vertices;
 208         off_t bestsize = LONG_MAX;
 209
 210         if(deltas == NULL) {
 211                 *path = NULL;
 212                 return bestsize;
 213         }
 214
 215         _alpm_log(handle, ALPM_LOG_DEBUG, "started delta shortest-path search for '%s'\n", to);
 216
 217         vertices = graph_init(deltas, 0);
 218         graph_init_size(handle, vertices);
 219         dijkstra(vertices);
 220         bestsize = shortest_path(vertices, to, &bestpath);
 221
 222         _alpm_log(handle, ALPM_LOG_DEBUG, "delta shortest-path search complete : '%jd'\n", (intmax_t)bestsize);
 223
 224         alpm_list_free_inner(vertices, _alpm_graph_free);
 225         alpm_list_free(vertices);
 226
 227         *path = bestpath;
 228         return bestsize;
 229 }
 230
 231 static alpm_list_t *find_unused(alpm_list_t *deltas, const char *to, off_t quota)
 232 {
 233         alpm_list_t *unused = NULL;
 234         alpm_list_t *vertices;
 235         alpm_list_t *i;
 236         vertices = graph_init(deltas, 1);
 237
 238         for(i = vertices; i; i = i->next) {
 239                 alpm_graph_t *v = i->data;
 240                 alpm_delta_t *vdelta = v->data;
 241                 if(strcmp(vdelta->to, to) == 0)
 242                 {
 243                         v->weight = vdelta->download_size;
 244                 }
 245         }
 246         dijkstra(vertices);
 247         for(i = vertices; i; i = i->next) {
 248                 alpm_graph_t *v = i->data;
 249                 alpm_delta_t *vdelta = v->data;
 250                 if(v->weight > quota) {
 251                         unused = alpm_list_add(unused, vdelta->delta);
 252                 }
 253         }
 254         alpm_list_free_inner(vertices, _alpm_graph_free);
 255         alpm_list_free(vertices);
 256         return unused;
 257 }
 258
 259 /** \addtogroup alpm_deltas Delta Functions
 260  * @brief Functions to manipulate libalpm deltas
 261  * @{
 262  */
 263
 264 alpm_list_t SYMEXPORT *alpm_pkg_unused_deltas(alpm_pkg_t *pkg)
 265 {
 266         ASSERT(pkg != NULL, return NULL);
 267         return find_unused(pkg->deltas, pkg->filename,
 268                         pkg->size * pkg->handle->deltaratio);
 269 }
 270
 271 /** @} */
 272
 273 /** Parses the string representation of a alpm_delta_t object.
 274  * This function assumes that the string is in the correct format.
 275  * This format is as follows:
 276  * $deltafile $deltamd5 $deltasize $oldfile $newfile
 277  * @param handle the context handle
 278  * @param line the string to parse
 279  * @return A pointer to the new alpm_delta_t object
 280  */
 281 alpm_delta_t *_alpm_delta_parse(alpm_handle_t *handle, const char *line)
 282 {
 283         alpm_delta_t *delta;
 284         const int num_matches = 6;
 285         size_t len;
 286         regmatch_t pmatch[num_matches];
 287         char filesize[32];
 288
 289         /* this is so we only have to compile the pattern once */
 290         if(!handle->delta_regex_compiled) {
 291                 /* $deltafile $deltamd5 $deltasize $oldfile $newfile*/
 292                 regcomp(&handle->delta_regex,
 293                                 "^([^[:space:]]+) ([[:xdigit:]]{32}) ([[:digit:]]+)"
 294                                 " ([^[:space:]]+) ([^[:space:]]+)$",
 295                                 REG_EXTENDED | REG_NEWLINE);
 296                 handle->delta_regex_compiled = 1;
 297         }
 298
 299         if(regexec(&handle->delta_regex, line, num_matches, pmatch, 0) != 0) {
 300                 /* delta line is invalid, return NULL */
 301                 return NULL;
 302         }
 303
 304         CALLOC(delta, 1, sizeof(alpm_delta_t), return NULL);
 305
 306         /* start at index 1 -- match 0 is the entire match */
 307         len = pmatch[1].rm_eo - pmatch[1].rm_so;
 308         STRNDUP(delta->delta, &line[pmatch[1].rm_so], len, return NULL);
 309
 310         len = pmatch[2].rm_eo - pmatch[2].rm_so;
 311         STRNDUP(delta->delta_md5, &line[pmatch[2].rm_so], len, return NULL);
 312
 313         len = pmatch[3].rm_eo - pmatch[3].rm_so;
 314         if(len < sizeof(filesize)) {
 315                 strncpy(filesize, &line[pmatch[3].rm_so], len);
 316                 filesize[len] = '\0';
 317                 delta->delta_size = _alpm_strtoofft(filesize);
 318         }
 319
 320         len = pmatch[4].rm_eo - pmatch[4].rm_so;
 321         STRNDUP(delta->from, &line[pmatch[4].rm_so], len, return NULL);
 322
 323         len = pmatch[5].rm_eo - pmatch[5].rm_so;
 324         STRNDUP(delta->to, &line[pmatch[5].rm_so], len, return NULL);
 325
 326         return delta;
 327 }
 328
 329 void _alpm_delta_free(alpm_delta_t *delta)
 330 {
 331         FREE(delta->delta);
 332         FREE(delta->delta_md5);
 333         FREE(delta->from);
 334         FREE(delta->to);
 335         FREE(delta);
 336 }
 337
 338 alpm_delta_t *_alpm_delta_dup(const alpm_delta_t *delta)
 339 {
 340         alpm_delta_t *newdelta;
 341         CALLOC(newdelta, 1, sizeof(alpm_delta_t), return NULL);
 342         STRDUP(newdelta->delta, delta->delta, return NULL);
 343         STRDUP(newdelta->delta_md5, delta->delta_md5, return NULL);
 344         STRDUP(newdelta->from, delta->from, return NULL);
 345         STRDUP(newdelta->to, delta->to, return NULL);
 346         newdelta->delta_size = delta->delta_size;
 347         newdelta->download_size = delta->download_size;
 348
 349         return newdelta;
 350 }
 351
 352 /* vim: set ts=2 sw=2 noet: */