package_alternatives.c

/*-
 * Copyright (c) 2015-2019 Juan Romero Pardines.
 * Copyright (c) 2019 Duncan Overbruck.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
 
#include <sys/stat.h>
 
#include <errno.h>
#include <libgen.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
 
#include "xbps_api_impl.h"
 
/**
 * @file lib/package_alternatives.c
 * @brief Alternatives generic routines
 * @defgroup alternatives Alternatives generic functions
 *
 * These functions implement the alternatives framework.
 */
 
static char *
left(const char *str)
{
        const char *e;
 
        e = strchr(str, ':');
        if (!e)
                return NULL;
 
        return strndup(str, e - str);
}
 
static const char *
right(const char *str)
{
        const char *p = strchr(str, ':');
        if (!p)
                return NULL;
        return p + 1;
}
 
static const char *
normpath(char *path)
{
        char *seg, *p;
 
        for (p = path, seg = NULL; *p; p++) {
                if (strncmp(p, "/../", 4) == 0 || strncmp(p, "/..", 4) == 0) {
                        memmove(seg ? seg : p, p+3, strlen(p+3) + 1);
                        return normpath(path);
                } else if (strncmp(p, "/./", 3) == 0 || strncmp(p, "/.", 3) == 0) {
                        memmove(p, p+2, strlen(p+2) + 1);
                } else if (strncmp(p, "//", 2) == 0 || strncmp(p, "/", 2) == 0) {
                        memmove(p, p+1, strlen(p+1) + 1);
                }
                if (*p == '/')
                        seg = p;
        }
        return path;
}
 
static char *
relpath(char *from, char *to)
{
        int up;
        char *p = to, *rel;
 
        assert(from[0] == '/');
        assert(to[0] == '/');
        normpath(from);
        normpath(to);
 
        for (; *from == *to && *to; from++, to++) {
                if (*to == '/')
                        p = to;
        }
 
        for (up = -1, from--; from && *from; from = strchr(from + 1, '/'), up++);
 
        rel = calloc(1, 3 * up + strlen(p) + 1);
        if (!rel)
                return NULL;
 
        while (up--)
                strcat(rel, "../");
        if (*p)
                strcat(rel, p+1);
        return rel;
}
 
static int
remove_symlinks(struct xbps_handle *xhp, xbps_array_t a, const char *grname)
{
        unsigned int i, cnt;
        struct stat st;
 
        cnt = xbps_array_count(a);
        for (i = 0; i < cnt; i++) {
                xbps_string_t str;
                char *l, *lnk;
 
                str = xbps_array_get(a, i);
                l = left(xbps_string_cstring_nocopy(str));
                assert(l);
                if (l[0] != '/') {
                        const char *tgt;
                        char *tgt_dup, *tgt_dir;
                        tgt = right(xbps_string_cstring_nocopy(str));
                        assert(tgt);
                        tgt_dup = strdup(tgt);
                        assert(tgt_dup);
                        tgt_dir = dirname(tgt_dup);
                        lnk = xbps_xasprintf("%s%s/%s", xhp->rootdir, tgt_dir, l);
                        free(tgt_dup);
                } else {
                        lnk = xbps_xasprintf("%s%s", xhp->rootdir, l);
                }
                if (lstat(lnk, &st) == -1 || !S_ISLNK(st.st_mode)) {
                        free(lnk);
                        free(l);
                        continue;
                }
                xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_LINK_REMOVED, 0, NULL,
                    "Removing '%s' alternatives group symlink: %s", grname, l);
                unlink(lnk);
                free(lnk);
                free(l);
        }
 
        return 0;
}
 
static int
create_symlinks(struct xbps_handle *xhp, xbps_array_t a, const char *grname)
{
        int rv;
        unsigned int i, n;
        char *alternative, *tok1, *tok2, *linkpath, *target, *dir, *p;
 
        n = xbps_array_count(a);
 
        for (i = 0; i < n; i++) {
                alternative = xbps_string_cstring(xbps_array_get(a, i));
 
                if (!(tok1 = strtok(alternative, ":")) ||
                    !(tok2 = strtok(NULL, ":"))) {
                        free(alternative);
                        return EINVAL;
                }
 
                target = strdup(tok2);
                dir = dirname(tok2);
 
                /* add target dir to relative links */
                if (tok1[0] != '/')
                        linkpath = xbps_xasprintf("%s/%s/%s", xhp->rootdir, dir, tok1);
                else
                        linkpath = xbps_xasprintf("%s/%s", xhp->rootdir, tok1);
 
                /* create target directory, necessary for dangling symlinks */
                dir = xbps_xasprintf("%s/%s", xhp->rootdir, dir);
                if (strcmp(dir, ".") && xbps_mkpath(dir, 0755) && errno != EEXIST) {
                        rv = errno;
                        xbps_dbg_printf(
                            "failed to create target dir '%s' for group '%s': %s\n",
                            dir, grname, strerror(errno));
                        free(dir);
                        goto err;
                }
                free(dir);
 
                /* create link directory, necessary for dangling symlinks */
                p = strdup(linkpath);
                dir = dirname(p);
                if (strcmp(dir, ".") && xbps_mkpath(dir, 0755) && errno != EEXIST) {
                        rv = errno;
                        xbps_dbg_printf(
                            "failed to create symlink dir '%s' for group '%s': %s\n",
                            dir, grname, strerror(errno));
                        free(p);
                        goto err;
                }
                free(p);
 
                xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_LINK_ADDED, 0, NULL,
                    "Creating '%s' alternatives group symlink: %s -> %s",
                    grname, tok1, target);
 
                if (target[0] == '/') {
                        p = relpath(linkpath + strlen(xhp->rootdir), target);
                        free(target);
                        target = p;
                }
 
                unlink(linkpath);
                if ((rv = symlink(target, linkpath)) != 0) {
                        xbps_dbg_printf(
                            "failed to create alt symlink '%s' for group '%s': %s\n",
                            linkpath, grname,  strerror(errno));
                        goto err;
                }
 
                free(alternative);
                free(target);
                free(linkpath);
        }
 
        return 0;
 
err:
        free(alternative);
        free(target);
        free(linkpath);
        return rv;
}
 
int
xbps_alternatives_set(struct xbps_handle *xhp, const char *pkgname,
                const char *group)
{
        xbps_array_t allkeys;
        xbps_dictionary_t alternatives, pkg_alternatives, pkgd, prevpkgd, prevpkg_alts;
        const char *pkgver = NULL, *prevpkgname = NULL;
        int rv = 0;
 
        assert(xhp);
        assert(pkgname);
 
        alternatives = xbps_dictionary_get(xhp->pkgdb, "_XBPS_ALTERNATIVES_");
        if (alternatives == NULL)
                return ENOENT;
 
        pkgd = xbps_pkgdb_get_pkg(xhp, pkgname);
        if (pkgd == NULL)
                return ENOENT;
 
        pkg_alternatives = xbps_dictionary_get(pkgd, "alternatives");
        if (!xbps_dictionary_count(pkg_alternatives))
                return ENOENT;
 
        if (group && !xbps_dictionary_get(pkg_alternatives, group))
                return ENOENT;
 
        xbps_dictionary_get_cstring_nocopy(pkgd, "pkgver", &pkgver);
 
        allkeys = xbps_dictionary_all_keys(pkg_alternatives);
        for (unsigned int i = 0; i < xbps_array_count(allkeys); i++) {
                xbps_array_t array;
                xbps_object_t keysym;
                xbps_string_t kstr;
                const char *keyname;
 
                keysym = xbps_array_get(allkeys, i);
                keyname = xbps_dictionary_keysym_cstring_nocopy(keysym);
 
                if (group && strcmp(keyname, group))
                        continue;
 
                array = xbps_dictionary_get(alternatives, keyname);
                if (array == NULL)
                        continue;
 
                /* remove symlinks from previous alternative */
                xbps_array_get_cstring_nocopy(array, 0, &prevpkgname);
                if (prevpkgname && strcmp(pkgname, prevpkgname) != 0) {
                        if ((prevpkgd = xbps_pkgdb_get_pkg(xhp, prevpkgname)) &&
                            (prevpkg_alts = xbps_dictionary_get(prevpkgd, "alternatives")) &&
                            xbps_dictionary_count(prevpkg_alts)) {
                                rv = remove_symlinks(xhp,
                                    xbps_dictionary_get(prevpkg_alts, keyname),
                                    keyname);
                                if (rv != 0)
                                        break;
                        }
                }
 
                /* put this alternative group at the head */
                xbps_remove_string_from_array(array, pkgname);
                kstr = xbps_string_create_cstring(pkgname);
                xbps_array_add_first(array, kstr);
                xbps_object_release(kstr);
 
                /* apply the alternatives group */
                xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_ADDED, 0, NULL,
                    "%s: applying '%s' alternatives group", pkgver, keyname);
                rv = create_symlinks(xhp, xbps_dictionary_get(pkg_alternatives, keyname), keyname);
                if (rv != 0 || group)
                        break;
        }
        xbps_object_release(allkeys);
        return rv;
}
 
static int
switch_alt_group(struct xbps_handle *xhp, const char *grpn, const char *pkgn,
                xbps_dictionary_t *pkg_alternatives)
{
        xbps_dictionary_t curpkgd, pkgalts;
 
        curpkgd = xbps_pkgdb_get_pkg(xhp, pkgn);
        assert(curpkgd);
 
        xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_SWITCHED, 0, NULL,
                "Switched '%s' alternatives group to '%s'", grpn, pkgn);
        pkgalts = xbps_dictionary_get(curpkgd, "alternatives");
        if (pkg_alternatives) *pkg_alternatives = pkgalts;
        return create_symlinks(xhp, xbps_dictionary_get(pkgalts, grpn), grpn);
}
 
int
xbps_alternatives_unregister(struct xbps_handle *xhp, xbps_dictionary_t pkgd)
{
        xbps_array_t allkeys;
        xbps_dictionary_t alternatives, pkg_alternatives;
        const char *pkgver, *pkgname;
        bool update = false;
        int rv = 0;
 
        assert(xhp);
 
        alternatives = xbps_dictionary_get(xhp->pkgdb, "_XBPS_ALTERNATIVES_");
        if (alternatives == NULL)
                return 0;
 
        pkg_alternatives = xbps_dictionary_get(pkgd, "alternatives");
        if (!xbps_dictionary_count(pkg_alternatives))
                return 0;
 
        xbps_dictionary_get_cstring_nocopy(pkgd, "pkgver", &pkgver);
        xbps_dictionary_get_cstring_nocopy(pkgd, "pkgname", &pkgname);
 
        xbps_dictionary_get_bool(pkgd, "alternatives-update", &update);
 
        allkeys = xbps_dictionary_all_keys(pkg_alternatives);
        for (unsigned int i = 0; i < xbps_array_count(allkeys); i++) {
                xbps_array_t array;
                xbps_object_t keysym;
                bool current = false;
                const char *first = NULL, *keyname;
 
                keysym = xbps_array_get(allkeys, i);
                keyname = xbps_dictionary_keysym_cstring_nocopy(keysym);
 
                array = xbps_dictionary_get(alternatives, keyname);
                if (array == NULL)
                        continue;
 
                xbps_array_get_cstring_nocopy(array, 0, &first);
                if (strcmp(pkgname, first) == 0) {
                        /* this pkg is the current alternative for this group */
                        current = true;
                        rv = remove_symlinks(xhp,
                                xbps_dictionary_get(pkg_alternatives, keyname),
                                keyname);
                        if (rv != 0)
                                break;
                }
 
                if (!update) {
                        xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_REMOVED, 0, NULL,
                            "%s: unregistered '%s' alternatives group", pkgver, keyname);
                        xbps_remove_string_from_array(array, pkgname);
                        xbps_array_get_cstring_nocopy(array, 0, &first);
                }
 
                if (xbps_array_count(array) == 0) {
                        xbps_dictionary_remove(alternatives, keyname);
                        continue;
                }
 
                if (update || !current)
                        continue;
 
                /* get the new alternative group package */
                if (switch_alt_group(xhp, keyname, first, &pkg_alternatives) != 0)
                        break;
        }
        xbps_object_release(allkeys);
 
        return rv;
}
 
/*
 * Prune the alternatives group from the db. This will first unregister
 * it for the package and if there's no other package left providing the
 * same, also ditch the whole group. When this is called, it is guaranteed
 * that what is happening is an upgrade, because it's only invoked when
 * the repo and installed alternatives sets differ for a specific package.
 */
static void
prune_altgroup(struct xbps_handle *xhp, xbps_dictionary_t repod,
                const char *pkgname, const char *pkgver, const char *keyname)
{
        const char *newpkg = NULL, *curpkg = NULL;
        xbps_array_t array;
        xbps_dictionary_t alternatives;
        xbps_string_t kstr;
        unsigned int grp_count;
        bool current = false;
 
        xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_REMOVED, 0, NULL,
                "%s: unregistered '%s' alternatives group", pkgver, keyname);
 
        alternatives = xbps_dictionary_get(xhp->pkgdb, "_XBPS_ALTERNATIVES_");
        assert(alternatives);
        array = xbps_dictionary_get(alternatives, keyname);
 
        /* if using alt group from another package, we won't switch anything */
        xbps_array_get_cstring_nocopy(array, 0, &curpkg);
        current = (strcmp(pkgname, curpkg) == 0);
 
        /* actually prune the alt group for the current package */
        xbps_remove_string_from_array(array, pkgname);
        grp_count = xbps_array_count(array);
        if (grp_count == 0) {
                /* it was the last one, ditch the whole thing */
                xbps_dictionary_remove(alternatives, keyname);
                return;
        }
        if (!current) {
                /* not the last one, and ours wasn't the one being used */
                return;
        }
 
        if (xbps_array_count(xbps_dictionary_get(repod, "run_depends")) == 0 &&
            xbps_array_count(xbps_dictionary_get(repod, "shlib-requires")) == 0) {
                /*
                 * Empty dependencies indicate a removed package (pure meta),
                 * use the first available group after ours has been pruned
                 */
                xbps_array_get_cstring_nocopy(array, 0, &newpkg);
                switch_alt_group(xhp, keyname, newpkg, NULL);
                return;
        }
 
        /*
         * Use the last group, as this indicates that a transitional metapackage
         * is replacing the original and therefore a new package has registered
         * a replacement group, which should be last in the array (most recent).
         */
        xbps_array_get_cstring_nocopy(array, grp_count - 1, &newpkg);
 
        /* put the new package as head */
        kstr = xbps_string_create_cstring(newpkg);
        xbps_remove_string_from_array(array, newpkg);
        xbps_array_add_first(array, kstr);
        xbps_array_get_cstring_nocopy(array, 0, &newpkg);
        xbps_object_release(kstr);
 
        switch_alt_group(xhp, keyname, newpkg, NULL);
}
 
 
static void
remove_obsoletes(struct xbps_handle *xhp, const char *pkgname, const char *pkgver,
                xbps_dictionary_t pkgdb_alts, xbps_dictionary_t repod)
{
        xbps_array_t allkeys;
        xbps_dictionary_t pkgd, pkgd_alts, repod_alts;
 
        pkgd = xbps_pkgdb_get_pkg(xhp, pkgname);
        if (xbps_object_type(pkgd) != XBPS_TYPE_DICTIONARY) {
                return;
        }
 
        pkgd_alts = xbps_dictionary_get(pkgd, "alternatives");
        repod_alts = xbps_dictionary_get(repod, "alternatives");
 
        if (xbps_object_type(pkgd_alts) != XBPS_TYPE_DICTIONARY) {
                return;
        }
 
        allkeys = xbps_dictionary_all_keys(pkgd_alts);
        for (unsigned int i = 0; i < xbps_array_count(allkeys); i++) {
                xbps_array_t array, array2, array_repo;
                xbps_object_t keysym;
                const char *keyname, *first = NULL;
 
                keysym = xbps_array_get(allkeys, i);
                array = xbps_dictionary_get_keysym(pkgd_alts, keysym);
                keyname = xbps_dictionary_keysym_cstring_nocopy(keysym);
 
                array_repo = xbps_dictionary_get(repod_alts, keyname);
                if (!xbps_array_equals(array, array_repo)) {
                        /*
                         * Check if current provider in pkgdb is this pkg.
                         */
                        array2 = xbps_dictionary_get(pkgdb_alts, keyname);
                        if (array2) {
                                xbps_array_get_cstring_nocopy(array2, 0, &first);
                                if (strcmp(pkgname, first) == 0) {
                                        remove_symlinks(xhp, array_repo, keyname);
                                }
                        }
                }
                /*
                 * There is nothing left in the alternatives group, which means
                 * the package is being upgraded and is removing it; if we don't
                 * prune it, the system will keep it set after removal of its
                 * parent package, but it will be empty and invalid...
                 */
                if (xbps_array_count(array_repo) == 0) {
                        prune_altgroup(xhp, repod, pkgname, pkgver, keyname);
                }
        }
        xbps_object_release(allkeys);
}
 
int
xbps_alternatives_register(struct xbps_handle *xhp, xbps_dictionary_t pkg_repod)
{
        xbps_array_t allkeys;
        xbps_dictionary_t alternatives, pkg_alternatives;
        const char *pkgver, *pkgname;
        int rv = 0;
 
        assert(xhp);
 
        if (xhp->pkgdb == NULL)
                return EINVAL;
 
        alternatives = xbps_dictionary_get(xhp->pkgdb, "_XBPS_ALTERNATIVES_");
        if (alternatives == NULL) {
                alternatives = xbps_dictionary_create();
                xbps_dictionary_set(xhp->pkgdb, "_XBPS_ALTERNATIVES_", alternatives);
                xbps_object_release(alternatives);
        }
        alternatives = xbps_dictionary_get(xhp->pkgdb, "_XBPS_ALTERNATIVES_");
        assert(alternatives);
 
        xbps_dictionary_get_cstring_nocopy(pkg_repod, "pkgver", &pkgver);
        xbps_dictionary_get_cstring_nocopy(pkg_repod, "pkgname", &pkgname);
 
        /*
         * Compare alternatives from pkgdb and repo and then remove obsolete
         * symlinks, also remove obsolete (empty) alternatives groups.
         */
        remove_obsoletes(xhp, pkgname, pkgver, alternatives, pkg_repod);
 
        pkg_alternatives = xbps_dictionary_get(pkg_repod, "alternatives");
        if (!xbps_dictionary_count(pkg_alternatives))
                return 0;
 
        allkeys = xbps_dictionary_all_keys(pkg_alternatives);
        for (unsigned int i = 0; i < xbps_array_count(allkeys); i++) {
                xbps_array_t array;
                xbps_object_t keysym;
                const char *keyname, *first = NULL;
 
                keysym = xbps_array_get(allkeys, i);
                keyname = xbps_dictionary_keysym_cstring_nocopy(keysym);
 
                array = xbps_dictionary_get(alternatives, keyname);
                if (array == NULL) {
                        array = xbps_array_create();
                } else {
                        if (xbps_match_string_in_array(array, pkgname)) {
                                xbps_array_get_cstring_nocopy(array, 0, &first);
                                if (strcmp(pkgname, first)) {
                                        /* current alternative does not match */
                                        continue;
                                }
                                /* already registered, update symlinks */
                                rv = create_symlinks(xhp,
                                        xbps_dictionary_get(pkg_alternatives, keyname),
                                        keyname);
                                if (rv != 0)
                                        break;
                        } else {
                                /* not registered, add provider */
                                xbps_array_add_cstring(array, pkgname);
                                xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_ADDED, 0, NULL,
                                    "%s: registered '%s' alternatives group", pkgver, keyname);
                        }
                        continue;
                }
 
                xbps_array_add_cstring(array, pkgname);
                xbps_dictionary_set(alternatives, keyname, array);
                xbps_set_cb_state(xhp, XBPS_STATE_ALTGROUP_ADDED, 0, NULL,
                    "%s: registered '%s' alternatives group", pkgver, keyname);
                /* apply alternatives for this group */
                rv = create_symlinks(xhp,
                        xbps_dictionary_get(pkg_alternatives, keyname),
                        keyname);
                xbps_object_release(array);
                if (rv != 0)
                        break;
        }
        xbps_object_release(allkeys);
 
        return rv;
}