1 files changed, 145 insertions, 0 deletions
diff --git a/src/basic/nulstr-util.c b/src/basic/nulstr-util.c
new file mode 100644
index 0000000..06fa219
--- /dev/null
+++ b/src/basic/nulstr-util.c
@@ -0,0 +1,145 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "nulstr-util.h"
+#include "string-util.h"
+#include "strv.h"
+
+char** strv_parse_nulstr_full(const char *s, size_t l, bool drop_trailing_nuls) {
+        /* l is the length of the input data, which will be split at NULs into elements of the resulting
+         * strv. Hence, the number of items in the resulting strv will be equal to one plus the number of NUL
+         * bytes in the l bytes starting at s, unless s[l-1] is NUL, in which case the final empty string is
+         * not stored in the resulting strv, and length is equal to the number of NUL bytes.
+         *
+         * Note that contrary to a normal nulstr which cannot contain empty strings, because the input data
+         * is terminated by any two consequent NUL bytes, this parser accepts empty strings in s. */
+
+        _cleanup_strv_free_ char **v = NULL;
+        size_t c = 0, i = 0;
+
+        assert(s || l <= 0);
+
+        if (drop_trailing_nuls)
+                while (l > 0 && s[l-1] == '\0')
+                        l--;
+
+        if (l <= 0)
+                return new0(char*, 1);
+
+        for (const char *p = s; p < s + l; p++)
+                if (*p == 0)
+                        c++;
+
+        if (s[l-1] != 0)
+                c++;
+
+        v = new0(char*, c+1);
+        if (!v)
+                return NULL;
+
+        for (const char *p = s; p < s + l; ) {
+                const char *e;
+
+                e = memchr(p, 0, s + l - p);
+
+                v[i] = memdup_suffix0(p, e ? e - p : s + l - p);
+                if (!v[i])
+                        return NULL;
+
+                i++;
+
+                if (!e)
+                        break;
+
+                p = e + 1;
+        }
+
+        assert(i == c);
+
+        return TAKE_PTR(v);
+}
+
+char** strv_split_nulstr(const char *s) {
+        _cleanup_strv_free_ char **l = NULL;
+
+        /* This parses a nulstr, without specification of size, and stops at an empty string. This cannot
+         * parse nulstrs with embedded empty strings hence, as an empty string is an end marker. Use
+         * strv_parse_nulstr() above to parse a nulstr with embedded empty strings (which however requires a
+         * size to be specified) */
+
+        NULSTR_FOREACH(i, s)
+                if (strv_extend(&l, i) < 0)
+                        return NULL;
+
+        return l ? TAKE_PTR(l) : strv_new(NULL);
+}
+
+int strv_make_nulstr(char * const *l, char **ret, size_t *ret_size) {
+        /* Builds a nulstr and returns it together with the size. An extra NUL byte will be appended (⚠️ but
+         * not included in the size! ⚠️). This is done so that the nulstr can be used both in
+         * strv_parse_nulstr() and in NULSTR_FOREACH()/strv_split_nulstr() contexts, i.e. with and without a
+         * size parameter. In the former case we can include empty strings, in the latter case we cannot (as
+         * that is the end marker).
+         *
+         * When NULSTR_FOREACH()/strv_split_nulstr() is used it is often assumed that the nulstr ends in two
+         * NUL bytes (which it will, if not empty). To ensure that this assumption *always* holds, we'll
+         * return a buffer with two NUL bytes in that case, but return a size of zero. */
+
+        _cleanup_free_ char *m = NULL;
+        size_t n = 0;
+
+        assert(ret);
+
+        STRV_FOREACH(i, l) {
+                size_t z;
+
+                z = strlen(*i);
+
+                if (!GREEDY_REALLOC(m, n + z + 2))
+                        return -ENOMEM;
+
+                memcpy(m + n, *i, z + 1);
+                n += z + 1;
+        }
+
+        if (!m) {
+                /* return a buffer with an extra NUL, so that the assumption that we always have two trailing NULs holds */
+                m = new0(char, 2);
+                if (!m)
+                        return -ENOMEM;
+
+                n = 0;
+        } else
+                /* Make sure there is a second extra NUL at the end of resulting nulstr (not counted in return size) */
+                m[n] = '\0';
+
+        *ret = TAKE_PTR(m);
+        if (ret_size)
+                *ret_size = n;
+
+        return 0;
+}
+
+int set_make_nulstr(Set *s, char **ret, size_t *ret_size) {
+        /* Use _cleanup_free_ instead of _cleanup_strv_free_ because we need to clean the strv only, not
+         * the strings owned by the set. */
+        _cleanup_free_ char **strv = NULL;
+
+        assert(ret);
+
+        strv = set_get_strv(s);
+        if (!strv)
+                return -ENOMEM;
+
+        return strv_make_nulstr(strv, ret, ret_size);
+}
+
+const char* nulstr_get(const char *nulstr, const char *needle) {
+        if (!nulstr)
+                return NULL;
+
+        NULSTR_FOREACH(i, nulstr)
+                if (streq(i, needle))
+                        return i;
+
+        return NULL;
+}