libopkg/pkg_alternatives.c

   1 /* pkg_alternatives.c - the opkg package management system
   2
   3    Copyright (C) 2017 Yousong Zhou
   4
   5    This program is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU General Public License as
   7    published by the Free Software Foundation; either version 2, or (at
   8    your option) any later version.
   9
  10    This program is distributed in the hope that it will be useful, but
  11    WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    General Public License for more details.
  14 */
  15
  16 #include <stdio.h>
  17 #include <sys/types.h>          /* stat */
  18 #include <sys/stat.h>
  19 #include <libgen.h>                     /* dirname */
  20 #include <unistd.h>
  21
  22 #include "file_util.h"
  23 #include "libbb/libbb.h"
  24 #include "opkg_message.h"
  25 #include "pkg.h"
  26 #include "pkg_hash.h"
  27 #include "pkg_alternatives.h"
  28 #include "sprintf_alloc.h"
  29
  30 static int pkg_alternatives_update_path(pkg_t *pkg, const pkg_vec_t *installed, const char *path)
  31 {
  32         struct pkg_alternatives *pkg_alts;
  33         struct pkg_alternative *the_alt = NULL;
  34         pkg_t *the_pkg = pkg;
  35         int i, j;
  36         int r;
  37         char *path_in_dest;
  38
  39         for (i = 0; i < installed->len; i++) {
  40                 pkg_t *pkg = installed->pkgs[i];
  41                 pkg_alts = pkg_get_ptr(pkg, PKG_ALTERNATIVES);
  42                 if (!pkg_alts)
  43                         continue;
  44
  45                 for (j = 0; j < pkg_alts->nalts; j++) {
  46                         struct pkg_alternative *alt = pkg_alts->alts[j];
  47
  48                         if (strcmp(path, alt->path))
  49                                 continue;
  50                         if (!the_alt || the_alt->prio < alt->prio) {
  51                                 the_pkg = pkg;
  52                                 the_alt = alt;
  53                         }
  54                 }
  55         }
  56
  57         /* path is assumed to be an absolute one */
  58         sprintf_alloc(&path_in_dest, "%s%s", the_pkg->dest->root_dir, &path[1]);
  59         if (!path_in_dest)
  60                 return -1;
  61
  62         if (the_alt) {
  63                 struct stat sb;
  64
  65                 r = lstat(path_in_dest, &sb);
  66                 if (!r) {
  67                         char *realpath;
  68
  69                         if (!S_ISLNK(sb.st_mode)) {
  70                                 opkg_msg(ERROR, "%s exists but is not a symlink\n", path_in_dest);
  71                                 r = -1;
  72                                 goto out;
  73                         }
  74                         realpath = xreadlink(path_in_dest);
  75                         if (realpath && strcmp(realpath, the_alt->altpath))
  76                                 unlink(path_in_dest);
  77                         free(realpath);
  78                 } else if (errno != ENOENT) {
  79                         goto out;
  80                 }
  81                 {
  82                         char *path_copy = xstrdup(path_in_dest);
  83                         char *path_parent = dirname(path_copy);
  84
  85                         r = file_mkdir_hier(path_parent, 0755);
  86                         free(path_copy);
  87                         if (r) {
  88                                 goto out;
  89                         }
  90                         r = symlink(the_alt->altpath, path_in_dest);
  91                         if (r && errno == EEXIST) {
  92                                 /*
  93                                  * the strcmp & unlink check above will make sure that if EEXIST
  94                                  * happens, the symlink target also matches
  95                                  */
  96                                 r = 0;
  97                         }
  98                         if (r) {
  99                                 opkg_perror(ERROR, "failed symlinking %s -> %s", path_in_dest, the_alt->altpath);
 100                         }
 101                 }
 102         } else {
 103                 unlink(path_in_dest);
 104                 r = 0;
 105         }
 106
 107 out:
 108         free(path_in_dest);
 109         return r;
 110 }
 111
 112 int pkg_alternatives_update(pkg_t * pkg)
 113 {
 114         int r = 0;
 115         int i;
 116         struct pkg_alternatives *pkg_alts;
 117         struct pkg_alternative *alt = NULL;
 118         pkg_vec_t *installed;
 119
 120         pkg_alts = pkg_get_ptr(pkg, PKG_ALTERNATIVES);
 121         if (!pkg_alts)
 122                 return 0;
 123
 124         installed = pkg_vec_alloc();
 125         pkg_hash_fetch_all_installed(installed);
 126         for (i = 0; i < pkg_alts->nalts; i++) {
 127                 alt = pkg_alts->alts[i];
 128                 r |= pkg_alternatives_update_path(pkg, installed, alt->path);
 129         }
 130         pkg_vec_free(installed);
 131
 132         return r;
 133 }