systemd/src/core/unit-printf.c

/* SPDX-License-Identifier: LGPL-2.1+ */

#include "alloc-util.h"
#include "cgroup-util.h"
#include "format-util.h"
#include "macro.h"
#include "specifier.h"
#include "string-util.h"
#include "strv.h"
#include "unit-name.h"
#include "unit-printf.h"
#include "unit.h"
#include "user-util.h"

static int specifier_prefix_and_instance(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;

        assert(u);

        return unit_name_to_prefix_and_instance(u->id, ret);
}

static int specifier_prefix(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;

        assert(u);

        return unit_name_to_prefix(u->id, ret);
}

static int specifier_prefix_unescaped(char specifier, const void *data, const void *userdata, char **ret) {
        _cleanup_free_ char *p = NULL;
        const Unit *u = userdata;
        int r;

        assert(u);

        r = unit_name_to_prefix(u->id, &p);
        if (r < 0)
                return r;

        return unit_name_unescape(p, ret);
}

static int specifier_instance_unescaped(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;

        assert(u);

        return unit_name_unescape(strempty(u->instance), ret);
}

static int specifier_last_component(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;
        _cleanup_free_ char *prefix = NULL;
        char *dash;
        int r;

        assert(u);

        r = unit_name_to_prefix(u->id, &prefix);
        if (r < 0)
                return r;

        dash = strrchr(prefix, '-');
        if (dash)
                return specifier_string(specifier, dash + 1, userdata, ret);

        *ret = TAKE_PTR(prefix);
        return 0;
}

static int specifier_last_component_unescaped(char specifier, const void *data, const void *userdata, char **ret) {
        _cleanup_free_ char *p = NULL;
        int r;

        r = specifier_last_component(specifier, data, userdata, &p);
        if (r < 0)
                return r;

        return unit_name_unescape(p, ret);
}

static int specifier_filename(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;

        assert(u);

        if (u->instance)
                return unit_name_path_unescape(u->instance, ret);
        else
                return unit_name_to_path(u->id, ret);
}

static void bad_specifier(const Unit *u, char specifier) {
        log_unit_warning(u, "Specifier '%%%c' used in unit configuration, which is deprecated. Please update your unit file, as it does not work as intended.", specifier);
}

static int specifier_cgroup(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;
        char *n;

        assert(u);

        bad_specifier(u, specifier);

        if (u->cgroup_path)
                n = strdup(u->cgroup_path);
        else
                n = unit_default_cgroup_path(u);
        if (!n)
                return -ENOMEM;

        *ret = n;
        return 0;
}

static int specifier_cgroup_root(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;
        char *n;

        assert(u);

        bad_specifier(u, specifier);

        n = strdup(u->manager->cgroup_root);
        if (!n)
                return -ENOMEM;

        *ret = n;
        return 0;
}

static int specifier_cgroup_slice(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;
        char *n;

        assert(u);

        bad_specifier(u, specifier);

        if (UNIT_ISSET(u->slice)) {
                const Unit *slice;

                slice = UNIT_DEREF(u->slice);

                if (slice->cgroup_path)
                        n = strdup(slice->cgroup_path);
                else
                        n = unit_default_cgroup_path(slice);
        } else
                n = strdup(u->manager->cgroup_root);
        if (!n)
                return -ENOMEM;

        *ret = n;
        return 0;
}

static int specifier_special_directory(char specifier, const void *data, const void *userdata, char **ret) {
        const Unit *u = userdata;
        char *n = NULL;

        assert(u);

        n = strdup(u->manager->prefix[PTR_TO_UINT(data)]);
        if (!n)
                return -ENOMEM;

        *ret = n;
        return 0;
}

int unit_name_printf(Unit *u, const char* format, char **ret) {

        /*
         * This will use the passed string as format string and replace the following specifiers (which should all be
         * safe for inclusion in unit names):
         *
         * %n: the full id of the unit                 (foo@bar.waldo)
         * %N: the id of the unit without the suffix   (foo@bar)
         * %p: the prefix                              (foo)
         * %i: the instance                            (bar)
         *
         * %U: the UID of the running user
         * %u: the username of the running user
         *
         * %m: the machine ID of the running system
         * %H: the host name of the running system
         * %b: the boot ID of the running system
         */

        const Specifier table[] = {
                { 'n', specifier_string,              u->id },
                { 'N', specifier_prefix_and_instance, NULL },
                { 'p', specifier_prefix,              NULL },
                { 'i', specifier_string,              u->instance },

                { 'g', specifier_group_name,          NULL },
                { 'G', specifier_group_id,            NULL },
                { 'U', specifier_user_id,             NULL },
                { 'u', specifier_user_name,           NULL },

                { 'm', specifier_machine_id,          NULL },
                { 'H', specifier_host_name,           NULL },
                { 'b', specifier_boot_id,             NULL },
                {}
        };

        assert(u);
        assert(format);
        assert(ret);

        return specifier_printf(format, table, u, ret);
}

int unit_full_printf(Unit *u, const char *format, char **ret) {

        /* This is similar to unit_name_printf() but also supports unescaping. Also, adds a couple of additional codes
         * (which are likely not suitable for unescaped inclusion in unit names):
         *
         * %f: the unescaped instance if set, otherwise the id unescaped as path
         *
         * %c: cgroup path of unit (deprecated)
         * %r: where units in this slice are placed in the cgroup tree (deprecated)
         * %R: the root of this systemd's instance tree (deprecated)
         *
         * %t: the runtime directory root (e.g. /run or $XDG_RUNTIME_DIR)
         * %S: the state directory root (e.g. /var/lib or $XDG_CONFIG_HOME)
         * %C: the cache directory root (e.g. /var/cache or $XDG_CACHE_HOME)
         * %L: the log directory root (e.g. /var/log or $XDG_CONFIG_HOME/log)
         * %E: the configuration directory root (e.g. /etc or $XDG_CONFIG_HOME)
         * %T: the temporary directory (e.g. /tmp, or $TMPDIR, $TEMP, $TMP)
         * %V: the temporary directory for large, persistent stuff (e.g. /var/tmp, or $TMPDIR, $TEMP, $TMP)
         *
         * %h: the homedir of the running user
         * %s: the shell of the running user
         *
         * %v: `uname -r` of the running system
         *
         * NOTICE: When you add new entries here, please be careful: specifiers which depend on settings of the unit
         * file itself are broken by design, as they would resolve differently depending on whether they are used
         * before or after the relevant configuration setting. Hence: don't add them.
         */

        const Specifier table[] = {
                { 'n', specifier_string,                   u->id },
                { 'N', specifier_prefix_and_instance,      NULL },
                { 'p', specifier_prefix,                   NULL },
                { 'P', specifier_prefix_unescaped,         NULL },
                { 'i', specifier_string,                   u->instance },
                { 'I', specifier_instance_unescaped,       NULL },
                { 'j', specifier_last_component,           NULL },
                { 'J', specifier_last_component_unescaped, NULL },

                { 'f', specifier_filename,                 NULL },
                { 'c', specifier_cgroup,                   NULL },
                { 'r', specifier_cgroup_slice,             NULL },
                { 'R', specifier_cgroup_root,              NULL },

                { 't', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_RUNTIME) },
                { 'S', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_STATE) },
                { 'C', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_CACHE) },
                { 'L', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_LOGS) },
                { 'E', specifier_special_directory,        UINT_TO_PTR(EXEC_DIRECTORY_CONFIGURATION) },
                { 'T', specifier_tmp_dir,                  NULL },
                { 'V', specifier_var_tmp_dir,              NULL },

                { 'g', specifier_group_name,               NULL },
                { 'G', specifier_group_id,                 NULL },
                { 'U', specifier_user_id,                  NULL },
                { 'u', specifier_user_name,                NULL },
                { 'h', specifier_user_home,                NULL },
                { 's', specifier_user_shell,               NULL },

                { 'm', specifier_machine_id,               NULL },
                { 'H', specifier_host_name,                NULL },
                { 'b', specifier_boot_id,                  NULL },
                { 'v', specifier_kernel_release,           NULL },
                {}
        };

        assert(u);
        assert(format);
        assert(ret);

        return specifier_printf(format, table, u, ret);
}