core: rework unit name validation and manipulation logic

A variety of changes:

- Make sure all our calls distuingish OOM from other errors if OOM is
  not the only error possible.

- Be much stricter when parsing escaped paths, do not accept trailing or
  leading escaped slashes.

- Change unit validation to take a bit mask for allowing plain names,
  instance names or template names or an combination thereof.

- Refuse manipulating invalid unit name

1 files changed, 377 insertions, 223 deletions

diff --git a/src/shared/unit-name.c b/src/shared/unit-name.c
index 86d6ce3df1..c41d7d86a7 100644
--- a/src/shared/unit-name.c
+++ b/src/shared/unit-name.c
@@ -33,45 +33,13 @@
         DIGITS LETTERS                          \
         ":-_.\\"
 
-static const char* const unit_type_table[_UNIT_TYPE_MAX] = {
-        [UNIT_SERVICE] = "service",
-        [UNIT_SOCKET] = "socket",
-        [UNIT_BUSNAME] = "busname",
-        [UNIT_TARGET] = "target",
-        [UNIT_SNAPSHOT] = "snapshot",
-        [UNIT_DEVICE] = "device",
-        [UNIT_MOUNT] = "mount",
-        [UNIT_AUTOMOUNT] = "automount",
-        [UNIT_SWAP] = "swap",
-        [UNIT_TIMER] = "timer",
-        [UNIT_PATH] = "path",
-        [UNIT_SLICE] = "slice",
-        [UNIT_SCOPE] = "scope"
-};
-
-DEFINE_STRING_TABLE_LOOKUP(unit_type, UnitType);
-
-static const char* const unit_load_state_table[_UNIT_LOAD_STATE_MAX] = {
-        [UNIT_STUB] = "stub",
-        [UNIT_LOADED] = "loaded",
-        [UNIT_NOT_FOUND] = "not-found",
-        [UNIT_ERROR] = "error",
-        [UNIT_MERGED] = "merged",
-        [UNIT_MASKED] = "masked"
-};
-
-DEFINE_STRING_TABLE_LOOKUP(unit_load_state, UnitLoadState);
-
-bool unit_name_is_valid(const char *n, enum template_valid template_ok) {
+bool unit_name_is_valid(const char *n, UnitNameFlags flags) {
         const char *e, *i, *at;
 
-        /* Valid formats:
-         *
-         *         string@instance.suffix
-         *         string.suffix
-         */
+        assert((flags & ~(UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE)) == 0);
 
-        assert(IN_SET(template_ok, TEMPLATE_VALID, TEMPLATE_INVALID));
+        if (_unlikely_(flags == 0))
+                return false;
 
         if (isempty(n))
                 return false;
@@ -95,15 +63,32 @@ bool unit_name_is_valid(const char *n, enum template_valid template_ok) {
                         return false;
         }
 
-        if (at) {
-                if (at == n)
-                        return false;
+        if (at == n)
+                return false;
 
-                if (template_ok != TEMPLATE_VALID && at+1 == e)
-                        return false;
-        }
+        if (flags & UNIT_NAME_PLAIN)
+                if (!at)
+                        return true;
 
-        return true;
+        if (flags & UNIT_NAME_INSTANCE)
+                if (at && e > at + 1)
+                        return true;
+
+        if (flags & UNIT_NAME_TEMPLATE)
+                if (at && e == at + 1)
+                        return true;
+
+        return false;
+}
+
+bool unit_prefix_is_valid(const char *p) {
+
+        /* We don't allow additional @ in the prefix string */
+
+        if (isempty(p))
+                return false;
+
+        return in_charset(p, VALID_CHARS);
 }
 
 bool unit_instance_is_valid(const char *i) {
@@ -120,14 +105,41 @@ bool unit_instance_is_valid(const char *i) {
         return in_charset(i, "@" VALID_CHARS);
 }
 
-bool unit_prefix_is_valid(const char *p) {
+bool unit_suffix_is_valid(const char *s) {
+        if (isempty(s))
+                return false;
 
-        /* We don't allow additional @ in the instance string */
+        if (s[0] != '.')
+                return false;
 
-        if (isempty(p))
+        if (unit_type_from_string(s + 1) < 0)
                 return false;
 
-        return in_charset(p, VALID_CHARS);
+        return true;
+}
+
+int unit_name_to_prefix(const char *n, char **ret) {
+        const char *p;
+        char *s;
+
+        assert(n);
+        assert(ret);
+
+        if (!unit_name_is_valid(n, UNIT_NAME_ANY))
+                return -EINVAL;
+
+        p = strchr(n, '@');
+        if (!p)
+                p = strrchr(n, '.');
+
+        assert_se(p);
+
+        s = strndup(n, p - n);
+        if (!s)
+                return -ENOMEM;
+
+        *ret = s;
+        return 0;
 }
 
 int unit_name_to_instance(const char *n, char **instance) {
@@ -137,6 +149,9 @@ int unit_name_to_instance(const char *n, char **instance) {
         assert(n);
         assert(instance);
 
+        if (!unit_name_is_valid(n, UNIT_NAME_ANY))
+                return -EINVAL;
+
         /* Everything past the first @ and before the last . is the instance */
         p = strchr(n, '@');
         if (!p) {
@@ -144,13 +159,13 @@ int unit_name_to_instance(const char *n, char **instance) {
                 return 0;
         }
 
-        d = strrchr(n, '.');
+        p++;
+
+        d = strrchr(p, '.');
         if (!d)
                 return -EINVAL;
-        if (d < p)
-                return -EINVAL;
 
-        i = strndup(p+1, d-p-1);
+        i = strndup(p, d-p);
         if (!i)
                 return -ENOMEM;
 
@@ -158,55 +173,95 @@ int unit_name_to_instance(const char *n, char **instance) {
         return 1;
 }
 
-char *unit_name_to_prefix_and_instance(const char *n) {
+int unit_name_to_prefix_and_instance(const char *n, char **ret) {
         const char *d;
+        char *s;
 
         assert(n);
+        assert(ret);
+
+        if (!unit_name_is_valid(n, UNIT_NAME_ANY))
+                return -EINVAL;
 
-        assert_se(d = strrchr(n, '.'));
-        return strndup(n, d - n);
+        d = strrchr(n, '.');
+        if (!d)
+                return -EINVAL;
+
+        s = strndup(n, d - n);
+        if (!s)
+                return -ENOMEM;
+
+        *ret = s;
+        return 0;
 }
 
-char *unit_name_to_prefix(const char *n) {
-        const char *p;
+UnitType unit_name_to_type(const char *n) {
+        const char *e;
 
         assert(n);
 
-        p = strchr(n, '@');
-        if (p)
-                return strndup(n, p - n);
+        if (!unit_name_is_valid(n, UNIT_NAME_ANY))
+                return _UNIT_TYPE_INVALID;
 
-        return unit_name_to_prefix_and_instance(n);
+        assert_se(e = strrchr(n, '.'));
+
+        return unit_type_from_string(e + 1);
 }
 
-char *unit_name_change_suffix(const char *n, const char *suffix) {
-        char *e, *r;
+int unit_name_change_suffix(const char *n, const char *suffix, char **ret) {
+        char *e, *s;
         size_t a, b;
 
         assert(n);
         assert(suffix);
-        assert(suffix[0] == '.');
+        assert(ret);
+
+        if (!unit_name_is_valid(n, UNIT_NAME_ANY))
+                return -EINVAL;
+
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
 
         assert_se(e = strrchr(n, '.'));
+
         a = e - n;
         b = strlen(suffix);
 
-        r = new(char, a + b + 1);
-        if (!r)
-                return NULL;
+        s = new(char, a + b + 1);
+        if (!s)
+                return -ENOMEM;
 
-        strcpy(mempcpy(r, n, a), suffix);
-        return r;
+        strcpy(mempcpy(s, n, a), suffix);
+        *ret = s;
+
+        return 0;
 }
 
-char *unit_name_build(const char *prefix, const char *instance, const char *suffix) {
+int unit_name_build(const char *prefix, const char *instance, const char *suffix, char **ret) {
+        char *s;
+
         assert(prefix);
         assert(suffix);
+        assert(ret);
+
+        if (!unit_prefix_is_valid(prefix))
+                return -EINVAL;
+
+        if (instance && !unit_instance_is_valid(instance))
+                return -EINVAL;
+
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
 
         if (!instance)
-                return strappend(prefix, suffix);
+                s = strappend(prefix, suffix);
+        else
+                s = strjoin(prefix, "@", instance, suffix, NULL);
+        if (!s)
+                return -ENOMEM;
 
-        return strjoin(prefix, "@", instance, suffix, NULL);
+        *ret = s;
+        return 0;
 }
 
 static char *do_escape_char(char c, char *t) {
@@ -242,30 +297,6 @@ static char *do_escape(const char *f, char *t) {
         return t;
 }
 
-static char *do_escape_mangle(const char *f, enum unit_name_mangle allow_globs, char *t) {
-        const char *valid_chars;
-
-        assert(f);
-        assert(IN_SET(allow_globs, MANGLE_GLOB, MANGLE_NOGLOB));
-        assert(t);
-
-        /* We'll only escape the obvious characters here, to play
-         * safe. */
-
-        valid_chars = allow_globs == MANGLE_GLOB ? "@" VALID_CHARS "[]!-*?" : "@" VALID_CHARS;
-
-        for (; *f; f++) {
-                if (*f == '/')
-                        *(t++) = '-';
-                else if (!strchr(valid_chars, *f))
-                        t = do_escape_char(*f, t);
-                else
-                        *(t++) = *f;
-        }
-
-        return t;
-}
-
 char *unit_name_escape(const char *f) {
         char *r, *t;
 
@@ -281,14 +312,15 @@ char *unit_name_escape(const char *f) {
         return r;
 }
 
-char *unit_name_unescape(const char *f) {
-        char *r, *t;
+int unit_name_unescape(const char *f, char **ret) {
+        _cleanup_free_ char *r = NULL;
+        char *t;
 
         assert(f);
 
         r = strdup(f);
         if (!r)
-                return NULL;
+                return -ENOMEM;
 
         for (t = r; *f; f++) {
                 if (*f == '-')
@@ -296,180 +328,228 @@ char *unit_name_unescape(const char *f) {
                 else if (*f == '\\') {
                         int a, b;
 
-                        if (f[1] != 'x' ||
-                            (a = unhexchar(f[2])) < 0 ||
-                            (b = unhexchar(f[3])) < 0) {
-                                /* Invalid escape code, let's take it literal then */
-                                *(t++) = '\\';
-                        } else {
-                                *(t++) = (char) ((a << 4) | b);
-                                f += 3;
-                        }
+                        if (f[1] != 'x')
+                                return -EINVAL;
+
+                        a = unhexchar(f[2]);
+                        if (a < 0)
+                                return -EINVAL;
+
+                        b = unhexchar(f[3]);
+                        if (b < 0)
+                                return -EINVAL;
+
+                        *(t++) = (char) ((a << 4) | b);
+                        f += 3;
                 } else
                         *(t++) = *f;
         }
 
         *t = 0;
 
-        return r;
+        *ret = r;
+        r = NULL;
+
+        return 0;
 }
 
-char *unit_name_path_escape(const char *f) {
-        _cleanup_free_ char *p = NULL;
+int unit_name_path_escape(const char *f, char **ret) {
+        char *p, *s;
 
         assert(f);
+        assert(ret);
 
-        p = strdup(f);
+        p = strdupa(f);
         if (!p)
-                return NULL;
+                return -ENOMEM;
 
         path_kill_slashes(p);
 
         if (STR_IN_SET(p, "/", ""))
-                return strdup("-");
-
-        return unit_name_escape(p[0] == '/' ? p + 1 : p);
-}
+                s = strdup("-");
+        else {
+                char *e;
 
-char *unit_name_path_unescape(const char *f) {
-        char *e, *w;
+                if (!path_is_safe(p))
+                        return -EINVAL;
 
-        assert(f);
+                /* Truncate trailing slashes */
+                e = endswith(p, "/");
+                if (e)
+                        *e = 0;
 
-        e = unit_name_unescape(f);
-        if (!e)
-                return NULL;
+                /* Truncate leading slashes */
+                if (p[0] == '/')
+                        p++;
 
-        if (e[0] != '/') {
-                w = strappend("/", e);
-                free(e);
-                return w;
+                s = unit_name_escape(p);
         }
+        if (!s)
+                return -ENOMEM;
 
-        return e;
+        *ret = s;
+        return 0;
 }
 
-bool unit_name_is_template(const char *n) {
-        const char *p, *e;
-
-        assert(n);
+int unit_name_path_unescape(const char *f, char **ret) {
+        char *s, *w;
+        int r;
 
-        p = strchr(n, '@');
-        if (!p)
-                return false;
+        assert(f);
 
-        e = strrchr(p+1, '.');
-        if (!e)
-                return false;
+        if (streq(f, "-")) {
+                s = strdup("/");
+                if (!s)
+                        return -ENOMEM;
 
-        return e == p + 1;
-}
+                *ret = s;
+                return 0;
+        }
 
-bool unit_name_is_instance(const char *n) {
-        const char *p, *e;
+        r = unit_name_unescape(f, &s);
+        if (r < 0)
+                return r;
 
-        assert(n);
+        /* Don't accept trailing or leading slashes */
+        if (startswith(s, "/") || endswith(s, "/")) {
+                free(s);
+                return -EINVAL;
+        }
 
-        p = strchr(n, '@');
-        if (!p)
-                return false;
+        /* Prefix a slash again */
+        w = strappend("/", s);
+        free(s);
+        if (!w)
+                return -ENOMEM;
 
-        e = strrchr(p+1, '.');
-        if (!e)
-                return false;
+        if (!path_is_safe(w)) {
+                free(w);
+                return -EINVAL;
+        }
 
-        return e > p + 1;
+        *ret = w;
+        return 0;
 }
 
-char *unit_name_replace_instance(const char *f, const char *i) {
+int unit_name_replace_instance(const char *f, const char *i, char **ret) {
         const char *p, *e;
-        char *r;
+        char *s;
         size_t a, b;
 
         assert(f);
         assert(i);
+        assert(ret);
 
-        p = strchr(f, '@');
-        if (!p)
-                return strdup(f);
+        if (!unit_name_is_valid(f, UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE))
+                return -EINVAL;
+        if (!unit_instance_is_valid(i))
+                return -EINVAL;
 
-        e = strrchr(f, '.');
-        if (!e)
-                e = strchr(f, 0);
+        assert_se(p = strchr(f, '@'));
+        assert_se(e = strrchr(f, '.'));
 
         a = p - f;
         b = strlen(i);
 
-        r = new(char, a + 1 + b + strlen(e) + 1);
-        if (!r)
-                return NULL;
+        s = new(char, a + 1 + b + strlen(e) + 1);
+        if (!s)
+                return -ENOMEM;
 
-        strcpy(mempcpy(mempcpy(r, f, a + 1), i, b), e);
-        return r;
+        strcpy(mempcpy(mempcpy(s, f, a + 1), i, b), e);
+
+        *ret = s;
+        return 0;
 }
 
-char *unit_name_template(const char *f) {
+int unit_name_template(const char *f, char **ret) {
         const char *p, *e;
-        char *r;
+        char *s;
         size_t a;
 
         assert(f);
+        assert(ret);
 
-        p = strchr(f, '@');
-        if (!p)
-                return strdup(f);
+        if (!unit_name_is_valid(f, UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE))
+                return -EINVAL;
 
-        e = strrchr(f, '.');
-        if (!e)
-                e = strchr(f, 0);
+        assert_se(p = strchr(f, '@'));
+        assert_se(e = strrchr(f, '.'));
 
         a = p - f;
 
-        r = new(char, a + 1 + strlen(e) + 1);
-        if (!r)
-                return NULL;
+        s = new(char, a + 1 + strlen(e) + 1);
+        if (!s)
+                return -ENOMEM;
 
-        strcpy(mempcpy(r, f, a + 1), e);
-        return r;
+        strcpy(mempcpy(s, f, a + 1), e);
+
+        *ret = s;
+        return 0;
 }
 
-char *unit_name_from_path(const char *path, const char *suffix) {
+int unit_name_from_path(const char *path, const char *suffix, char **ret) {
         _cleanup_free_ char *p = NULL;
+        char *s = NULL;
+        int r;
 
         assert(path);
         assert(suffix);
+        assert(ret);
 
-        p = unit_name_path_escape(path);
-        if (!p)
-                return NULL;
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
 
-        return strappend(p, suffix);
+        r = unit_name_path_escape(path, &p);
+        if (r < 0)
+                return r;
+
+        s = strappend(p, suffix);
+        if (!s)
+                return -ENOMEM;
+
+        *ret = s;
+        return 0;
 }
 
-char *unit_name_from_path_instance(const char *prefix, const char *path, const char *suffix) {
+int unit_name_from_path_instance(const char *prefix, const char *path, const char *suffix, char **ret) {
         _cleanup_free_ char *p = NULL;
+        char *s;
+        int r;
 
         assert(prefix);
         assert(path);
         assert(suffix);
+        assert(ret);
 
-        p = unit_name_path_escape(path);
-        if (!p)
-                return NULL;
+        if (!unit_prefix_is_valid(prefix))
+                return -EINVAL;
+
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
+
+        r = unit_name_path_escape(path, &p);
+        if (r < 0)
+                return r;
+
+        s = strjoin(prefix, "@", p, suffix, NULL);
+        if (!s)
+                return -ENOMEM;
 
-        return strjoin(prefix, "@", p, suffix, NULL);
+        *ret = s;
+        return 0;
 }
 
-char *unit_name_to_path(const char *name) {
-        _cleanup_free_ char *w = NULL;
+int unit_name_to_path(const char *name, char **ret) {
+        _cleanup_free_ char *prefix = NULL;
+        int r;
 
         assert(name);
 
-        w = unit_name_to_prefix(name);
-        if (!w)
-                return NULL;
+        r = unit_name_to_prefix(name, &prefix);
+        if (r < 0)
+                return r;
 
-        return unit_name_path_unescape(w);
+        return unit_name_path_unescape(prefix, ret);
 }
 
 char *unit_dbus_path_from_name(const char *name) {
@@ -500,6 +580,30 @@ int unit_name_from_dbus_path(const char *path, char **name) {
         return 0;
 }
 
+static char *do_escape_mangle(const char *f, UnitNameMangle allow_globs, char *t) {
+        const char *valid_chars;
+
+        assert(f);
+        assert(IN_SET(allow_globs, UNIT_NAME_GLOB, UNIT_NAME_NOGLOB));
+        assert(t);
+
+        /* We'll only escape the obvious characters here, to play
+         * safe. */
+
+        valid_chars = allow_globs == UNIT_NAME_GLOB ? "@" VALID_CHARS "[]!-*?" : "@" VALID_CHARS;
+
+        for (; *f; f++) {
+                if (*f == '/')
+                        *(t++) = '-';
+                else if (!strchr(valid_chars, *f))
+                        t = do_escape_char(*f, t);
+                else
+                        *(t++) = *f;
+        }
+
+        return t;
+}
+
 /**
  *  Convert a string to a unit name. /dev/blah is converted to dev-blah.device,
  *  /blah/blah is converted to blah-blah.mount, anything else is left alone,
@@ -507,54 +611,75 @@ int unit_name_from_dbus_path(const char *path, char **name) {
  *
  *  If @allow_globs, globs characters are preserved. Otherwise they are escaped.
  */
-char *unit_name_mangle_with_suffix(const char *name, enum unit_name_mangle allow_globs, const char *suffix) {
-        char *r, *t;
+int unit_name_mangle_with_suffix(const char *name, UnitNameMangle allow_globs, const char *suffix, char **ret) {
+        char *s, *t;
+        int r;
 
         assert(name);
         assert(suffix);
-        assert(suffix[0] == '.');
+        assert(ret);
 
-        if (is_device_path(name))
-                return unit_name_from_path(name, ".device");
+        if (isempty(name)) /* We cannot mangle empty unit names to become valid, sorry. */
+                return -EINVAL;
 
-        if (path_is_absolute(name))
-                return unit_name_from_path(name, ".mount");
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
 
-        r = new(char, strlen(name) * 4 + strlen(suffix) + 1);
-        if (!r)
-                return NULL;
+        if (unit_name_is_valid(name, UNIT_NAME_ANY)) {
+                /* No mangling necessary... */
+                s = strdup(name);
+                if (!s)
+                        return -ENOMEM;
 
-        t = do_escape_mangle(name, allow_globs, r);
+                *ret = s;
+                return 0;
+        }
 
-        if (unit_name_to_type(name) < 0)
-                strcpy(t, suffix);
-        else
-                *t = 0;
+        if (is_device_path(name)) {
+                r = unit_name_from_path(name, ".device", ret);
+                if (r >= 0)
+                        return 1;
+                if (r != -EINVAL)
+                        return r;
+        }
 
-        return r;
-}
+        if (path_is_absolute(name)) {
+                r = unit_name_from_path(name, ".mount", ret);
+                if (r >= 0)
+                        return 1;
+                if (r != -EINVAL)
+                        return r;
+        }
 
-UnitType unit_name_to_type(const char *n) {
-        const char *e;
+        s = new(char, strlen(name) * 4 + strlen(suffix) + 1);
+        if (!s)
+                return -ENOMEM;
 
-        assert(n);
+        t = do_escape_mangle(name, allow_globs, s);
+        *t = 0;
 
-        e = strrchr(n, '.');
-        if (!e)
-                return _UNIT_TYPE_INVALID;
+        if (unit_name_to_type(s) < 0)
+                strcpy(t, suffix);
 
-        return unit_type_from_string(e + 1);
+        *ret = s;
+        return 1;
 }
 
-int build_subslice(const char *slice, const char*name, char **subslice) {
-        char *ret;
+int slice_build_subslice(const char *slice, const char*name, char **ret) {
+        char *subslice;
 
         assert(slice);
         assert(name);
-        assert(subslice);
+        assert(ret);
+
+        if (!unit_name_is_valid(slice, UNIT_NAME_PLAIN))
+                return -EINVAL;
+
+        if (!unit_prefix_is_valid(name))
+                return -EINVAL;
 
         if (streq(slice, "-.slice"))
-                ret = strappend(name, ".slice");
+                subslice = strappend(name, ".slice");
         else {
                 char *e;
 
@@ -562,17 +687,46 @@ int build_subslice(const char *slice, const char*name, char **subslice) {
                 if (!e)
                         return -EINVAL;
 
-                ret = new(char, (e - slice) + 1 + strlen(name) + 6 + 1);
-                if (!ret)
+                subslice = new(char, (e - slice) + 1 + strlen(name) + 6 + 1);
+                if (!subslice)
                         return -ENOMEM;
 
-                stpcpy(stpcpy(stpcpy(mempcpy(ret, slice, e - slice), "-"), name), ".slice");
+                stpcpy(stpcpy(stpcpy(mempcpy(subslice, slice, e - slice), "-"), name), ".slice");
         }
 
-        *subslice = ret;
+        *ret = subslice;
         return 0;
 }
 
+static const char* const unit_type_table[_UNIT_TYPE_MAX] = {
+        [UNIT_SERVICE] = "service",
+        [UNIT_SOCKET] = "socket",
+        [UNIT_BUSNAME] = "busname",
+        [UNIT_TARGET] = "target",
+        [UNIT_SNAPSHOT] = "snapshot",
+        [UNIT_DEVICE] = "device",
+        [UNIT_MOUNT] = "mount",
+        [UNIT_AUTOMOUNT] = "automount",
+        [UNIT_SWAP] = "swap",
+        [UNIT_TIMER] = "timer",
+        [UNIT_PATH] = "path",
+        [UNIT_SLICE] = "slice",
+        [UNIT_SCOPE] = "scope"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(unit_type, UnitType);
+
+static const char* const unit_load_state_table[_UNIT_LOAD_STATE_MAX] = {
+        [UNIT_STUB] = "stub",
+        [UNIT_LOADED] = "loaded",
+        [UNIT_NOT_FOUND] = "not-found",
+        [UNIT_ERROR] = "error",
+        [UNIT_MERGED] = "merged",
+        [UNIT_MASKED] = "masked"
+};
+
+DEFINE_STRING_TABLE_LOOKUP(unit_load_state, UnitLoadState);
+
 static const char* const unit_dependency_table[_UNIT_DEPENDENCY_MAX] = {
         [UNIT_REQUIRES] = "Requires",
         [UNIT_REQUIRES_OVERRIDABLE] = "RequiresOverridable",