Adding upstream version 252.22.upstream/252.22upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 905 insertions, 0 deletions

diff --git a/src/basic/unit-name.c b/src/basic/unit-name.c
new file mode 100644
index 0000000..3b739c7
--- /dev/null
+++ b/src/basic/unit-name.c
@@ -0,0 +1,905 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+#include "sd-id128.h"
+
+#include "alloc-util.h"
+#include "glob-util.h"
+#include "hexdecoct.h"
+#include "memory-util.h"
+#include "path-util.h"
+#include "random-util.h"
+#include "sparse-endian.h"
+#include "special.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "unit-name.h"
+
+/* Characters valid in a unit name. */
+#define VALID_CHARS                             \
+        DIGITS                                  \
+        LETTERS                                 \
+        ":-_.\\"
+
+/* The same, but also permits the single @ character that may appear */
+#define VALID_CHARS_WITH_AT                     \
+        "@"                                     \
+        VALID_CHARS
+
+/* All chars valid in a unit name glob */
+#define VALID_CHARS_GLOB                        \
+        VALID_CHARS_WITH_AT                     \
+        "[]!-*?"
+
+#define LONG_UNIT_NAME_HASH_KEY SD_ID128_MAKE(ec,f2,37,fb,58,32,4a,32,84,9f,06,9b,0d,21,eb,9a)
+#define UNIT_NAME_HASH_LENGTH_CHARS 16
+
+bool unit_name_is_valid(const char *n, UnitNameFlags flags) {
+        const char *e, *i, *at;
+
+        assert((flags & ~(UNIT_NAME_PLAIN|UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE)) == 0);
+
+        if (_unlikely_(flags == 0))
+                return false;
+
+        if (isempty(n))
+                return false;
+
+        if (strlen(n) >= UNIT_NAME_MAX)
+                return false;
+
+        e = strrchr(n, '.');
+        if (!e || e == n)
+                return false;
+
+        if (unit_type_from_string(e + 1) < 0)
+                return false;
+
+        for (i = n, at = NULL; i < e; i++) {
+
+                if (*i == '@' && !at)
+                        at = i;
+
+                if (!strchr(VALID_CHARS_WITH_AT, *i))
+                        return false;
+        }
+
+        if (at == n)
+                return false;
+
+        if (flags & UNIT_NAME_PLAIN)
+                if (!at)
+                        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) {
+
+        /* The max length depends on the length of the string, so we
+         * don't really check this here. */
+
+        if (isempty(i))
+                return false;
+
+        /* We allow additional @ in the instance string, we do not
+         * allow them in the prefix! */
+
+        return in_charset(i, "@" VALID_CHARS);
+}
+
+bool unit_suffix_is_valid(const char *s) {
+        if (isempty(s))
+                return false;
+
+        if (s[0] != '.')
+                return false;
+
+        if (unit_type_from_string(s + 1) < 0)
+                return false;
+
+        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;
+}
+
+UnitNameFlags unit_name_to_instance(const char *n, char **ret) {
+        const char *p, *d;
+
+        assert(n);
+
+        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) {
+                if (ret)
+                        *ret = NULL;
+                return UNIT_NAME_PLAIN;
+        }
+
+        p++;
+
+        d = strrchr(p, '.');
+        if (!d)
+                return -EINVAL;
+
+        if (ret) {
+                char *i = strndup(p, d-p);
+                if (!i)
+                        return -ENOMEM;
+
+                *ret = i;
+        }
+        return d > p ? UNIT_NAME_INSTANCE : UNIT_NAME_TEMPLATE;
+}
+
+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;
+
+        d = strrchr(n, '.');
+        if (!d)
+                return -EINVAL;
+
+        s = strndup(n, d - n);
+        if (!s)
+                return -ENOMEM;
+
+        *ret = s;
+        return 0;
+}
+
+UnitType unit_name_to_type(const char *n) {
+        const char *e;
+
+        assert(n);
+
+        if (!unit_name_is_valid(n, UNIT_NAME_ANY))
+                return _UNIT_TYPE_INVALID;
+
+        assert_se(e = strrchr(n, '.'));
+
+        return unit_type_from_string(e + 1);
+}
+
+int unit_name_change_suffix(const char *n, const char *suffix, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        size_t a, b;
+        char *e;
+
+        assert(n);
+        assert(suffix);
+        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);
+
+        s = new(char, a + b + 1);
+        if (!s)
+                return -ENOMEM;
+
+        strcpy(mempcpy(s, n, a), suffix);
+
+        /* Make sure the name is still valid (i.e. didn't grow too large due to longer suffix) */
+        if (!unit_name_is_valid(s, UNIT_NAME_ANY))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+int unit_name_build(const char *prefix, const char *instance, const char *suffix, char **ret) {
+        UnitType type;
+
+        assert(prefix);
+        assert(suffix);
+        assert(ret);
+
+        if (suffix[0] != '.')
+                return -EINVAL;
+
+        type = unit_type_from_string(suffix + 1);
+        if (type < 0)
+                return type;
+
+        return unit_name_build_from_type(prefix, instance, type, ret);
+}
+
+int unit_name_build_from_type(const char *prefix, const char *instance, UnitType type, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        const char *ut;
+
+        assert(prefix);
+        assert(type >= 0);
+        assert(type < _UNIT_TYPE_MAX);
+        assert(ret);
+
+        if (!unit_prefix_is_valid(prefix))
+                return -EINVAL;
+
+        ut = unit_type_to_string(type);
+
+        if (instance) {
+                if (!unit_instance_is_valid(instance))
+                        return -EINVAL;
+
+                s = strjoin(prefix, "@", instance, ".", ut);
+        } else
+                s = strjoin(prefix, ".", ut);
+        if (!s)
+                return -ENOMEM;
+
+        /* Verify that this didn't grow too large (or otherwise is invalid) */
+        if (!unit_name_is_valid(s, instance ? UNIT_NAME_INSTANCE : UNIT_NAME_PLAIN))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+static char *do_escape_char(char c, char *t) {
+        assert(t);
+
+        *(t++) = '\\';
+        *(t++) = 'x';
+        *(t++) = hexchar(c >> 4);
+        *(t++) = hexchar(c);
+
+        return t;
+}
+
+static char *do_escape(const char *f, char *t) {
+        assert(f);
+        assert(t);
+
+        /* do not create units with a leading '.', like for "/.dotdir" mount points */
+        if (*f == '.') {
+                t = do_escape_char(*f, t);
+                f++;
+        }
+
+        for (; *f; f++) {
+                if (*f == '/')
+                        *(t++) = '-';
+                else if (IN_SET(*f, '-', '\\') || !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;
+
+        assert(f);
+
+        r = new(char, strlen(f)*4+1);
+        if (!r)
+                return NULL;
+
+        t = do_escape(f, r);
+        *t = 0;
+
+        return r;
+}
+
+int unit_name_unescape(const char *f, char **ret) {
+        _cleanup_free_ char *r = NULL;
+        char *t;
+
+        assert(f);
+
+        r = strdup(f);
+        if (!r)
+                return -ENOMEM;
+
+        for (t = r; *f; f++) {
+                if (*f == '-')
+                        *(t++) = '/';
+                else if (*f == '\\') {
+                        int a, b;
+
+                        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) (((uint8_t) a << 4U) | (uint8_t) b);
+                        f += 3;
+                } else
+                        *(t++) = *f;
+        }
+
+        *t = 0;
+
+        *ret = TAKE_PTR(r);
+
+        return 0;
+}
+
+int unit_name_path_escape(const char *f, char **ret) {
+        _cleanup_free_ char *p = NULL;
+        char *s;
+
+        assert(f);
+        assert(ret);
+
+        p = strdup(f);
+        if (!p)
+                return -ENOMEM;
+
+        path_simplify(p);
+
+        if (empty_or_root(p))
+                s = strdup("-");
+        else {
+                if (!path_is_normalized(p))
+                        return -EINVAL;
+
+                /* Truncate trailing slashes and skip leading slashes */
+                delete_trailing_chars(p, "/");
+                s = unit_name_escape(skip_leading_chars(p, "/"));
+        }
+        if (!s)
+                return -ENOMEM;
+
+        *ret = s;
+        return 0;
+}
+
+int unit_name_path_unescape(const char *f, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        int r;
+
+        assert(f);
+
+        if (isempty(f))
+                return -EINVAL;
+
+        if (streq(f, "-")) {
+                s = strdup("/");
+                if (!s)
+                        return -ENOMEM;
+        } else {
+                _cleanup_free_ char *w = NULL;
+
+                r = unit_name_unescape(f, &w);
+                if (r < 0)
+                        return r;
+
+                /* Don't accept trailing or leading slashes */
+                if (startswith(w, "/") || endswith(w, "/"))
+                        return -EINVAL;
+
+                /* Prefix a slash again */
+                s = strjoin("/", w);
+                if (!s)
+                        return -ENOMEM;
+
+                if (!path_is_normalized(s))
+                        return -EINVAL;
+        }
+
+        if (ret)
+                *ret = TAKE_PTR(s);
+
+        return 0;
+}
+
+int unit_name_replace_instance(const char *f, const char *i, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        const char *p, *e;
+        size_t a, b;
+
+        assert(f);
+        assert(i);
+        assert(ret);
+
+        if (!unit_name_is_valid(f, UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE))
+                return -EINVAL;
+        if (!unit_instance_is_valid(i))
+                return -EINVAL;
+
+        assert_se(p = strchr(f, '@'));
+        assert_se(e = strrchr(f, '.'));
+
+        a = p - f;
+        b = strlen(i);
+
+        s = new(char, a + 1 + b + strlen(e) + 1);
+        if (!s)
+                return -ENOMEM;
+
+        strcpy(mempcpy(mempcpy(s, f, a + 1), i, b), e);
+
+        /* Make sure the resulting name still is valid, i.e. didn't grow too large */
+        if (!unit_name_is_valid(s, UNIT_NAME_INSTANCE))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+int unit_name_template(const char *f, char **ret) {
+        const char *p, *e;
+        char *s;
+        size_t a;
+
+        assert(f);
+        assert(ret);
+
+        if (!unit_name_is_valid(f, UNIT_NAME_INSTANCE|UNIT_NAME_TEMPLATE))
+                return -EINVAL;
+
+        assert_se(p = strchr(f, '@'));
+        assert_se(e = strrchr(f, '.'));
+
+        a = p - f;
+
+        s = new(char, a + 1 + strlen(e) + 1);
+        if (!s)
+                return -ENOMEM;
+
+        strcpy(mempcpy(s, f, a + 1), e);
+
+        *ret = s;
+        return 0;
+}
+
+bool unit_name_is_hashed(const char *name) {
+        char *s;
+
+        if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))
+                return false;
+
+        assert_se(s = strrchr(name, '.'));
+
+        if (s - name < UNIT_NAME_HASH_LENGTH_CHARS + 1)
+                return false;
+
+        s -= UNIT_NAME_HASH_LENGTH_CHARS;
+        if (s[-1] != '_')
+                return false;
+
+        for (size_t i = 0; i < UNIT_NAME_HASH_LENGTH_CHARS; i++)
+                if (!strchr(LOWERCASE_HEXDIGITS, s[i]))
+                        return false;
+
+        return true;
+}
+
+int unit_name_hash_long(const char *name, char **ret) {
+        _cleanup_free_ char *n = NULL, *hash = NULL;
+        char *suffix;
+        le64_t h;
+        size_t len;
+
+        if (strlen(name) < UNIT_NAME_MAX)
+                return -EMSGSIZE;
+
+        suffix = strrchr(name, '.');
+        if (!suffix)
+                return -EINVAL;
+
+        if (unit_type_from_string(suffix+1) < 0)
+                return -EINVAL;
+
+        h = htole64(siphash24_string(name, LONG_UNIT_NAME_HASH_KEY.bytes));
+
+        hash = hexmem(&h, sizeof(h));
+        if (!hash)
+                return -ENOMEM;
+
+        assert_se(strlen(hash) == UNIT_NAME_HASH_LENGTH_CHARS);
+
+        len = UNIT_NAME_MAX - 1 - strlen(suffix+1) - UNIT_NAME_HASH_LENGTH_CHARS - 2;
+        assert(len > 0 && len < UNIT_NAME_MAX);
+
+        n = strndup(name, len);
+        if (!n)
+                return -ENOMEM;
+
+        if (!strextend(&n, "_", hash, suffix))
+                return -ENOMEM;
+        assert_se(unit_name_is_valid(n, UNIT_NAME_PLAIN));
+
+        *ret = TAKE_PTR(n);
+
+        return 0;
+}
+
+int unit_name_from_path(const char *path, const char *suffix, char **ret) {
+        _cleanup_free_ char *p = NULL, *s = NULL;
+        int r;
+
+        assert(path);
+        assert(suffix);
+        assert(ret);
+
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
+
+        r = unit_name_path_escape(path, &p);
+        if (r < 0)
+                return r;
+
+        s = strjoin(p, suffix);
+        if (!s)
+                return -ENOMEM;
+
+        if (strlen(s) >= UNIT_NAME_MAX) {
+                _cleanup_free_ char *n = NULL;
+
+                log_debug("Unit name \"%s\" too long, falling back to hashed unit name.", s);
+
+                r = unit_name_hash_long(s, &n);
+                if (r < 0)
+                        return r;
+
+                free_and_replace(s, n);
+        }
+
+        /* Refuse if this for some other reason didn't result in a valid name */
+        if (!unit_name_is_valid(s, UNIT_NAME_PLAIN))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+int unit_name_from_path_instance(const char *prefix, const char *path, const char *suffix, char **ret) {
+        _cleanup_free_ char *p = NULL, *s = NULL;
+        int r;
+
+        assert(prefix);
+        assert(path);
+        assert(suffix);
+        assert(ret);
+
+        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);
+        if (!s)
+                return -ENOMEM;
+
+        if (strlen(s) >= UNIT_NAME_MAX) /* Return a slightly more descriptive error for this specific condition */
+                return -ENAMETOOLONG;
+
+        /* Refuse if this for some other reason didn't result in a valid name */
+        if (!unit_name_is_valid(s, UNIT_NAME_INSTANCE))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+int unit_name_to_path(const char *name, char **ret) {
+        _cleanup_free_ char *prefix = NULL;
+        int r;
+
+        assert(name);
+
+        r = unit_name_to_prefix(name, &prefix);
+        if (r < 0)
+                return r;
+
+        if (unit_name_is_hashed(name))
+                return -ENAMETOOLONG;
+
+        return unit_name_path_unescape(prefix, ret);
+}
+
+static bool do_escape_mangle(const char *f, bool allow_globs, char *t) {
+        const char *valid_chars;
+        bool mangled = false;
+
+        assert(f);
+        assert(t);
+
+        /* We'll only escape the obvious characters here, to play safe.
+         *
+         * Returns true if any characters were mangled, false otherwise.
+         */
+
+        valid_chars = allow_globs ? VALID_CHARS_GLOB : VALID_CHARS_WITH_AT;
+
+        for (; *f; f++)
+                if (*f == '/') {
+                        *(t++) = '-';
+                        mangled = true;
+                } else if (!strchr(valid_chars, *f)) {
+                        t = do_escape_char(*f, t);
+                        mangled = true;
+                } else
+                        *(t++) = *f;
+        *t = 0;
+
+        return mangled;
+}
+
+/**
+ *  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,
+ *  except that @suffix is appended if a valid unit suffix is not present.
+ *
+ *  If @allow_globs, globs characters are preserved. Otherwise, they are escaped.
+ */
+int unit_name_mangle_with_suffix(const char *name, const char *operation, UnitNameMangle flags, const char *suffix, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        bool mangled, suggest_escape = true;
+        int r;
+
+        assert(name);
+        assert(suffix);
+        assert(ret);
+
+        if (isempty(name)) /* We cannot mangle empty unit names to become valid, sorry. */
+                return -EINVAL;
+
+        if (!unit_suffix_is_valid(suffix))
+                return -EINVAL;
+
+        /* Already a fully valid unit name? If so, no mangling is necessary... */
+        if (unit_name_is_valid(name, UNIT_NAME_ANY))
+                goto good;
+
+        /* Already a fully valid globbing expression? If so, no mangling is necessary either... */
+        if (string_is_glob(name) && in_charset(name, VALID_CHARS_GLOB)) {
+                if (flags & UNIT_NAME_MANGLE_GLOB)
+                        goto good;
+                log_full(flags & UNIT_NAME_MANGLE_WARN ? LOG_NOTICE : LOG_DEBUG,
+                         "Glob pattern passed%s%s, but globs are not supported for this.",
+                         operation ? " " : "", strempty(operation));
+                suggest_escape = false;
+        }
+
+        if (is_device_path(name)) {
+                r = unit_name_from_path(name, ".device", ret);
+                if (r >= 0)
+                        return 1;
+                if (r != -EINVAL)
+                        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;
+        }
+
+        s = new(char, strlen(name) * 4 + strlen(suffix) + 1);
+        if (!s)
+                return -ENOMEM;
+
+        mangled = do_escape_mangle(name, flags & UNIT_NAME_MANGLE_GLOB, s);
+        if (mangled)
+                log_full(flags & UNIT_NAME_MANGLE_WARN ? LOG_NOTICE : LOG_DEBUG,
+                         "Invalid unit name \"%s\" escaped as \"%s\"%s.",
+                         name, s,
+                         suggest_escape ? " (maybe you should use systemd-escape?)" : "");
+
+        /* Append a suffix if it doesn't have any, but only if this is not a glob, so that we can allow
+         * "foo.*" as a valid glob. */
+        if ((!(flags & UNIT_NAME_MANGLE_GLOB) || !string_is_glob(s)) && unit_name_to_type(s) < 0)
+                strcat(s, suffix);
+
+        /* Make sure mangling didn't grow this too large (but don't do this check if globbing is allowed,
+         * since globs generally do not qualify as valid unit names) */
+        if (!FLAGS_SET(flags, UNIT_NAME_MANGLE_GLOB) && !unit_name_is_valid(s, UNIT_NAME_ANY))
+                return -EINVAL;
+
+        *ret = TAKE_PTR(s);
+        return 1;
+
+good:
+        s = strdup(name);
+        if (!s)
+                return -ENOMEM;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+int slice_build_parent_slice(const char *slice, char **ret) {
+        _cleanup_free_ char *s = NULL;
+        char *dash;
+        int r;
+
+        assert(slice);
+        assert(ret);
+
+        if (!slice_name_is_valid(slice))
+                return -EINVAL;
+
+        if (streq(slice, SPECIAL_ROOT_SLICE)) {
+                *ret = NULL;
+                return 0;
+        }
+
+        s = strdup(slice);
+        if (!s)
+                return -ENOMEM;
+
+        dash = strrchr(s, '-');
+        if (dash)
+                strcpy(dash, ".slice");
+        else {
+                r = free_and_strdup(&s, SPECIAL_ROOT_SLICE);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = TAKE_PTR(s);
+        return 1;
+}
+
+int slice_build_subslice(const char *slice, const char *name, char **ret) {
+        char *subslice;
+
+        assert(slice);
+        assert(name);
+        assert(ret);
+
+        if (!slice_name_is_valid(slice))
+                return -EINVAL;
+
+        if (!unit_prefix_is_valid(name))
+                return -EINVAL;
+
+        if (streq(slice, SPECIAL_ROOT_SLICE))
+                subslice = strjoin(name, ".slice");
+        else {
+                char *e;
+
+                assert_se(e = endswith(slice, ".slice"));
+
+                subslice = new(char, (e - slice) + 1 + strlen(name) + 6 + 1);
+                if (!subslice)
+                        return -ENOMEM;
+
+                stpcpy(stpcpy(stpcpy(mempcpy(subslice, slice, e - slice), "-"), name), ".slice");
+        }
+
+        *ret = subslice;
+        return 0;
+}
+
+bool slice_name_is_valid(const char *name) {
+        const char *p, *e;
+        bool dash = false;
+
+        if (!unit_name_is_valid(name, UNIT_NAME_PLAIN))
+                return false;
+
+        if (streq(name, SPECIAL_ROOT_SLICE))
+                return true;
+
+        e = endswith(name, ".slice");
+        if (!e)
+                return false;
+
+        for (p = name; p < e; p++) {
+
+                if (*p == '-') {
+
+                        /* Don't allow initial dash */
+                        if (p == name)
+                                return false;
+
+                        /* Don't allow multiple dashes */
+                        if (dash)
+                                return false;
+
+                        dash = true;
+                } else
+                        dash = false;
+        }
+
+        /* Don't allow trailing hash */
+        if (dash)
+                return false;
+
+        return true;
+}
+
+bool unit_name_prefix_equal(const char *a, const char *b) {
+        const char *p, *q;
+
+        assert(a);
+        assert(b);
+
+        if (!unit_name_is_valid(a, UNIT_NAME_ANY) || !unit_name_is_valid(b, UNIT_NAME_ANY))
+                return false;
+
+        p = strchr(a, '@');
+        if (!p)
+                p = strrchr(a, '.');
+
+        q = strchr(b, '@');
+        if (!q)
+                q = strrchr(b, '.');
+
+        assert(p);
+        assert(q);
+
+        return memcmp_nn(a, p - a, b, q - b) == 0;
+}