ostree: move admindir to /etc/alternatives.admindir

`ostree container commit` wipes /var and thereby erases the data in
/var/lib/alternatives; the directory used to store configs/symlinks of
alternatives.

/var is not a good place for storing such configs since it won't receive
updates on bootc images either.  We need to move to another location.

Hence, use /etc/alternatives.admindir when running on an ostree-based
system unless /var/lib/alternatives is already present; a user may have
worked around the problem.  This way we enable alternatives to work on
ostree-based systems without breaking backwards compat.

Fixes: #9
Signed-off-by: Valentin Rothberg <vrothberg@redhat.com>

Makefile

@@ -9,7 +9,6 @@ PROG = chkconfig
 BINDIR = /sbin
 SBINDIR = /usr/sbin
 MANDIR = /usr/man
-ALTDIR = /var/lib/alternatives
 ALTDATADIR = /etc/alternatives
 SYSTEMDUTILDIR = $(shell pkg-config --variable=systemdutildir systemd)
 SUBDIRS = po
@@ -55,7 +54,6 @@ install:
 	[ -d $(DESTDIR)/$(SBINDIR) ] || mkdir -p $(DESTDIR)/$(SBINDIR)
 	[ -d $(DESTDIR)/$(MANDIR) ] || mkdir -p $(DESTDIR)/$(MANDIR)
 	[ -d $(DESTDIR)/$(MANDIR)/man8 ] || mkdir -p $(DESTDIR)/$(MANDIR)/man8
-	[ -d $(DESTDIR)/$(ALTDIR) ] || mkdir -p -m 755 $(DESTDIR)/$(ALTDIR)
 	[ -d $(DESTDIR)/$(ALTDATADIR) ] || mkdir -p -m 755 $(DESTDIR)/$(ALTDATADIR)
 	[ -d $(DESTDIR)/$(SYSTEMDUTILDIR) ] || mkdir -p -m 755 $(DESTDIR)/$(SYSTEMDUTILDIR)
 

alternatives.8

@@ -214,6 +214,7 @@ A directory, by default
 containing
 .BR alternatives '
 state information.
+/etc/.alternatives.state on OSTree-based systems.
 .TP
 link group
 A set of related symlinks, intended to be updated as a group.
@@ -416,6 +417,7 @@ option.
 .TP
 .I /var/lib/alternatives/
 The default administration directory.
+/etc/alternatives.admindir on OSTree-based systems.
 Can be overridden by the
 .B --admindir
 option.

alternatives.c

@@ -1290,6 +1290,32 @@ static int listServices(const char *altDir, const char *stateDir, int flags) {
     return 0;
 }
 
+int dirExists(const char *path) {
+    struct stat stats;
+    stat(path, &stats);
+
+    if (S_ISDIR(stats.st_mode))
+        return 1;
+
+    return 0;
+}
+
+int canUseAlternativeAdminDir() {
+    if (dirExists("/var/lib/alternatives")) {
+        return 0;
+    }
+
+    if (fileExists("/run/ostree-booted")) {
+        return 1;
+    }
+
+    if (isLink("/ostree")) {
+        return 1;
+    }
+
+    return 0;
+}
+
 int main(int argc, const char **argv) {
     const char **nextArg;
     char *end;
@@ -1304,13 +1330,18 @@ int main(int argc, const char **argv) {
     struct stat sb;
     struct linkSet newSet = {NULL, NULL, NULL};
 
+    if (canUseAlternativeAdminDir()) {
+        stateDir = "/etc/alternatives.admindir";
+    }
+
     setlocale(LC_ALL, "");
     bindtextdomain("chkconfig", "/usr/share/locale");
     textdomain("chkconfig");
 
     if (!argv[1])
         return usage(2);
 
+    int statedir_changed = 0;
     nextArg = argv + 1;
     while (*nextArg) {
         if (!strcmp(*nextArg, "--install")) {
@@ -1408,6 +1439,7 @@ int main(int argc, const char **argv) {
             altDir = normalize_path_alloc(*nextArg);
             nextArg++;
         } else if (!strcmp(*nextArg, "--admindir")) {
+            statedir_changed = 1;
             nextArg++;
             if (!*nextArg)
                 usage(2);
@@ -1428,6 +1460,13 @@ int main(int argc, const char **argv) {
         exit(2);
     }
 
+    if ((statedir_changed == 0) && (stat(stateDir, &sb) == -1)) {
+        if (mkdir(stateDir, 0755) == -1) {
+            fprintf(stderr, _("creating admindir: %s\n"), strerror(errno));
+            exit(2);
+        }
+    }
+
     if (stat(stateDir, &sb) || !S_ISDIR(sb.st_mode) || access(stateDir, F_OK)) {
         fprintf(stderr, _("admindir %s invalid\n"), stateDir);
         exit(2);

chkconfig.spec

@@ -81,9 +81,7 @@ mkdir -p $RPM_BUILD_ROOT/etc/chkconfig.d
 %{_sysconfdir}/chkconfig.d
 %{_sysconfdir}/init.d
 %{_sysconfdir}/rc.d
-%{_sysconfdir}/rc.d/init.d
 %{_sysconfdir}/rc[0-6].d
-%{_sysconfdir}/rc.d/rc[0-6].d
 %{_mandir}/*/chkconfig*
 %{_prefix}/lib/systemd/systemd-sysv-install
 
@@ -95,11 +93,12 @@ mkdir -p $RPM_BUILD_ROOT/etc/chkconfig.d
 %files -n alternatives
 %license COPYING
 %dir /etc/alternatives
+%ghost /etc/alternatives.admindir
+%ghost /var/lib/alternatives
 %{_sbindir}/update-alternatives
 %{_sbindir}/alternatives
 %{_mandir}/*/update-alternatives*
 %{_mandir}/*/alternatives*
-%dir /var/lib/alternatives
 
 %changelog
 * Fri Jun 21 2024 Jan Macku <jamacku@redhat.com> - 1.28-1

po/chkconfig.pot

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: PACKAGE VERSION\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2024-07-26 11:46+0200\n"
+"POT-Creation-Date: 2024-07-26 12:14+0200\n"
 "PO-Revision-Date: YEAR-MO-DA HO:MI+ZONE\n"
 "Last-Translator: FULL NAME <EMAIL@ADDRESS>\n"
 "Language-Team: LANGUAGE <LL@li.org>\n"
@@ -562,22 +562,27 @@ msgstr ""
 msgid "failed to remove %s: %s\n"
 msgstr ""
 
-#: ../alternatives.c:1365
+#: ../alternatives.c:1396
 #, c-format
 msgid "--family can't contain the symbol '@'\n"
 msgstr ""
 
-#: ../alternatives.c:1427
+#: ../alternatives.c:1459
 #, c-format
 msgid "altdir %s invalid\n"
 msgstr ""
 
-#: ../alternatives.c:1432
+#: ../alternatives.c:1465
+#, c-format
+msgid "creating admindir: %s\n"
+msgstr ""
+
+#: ../alternatives.c:1471
 #, c-format
 msgid "admindir %s invalid\n"
 msgstr ""
 
-#: ../alternatives.c:1442
+#: ../alternatives.c:1481
 #, c-format
 msgid "alternatives version %s\n"
 msgstr ""